EPA 600/4-87/Q26
September 1987
Handbook of Methods for Acid Deposition Studies
Laboratory Analysis for Surface Water Chemistry
A Contribution to the
National Acid Precipitation Assessment Program
U.S. Environmental Protection Agency
Acid Deposition and Atmospheric Research Division
Office of Acid Deposition, Environmental Monitoring, and Quality Assurance
Office ot Research and Development
Washington, D.C. 20460
Environmental Monitoring Systems Laboratory, Las Vegas, Nevada 89193
Environmental Research Laboratory, Corvallis, Oregon 97333
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NOTICE
The development of this document has been funded wholly or in part by the
U.S. Environmental Protection Agency under Contract No. 68-03-3249 to Lockheed
Engineering and Management Services Company, Inc. Additional cooperation has
been provided under Contract No. 68-03-3246 to Northrop Services, Inc.; No.
68-02-3889 to Radian Corporation; No. 68-03-3439 to Kilkelly Environmental
Associates; and Interagency Agreement No. 40-1441-84 with the U.S. Department
of Energy. It has been subject to the Agency's peer and administrative review
and it has been approved for publication as an EPA document.
Mention of corporation names, trade names, or commercial products does
not constitute endorsement or recommendation for use.
This document is a contribution to the National Acid Precipitation Assess-
ment Program. The methods contained in this document have been developed for
use in the component programs of the Aquatic Effects Research Program. Pre-
vious publications from which these methods have been extracted, include:
Hillman, D. C., J. F. Potter, and S. J. Simon, 1986. National Surface Water
Survey, Eastern Lake Survey - Phase I, Analytical Methods Manual. EPA-
600/4-86/009. U.S. Environmental Protection Agency, Las Vegas, Nevada.
Kerfoot, H. B., and M. L. Faber, 1987. National Surface Water Survey, Western
Lake Survey (Phase I - Synoptic Chemistry) Analytical Methods Manual.
EPA-600/8-87/038. U.S. Environmental Protection Agency, Las Vegas, Nevada.
Hillman, D. C., S. H. Pia, and S. J. Simon, 1987. National Surface Water Sur-
vey, National Stream Survey (Phase I - Pilot, Mid-Atlantic Phase I, South-
east Screening, and Episodes Pilot) Analytical Methods Manual. EPA-600/
8-87/005. U.S. Environmental Protection Agency, Las Vegas, Nevada.
Chaloud, D. J., L. J. Arent, B. B. Dickes, J. D. Nitterauer, M. 0. Morison, and
D. V. Peck, 1986. National Surface Water Survey (Eastern Lake Survey -
Phase II, National Stream Survey - Phase I) Processing Laboratory Training
and Operations Manual. Internal report. U.S. Environmental Protection
Agency, Las Vegas, Nevada.
Kerfoot, H. B., T. E. Lewis, D. C. Hillman, and M. L. Faber, 1987. National
Surface Water Survey, Eastern Lake Survey (Phase II - Temporal Variability)
Analytical Methods Manual. EPA-600/X-87/008, U.S. Environmental Protection
Agency, Las Vegas, Nevada.
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1
ABSTRACT
The U.S. Environmental Protection Agency requires that data collection
activities be based on a program which ensures that the resulting data are of
known quality and are suitable for their intended purpose. In addition, it
is necessary that the data obtained be consistent and comparable. For these
reasons, the same reliable, detailed analytical methodology should be available
to and should be used by all analysts participating in the study.
This handbook describes methods used to process and analyze surface water
samples of low ionic strength. It is intended as a guidance document for
groups involved in acidic deposition monitoring activities similar to those
implemented by the Aquatic Effects Research Program of the National Acid
Precipitation Assessment Program.
The chemical and physical parameters measured and the analytical methods
used are listed below. Each parameter or activity marked by an asterisk is
measured or performed at a processing laboratory before samples are shipped to
an analytical laboratory.
Parameter or Procedure
Acidity, Alkalinity, and pH
Aliquot preparation*
Aluminum, total extractable*
Aluminum, total and nonexchangeable
PCV-reactive*
Ammonium, dissolved
Ammonium, dissolved (alterate)
Chloride, Nitrate, and Sulfate
Chlorophyll £
Dissolved Inorganic Carbon*
Dissolved Inorganic Carbon and
Dissolved Organic Carbon
Method
Titration with Gran plot
Filtration and preservation
Extraction with 8-hydroxyquinoline
into methyl iso-butyl ketone
Flow injection analysis colori-
metry (pyrocatechol violet)
Automated colorimetry (phenate)
Flow injection analysis colorimetry
Ion chromatograhy
Fluorometric and high performance
liquid chromatographic analysis
Instrumental
Instrumental
m
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Parameter or Procedure
Method
Fluoride, dissolved
Metals (Al, Ca, Fe, K, Mg, Mn, Na)
Metals (Ca, Fe, Mg, Mn) (alternate)
Nitrogen, total
pH, closed system*
pH, open system*
Phosphorus, total
Silica, dissolved
Specific conductance
True Color*
Turbidity*
Ion selective electrode and meter
Atomic absorption spectroscopy
Inductively coupled plasma emission
spectroscopy
Flow injection analysis
pH electrode, meter, and subchamber
pH electrode and meter
Automated colorimetry (phosphomolyb-
date)
Automated colorimetry (molybdate
blue)
Conductivity cell and meter
Comparison to platinum-cobalt color
standards
Instrumental (nephelometer)
These methods were developed for use in component projects of the Aquatic
Effects Research Program under the Acid Deposition and Atmospheric Research
Division of the Office of Acid Deposition, Environmental Monitoring and Quality
Assurance. This program addresses the following questions relating to the
effects of acidic deposition of aquatic ecosystems:
1. The extent and magnitude of past change.
2. The change to be expected in the future under various deposition
scenarios.
3. The maximum rates of deposition below which further change is not
expected.
4. The rate of change or recovery of aquatic ecosystems if deposition
rates are decreased.
This handbook was submitted in fulfillment of Contract Number 68-03-3249
by Lockheed Engineering and Management Services Company, Inc., under the
sponsorship of the U.S. Environmental Protection Agency.
iv
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Section Glossary
Revision 0
Date: 8/87
Page 1 of 5
GLOSSARY
I. DEFINITIONS .-,...
Accuracy The degree of agreement of a measurement with an accepted or
true value. As used here, accuracy is determined from the difference
between recorded measurements and accepted true values of audit
samples and calibration standards. Accuracy is generally expressed
as percent bias.
Acid Neutralizing Capacity The buffering capacity of a carbonate system to
acid inputs; specifically, the quantity of H+ ions reacted over a given
pH range during acid titration.
Aliquot A portion of sample treated (processed) in a specific way for a
particular parameter or set of parameters.
Audit Sample A material,with known characteristics which Is used to deter-
mine the accuracy of the measurement system. In the AERP studies, natural
lake samples, prepared matrices, and certified (purchased) audit samples
are employed.
Base Neutralizing Capacity --. The buffering capacity of a carbonate system to
alkali inputs; specifically, the quantity of OH~ ions reacted over a given
pH range in a base titration.
Batch --. All samples, including routine, duplicate or replicate, blank, and
"audit samples, that are processed together at a single laboratory on a
single day. . ,
Bias A systemic difference between repeated measurements and an accepted
or true value.
Blank s-ample -- Four different blank samples are referenced in these methods:
1. Calibration blank -- A 0 mg L"1 standard, containing only the matrix
of the calibration standards. The measured concentration should be
less than twice the instrumental detection limit.
2. Laboratory blank A deionized water sample prepared at the pro-
cessing laboratory and treated as a regular sample. It serves as a
check of processing laboratory-introduced contamination.
3. Reagent blank A reagent blank contains all of the reagents (in the
same quantities) used in preparing a regular sample for analysis. It
is processed in the same manner as a regular sample. The measured
concentration should-be less than twice the instrumental detection
limit.
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Section Glossary
Revision 0
Date: 8/87
Page 2 of 5
GLOSSARY (Continued)
4.
System blank A deionized water sample collected by field personnel,
then treated as a regular sample. It serves as a check of overall
system contamination.
Calibration Establishment of a relationship between standards of known values
and the recorded output of a measurement system. As used here, a calibra-
tion range is defined as the concentration range over which acceptable
results of standards are obtained.
Confidence Interval A value interval that has a designated probability of
including some defined parameter of the population.
Detection limit (also method detection limit or MDL) -- Three times the stan-
dard deviation of 10 nonconsecutive reagent or calibration blank analyses.
Dissolved -- Refers to all constituents which remain after filtration through
a~DT45 urn filter.
Duplicate A second, independent determination of the same sample, performed
by the same analyst, at essentially the same time and under the same
conditions.
Matrix spike sample Addition of a known amount of analyte (spike) to a
sample portion used to investigate chemical and matrix interferences.
The spike should be a twice the endogenous level or ten times the detec-
tion limit, whichever is larger. See Section 16.1.4.
NBS-traceable A material or instrument which is certified against a
National Bureau of Standards primary standard.
Percent relative standard deviation (%RSD) An expression of precision,
calculated by:
%RSD = - x 100
X
where:
s = standard deviation
"X" » mean of recorded measurements
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GLOSSARY (Continued)
Precision The mutual agreement among individual measurements of the same
property. As used here, precision is calculated from results of dupli-
cate analyses and repetitive analyses of audit samples and quality
control check solutions. Precision is generally expressed in terms of
percent relative standard deviation.
Quality assurance The overall system used to ensure that the quality control
system is performing.
Quality control ~ The specific procedures and checks used to provide a quality
product.
Quality control check sample (QCCS) A known sample containing the analyte of
interest at a concentration in the low- to mid-calibration range. Whenever
possible, the QCCS should be prepared from a source independent of that
used to prepare calibration standards.
Standard additions A method of analysis in which equal volumes of a sample
are added to a deionized water blank and to three standards containing
different known amounts of the test element. Standard additions are used
when matrix or chemical interferences are present. See Section 16.4.1.
Standard deviation -- The square root of the variance of a set of values.
Turbidity Organic and inorganic material suspended in the water column.
II. ACRONYMS AND ABBREVIATIONS
ACS = American Chemical Society CE
AERP = Aquatic Effects Research Program CPR =
ALK = alkalinity
ANC = acid neutralizing capacity DDRP =
APHA = American Public Health
Administration DHEW =
ASTM = American Society of Testing
and Materials DIC =
AW = acid-washed DIW =
BNC = base neutralizing capacity DL
BRC = Biologically Relevant Chemistry DOC =
% CD = percent conductivity difference EDTA =
CDTA = 1,2 cyclohexylene dinitrilo
tetraacetic acid
column efficiency
cardio-plumonary resusci-
tation
Direct/Delayed Response
Project
Department of Health,
Education, and Welfare
dissolved inorganic carbon
deionized-water washed
detection limit
dissolved organic carbon
disodium ethylenediamine
tetraacetate
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Section Glossary
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Page 4 of 5
GLOSSARY (Continued)
ELS-I = Eastern Lake Survey - Phase I NLS-I
EMSL = Environmental Monitoring and II
Systems Laboratory No.
EMSL-LV = Environmental Monitoring NSS-I
Systems Laboratory - Las Vegas
EPA ~ Environmental Protection Agency NSWS
ERP = Episodic Response Project
FIA ~ flow injection analysis NIL) =
GFAA = graphite furnace atomic
absorption OSHA
HPLC * high-performance liquid
chromatography PCU
1C = ion chromatography PCV
ICP = inductively-coupled plasma QA
ID = identification QC
%ID = percent ion difference QCCS
IHHE = Indirect Human Health Effects
Inc. - Incorporated RF =
IR = infrared %RSD =
IS = internal standard
ISE = ion selective electrode s or SD =
KHP ~ potassium hydrogen phthalate TIME
MDL = method detection limit
MIBK - methyl isobutyl ketone
NAPAP = National Acid Precipitation TISAB
Assessment Program
NBS = National Bureau of Standards U.S.
NED = N-(l-naphthyl)-ethylene WLS-I
diamine dihyrochloride
NIOSH = National Institute for WMP
Occupational Safety
and Health
National Lake Survey -
Phase I, Phase II
Number
National Stream
Survey - Phase I
National Surface Water
Survey
nephelometer turbidity
units
Occupational Safety and
Health Administration
platinum-cobalt units
pyrocatechol violet
quality assurance
quality control
quality control check
solution
radio frequency
percent relative stan-
dard deviation
standard deviation
Temporal Integrated
Monitoring of
Ecosystems
total ionic strength
buffer solution
United States
Western Lake Survey -
Phase I
Watershed Manipulation
Project
III. MEASUREMENT SYMBOLS
aq = aqueous
°C = degrees, Centigrade
d s density
eq = equivalent
g s gram
°K = degrees, Kelvin
L s 1i ter
m = meter
M = molarity
mA = milliAngstrom
mg = milligram, 10"3 g
min. = minute
mL = milliliter, 10"3 L
mm = millimeter, 10~3 m
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Section Glossary
Revision 0
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Page 5 of 5
GLOSSARY (Continued)
mV = millivolt, 1(T3 V
N = normality
nm = nanometer, 10"y m
ppm = parts per million
psi = pounds per square
sp. gr. = specific gravity
V = volts
v/v = volume to volume
w/v = weight to volume
w/w = weight to weight
inch
2
ueq
M9
ML
urn
umho
uSCnT1
less than
summation.
microequivalent
microgram, 10~6 g
microliter,.10~b L
micron, 10
micromho
microSieman
percent
-6
m
per centimeter
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CONTENTS
Effec
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Abstract ......................... "J "" ~~
Glossarv ................... 1 of 5 0 8/87
uiubbary .............. _ _ 0/07
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of 2 o 8/87
1.0 Introduction to the Aquatic Effects Research
Program. , .................... * of 5 ° 8/87
1.1 National Surface Water Survey (NSWS) ...... 3 of 5 0 8/87
1.2 Direct/Delayed Response Project (DORP) ..... 3 of 5 0 8/87
1.3 Episodic Response Project (ERP) ........ 4 of 5 0 8/87
1.4 Watershed Manipulation Project (WMP) ..... . 4 of 5 0 8/87
1.5 Temporal Integrated Monitoring of
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1.6 Biologically Relevant Chemistry (BRC) Project . 4 of 5 0 8/8/
1.7 Indirect Human Health Effects (IHHE) Project. . 4 of 5 0 8/87
2.0 Overview of AERP Handbooks . ............ 1 of 2 0 8/87
2.1 Purpose of Handbooks ............. 1 of 2 0 8/87
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2.1.2 Structure of Volumes .......... 1 of 2 0 b/b/
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2.2 Content of Laboratory Handbook ......... 1 of 2 0 8/87
2.2.1 Laboratory Methods ........... 2 of 2 0 b/b/
2.2.2 Suitable Sample Types .......... 2 of 2 0 b/b/
3.0 Laboratory Facilities and Organization 1 of 7 0 8/87
3.1 Mobile Laboratories \ of 7 0 8/87
3.2 Minimum Facility Requirements 2 of / u b/b/
3.3 Laboratory Staffing 3 of 7 0 b/b/
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3.5 Contamination Avoidance ° °I ' « oio(
3.6 Safety 6 of 7 0 8/87
3.7 References 7 of 7 ° 8/87
4.0 Sample Handling l of 9 ° 8/87
4.1 Sample Types and Sample Containers.
1 of 9 0 8/87
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CONTENTS (Continued)
Page
4.2 Sample Transport and Transfer ......... 1 of 9
4.3 Sample Processing * 2 of 9
4.4 Sample Analysis .'.'!' 6 of 9
4.5 Data Tracking and Recording .......... 6 of 9
4.6 References . . . . 9 of 9
5.0 Determination of Acidity, Alkalinity, and pH
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5.1
b.2
5.3
b.4
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5.1.1 Scope and Application
5.1.2 Summary of Method ....
5.1.3 Interferences
5.1.4 Safety
Sample Collection, Preservation, and Storage.
Equipment and Supplies
5.3.1 Equipment Specifications .....
5.3.2 Apparatus
5.3.3 Reagents and Consumable Materials. . .
Preparation
5.4.1 Standardization of HC1 Titrant
5.4.2 Initial Standardization of NaOH Titrant'
with KHP
5.4.3 NaOH-HCl Standardization Crosscheck. . ,
5.4.4 Daily NaOH Standardization with
Standardized HC1 . . . .
5.4.5 Rigorous Calibration and Characteriza-
tion of Electrodes
5.4.6 Daily Calibration and Characterization
of Electrodes
Procedure
5.5.1 Acid Titration
5.5.2 Base Titration ......
5.5.3 Air-Equilibrated pH Measurement
5.5.4 Calculations
Quality Assurance and Quality Control
5.6.1 Comparison of Initial Titration pH
Values
5.6.2 Comparison of Calculated ANC and
Measured ANC .......
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CONTENTS (Continued)
6.0
7.0
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5 6.3 Comparison of Calculated BNC and
Measured BNC 27 of 29
5.6.4 Comparison of Calculated Total Carbon-
ate and Measured Total Carbonate ... 27 of 29
5.6.5 Quality Control Checks 28 of 29
References 29 of ^9
Preparation of Aliquots
6.1
6.2
6.3
6.4
6.5
6.6
6.7
Overview
6.1.1 Scope and Application.
6.1.2 Summary of Method
6.1.3 Interferences
6.1.4 Safety . . . . . . . . . .. . .
Sample Collection, Preservation, and Storage. .
Equipment and Supplies.
6.3.1 Apparatus.
6.3.2 Reagents and Consumable Supplies . . . .
Preparation
6.4.1 Filtration Unit Assembly
6.4.2 Maintenance. .......>'
Procedure
6.5.1 Filter Rinsing .
6.5.2 Sample Filtration. ....
6.5.3 Between Sample Rinsing ...
6.5.4 Unfiltered Aliquots
6.5.5 Preservation
6.5.6 Shipping Instructions. . ....... . . .
Quality Assurance and Quality Control ......
References
Preparation of Total Extractable Aluminum^ Aliquot. .
7.1
7.2
7.3
Overview . . .
7.1.1 Scope and Application. ...
7.1.2 Summary of Method. . . .
7.1.3 Interferences
7.1.4 Safety
Sample Collection, Preservation, and Storage. .
Equipment and Supplies
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CONTENTS (Continued)
8.0
7.3.1 Apparatus
7.3.2 Reagents and Consumable Materials. . .
7.4 Preparation
7.4.1 Calibration and Standardization
7.4.2 Maintenance
7.5 Procedure
7.5.1 Filtration
7.5.2 Extraction
7.5.3 Cleanup
Fractional on and Determination of Aluminum Species.
8.1 Overview
8.1.1 Scope and Application
8.1.2 Summary of Method
8.1.3 Interferences
8.1.4 Safety
8.2 Sample Collection, Preservation, and Storage
8.3 Equipment and Supplies
8.3.1 Equipment Specifications ....
8.3.2 Consumable Materials ....
8.3.3 Reagents
8.3.4 Amberlite Cation Exchange Resin
8.3.5 Aluminum Stock Solutions ...
8.3.6 Aluminum Calibration Standards
8.3.7 Quality Control Standards. . .
8.3.8 Reagent Filtering/Degassing. . . .
8.4 Preparation
8.4.1 Precalibration Procedure ....
8.4.2 Calibration and Standardization
8.4.3 Maintenance
8.4.4 Column Packing Procedure .
8.4.5 Troubleshooting
8.5 Procedure
8.5.1 Syringe Pump Setup
8.5.2 Sample Injection
8.5.3 Cleanup
8.6 Quality Assurance and Quality Control
8.6.1 Precision and Accuracy ....
8.6.2 Quality Control Checks . . .
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CONTENTS (Continued)
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References
9.0 Determination of. Ammonium.
9.
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Overview
9.1.1 Scope and Application
9.1.2 Summary of Method
9.1.3 Interferences
9.1.4 Safety
Sample Collection, Preservation, and Storage.
Equipment and Supplies. ......;
9.3.1 Apparatus and Equipment
9.3.2 Reagents and Consumable Materials. . .
Preparation ........
9.4.1 Calibration and Standardization. ...
Procedure
9.5.1 Standard Operating Procedure
9.5.2 Calculations -
Quality Assurance and Quality Control ....
9.6.1 Precision and Accuracy . . . . . . .
9.6.2 Quality Control Checks . .. .
References . .
10.0 Determination of Ammonium by Flow Injection
Analysis
10,
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.1
.2
.3
.4
.5
Overview
10.1.1 Scope and Application
10.1.2 Summary of Method . . .
10.1.3 Interferences . .
10.1.4 Safety
Sample Collection, Preservation, and Storage.
Equipment and Supplies -
10.3.1 Equipment and Apparatus
10.3.2 Reagents and Consumable Materials . .
Preparation . .
10.4.1 Calibration and Standardization . . .
Procedure
10.5.1 Standard Operating Procedure. . . . .
10.5.2 Calculations
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10.6.1 Precision and Accuracy 4 of 5 2 8/87
10.6.2 Quality Control Checks 4 of 5 2 8/87
10.7 References 5 of 5 2 8/87
11.0 Determination of Chloride, Nitrate, and Sulfate
by Ion Chromatography 1 of 6 10 8/87
11.1 Overview 1 of 6 10 8/87
11.1.1 Scope and Application 1 of 6 10 8/87
11.1.2 Summary of Method 1 of 6 10 8/87
11.1.3 Interferences 2 of 6 10 8/87
11.1.4 Safety 2 of 6 10 8/87
11.2 Sample Collection, Preservation, and Storage. . 2 of 6 10 8/87
11.3 Equipment and Supplies 2 of 6 10 8/87
11.3.1 Equipment Specifications 2 of 6 10 8/87
11.3.2 Reagents and Consumable Materials ... 3 of 6 10 8/87
11.4 Preparation 4 of 6 10 8/87
11.4.1 Calibration and Standardization .... 4 of 6 10 8/87
11.5 Procedure 4 of 6 10 8/87
11.5.1 Standard Operating Procedure 4 of 6 10 8/87
11.5.2 Calculations 5 of 6 10 8/87
11.6 Quality Assurance and Quality Control 5 of 6 10 8/87
11.6.1 Precision and Accuracy 5 of 6 10 8/87
11.6.2 Quality Control Checks 5 of 6 10 8/87
11.7 References 6 of 6 10 8/87
12.0 Determination of Chlorophyll a_ 1 of 11 4 8/87
12.1 Overview 1 of 11 4 8/87
12.1.1 Scope and Application 1 of 11 4 8/87
12.1.2 Summary of Method 1 of 11 4 8/87
12.1.3 Interferences 1 of 11 4 8/87
12.1.4 Safety 1 of 11 4 8/87
12.2 Sample Collection, Preservation, and Storage. . 2 of 11 4 8/87
12.3 Equipment and Supplies 2 of 11 4 8/87
12.3.1 Equipment Specifications 2 of 11 4 8/87
12.3.2 Apparatus 3 of 11 4 8/87
12.3.3 Reagents and Consumable Materials ... 3 of 11 4 8/87
12.4 Preparation 4 of 11 4 8/87
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CONTENTS (Continued)
P_a_cje_ Rev
12.4.1 HPLC Calibration . . . .
12.4.2 Fluorometry Calibration
12.5 Procedure
12.5.1 Sample Extraction
12.5.2 Analysis
12.5.3 Calculations
12.6 Quality Assurance and Quality Control . . . .
12.6.1 Precision and Accuracy . .
12.6.2 HPLC Analysis Quality Control Checks.
12.6.3 Fluorometry Quality Control Checks. .
12.7 References
13.0 Determination of Dissolved Inorganic Carbon. . .
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13.
13.
13.
13.
1.3.
13.
13,
1
2
3
4
.5
.6
.7
Overview
13.1.1 Scope and Application
13.1.2 Summary of Method
13.1.3 Interferences
13.1.4 Safety
Sample Collection, Preservation, and Storage. .
Equipment and Supplies ...
13.3.1 Equipment Specifications
13.3.2 Apparatus
13.3.3 Reagents and Consumable Materials . . .
Preparation
13.4.1 Instrument Setup
13.4.2 Initial Calibration . .
13.4.3 Linearity Check
13.4.4 Maintenance
Procedure
13.5.1 Sample Analysis . . . .
13.5.2 Data Reporting
13.5.3 Cleanup
Quality Assurance and Quality Control
13.6.1 Precision and Accuracy
13.6.2 Quality Control Checks
References
1
1
1
1
2
2
2
2
2
2
5
5
11
13
14
14
14
15
15
16
16
Ib
16
Of
of
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ot
Of
of
of
of
of
of
of
of
ot
of
ot
ot
ot
of
of
of
of
ot
of
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I/
LI
L/
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I/
I/
I/
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L/
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LI
17
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14.0 Determination of Dissolved Organic Carbon and
Dissolved Inorganic Carbon . .
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CONTENTS (Continued)
14.1
14.2
14.3
14.4
14.5
14.6
14.7
Overview
14.1.1 Scope and Application ]
14.1.2 Summary of Method ......
14.1.3 Interferences '
14.1.4 Safety .'."!!
Sample Collection, Preservation, and Storage.'
Equipment and Supplies 2
14.3.1 Equipment Specifications '.'.'. 2
14.3.2 Apparatus 2
14.3.3 Reagents and Consumable Materials . '. '. 2
Preparation 4
14.4.1 Instrument Setup '.'.'' 4
14.4.2 DOC Calibration '4
14.4.3 DIC Calibration ..'.'!.' 6
Procedure 5
14.5.1 DOC Standard Operating Procedure. . .
14.5.2 DIC Standard Operating Procedure. . .
14.5.3 Calculations 5
Quality Assurance and Quality Control . . . ! '
14.6.1 Precision and Accuracy 7
14.6.2 Quality Control Checks
References
Page
1 of
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15.0 Determination of Total Dissolved Fluoride by Ion-
Selective Electrode
1 of 5 10 8/87
15.1
15.2
15.3
15.4
15.5
Overview
15.1.1 Scope and Application ........
15.1.2 Summary of Method ....
15.1.3 Interferences ......... "
15.1.4 Safety :........'!
Sample Collection, Preservation, and Storage! .
Equipment and Supplies. . 2
15.3.1 Equipment and Apparatus ........ 2
15.3.2 Reagents and Consumable Materials ...
Preparation 3
15.4.1 Calibration and Standardization .*."!
15.4.2 Maintenance 4
Procedure ...... 4
15.5.1 Standard Operating Procedure. . . . . . 4
1 of
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CONTENTS (Continued)
15.5.2 Calculations
15.6 Quality Assurance and Quality Control
15.6.1 Precision and Accuracy
15.6.2 Quality Control Checks
15.7 References
16.0 Determination of Metals (Al, Ca, Fe, K, Mg, Mn, Na)
by Atomic Absorption Spectroscopy
16.1 Overview
16.1.1 Scope and Application
16.1.2 Summary of Method
16.1.3 Definitions
16.1.4 Interferences
16.1.5 Safety
16.2 Sample Collection, Preservation, and Storage. .
16.3 Equipment and Supplies
16.3.1 Equipment and Apparatus
16.3.2 Reagents and Consumable Materials . . .
16.4 Preparation
16.4.1 Calibration and Standardization ....
16.5 Procedure
16.5.1 Flame Atomic Absorption Spectroscopy. .
16.5.2 Furnace Atomic Absorption Spectroscopy.
16.5.3 Procedure for Determination of Total
Aluminum
16.5.4 Procedure for Determination of Total
Extractable Aluminum
16.5.5 Procedure for Determination of
Dissolved Calcium
16.5.6 Procedure for Determination of
Dissolved Iron
16.5.7 Procedure for Determination of
Dissolved Magnesium
16.5.8 Procedure for Determination of
Dissolved Manganese
16.5.9 Procedure for Determination of
Dissolved Potassium
16.5.10 Procedure for Determination of
Dissolved Sodium
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CONTENTS (Continued)
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16.6
16.7
16.5.11 Calculations . . .
Quality Assurance and Quality Control
16.6.1 Precision and Accuracy. . . .
16.6.2 Quality Control Checks. . . .
References ,
21 of 23
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17.0 Determination of Dissolved Metals (Ca, Fe, Mg, and
Mn) by Inductively Coupled Plasma Emission
Spectroscopy
17.1
17.2
17.3
17.4
17.5
17.6
17.7
17.1.3
17.1.4
17.1.5
Overview
17.1.1 Scope and Application
17.1.2 Summary of Method
Interferences .'
Interference Tests
Safety
Sample Collection, Preservation, and Storage.'
Equipment and Supplies
17.3.1 Equipment Specifications. ......
17.3.2 Reagents and Consumable Materials . .
Preparation
17.4.1 Calibration and Standardization . . !
Procedure
17.5.1 Standard Operating Procedure. ...'.'
17.5.2 Calculations
Quality Assurance and Quality Control . . . .
17.6.1 Precision and Accuracy
17.6.2 Quality Control Checks
References
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18.1 Overview
18.1.1 Scope and Application
18.1.2 Summary of Method .
18.1.3 Definitions . . . . /,
18.1.4 Interferences
18.1.5 Safety. . .' "....'.!
Sample Collection, Preservation, and Storage.
Equipment and Supplies. ....
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18.0 Determination of Total Nitrogen 1 of 10 4
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CONTENTS (Continued)
18.4
18.5
18.6
18.3.2 Reagents and Consumable Materials . . .
18.3.3 Reduction Column and Reagents
18.4.1 Calibration and Standardization ....
18.4.2 Preparation of Reduction Column ....
Quality Assurance and Quality Control
18.6.3 Reduction Column Quality Control
References
Page
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Detei
19.1
19.2
19. '3
19.4
19.5
rminafion or pn itiosea iys-tenu . ........
Overview
19.1.1 Scope and Application. ....
19.1.2 Summary of Method
19.1.3 Interferences. .... .
19.1.4 Safety
Sample Collection, Preservation, and Storage. .
Equipment and Supplies ............
19.3.1 Apparatus and Equipment. ........
19.3.2 Reagents and Consumable Materials. . , .
Preparation
19.4.1 Instrument Preparation. ... . . . . .
19.4.2 Calibration and Standardization . . . .
19.4.3 Maintenance . .
19.4.4 pH Meter Electronic Checkout. . . . . .
19.4.5 Electrode Etching ....
Procedure ..-..
19.5.1 Sample Chamber Assembly . . . . . ...-' .
19.5.2 Initial QCCS Check
19.5.3 Sample Measurement. .... . . . -.'".".
19.5.4 Additional Procedures Using Two pH
Meters
±
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CONTENTS (Continued)
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19.5.5 Cleanup 15 of 16
19.6 Quality Assurance and Quality Control ...'!! 15 of 16
19.6.1 Precision and Accuacy 15 of 16
10.6.2 Quality Control Checks 15 of 16
19.7 References 16 of 16
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20.0 Determination of pH (Open System) 1 of 7 2 8/87
20.1 Overview
20.1.1 Scope and Application
20.1.2 Summary of Method
20.1.3 Interferences
20.1.4 Safety
20.2 Sample Collection, Preservation, and Storage. .
20.3 Equipment and Supplies
20.3.1 Apparatus and Equipment
20.3.2 Reagents and Consumable Materials . . .
20.4 Preparation
20.4.1 Instrument Preparation
20.4.2 Calibration and Standardization . . . .
20.4.3 Maintenance
20.4.4 pH Meter Electronic Checkout
20.4.5 Electrode Etching Procedure ...
20.4.6 Sample Preparation
20.5 Procedure
20.5.1 Initial Quality Control Check
20.5.2 Sample Measurement
20.5.3 Routine Quality Control Check
20.5.4 Cleanup
20.6 Quality Assurance and Quality Control ....
20.7 References
21.0 Determination of Total Phosphorus .
21.1 Overview
21.1.1 Scope and Application
21.1.2 Summary of Method
21.1.3 Interferences
21.1.4 Safety
21.2 Sample Collection, Preservation, and Storage. .
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21.3.2 Apparatus 2 of 7 10 8/87
21.3.3 Reagents and Consumable Materials ... 2 of 7 10 8/87
21.4 Preparation 4 of 7 10 8/87
21.4.1 Calibration and Standardization .... 4 of 7 10 8/87
21.5 Procedure 4 of 7 10 8/87
21.5.1 Standard Operating Procedure 4 of 7 10 8/87
21.5.2 Calculations 5 of 7 10 8/87
21.6 Quality Assurance and Quality Control 5 of 7 10 8/87
21.6.1 Precision and Accuracy 5 of 7 10 8/87
21.6.2 Quality Control Checks 6 of 7 10 8/87
21.7 References 6 of 7 10 8/87
22.0 Determination of Dissolved Silica 1 of 7 10 8/87
22.1 Overview 1 of 7 10 8/87
22.1.1 Scope and Application 1 of 7 10 8/87
22.1.2 Summary of Method . . . . " . . 1 of 7 10 8/87
22.1.3 Interferences . . . . . ........ 1 of 7 10 8/87
22.1.4 Safety . 1 of 7 10 8/87
22.2 Sample Collection, Preservation, and Storage. . 1 of 7 10 8/87
22.3 Equipment and Supplies 2 of 7 10 8/87
22.3.1 Equipment Specifications 2 of 7 10 8/87
22.3.2 Reagents and Consumable Materials ... 2 of 7 10 8/87
22.4 Preparation . 3 of 7 10 8/87
22.4.1 Calibration and Standardization .... 3 of 7 10 8/87
22.5 Procedure 4 of 7 10 8/87
22.5.1 Standard Operating Procedure 4 of 7 10 8/87
22.5.2 Calculations. ............. 6 of 7 10 8/87
22.6 Quality Assurance and Quality Control 6 of 7 10 8/87
22.6.1 Precision and Accuracy 6 of 7 10 8/87
22.6.2 Quality Control Checks 6 of 7 10 8/87
22.7 References 6 of 7 10 8/87
23.0 Determination of Specific Conductance. . 1 of 10 4 8/87
23.1 Overview. 1 of 10 4 8/87
23.1.1 Scope and Application 1 of 10 4 8/87
23.1.2 Summary of Method 1 of 10 4 8/87
23.1.3 Interferences 1 of 10 4 8/87
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CONTENTS (Continued)
23.
23.
23.4
23.
23.
23.7
23.1.4 Safety
Sample Collection, Preservation, and Storage.
Equipment and Supplies
23.3.1 Equipment Specifications '.
23.3.2 Apparatus
23.3.3 Reagents and Consumable Materials . !
Preparation
23.4.1 Electronics Check '.'.'.
23.4.2 Conductivity Cell Calibration Check .
23.4.3 Quality Control Check
23.4.4 Maintenance
Procedure
Quality Assurance and Quality Control . . ! .
23.6.1 Precision and Accuracy
23.6.2 Quality Control Checks
References
Page
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24.0 Determination of True Color 1 of 5
24.
24.
24.1 Overview
24.1.1 Scope and Application !
24.1.2 Summary of Method
24.1.3 Interferences
24.1.4 Safety
Sample Collection, Preservation, and Storage.
Equipment and Supplies
24.3.1 Apparatus and Equipment . .
24.3.2 Reagents and Consumable Materials . .
24.4 Preparation
24.4.1 Sample Preparation .
24.4.2 Color Kit Preparation
24.5 Procedure
24.5.1 Low Range Sample Color Determination. ,
24.5.2 High Range (100-500 PCU) Sample Color
Determination
24.5.3 High Range (500-1000 PCU) Sample Color
Determination
24.5.4 Cleanup \
24.6 Quality Assurance and Quality Control . . . . .
24.6.1 Precision and Accuracy
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CONTENTS (Continued)
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24.6.2 Quality Control Checks.
24.7 References
5 of 5
5 of 5
25.1 Overview
25.1.1 Scope and Application
25.1.2 Summary of Method
25.1.3 Interferences
25.1.4 Safety
25.2 Sample Collection, Preservation, and Storage,
25.3 Equipment and Supplies
25.3.1 Equipment and Apparatus
25.3.2 Reagents and Consumable Materials . ,
25.4 Preparation
25.4.1 Daily Calibration ,
25.4.2 Maintenance
25.5 Procedure
25.6
25.7
Appendices
Appendix A
Appendix B
Appendix C
Appendix D
Appendix E
Appendix F
Appendix G
25.5.1 Low Turbidity Samples
25.5.2 High Turbidity Samples
25.5.3 Cleanup
25.5.4 General Precautionary Notes for
Procedure
Quality Assurance and Quality Control .
25.6.1 Precision and Accuracy
25.6.2 Quality Control Checks
References
National Surface Water Survey Mobile
Laboratory Specifications
Processing Laboratory Equipment List . . . .
General Laboratory Procedures
National Surface Water Survey Blank Data
Forms
Examples of Calculations Required for ANC
and BMC Determinations
The Aid Photoionization Detector for Use as
an MIBK Detection System
Internal Quality Control Requirements. . . .
Effec-
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Date
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25.0 Determination of Turbidity 1 of 9 10 8/87
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Section Figures
Revision 0
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Page 1 of 2
FIGURES
Page
Effec-
tive
Rev Date
1-1 Aquatic Effects Research Program component
projects 2
1-2 Regions sampled during National Surface Water
Survey 3
6-1 Filtration apparatus 4
7-1 Aluminum extraction flowchart 6
8-1 Schematic of flow injection system for aluminum
speciation 13
9-1 Ammonia manifold AAI 5
9-2 Ammonia manifold AAII . 5
12-1 Example high performance liquid chromatography
chromatogram 5
13-1 Flowchart for dissolved inorganic carbon analysis . 6
13-2 Troubleshooting flowchart for dissolved inorganic
carbon analysis 7
13-3 Diagram of the Dohrmann carbon analyzer 8
13-4 External plumbing of the Dohrmann carbon analyzer . 9
13-5 Internal connections of the Dohrmann carbon
analyzer 10
16-1 Standard addition plot 8
18-1 Schematic of flow injection system for determi-
nation of total nitrogen 7
19-1 Schematic of pH measurement system 2
19-2 pH sample chamber 3
19-3 Flowchart for pH determination 10
19-4 Troubleshooting flowchart for pH determination. . . 11
19-5 pH logbook and example page; organization of raw
data 12
20-1 Flowchart for pH determination 4
20-2 Troubleshooting flowchart for pH determination. . . 5
21-1 Total phosphorus manifold 5
22-1 Silica manifold 5
23-1 Flowchart for specific conductance measurement. . . 5
25-1 Flowchart for turbidity 5
A-l Schematic drawing of laboratory trailer and
features, curbside view 2
A-2 Schematic drawing of laboratory trailer and
features, roadside view 3
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Section Figures
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Page 2 of 2
FIGURES (Continued)
Effec-
tive
Page Rev Date
E-l Plot of Fib versus V for HC1 standardization. ... 2 of 22 4 8/87
E-2 Plot of FSK versus V for initial NaOH
standardization with KHP. . . 5 of 22 4 8/87
E-3 Plot of Fi versus V for NaOH-HCl standardization
cross-check 7 of 22 4 8/87
E-4 Plot of FI versus V for daily NaOH standardization. 9 of 22 4 8/87
E-5 Plot of pH* versus pH for electrode calibration .. 12 of 22 4 8/87
E-6 Plot of Fia versus V for ANC determination
of blank? 13 of 22 4 8/87
E-7 Plot of Fia versus Va for initial determination
of Y! ...... 7 16 of 22 4 8/87
E-8 Plot of Flc versus Va for Vi determination 18 of 22 4 8/87
E-9 Plot of ?2c versus Vb for V£ determination 19 of 22 4 8/87
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Section Tables
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Page 1 of 2
TABLES
Effec-
tive
Rev Date
4-1 Aliquots, Containers, Preservatives, and
Corresponding Parameters for the National
Surface Water Survey
4-2 Samples for Special Studies Conducted During the
National Surface Water Survey ...
4-3 National Surface Water Survey Standard Analyses .
4-4 National Surface Water Survey Experimental or
Special Study Analyses
5-1 Calculation Procedures for Combinations of Initial
YI and pH*. .
5-2 Constants and Variable Descriptions
6-1 Aliquots, Containers, Preservatives, and .
Corresponding Parameters for the National
Surface Water Survey
8-1 Volume of Aluminum Stock Standards Required to
Prepare Daily Standards ,
8-2 Volume of Aluminum Stock Standards Required for
High Range Calibration Standards
8-3 Precision and Accuracy for Single Operator and
Single Laboratory Analysis of Inorganic Mono-
men" c Aluminum by Flow Injection/Pyrocatechol
Violet Method ,
8-4 Precision and Accuracy for Single Operator and
Single Laboratory Analysis of Inorganic Mono-
men c Aluminum by Flow Injection/Pyrocatechol
Violet Method
8-5 Percent Recovery of Monomeric Al From Two Spiked
Natural Surface Water Samples Analyzed by the
Flow Injection/Pyrocatechol Violet Method . . . .
11-1 Suggested Concentration of Dilute Calibration
Standards
11-2 Typical Ion Chromatograph Operating Conditions. . .
11-3 Single Operator Accuracy and Precision
12-1 Dilutions of Chlorophyll a_ Stock Standard to Make
Working Standards
16-1 Atomic Absorption Concentrations Ranges .
17-1 Recommended Wavelengths and Estimated Instrumental
Detection Limits
17-2 Analyte Concentation Equivalents (mg L"1) Arising
from Interferences at the 100-mg L"1 Level. . . .
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TABLES (Continued)
Section Tables
Revision 0
Date: 8/87
Page 2 of 2
Effec-
tive
Rev Date
17-3 Interference and Analyte Elemental Concentrations
Used for Interference Measurements in Table 17-2. 5 of 10 10 8/87
17-4 Inductively Coupled Plasma Emission Spectroscopy
Precision and Accuracy Data . 10 of 10 10 8/87
19-1 pH Values of Buffers at Various Temperatures. ... 7 of 16 10 8/87
21-1 Percent Recovery of Total Phosphorus in the
Presence of Silica 1 of 7 10 8/87
21-2 Precision and Accuracy of the Phosphorus Method
for Natural Water Samples 6 of 7 10 8/87
21-3 Precision and Accuracy of the Phosphorus Method
for Analyst-Prepared Standards. 6 of 7 10 8/87
23-1 Temperature Correction Factors to Compute Specific
Conductance Values at 25.0 °C 8 of 10 4 8/87
E-l Acid Titration 10 of 22 4 8/87
E-2 Base Titration 11 of 22 4 8/87
G-l Summary of Internal Method Quality Control Checks . 2 of 10 10 8/87
G-2 Maximum Control Limits for Quality Control
Samples 3 of 10 10 8/87
G-3 Required Minimum Analytical Detection Limits,
Expected Ranges, and Intralaboratory Relative
Precision 5 of 10 10 8/87
G-4 Factors to Convert mg L"1 to ueq L"1 8 of 10 10 8/87
G-5 Chemical Reanalysis Criteria 9 of 10 10 8/87
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1.0 INTRODUCTION TO THE AQUATIC EFFECTS RESEARCH PROGRAM
Concern over the effects of acidic deposition on the nation's surface
water resources led the U.S. Environmental Protection Agency (EPA) to initiate
research in the field in the late 1970s. Early research, focusing on a diver-
sity of potential effects, provided insight into those research areas which
were considered central to key policy questions. Recognizing the need for
an integrated, stepwise approach to resolve the issues, EPA implemented the
Aquatic Effects Research Program (AERP) in 1983 with its present structure,
focus, and approach. The Program, a part of EPA's Office of Research and
Development, is administered by the Acid Deposition and Atmospheric Research
Division in the Office of Acid Deposition, Environmental Monitoring, and
Quality Assurance. The AERP is also a major component of the National Acid
Precipitation Assessment Program's (NAPAP) Aquatic Effects Research Task Group
6, a cooperative effort of nine federal agencies tasked with addressing impor-
tant policy and assessment questions relating to the acidic deposition
phenomenon and its effects.
Initially, AERP studies focused on process-oriented research at a few
sites to generate hypotheses for further testing and to identify key parameters
associated with the effects of acidic deposition on aquatic ecosystems. In
1983, after it was determined that regional assessments of the effects of
acidic deposition could not be made with confidence on the basis of available
historical data, the AERP redirected its focus to provide the required informa-
tion. Weaknesses of available data included possible inconsistencies
in the selection of study sites, lack of data for certain important parameters,
inconsistent sampling and analytical methods, and little or no information on
quality assurance.
The AERP addresses four major policy questions relating to the effects of
acidic deposition on aquatic ecosystems:
1. The extent and magnitude of past change.
2. The change to be expected in the future under various deposition
scenarios.
3. The maximum rates of deposition below which further change is not
expected.
4. The rate of change or recovery of aquatic ecosystems if deposition
rates are decreased.
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An integrated, stepwise approach is used within the AERP to provide the
necessary data for assessment and policy decisions related to effects of acidic
deposition on aquatic resources. The approach employs statistically based site
selection, standardized sampling procedures and analytical methods, and rigorous
quality assurance protocols. At present, the AERP includes five major research
component projects that have been initiated or are being planned: the National
Surface Water Survey (NSWS), the Direct/Delayed Response Project (DDRP), the
Episodic Response Project (ERP), the Watershed Manipulation Project (WMP), and
the Temporal Integrated Monitoring of Ecosystems (TIME) Project. Two addi-
tional projects, Biologically Relevant Chemistry (BRC) and Indirect Human
Health Effects (IHHE), have been incorporated into the AERP research design.
The AERP projects form an integrated program to quantify the chemical status of
surface waters, to predict the response of biologically relevant water chemis-
try to variable rates of acidic deposition, and to verify and validate the
predictions (Figure 1-1).
Status
Figure 1-1. Aquatic Effects Research Program component projects.
The AERP projects are concerned primarily with assessing chronic, or
long-term, acidification of surface waters as affected by sulfur deposition.
The Episodic Response Project will assess the importance of acute, or short-
term, acidification and nitrate deposition. Components of the Biologically
Relevant Chemistry Project address issues of both chronic and acute
acidification.
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1.1 NATIONAL SURFACE WATER SURVEY (NSWS)
The NSWS is divided into two components: the National Lake Survey (NLS)
and the National Stream Survey (NSS). Figure 1-2 shows the various regions
sampled during the NSWS.
Phase I activities of the NSWS provide information to determine the current
chemical status of lakes and streams. Phase II activities; of these surveys
describe seasonal variability in regional surface water chemistry. Because of
the statistical basis of the sampling design, data from the NSWS can be used to
classify lakes and streams so that selected,subsets can be identified for more
detailed studies during other components of the AERP. Results of these more
detailed studies can be interpreted then at a regional scale with greater
confidence.
1.2 DIRECT/DELAYED RESPONSE PROJECT (DDRP)
The DDRP provides data on watersheds and soils to complement the surface
water data of the NSWS. These data are used in three watershed acidification
models to predict the time scales over which surface waters are expected to
become chronically acidic, given different levels of acidic inputs.
NE Minnesota1
_.-_A
Upper Midwest
T
National Lake Survey (NLS)
National Stream Survey (NSS)
Overlap of MLS/NSS
'Eastern Lake Survey Phase I
'Western Lake Survey Phase I '
3National Stream Survey Phase I
'National Stream Survey Screening
5National Stream Survey Phase I
>> Central Rockies2 \
I )
l^% ^.j Upper Great Lakes Area
L 5"
r ^
-1--,
j.
Southern Rockies2
-L .i y,-
. r - /_/ ,7B\S
| Ozark Plateau' ^iH%>«;
, t V ''J^f-!-'."f-'f
^..
Figure 1-2. Regions sampled during the National Surface Water Survey.
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1.3 EPISODIC RESPONSE PROJECT (ERP)
The ERP has objectives similar to those of the NSWS, but focuses on the
magnitude, frequency, and duration of episodic acidification and the effect of
episodes on regional water chemistry and watershed processes. The ERP is
conducted at a small number of watersheds believed to represent the range of
conditions found within a region, based on the results of the NSWS and the
DDRP. Empirical and conceptual models are developed from these site-specific
studies to address the regional extent of episodes, using the NSWS statistical
frame.
1.4 WATERSHED MANIPULATION PROJECT (WMP)
The WMP, involving process-oriented research at a small number of water-
sheds, is designed to assess the quantitative and qualitative response of
watershed soils and surface waters to altered deposition. Designed primarily
to verify the models used for prediction in the DDRP, the WMP also determines
the interactions among biogeochemical mechanisms controlling the response of
surface waters to acidic inputs at various scales within watersheds, ranging
from plot to whole ecosystem studies.
1.5 TEMPORAL INTEGRATED MONITORING OF ECOSYSTEMS (TIME) PROJECT
The TIME Project, a long-term monitoring activity, evolves from the
existing projects within EPA and NAPAP. TIME sites are selected by evaluating
data from currently monitored systems and from the NSWS results. These sites,
which will be established throughout the United States by 1990, are monitored
to quantify the rate, direction, and magnitude of changes in surface water
chemistry due to increased and decreased levels of acidic deposition. The TIME
sites also provide information on surface water chemistry that can be used to
validate the conclusions of the DDRP, the ERP, and the WMP.
1.6 BIOLOGICALLY RELEVANT CHEMISTRY (BRC) PROJECT
Jhe BRC Project provides data that can be used to assess the risk that
acidic deposition poses to aquatic biota. Several complementary studies are
incorporated as components of the BRC. One study determines the present status
of fish populations in a subset of lakes sampled during the eastern component
of the NLS and quantifies the chemical characteristics of these lakes. Another
study, planned in conjunction with the ERP, determines the effects of episodic
acidification on fish populations.
1.7 INDIRECT HUMAN HEALTH EFFECTS (IHHE) PROJECT
The IHHE Project targets two areas: (1) the alteration of drinking water
supplies in response to acidic inputs and (2) the accumulation of mercury and
other potentially toxic metals in the muscle tissues of edible fish. Emphasiz-
ing precipitation-dominated surface water systems, drinking water studies
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include the examination of existing data to determine the potential modifica-
tion of drinking water quality by acidic deposition. In addition, existing
process-oriented and survey data are examined to evaluate the relationship
between mercury bioaccumulation in sport fish and surface water chemistry in
areas receiving high levels of acidic deposition.
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2.0 OVERVIEW OF AERP HANDBOOKS
2.1 PURPOSE OF HANDBOOKS
Numerous private, state, and federal groups have initiated research pro-
jects similar to those developed as components of the AERP. Existing AERP
field and laboratory manuals and quality assurance plans were not written for
an overall methods application or for general use. Developed for specific
survey requirements, available operational documents do not provide general
guidelines and procedures that can be adapted readily by different research
groups. AERP handbooks are designed to fill this gap. As guidance docu-
ments for groups involved in acidic deposition monitoring activities, the
handbooks enable researchers to avoid duplication of efforts and to make
maximum use of tested methods.
2.1.1 Types of Handbooks
AERP handbooks focus on surface water chemistry, based on documents written
for the NSWS, and on soil chemistry, based on the DDRP manuals. The handbooks
contain procedures for field operations, laboratory operations, and quality
assurance criteria for water and soil monitoring activities. Surface water
chemistry and soil chemistry are discussed in separate three-volume sets.
2.1.2 Structure of Volumes
Because the AERP is a dynamic program, inclusion of additional methods is
anticipated. Each document is contained in a three-ring binder to facilitate
insertion of revisions by handbook subscribers. Each document contains an
independent Table of Contents with titles, revision numbers, and effective
dates for revisions; a complete, updated Table of Contents will accompany
dissemination of each revision. The availability of each volume or revision
will be announced in the AERP status.
2.1.3 Interrelationship of Volumes
Each volume of a particular handbook set represents one aspect of an
acidic deposition monitoring activity. Collectively, the field, laboratory,
and quality assurance handbooks offer a comprehensive guide to surface water
chemistry or soil chemistry monitoring.
2.2 CONTENT OF LABORATORY HANDBOOK
This handbook describes methods used to process and analyze surface water
samples.
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2.2.1 Laboratory Methods
The chemical and physical parameters measured and the analytical methods
used are listed below:
Section
5.0
6.0
7.0
8.0
9.0
10.0
11.0
12.0
13.0
14.0
15.0
16.0
17.0
18.0
19.0
20.0
21.0
Parameter
Acidity, Alkalinity, and pH
Aliquot preparation3
Alumi num, total extractablea
Aluminum, total and non-
exchangeable
PCY-reactivea
Ammonium, dissolved
Ammonium, dissolved (alternate)
Chloride, Nitrate, and Sulfate
Chlorophyll a_
Dissolved Inorganic Carbon3
Dissolved Inorganic Carbon and
Dissolved Organic Carbon
Fluoride, dissolved
Metals (Al, Ca, Fe, K, Mg,
(Mn, Na)
Metals (Ca, Fe, Mg, Mn)
(alternate)
Nitrogen, total
pH, closed system3
pH, open system3
Phosphorus, total
22.0 Silica, dissolved
23.0 Specific conductance
24.0 True Color3
25.0 Turbidity3
Analytical Method
Titration with Gran plot
Filtration and preservation
Extraction with 8-hydroxyquinoline
into methyl isobutyl ketone
Flow injection analysis colorimetry
(pyrocatechol violet)
Automated colorimetry (phenate)
Flow injection analysis colorimetry
Ion chromatograhy
Fluorometric and high performance
liquid chromatographic analysis
Instrumental
Instrumental
Ion selective electrode and meter
Atomic absorption spectroscopy
Inductively coupled plasma emission
spectroscopy
Flow injection analysis
pH electrode, meter, and subchamber
pH electrode and meter
Automated colorimetry (phosphomolyb-
date)
Automated colorimetry (molybdate
blue)
Conductivity cell and meter
Comparison to platinum-cobalt color
standards
Instrumental (nephelometer)
Parameters measured or activities performed at the processing laboratory
before the samples are transmitted to the analytical laboratory.
2.2.2 Suitable Sample Types
The processing and analytical methods described in this handbook have been
used for surface water samples of low ionic strength and snowpack samples.
These methods can be altered slightly to apply to precipitation samples.
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3.0 LABORATORY FACILITIES AND ORGANIZATION
Many biological and chemical parameters are subject to rapid change or
degradation following sample collection. The period of time between sample
collection and sample analysis is defined as the holding time; the recommended
holding time is the maximum sample storage time before significant changes in
the parameter of interest can be expected to occur. Sample processing
procedures stabilize samples, thereby increasing the holding time. Sample
processing includes refrigeration, filtration, extraction, and chemical preser-
vation. In general, sample processing procedures do not produce quantitative
results. Procedures which do produce quantitative results are termed sample
analyses.
3.1 MOBILE LABORATORIES
Studies assessing the water quality of lakes or streams often involve
sampling in remote locations over a large geographic area. During large-scale
studies, a central, analytical laboratory cannot always perform all analyses
within the recommended holding times. Using mobile laboratories and multiple
analytical laboratories provides alternatives to the single-laboratory
approach.
For the NSWS, a mobile field laboratory was designed to provide sample
processing facilities. The mobile laboratory also was used to perform some
analyses, including pH, dissolved inorganic carbon (DIG), true color, and
turbidity. Six mobile laboratories were deployed during the ELS-I and WLS-I;
however, they were located centrally in Las Vegas during later surveys. The
decision processes followed by the NSWS can be used in similar situations to
determine whether mobile laboratories may be beneficial and what activities are
to be performed in the mobile or central processing laboratory. This decision
process is outlined below:
1. Determine parameters to be measured, recommended holding times for
those parameters, and processing alternatives to lengthen the
holding time. For processing techniques, determine holding time of
raw sample prior to processing.
2. Determine sampling locations and available shipping services (i.e.,
can samples be collected, shipped, received, and analyzed at a labora-
tory within the recommended holding times).
3. Determine the sample load and the length of time required to perform
processing or analysis. Determine the number of personnel and the
units of equipment necessary to complete the activity within the
holding time. Determine the space required.
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4. If more than one option is feasible, determine the costs of all viable
options.
During Phase I of the MLS, six mobile laboratories were used. In later
surveys, it was determined that additional mobile laboratories would be
required, or existing units would require relocation every three to four days,
with a downtime of at least two days during moves. Both options were
prohibitively expensive. In addition, an analytical method for aluminum deter-
mination was added to the processing laboratory-performed analyses, placing
limitations on trailer space. Because overnight courier services were avail-
able within reasonable distances of sampling points, the final decision was to
provide a central processing laboratory for these later surveys.
3.2 MINIMUM FACILITY REQUIREMENTS
Whether mobile laboratories or a central processing laboratory are used,
certain specifications should be considered. Specifications of the mobile
laboratory designed for the NSWS are provided in Appendix A; equipment used in
the processing laboratory is listed in Appendix B.
A clean air station is highly recommended to provide a contamination-free
work area for sample filtration and for possible use as a fume hood. The clean
air station shoud contain a high efficiency purification apparatus capable of
delivering Class 100 air (Federal Standard 209B, 1978). For sample filtration
the clean air station should be under slight positive pressure. If the clean
air station is also to be used as a fume hood, it should have adjustable flow
vents to allow conversion from positive pressure to negative pressure.
A supply of Type I reagent grade water (ASTM, 1984) also is recommended
for reagent preparation, glassware washing, and preparation of blank samples.
A reverse osmosis and deionization system is effective in providing Type I
water in the quantities needed. A specific conductance test should be per-
formed weekly to ensure that the system is meeting the Type I specification of
less than 1 uS cm'1 specific conductance. An analysis of the feed water, which
is available from the local water district, is valuable in determining car-
tridge arrangement and expected cartridge life expectancy.
Samples are generally shipped and stored at 4 °C prior to processing; pro-
cessed aliquots are also stored and shipped at 4 °C. Refrigerator space should
be adequate to provide storage, and temperature should be checked daily
Freeze-gel packs and insulated coolers provide refrigeration during shipment.
Adequate freezer space is needed to freeze the gel packs. Due to the freezer
space needed for a study of even moderate size, stand-alone freezers are
recommended. Additionally, some biological samples may require storage at
-20 C; only freezers that meet this specification should be used.
A number of logistical concerns should be considered, including electric
power, telephones, laboratory counter and storage space, solid and liquid waste
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disposal, water, shipping access, and chemical storage. Local building and
fire safety codes must be considered. Electric power should be adequate to
power the clean air station, the deionized water system, interior lights,
refrigerators and freezers, and the heating and air conditioning systems. A
large number of outlets is needed, for the.equipment. Fluctuations in power can
severely damage sensitive instruments; a constant voltage regulator and surge
protectors are recommended: Some instruments, particularly those interfaced to
computers, may lose memory or calibration during power outages; a battery back-
up system capable of maintaining power for at least 6 hours may be necessary.
3.3 LABORATORY STAFFING
The mobile laboratories used in the NSWS were designed for a staff of
five peoplethe coordinator, the laboratory supervisor, and three analysts.
These five positions were standard during NLS-I; a sixth position, to perform
pyrocatechol violet (PCV) aluminum analysis, was added in later surveys. Each
of these positions is described belowr
The laboratory coordinator has the following responsibilities:
1. Serves as overall laboratory administrator.
2. Oversees the laboratory installation and operations.
3. Serves as the liaison between management, the processing laboratory,
and the Quality Assurance manager.
4 Receives samples from the field; organizes the daily batch formation
and the insertion of associated quality assurance (QA) and quality
control (QC) samples.
5. Coordinates the shipment of processed aliquots to the analytical
laboratories.
6. Coordinates purchases and audit sample receipt.
7. Checks and transfers data from the laboratory to the.data base manager
via the quality assurance manager.
8. Coordinates sample and batch tracking from the field to the labora-
tory and then to the analytical laboratories. ;
9. Serves as a reserve laboratory analyst.
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Tne laboratory supervisor has the following responsibilities:
1. Oversees daily laboratory operations, including maintenance and
troubleshooting of all instrumentation and equipment.
2. Ensures that samples are processed in accordance with approved
methodologies and the quality assurance program.
3. Assists the laboratory coordinator in transcribing data from DIG, pH
turbidity, conductivity, PCV-aluminum, and true color determinations!
4. Supervises the preparation of sample aliquots for shipment.
5. Ensures laboratory safety, cleanliness, and security.
6. Tracks the field and laboratory supply inventory.
7. Serves, along with the laboratory coordinator, as facility safety
compliance officer.
8. Serves as the acting laboratory coordinator in the coordinator's
absence.
9. Serves as the reserve laboratory analyst.
In addition, the laboratory supervisor, or, alternately, a separate analyst:
1. Performs pH determinations and equipment maintenance.
2. Performs DIG determinations and carbon analyzer maintenance.
Analyst 1 has the following responsibilities:
1. Operates and maintains the flow injection analyzer to conduct
PCV-aluminum determinations.
Analyst 2 has the following responsibilities:
lm Xe5ares an al1c)uot for the analysis of extractable aluminum using
MIBK. -
2. Prepares MIBK aliquots for shipping.
3. Disposes of solid and liquid MIBK waste.
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Analyst 3 has the following responsibilities:
1. Assists the laboratory coordinator with sample batching.
2. Filters aliquots from routine, duplicate, blank, and audit samples.
3. Prepares aliquot bottles and labels.
4. Assists in preparing preserved aliquots for shipping.
Analyst 4 has the following responsibilities:
1. Preserves aliquots as they are filtered.
2. Performs turbidity and true color determinations.
3. Performs specific conductance measurements.
Additionally, Analyst 4, or a separate analyst, has the following responsi-
bilities:
1. Prepares and ships reagents and supplies to the field sites.
2. Maintains an ample stock of shipping containers and frozen gel packs.
3. Assists in preparing preserved aliquots for shipping.
4. Maintains the organization and cleanliness of the laboratory.
3.4 TRAINING
Recommended qualifications for processing laboratory personnel include a
knowledge of basic chemistry, laboratory experience, and a high level of work
neatness and precision. A college degree in one of the physical sciences is
recommended, but is not absolutely necessary. The nature of processing labora-
tory work demands close attention to detail and the ability to perform at a
consistently high quality level.
Laboratory training programs should include thorough coverage of each
procedure and hands-on practice sessions. Theory and rationale for each lab-
oratory rule and procedure should be covered in detail. A written laboratory
manual containing detailed, step-by-step procedures is invaluable during
training. At least one week should be devoted to training. A typical training
schedule should include one day of orientation (including explanation of lab-
oratory rules and an overview of operations). Another day should be devoted to
each method or procedure, including general laboratory procedures (Appendix C).
This training should include a lecture, an observation period, a question and
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answer period, and hands-on practice. At the conclusion of training, written
testing is recommended with follow-up, supervised practice in any areas of
weakness. Each analyst should be fully trained in all areas to provide
coverage for absences and potential for rotation of duties.
3.5 CONTAMINATION AVOIDANCE
thv. PartiC*lar ?mPhasis snould be Placed on avoiding sample contamination
throughout training and operation. Lake and stream samples in the AERP studies
are generally of low ionic strength; even a single fingerprint on the inside
edge of a sample container can contaminate the entire sample. For this reason
disposable sterile gloves and labcoats should be worn when handling samples. '
As much as possible, all sample handling should be done inside the clean air
station. Eating and smoking are forbidden inside the laboratory and all per-
sonnel should wash their hands after breaks. Personnel should not wear makeup
or perfume, including men's cologne. All glassware and plasticware should
be washed in Type I reagent grade water and rinsed with a portion of the
sample. When adding reagents to samples, the pipet tip should not contact the
sample. Acid-washed and deionized water-washed apparatus and glassware should
be stored separately and both types should be labeled clearly. Counter areas
should be covered in Benchkote, which should be changed frequently. The
laboratory floors and counters should be washed and swept daily. Only water
should be used for washing; no soap should be used. Additional precautions
regarding contamination avoidance are described in the methods relating to
sample processing.
3.6 SAFETY
Safety is also a primary consideration in the laboratory. In most
1° Ca. '".inspection and certification by the local fire department is required
S£M?,. f 6C and ClSSS A"B fire extinguishers are recommended and may be '
i GCJUl i Q*
Fire escape routes should be clearly marked and each person should be
aware of at least two escape routes from their work area. A circuit breaker
with a mainswitch shutoff should be located on the outside of each mobile
laboratory to avert electrical problems. Chemicals should be stored in
approved containers and cabinets; bases and acids should be stored in separate
places. Chemical spill kits should be located in each work area. Disaster
i !! * i?6 devel°Ped and Deluded in training so that each person knows
nUBbers
J!ers?n"el ,safety includes proper laboratory clothing (e.g., lab coat,
K S*L9la!SesZ: and Protect1ve footwear). If MIBK is used, personnel
shou d £ rfp2-d-f7-half~!?aSk resP1ratol"s with organics cartridges. Personnel
should be certified in cardio-pulmonary resuscitation (CPR) and first aid-
local Red Cross or American Heart Association groups can provide classes for a
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nominal fee. A medical surveillance program, including testing before and
after sample handling, is recommended if hazardous materials are used. A
complete physical, including blood testing, is recommended prior to initiation
of laboratory activities.
3.7 REFERENCES
American Society for Testing and Materials, 1984. Annual Book of ASTM
Standards, Vol. 11.01, Standard Specification for Reagent Water,,
D 1193-77 (reapproved 1983). ASTM, Philadelphia, Pennsylvania.
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4.0 SAMPLE HANDLING
The sections below describe some alternatives for sample handling. These
alternatives provide guidelines of the types of questions one should consider
in planning sample handling. The methods used for the NSWS are described for
illustration purposes.
4.1 SAMPLE TYPES AND SAMPLE CONTAINERS
The "basic" water sample consists of water collected in an appropriately
sized sample container. The quantity should be sufficient to prepare all
necessary aliquots, perform all analyses, and provide extra volume for rinses.
Generally, the sample container should not be washed with acid and should be
filled totally to minimize atmospheric contact. Filled containers are stored
at 4 °C in the dark until sample processing. Polyethylene containers are
recommended because of their durability, light weight, and low contamination
potential. Containers used for the NSWS include 4-L Cubitainers, 20-L Cubi-
tainers, and 500-mL bottles. Either dark or clear containers may be used.
Clear containers were used in the NSWS.
The containers described above are not impervious to C0£ exchange. There-
fore, for measurements in which C02 is a factor (pH, DIC, aluminum fractions),
the raw sample should be collected without atmospheric contact into containers
which limit gas exchange. For the AERP studies, 60-mL sterile syringes were
used with Leur Lok syringe valves. The valve attached to a port on the sample
collection device, allowing the syringe to be filled without atmospheric expo-
sure. Syringes then were sealed and stored at 4 °C in the dark until analysis.
Syringes also were used to collect samples from the oxygen-depleted hypolimnion.
Containers for processed aliquots are specific to the type of aliquot.
For the NSWS, the majority of aliquot containers were made of amber-colored,
high-density polyethylene. Clear polyallomer or polycarbonate centrifuge tubes
were used for MIBK extractions. The bottle size should be of sufficient volume
to perform required analyses and rinses. Extra volume is desirable to permit
replicate analyses. Bottles are acid-washed for acid-preserved aliquots and
deionized water-washed for aliquots not containing acid. Complete filling tOQ
eliminate headspace is required only for unpreserved aliquots. Storage at 4 C
in the dark is desirable for all aliquots, but is necessary only for certain
types. If aliquots are refrigerated, the lids should be retightened when
bottles have cooled because polyethylene tends to shrink, which causes leaks.
Specific aliquot types are discussed in Section 4.3.
4.2 SAMPLE TRANSPORT AND TRANSFER
Field-collected samples are transferred to a laboratory; if mobile or pro-
cessing laboratories are used, processed aliquots are transferred to analytical
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laboratories. Means of transportation depend on the distance between points
and the sample holding time. In all cases, careful packaging and shipment
tracking is needed. In many studies, particularly if results may be used for
litigation purposes, formal ehain-of-custody procedures may be required.
Raw samples should be processed as soon as possible, usually within 24
hours of collection. In the NLS-I, helicopters were used as sampling platforms
and were used to deliver samples to the mobile laboratory immediately after
collection. In later surveys, samples were shipped by overnight courier
service to the processing laboratory in Las Vegas. Samples were packed in
insulated styrofoam or plastic ice chests with frozen gel packs. Documentation
accompanied each shipment to identify samples and collection teams.
After processing, aliquots were shipped by overnight courier service to
analytical laboratories. Packing was similar to that described above for raw
samples. Overnight service was necessary because some aliquots had a seven-day
holding time. Documentation in each shipment included two copies of a four-
copy shipping form (see Appendix D). The shipping form provided the necessary
chain-of-custody documentation.
A central Communications Center tracked all shipments and provided coordi-
nation among field teams, processing laboratory(ies), analytical laboratories
quality assurance, and management. Airbill numbers, sample identification, and
the number of containers were called in to Communications immediately after
shipping. Communications notified the recipient and, the next day, verified
arrival and sample condition. In this way, problems were noted and resolved
quickly.
4.3 SAMPLE PROCESSING
The purpose of sample processing is to stabilize the chemical parameter of
interest. Processing may include refrigeration or freezing, filtration
f?era»o2! Presel"vatl"°n, or more complex procedures. The aliquots prepared for
the NSWS are shown in Table 4-1.
n\ °Lth? Sev?n standard NSWS aliquots, three are prepared by filtration with
(1) sulfuric acid preservation, (2) nitric acid preservation, and (3) no pre-
servative. Three are not filtered, with the same three treatments. The
remaining aliquot is an MIBK-extraction. The only variation of these seven
standard aliquots is Aliquot 6*, prepared for stream samples, which is
unfiltered for measurement of total phosphorus.
^ Additional aliquots or split samples were prepared for special studies
during one or more of the NSWS surveys. These aliquots are described in Table
"""
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TABLE 4-1. ALIQUOTS, CONTAINERS, PRESERVATIVES, AND CORRESPONDING
PARAMETERS FOR THE NATIONAL SURFACE WATER SURVEY
(15 ml, AW)
4
(125 ml, AW)
(500 mL, DIW)
Processing and
Preservation^
Parameters
1
(250 mL, AW)
Filtered
pH < 2 with HN03C
Ca, Mg, K,
Na, Mn, Fe
Filtered
MIBK Extract
Total Extractable Al
3 Fi 1 tered
(250 mL, DIW) No Preservative
ci-
S04"2
N03
Si02
Filtered
pH <2 with H2S04C
Untiltered
No Preservative
Dissolved organic carbon
Kill "*
NH,
pH
Alkalinity
Acidity
Conductance
Dissolved inorganic carbon
(125 mL, AW)
Fi1tered
pH <2 with H2S04C
Dissolved P
6*
(125 mL, AW)
Unfiltered
pH <2 with H2S04C
Total P
(125 mL, AW)
Unfiltered
pH <2 with HN03C
Total Al
aAW = acid-washed container DIW = deionized water-washed container.
bAliquots 2, 3, 4, 5, and 6 are stored at 4 °C in the dark.
C12M nitric acid, Baker Ultrex grade or equivalent.
d!8M sulfuric acid, Baker Ultrex grade or equivalent.
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TABLE 4-2. SAMPLES FOR SPECIAL STUDIES CONDUCTED DURING THE
NATIONAL SURFACE WATER SURVEY
Destination
Container9
Number
Processing; Analytes
EPA-Corvallis
(Oregon)
Norwegian Insti-
tute for Water
Research
(Norway)
Ontario Ministry
of the Environ-
ment (Canada)
Canada Centre
for Inland
Waters
Indiana
University
Indiana
University
Freshwater
Institute
(Canada)
125 ml, AW All samples
500 ml, DIW 90
2x500 mL, DIW 25
250 ml, AW 115
250 mL, DIW 115
125 mL, DIW 115
10-15 mL, AW All samples
10-15 mL, AW Anoxics study
samples
Chlorophyll
routine, dup-
licate, audit,
and referee
samples
b.
Filtered, pH <2 w/HN03
Aliquot 1 cations
Raw unfiltered sample;
PCV aluminum, ANC, Ca,
Cl, specific conductance,
K, Mg, Na, Nitrate, pH,
sulfate
Raw unfiltered sample;
pH < 2 w/HN03b; P, F, Al,
Fe, Mn
Raw unfiltered sample; pH,
Cl, N03, Ca, Si, DOC, DIG,
K, Na, Mg, S04, ANC,
specific conductance
Raw unfiltered sample; same
as above
b.
Filtered, pH <2 w/HN03
Pb, Cd, Ni, Mn, and Cu
Syringe-filtered, pH <2
w/HN03D; Pb, Cd, Ni, Mn,
and Cu
250 mL unpreserved sample
filtered, filter stored at
-20°C in dark; chloro-
phyll a
Oak Ridge
National
Laboratory
(Tennessee)
c Chlorophyll
audit and
referee sam-
ples only
250 mL unpreserved sample
filtered, filter stored
at -20°C in dark;
chlorophyll a
(continued)
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TABLE 4-2. (Continued)
Destination Containera
Number
Processing; Analytes
Academy of
Natural
Sciences of
Philadelphia
(Pennsylvania)
Environmental
Monitoring
Sytems Labora-
tory - Las Vegas
(EMSL-LV)
(Nevada)
EMSL-LV
EMSL-LV
3x250 mL, DIW
Glass
125 mL (in
HC1-washed
bottle)
60-125 mL, AW
30 mL, AW
clear poly-
ethene
Zooplankton
samples (3 tows
per lake) no
true duplicates,
no blanks or
audits
All samples
Anoxics study
sample
maximum 10
per batch
Filtered (net tow), pre-
served with 4 percent
formal in/sucrose;
zooplankton
Unfiltered, pH < 2
w/H2S04d; total N and
total P
Syringe-filtered, pH <2
w/HN03D; Fe and Mn
Filtered, pH <2 w/HN03
32 elements
b.
aAW = acid-washed container DI = deionized water-washed container.
b!2M nitric acid, Baker Ultrex grade or equivalent.
container not applicable. Chlorphyll samples are contained on a polycarbonate
filter.
dl8M sulfuric acid, Baker Ultrex grade or equivalent.
Three notes on aliquots are necessary. First, although Aliquot 1 was
always preserved with nitric acid during the NSWS, many researchers have found
that preservation is not absolutely necessary if analyses are completed within
30 days of sample collection. Second, comparisons of PCV aluminum and Aliquot
2 data indicate the FIA method may replace the aliquot as the preferred
measurement technique (Lewis et a!., 1986). Third, in-house studies have
indicated that the holding time for nitrate and sulfate may be extended to
three weeks if the aliquot is preserved with mercuric chloride (Suarez et al.,
1986).
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4.4 SAMPLE ANALYSIS
The analyses performed for the NSWS are listed in Table 4-3. Of these,
closed system pH, DIG, true color, and turbidity were performed in the mobile
laboratory; PCV aluminum and specific conductance were added later to the
mobile laboratory analyses. The remaining analyses were performed in analytical
laboratories or by special investigators.
In addition to the analyses listed in Table 4-3, other analyses were con-
ducted in conjunction with a single survey or as special interest studies.
These are listed in Table 4-4. As these additional methods are tested and
proven reliable, they will be included in the methods sections of this handbook.
4.5 DATA TRACKING AND RECORDING
Each form used in the NSWS assisted in data tracking or creation of the
final data base. Additional records were maintained to provide a complete
history of the survey and of laboratory operations. While the documentation
scheme should be tailored to the needs of an individual project or data user,
the basics addressed here should be considered. Copies of the forms used in
the NSWS are presented in Appendix D.
Sample tracking or chain-of-custody is needed to ensure the integrity of
the sample, as well as to provide a means of tracing lost or damaged samples.
Tracking is critically important if more than one organization is involved in
sample handling, or if results may be used for litigation purposes> In the
latter case, formal chain-of-custody documents are necessary. In the former
case, multicopy shipping or data forms with provision for inclusion of infor-
mation by both the originator and the recipient may be sufficient. Commercial
carriers generally require additional documentation, including a packing list,
bill of lading, or airbill, copies of which also should be kept.
Samples must be identified uniquely. An identification system can become
quite complex if more than one point in a single water body is sampled, tempo-
rally separate samples are taken from the same location, or multiple samples
are collected from a single location. Additionally, it is important in a
quality assurance program that QA and QC samples be, as far as possible,
indistinguishable from routine samples to the analyst, yet recognizable in the
final data base. In the NSWS, a batch system was used, whereby all samples
processed on a given day were assigned a sequential batch number and a unique,
randomly-selected sample number. Batches were prepared in the processing
laboratory and included routine, duplicate or replicate, blank, and audit
samples. The assigned number was recorded on the sample label and field data
form, in addition.to the primary processing laboratory data form (Form 2, see
Appendix D).
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TABLE 4-3. NATIONAL SURFACE WATER SURVEY STANDARD ANALYSES
Parameter Method
Acidity, alkalinity, and pH
Aluminum, total extractable
Aluminum, total and non-exchangeable
PCV reactive
Ammonium, dissolved
Chloride, Nitrate, and Sulfate
Dissolved Inorganic Carbon and
Dissolved Organic Carbon
Fluoride, dissolved
Metals (AT, Ca, Fe, K, Mg, Mn, Na)
Metals (Ca, Fe, Mg, Mn) (alternate)
pHa closed system
pHa open system
Phosphorus, total
Silica, dissolved
Specific Conductance
True Color
Turbidity
Titration with Gran plot
Extraction with 8-hydroxyquinoline
into MIBK followed by atomic
absorption spectroscopy (AAS)
Flow injection analysis
colorimetry (pyrocatechol violet)
Automated colorimetry (phenate)
Ion chromatograpihy
Instrumental
Ion selective electrode and meter
Atomic absorption spectroscopy
Inductively coupled plasma emission
spectroscopy
pH electrode, meter, and subchamber
pH electrode and meter
Automated colorimetry (phosphomolyb-
date)
Automated colorimetry (molybdate
blue)
Conductivity cell and meter
Comparison to platinum-cobalt color
standards
Instrumental (nephelometer)
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TABLE 4-4. NATIONAL SURFACE WATER SURVEY EXPERIMENTAL OR
SPECIAL STUDY ANALYSES
Parameter Method
Ammonium, dissolved3 Flow injection analysis colorimetry
Chlorophyll a3 Fluorimetric and high performance
liquid chromatographic analysis
Mercury, total Atomic absorption spectroscopy
(cold vapor)
Mercury, total organic Gas chromatography
Methyl Mercury Gas chromatography/Mass spectroscopy
Nitrogen, total3 Flow injection analysis
Indicates method included in this handbook.
Logbooks should be used to maintain complete records of each laboratory
activity. At a minimum, the logbook should contain: batch and sample identi-
fication (ID) instrumentation ID, data, analyst name or ID, calibration
information, all raw data, and complete narrative descriptions of any unusual
circumstances or observations. Logbooks should be checked after completion of
the day's activity, both by the analyst recording the information and by the
laboratory supervisor or QA personnel.
Data are transcribed onto Form 2. Transcribed values should be checked
against logbook entries by the person transcribing the data and by the labora-
tory supervisor or QA personnel. Data also may be entered into a computer-
based data system. Double entry is recommended to guard against transcription
errors.
Verification and validation of the raw data base are covered in detail in
the Handbook of Methods for Acid Deposition Studies, Quality Assurance for
Surface Water Chemistry. Within the laboratory, the following quality control
records should be maintained:
1. Records of audit samples used, tabulation of audit sample analysis
values, and periodic calculation of mean and range (standard devia-
tion) for each analyzed parameter.
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2. Control charts of QC checks for each instrument and periodic computa-
tion of mean, warning limits, and control limits.
3. Periodic determination of detection limits for each instrument.
4. Calculation of percent difference between duplicate analyses of the
same sample and, if samples are identifiable, percent differences
between analyses of the field routine and any replicates.
5. Records of pi pet and balance calibrations (see Appendix C).
6. Records of refrigeraor and freezer temperatures.
7. Records of deionized water system performance and specific conductance,
In addition, it is recommended that the laboratory coordinator or super-
visor maintain a detailed, daily log of all laboratory activities. At a mini-
mum, this log should identify the analysts performing each procedure, describe
any observed problems or successes, and describe any deviations from the pre-
scribed protocols. Changes to protocols should be documented and the protocol
revised after the change has been substantiated as an improvement. For this
reason, all the methods contained in this handbook are identified with a
revision number. Updates to this handbook will be provided as protocols are
revised or new protocols are developed.
4.6 REFERENCES
Lewis, T. E., J. M. Henshaw, and E. M. Heithmar, 1986. A comparison of PCV-
reactive and 8-hydroxyquinoline-extractable aluminum in lake and stream
waters. Presented at the North American Lake Management Society Annual
Meeting. November 3-7, Portland, Oregon.
Suarez, F. X., D. C. Hi 11 man, and E. M. Heithmar, 1986. Stability of nitrate
in preserved and unpreserved natural surface waters. Presented at
the Rocky Mountain Conference on Analytical Chemistry, August 3-5,
Denver, Colorado.
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5.0 DETERMINATION OF ACIDITY, ALKALINITY, AND pH
5.1 OVERVIEW
This procedure is a slight modification of the one used during Phase I of
the National Lake Survey. In this procedure, pH is determined prior to sample
titration rather than during sample titration.
5.1.1 Scope and Application
This procedure is applicable to the determination of pH, acid neutralizing
capacity (ANC), and base neutralizing capacity (BNC) in weakly buffered natural
waters of low ionic strength. The terms ANC and BNC refer to the alkalinity
and acidity of systems which are based on the carbonate ion system. The sol-
uble reacting species are H2C03, HC03~, and C03"^. For calculation purposes,
it is assumed that surface waters are represented by a carbonate ion system;
hence, the ANC and BNC definitions are made in relation to the carbonate ion
species (Kramer, 1982; Butler, 1982).
This method is applicable to ANC in the range of 10 to 150 ueq L~l, BNC
in the range of -100 to 1,000 ueq L'1 and pH in the range of 3-8 pH units.
5.1.2 Summary of Method
The pH is determined prior to the start of sample titration. The same
electrode used during titration is used to measure initial pH (U.S. EPA,
1983; McQuaker et al., 1983; NBS, 1982). While pH is monitored and recorded,
samples are titrated with standardized acid or base.
ANC and BNC are determined by analyzing the titration data using a
modified Gran analysis technique (Kramer, 1982; Butler, 1982; Kramer, 1984;
Gran, 1952). The Gran analysis technique defines the Gran functions FI and £3,
which are calculated from sample volume, acid (base) volume added, and con-
stants. The Gran function is calculated for several titration data pairs
(volume of titrant added, resulting pH) on either side of the equivalence
point. When the Gran function is plotted versus volume of titrant added, a
linear curve is obtained. The equivalent point can be interpolated from where
the line crosses the volume axis.
The air-equilibrated pH is determined after equilibrating the sample
with 300 ppm C02 in air. Air equilibration is expected to normalize pH values
by factoring out the day-to-day and seasonal fluctuations in dissolved
concentrations.
5.1.3 Interferences
No interferences are known.
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5.1.4 Safety
The standards, sample types, and most reagents pose no hazard to the
analyst. Protective clothing (lab coat, gloves, and safety glasses) should be
used when handling concentrated acids and bases.
Gas cylinders should be secured in an upright position.
5.2 SAMPLE COLLECTION, PRESERVATION, AND STORAGE
The sample for which ANC, BNC, and pH are to be determined is raw sample
(not filtered or chemically preserved) stored in a 500-mL amber polyethylene
bottle. The bottle should be completely filled to eliminate headspace. Only
deionized water-washed containers should be used to collect and store the
sample. Store at 4 °C and minimize atmosphere exposure.
5.3 EQUIPMENT AND SUPPLIES
5.3.1 Equipment Specifications
1.
2.
3.
pH/mV MeterA digital pH/mV meter capable of measuring pH to ±0.01 pH
unit, potential to ±1 mV, and temperature to ±0.5 ?C is required. The
meter should also have automatic temperature compensation capability.
pH ElectrodesHigh-quality, low-sodium glass pH and reference elec-
trodes should be used. (Gel-type reference electrodes should not be
used.) A combination electrode is recommended (such as the Orion Ross
combination pH electrode or equivalent). This procedure is written
assuming a combination electrode is used.
BuretA microburet capable of precisely and accurately delivering 10
to 50 uL is required (relative error and standard deviation less than
0.5 percent).
5.3.2 Apparatus
1. Teflon-coated stir bars.
2. Variable-speed magnetic stirrer.
3. Plastic gas dispersion tube.
NOTE: A glass dispersion tube should not be used because it can add
ANC to a sample. Plastic dispersion tubes are available in
most aquarium supply stores.
4. Titration SystemA commercial titration instrument may be used in
place of the pH/mV meter, pH electrode, and buret if the instrument
meets all required specifications.
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5.3.3 Reagents and Consumable Materials
1. Carbon Dioxide Gas (300 ppm C0£ in Air)Certified standard grade or
better.
2. Hydrochloric Acid Titrant (0.01N HC1)Add 0.8 ml concentrated hydro-
chloric acid (HC1, 12N, ACS reagent grade or equivalent) to 500 mL
water, then dilute to 1.00 L with water. Standardize as described in
Section 5.4.1. Store in a clean polyethylene bottle. Although
stable, it should be restandardized monthly.
3. Nitrogen Gas (N2)~C02-free.
4. Potassium Chloride Solution (0.10M KC1) Dissolve 75 g KC1 (Alfa
Ultrapure or equivalent) in water, then dilute to 1.00 L with water.
5. Potassium Hydrogen Phthalate (KHP)Dry 5 to 10 g KHP (ACS-certified
primary standard grade or equivalent) at 110 °C for 2 hours, then
store in a desiccator.
6. pH Calibration Buffers (pH 4, 7, and 10)NBS-traceable pH buffers at
pH values of 4, 7, and 10.
7. pH 4 QC sample--Dilute 1.00 mL standardized 0.01N HC1 titrant to
100.00 ml with water (prepare daily). The theoretical pH is
calculated by:
/,
NHCI
pH = -log I-
\100
8. pH 10 QC sampleDilute 1.0.0 ml standardized 0.01N MaOH titrant to
100.00 mL with water (prepare daily). The theoretical pH is
calculated by:
A
NNaOH
pH = -log I
\ 100
9. Sodium Carbonate (Na2C03)~Dry 5 to 10 g Na2C03 (ACS-certified primary
standard grade or equivalent) at 110 °C for 2 hours, then store in a
desiccator.
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10.
11.
12.
Sodium Hydroxide Stock Solution (50 percent w/v NaOH)Dissolve 100 g
NaOH (ACS reagent grade or equivalent) in 100 mL water. After cooling
solution and allowing precipitate to settle (may'be hastened by centri-
fugation), transfer the supernatant to a linear polyethylene or Teflon
container. Store bottle tightly capped and avoid exposing solution to
the atmosphere.
Sodium Hydroxide Titrant (0.01N NaOH)Dilute 0.6 to 0.7 ml 50 per-
cent NaOH to 1.0 L with water. Standardize as described in Section
5.4.2. Store in linear polyethylene or Teflon container with a C0£-
free atmosphere (e.g., under C02~free air, nitrogen, or argon).
WateiAt the point of use, water used to prepare reagents and stan-
dards should conform to ASTM specifications'for Type I reagent grade
water (ASTM, 1984). ,
5.4 PREPARATION
5.4.1 Standardization of HC1 Titrant
1. Weigh about 1 g anhydrous Na2C03 to the nearest 0.1 mg, dissolve
in water, then dilute to 1.000 L. Calculate the concentration by:
NNa2C03 =
wt.
106.00 g 1 mole
mole 2 eq
1 L
NOTE: Fresh Na2C03 solution is to be prepared just before use.
2. Calibrate the pH meter and electrode as recommended by the
manufacturer.
3. Pi pet 1.00 ml standard Na2C03, 4.00 ml l.OM KC1 , plus 36.00 ml
free deionized water into a clean, dry titration vessel. Add a
Teflon stir bar and stir at medium speed (no visible vortex).
4. Immerse the pH electrode and record the pH when a stable reading is
obtained.
5. Add a known volume of the HC1 titrant and record the pH when a stable
reading is obtained. Use the following table as a guide to the
volume of titrant that should be added for each pH range:
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Maximum Volume Increment
.- pH of HC1 Titrant (ml)
>7.5 0.2
4 to 7.5 .0.1
<4 0.2
Continue the titration until the pH is less than 4. Obtain at least
seven data points in the range pH 4 to 7.
6. Calculate F^ for each data pair (volume acid added, pH) with pH in the
range 4 to 7:
/' \
Flb = (V. + V) ^ I 1 1+ ~ [H+]
(vs + v)
vsc
(Vs + V)
(
[H+]2 +
N
i O [/ ]/
1 1 2,
where
= Gran function
Vs = initial sample volume (40.00 ml)
V = volume of HC1 added (ml)
C = NNa2C03/(2 x dilution factor)
Ki = 7.079 x 10~7 (25 °C, 0.1 ionic strength, Butler, 1982)
Ko = 1.202 x 10~10 (25 °C, 0.1 ionic strength, Butler, 1982)
K^ = 1.660 x 10"14 (25 °C, 0.1 ionic strength, Butler, 1982)
7. Plot Fib versus V. Using the points on the linear portion of the plot,
perform a linear regression of Fib on v to obtain the coefficients of
the line Fib = a + bV. The correlation coefficient should exceed
0.999. If it does not, reexamine the plot to make sure only points
on the linear portion are used in the linear regression.
8. Calculate the equivalence volume, YI, by:
YI = -a/b
Then calculate the HC1 normality by:
NNa2C03 x vNa2C03
NHCI = * ~
Vl
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9. Perform steps 5 through 8 two more times. Calculate an average NHCI
and standard deviation. The percent relative standard deviation
(%RSD) should be less than 2 percent. If it is not, the entire stan-
dardization should be repeated until the %RSD is less than 2 percent.
The concentration of each new batch of HC1 titrant should be cross-
checked using the procedure described in Section 5.4.3.
NOTE: An example of an HC1 standardization is given in Appendix E,
Section 1.0.
5.4.2 Initial Standardization of NaOH Titrant with KHP
Every batch of NaOH titrant is initially standardized against KHP (see
below) and the standardization is crosschecked against standardized HC1
titrant (Section 5.4.3). Thereafter, it is restandardized daily against the
HC1 titrant (Section 5.4.4).
1. Weigh about 0.2 g KHP to the nearest 0.1 mg, dissolve in water, then
dilute to 1.000 L. Calculate the normality of the solution by:
wt. KHP g 1
NKHP = x
204.22 g 1 L
eq
2. Calibrate the pH electrode and meter as recommended by the
manufacturer.
3. Purge the titration vessel with C02~free nitrogen, then pipet 5.00 ml
standard KHP solution, 2.00 ml l.OM KC1, and 18.00 ml C02-free water
into the vessel. Maintain a C02~free atmosphere above the sample
throughout the titration. Add a Teflon stir bar and stir at medium
speed (no visible vortex).
4. Immerse the pH electrode and record the reading when it stabilizes.
5. Titrate with the 0.01N NaOH using the increments specified in the
table below. Record the volume and pH (when stable) between addi-
tions. Continue the titration until the pH is greater than 10.
Obtain at least four data points in the pH range 5 to 7 and four data
points in the pH range 7 to 10.
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pH
<5
5 to 9
>9
Maximum Volume Increment of
NaOH Titrant (ml)
0.10
0.05
0.2
6. Calculate F^b for eacn data Pai'r (volume acid added, pH) that has
a pH greater than 9 by:
F3b =
where
v
v
+ 2 [H+]2
(v + v)
[H+]2
+ IH+] -
K,.
= Gran function
= initial sample volume (20.00 ml)
V = volume NaOH added (ml)
C = NKHP corrected for initial dilution = NKHP/E!
[H+] = 10-PH
= 1.3 x 10'
K;
K,
w
= 3*.9 x 10"6 iyi
1.660 x 10~M
Plot Fsb versus V. Using the points on the linear portion of the plot,
perform a linear regression of f^ on V to obtain the coefficients of
the line F^ = a + bV. The correlation coefficient should exceed
0.999. If it does not, examine the plot to ensure that only points on
the linear portion are used in the linear regression.
8
Calculate the equivalence volume, V3, by:
V3 = -a/b
Then calculate the NaOH normality by:
; NKHP x VKHP
NNaOH =
9. Perform steps 5 through 8 two more times. Calculate an average NNaOH
and standard deviation. The %RSD should be less than 2 percent. If it is
not, the entire standardization should be repeated until the %RSD is less
than 2 percent.
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NOTE: An example of an NaOH standardization is given in Appendix E
Section 2.0.
5.4.3 NaOH-HCl Standardization Crosscheck
1. Purge a titration vessel with C02~free nitrogen, then pipet 0.500 ml
0.01N NaOH, 2.50 ml l.OM KC1, and 22.00 ml C02-free water into the
vessel. Maintain a C02~free atmosphere above the sample. Add a
Teflon stir bar and stir at medium speed.
2. Immerse the pH electrode and record the reading when it stabilizes.
3. Titrate with the standardized 0.01N HC1 using the increments specified
in the table below. Record the volume and pH (when stable) between
additions. Continue the titration until the pH is less than 3.5.
Obtain at least seven data points in the pH range 4 to 10.
pH
4 to 10
<4
Maximum Volume Increment of
HC1 Titrant (ml)
0.2
0.05
0.2
4. Calculate FI for each data pair (V, pH) that has a pH in the range 4
to 10 by:
+ V)
- EH+]
where
Vs
5.
= Gran function
= initial sample volume (25.5 mL)
= volume of HC1 added (mL)
= 1.660 x 10~14
Plot FI versus V. Using the points on the linear portion of the plot,
perform a linear regression of FI on V to obtain the coefficients of
the line FI = a + bV. The correlation coefficient should exceed
0.999. If it does not, reexamine the plot to ensure that only points
on the linear portion are used in the linear regression.
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6. Calculate the equivalence volume, YI, by:
YI = -a/b
Then calculate the HC1 normality (designated as N'nci) by:
NNaOH x vNaOH
N'HCl = -
Vl
where
VNaOH = 0.500
7. Calculate the absolute relative percent difference (RPD) between
and NHCI by:
N'HCl -
RPD
0.5 (N'HCl
x 100
The absolute RPD should be less than 5 percent. If it is not, a problem
exists in the acid or the base standardization or both (bad reagents,
out-of-'calibration burets). The problem should be identified and both
procedures (standardization of HC1 titrant and standardization of NaOH
titrant) should be repeated until the calculated RPD is less than
5 percent.
NOTE: An example of an NaOH-HCl standardization crosscheck is given
in Appendix E, Section 3.0.
5.4.4 Daily NaOH Standardization with Standardized HC1
1. Calibrate the pH meter and electrode as recommended by the
manufacturer.
2. Purge the titration vessel with C02~free nitrogen, then pipet 0.500 ml
NaOH titrant, 2.50 ml l.OM KC1, and 22.00 mL C02~free deionized
water into the vessel. Maintain a C02-free nitrogen atmosphere above
the sample. (Smaller or larger volumes of NaOH may be used. A known
volume of C02~free water should be added to bring solution to
25.00 ml). Add a Teflon stir bar and stir at medium speed.
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3. Immerse the pH electrode and record the reading when it stabilizes.
4. Titrate with the standardized HC1 titrant using the increments speci-
fied in the table below. Record the volume and pH between additions.
Continue the titration until the pH is less than 4. Obtain at least
seven data points in the pH range 4 to 10.
PH
4 to 10
<4
Maximum Volume Increment of
HC1 Titrant (ml)
0.2
0.05
0.2
5. Calculate FI for each data pair (volume acid added, pH) in the pH
range 4 to 10 by:
= (Vs + V)
where
VS
Gran function
initial sample volume (25.00 mL)
volume of HC1 added (mL)
1.660 x 10~14
KTPH
6. Plot FI versus V. Using the points on the linear portion of the plot,
perform a linear regression of FI on V to obtain the coefficients of
the line FI = a + bV. The correlation coefficient should exceed
0.999. If it does not, reexamine the plot to make sure that only
points on the linear portion are used in the linear regression.
7. Calculate the equivalence volume, Vj, by:
Vi = -a/b
Then calculate the NaOH normality by:
NHC1 x V,
NNaOH =
vNaOH
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8 Perform, steps 4 through 7 two more times. Calculate an average NNaOH
and standard deviation. The %RSD should be less than 2 percent If
it is not, the entire standardization should be repeated until the RSD
is less than 2 percent. ;
Because the NaOH titrant can readily deteriorate through eixposure^to the
air every effort should be made to prevent its exposure to the air at all
times Furthermore, it should be standardized daily or before every major
work shift. Store in a linear polyethylene or Teflon container with a
C02-free atmosphere (e.g., under C02-free air, nitrogen,-or argon).
NOTE: An example of daily NaOH standardization is given in Appendix E,
Section 4.0.
5.4.5 Rigorous Calibration and Characterization of Electrodes
Seoarate electrodes should be used for the acid and base titration. Each
new electrode pair should be rigorously evaluated for Nernstian response, using
the rigorous calibration procedure described below, prior to analyzing samples.
Also it familiarizes the 'analyst with the electrode's characteristic response
time After the initial electrode evaluation, the electrodes are calibrated
daily using the procedure in the daily calibration procedure described in
Section 5.4.6.
1 Following the manufacturer's instructions, calibrate the electrode and
meter used for acid titrations with pH 7 and 4 buffer solutions, and
calibrate the electrode used for base titrations with pH 7 and 10
buffer solutions.
2 Prepare a blank solution by pipetting 45.00 ml C02-free water and
5.0 ml l.OM KC1 into a titration ves.sel. Add a Teflon stir bar and
stir at medium speed using a magnetic stirrer.
3 Titrate the blank with standardized 0.01N HC1 using the increments
specified below. Continue the titration until the pH is in the range
3 3 to 3.5. Record the pH between each addition, noting the time
required'for stabilization. Obtain at least seven data points that
have a pH less than 4.
Maximum Volume Increment of
pH HC1 Titrant (ml) ;
>4 0.050
<4 . 0.3
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4. Prepare a fresh aliquot of water and l.OM KC1 as in step 2.
5' ManST a.C°2;free atmosphere, titrate the blank with standardized 0.01N
NaOH using the increments specified below:
PH
Maximum Volume Increment of
NaOH Titrant (mL)
0.10
0.20
6> p±^!h^!:a!i?n.^n^e.PH isJn ?* range 10.5 to 11.
at least 10
7. For each titration, calculate the pH for each data point by:
pH = -log [H+] . . . . .
where, for acid titration:
VA CA
CH+] =
VA
and for base titration:
CH+] =
\w
and where
VA =
CA -
Vs
Kw =
VB
B
acid volume (mL)
HC1 concentration (eq I'1)
sample volume (50.0 mL)
1.660 x 10~14
base volume (mL)
NaOH concentration (eq L""1)
8.
For each titration, plot the measured pH versus the calculated pH
(designated as pH*). Perform a linear regression on each plot to
obtain the coefficients of the line pH = a + b(pH*). The plots should
be linear with b = 1.00 ± 0.05 and r > 0.999. Typically some
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nonlinearity exists in the pH region 6 to 8. This is most likely due
to small errors in titrant standardization, impure salt solutions, or
atmospheric C02 contamination. The nonlinear points should not be
used in the linear regression.
If the plots are not linear and do not meet the specifications above,
the electrode should be considered suspect. The electrode character-
ization should then be repeated. If results are still unacceptable,
the electrode should be replaced.
9 Combine the data from both titrations and perform a linear least-
squares analysis on the combined data to obtain new estimates for the
coefficients of pH = a + b(pH*). The electrodes are now calibrated.
Do not move any controls on the meter.
The plots for both titrations should be coincident. If the two plots
are not coincident (i.e., the coefficients a and b do not overlap),
the characterization should be repeated. If the plots are still not
coincident, the electrode should be replaced.
5.4.6 Daily Calibration and Characterization of Electrodes
Generally, the calibration curve prepared during the rigorous calibration
procedure is stable from day to day. This daily calibration is designed to
verify the calibration on a day-to-day basis.
1 Copiously rinse the electrode with water. Immerse the electrode in
20 ml pH 7 buffer and stir for 1 to 2 minutes. Discard the buffer and
replace with 40 ml pH 7 buffer. While the solution is stirred gently,
measure the pH. Adjust the pH meter calibration knob until the pH is
equal to the theoretical pH of the buffer. Record the theoretical pH
and the final, measured pH reading. The two values should be
identical.
2 Copiously rinse the electrode with water. Immerse it in 20-mL pH 4 QC
sample and stir for 1 to 2 minutes. Discard the sample and replace
with 40-mL pH 4 QC sample. While the solution is stirred, measure and
record the pH. From the calibration curve of pH versus pH*, determine
the pH* for the observed pH. Compare pH* to the theoretical pH of the
QC sample. The two values should agree within ±0.05 pH unit. If the
two values do not agree, the rigorous calibration procedure .should be
performed (Section 5.4.5) prior to sample analysis.
3 Repeat step 2 with the pH 10 QC sample. This sample should be kept
under a C02-free atmosphere when in use, or acceptable results may not
be obtained.
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The electrode calibration procedure is described in detail in Section
5.0 of Appendix E.
5.5 PROCEDURE
An acid titration (Section 5.5.1) and a base titration (Section 552) are
necessary to determine the BNC and ANC of a sample. As part of each titration
the sample pH is determined. The air-equilibrated pH is determined in a
separate sample portion (Section 5.5.3).
5.5.1 Acid Titration
1. Allow a sealed sample to reach ambient temperature.
2. Copiously rinse the electrode with deionized water, then immerse in 10
to 20 ml of sample. Stir for 30 to 60 seconds.
3.
4.
5.
6.
Pi pet 36.00 ml of sample into a clean, dry titration flask. Add a
clean Teflon stir bar and place flask on a magnetic stirrer. Stir
at medium speed (no visible vortex).
Immerse the pH electrode and read pH. Record pH on forms similar to
Forms 11 and 13 (Appendix D) when the reading stabilizes (1 to 2
minutes). This is the initial measured pH at Vtl-trant = 0.
Add 4.00 ml l.OM KC1. Read pH and record the value on Form 13.
This is the initial measured pH at Vt1trant = 0 after addition of KC1
spike.
Add increments of 0.01N HC1 as specified in the table below. Record
the volume of HC1 added, and record the pH when a stable reading is
obtained. Adjust the volume increment of titrant so that readings can
be taken at pH values of 4.5 and 4.2. Continue the titration until
the pH is between 3.3 and 3.5. Obtain at least six data points be-
tween a pH of 4.5 and 5.5 and at least six that have a pH less than 4.
pH
>9 '
7.0 to 9.0
5.5 to 7.0
4.5 to 5.5
4.50 to 3.75
<3.75
Maximum Volume Increment of
HC1 Titrant (mL)
0.1
0.025
0.1
0.05
0.1
0.3
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5.5.2 Base Titration
1. Take a portion of the sample for dissolved inorganic carbon (DIC)
determination. If the DIC is not determined immediately, the sample
should be kept sealed from the atmosphere and stored at 4 °C. A simple
way to do this is to withdraw the sample for DIC using a syringe
equipped with a syringe valve. By closing the valve, the sample is
sealed from the atmosphere (syringe valves that fit standard Luer-Lok
syringes are available from most chromatography supply companies).
2. Purge the titration vessel with C02~free air, nitrogen, or argon.
3. Copiously rinse the electrode with deioni zed water, then immerse
it in 10 to 20 ml of sample for 30 to 60 seconds.
4. Pipet .36.00 ml of sample into the C02-free titration vessel. Maintain
a C02~free atmosphere above the sample. Do not bubble the nitrogen
(or other C02~free gas) through the sample. Add a clean Teflon stir
bar and place on a magnetic stirrer. Stir at medium speed (no visible
vortex).
5. Immerse the pH electrode, read pH, and record pH on forms similar to
Forms 11 and 13 (Appendix D) when the pH stabilizes. This is the
initial measured pH at V-titr&nt = 0.
6. Add 4.0 mL l.OM KC1 . Read pH, and record pH on Form 13.
7. Add 0.025 ml of 0.01N NaOH. Record the NaOH volume and pH when it
stabilizes. Continue the titration by adding increments of NaOH as
specified below until the pH is greater than 11. Record the volume of
NaOH added and the pH after each addition. Obtain at least 6 data
points in the pH region 7 to 9 and at least 6 with a pH greater
than 10. If the initial sample pH is less than 7, obtain at least
five data points below pH 8.
Maximum Volume Increment of
pH NaOH Titrant (ml) __
<5 0.025
5 to 7 0.050
7 to 9 0.025
9 to 10 0.10
10 to 10.5 0.30
>10.5 1.00
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4.
5.
5.5.3 Air-Equilibrated pH Measurement
1. Allow the sealed sample to reach ambient temperature.
2. Copiously rinse the electrode with deionized water, then immerse in 10
to 20 ml of sample. Stir for 30 to 60 seconds.
3. Pipet 20 to 40 ml of sample into a clean, dry titration flask. Add a
clean Teflon stir bar and place flask on a magnetic stirrer. Stir
at a medium speed. .
Bubble standard gas containing 300 ppm C02 through the sample for
20 minutes. Raise gas tube above the liquid surface to maintain
atmosphere above sample. Measure and record the pH.
While maintaining 300 ppm COg atmosphere, take a subsample for DIG
determination. The subsample should be kept sealed from the
atmosphere prior to analysis. The DIG should be measured as soon as
possible (see Section 14.5.2).
5.5.4 Calculations
During the titrations, any substance which reacts with the acid or base
is titrated. However, for calculations, it is assumed that the samples repre-
sent_carbonate_systems and that the only reacting species are H+, OH", H2COo,
HC03 , and COo" . Using this assumption, the two parameters "ANC" (ANC) and
C02-BNC' (BNC) are calculated. The validity of the assumption is checked as
described in previous sections.
The theory behind the calculations is available elsewhere (Kramer, 1982-
Butler, 1982; Kramer, 1984). Examples of the calculations are given in
Appendix E.
1. Initial Calculations-
a.
From the calibration curve of measured pH versus calculated pH
(pH*), determine pH* for each pH value obtained during both the
acid and base titrations. Next, convert all pH* values to
hydrogen ion concentrations by:
b.
Using the acid titration data, calculate the Gran function
Fla for each data pair (Va, pH*) in which pH* is less than 4 by:
"la
= (V. + VJ [H+]
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where
V,. = total initial sample volume (36.00 + 4.00) ml
Va = cumulative volume of acid titrant added
c. Plot Fia versus Va. The data should be on a straight line with
the equation Fia = a + bV.
d. Perform a linear regression of Fla on Va to determine the
correlation coefficient (r) and the coefficients a and b. The
coefficient r should exceed 0.999. If it does not, examine the
data to ensure that only data on the linear portion of the plot
were used in the regression. If any outliers are detected,
repeat the regression analysis. Calculate an initial estimate ot
the equivalence volume (Vj) by:
Vi = -a/b
Further calculations are based on this initial estimate of YI and the
initial sample pH*. Table 5-1 lists the appropriate calculation
procedure for the different combinations of V; and initial sample
pH*. These calculation procedures are given in steps 2 through 4.
NOTE: For blank analyses, calculate ANC by:
where
Ca = concentration of acid titrant
Vsa = original sample volume (acid titration)
Further calculations are not necessary.
Throughout the calculations, Equations 5-1 and 5-2 (given in step 2),
as well as the constants listed in Table 5-2, are used frequently.
2. Calculation Procedure A (Initial YI <0)
a From the base titration data, determine which data set (V,_pH*)
has the pH* nearest (but not exceeding) pHe2 (calculate using
Equation 5-4). As an initial estimate, set the equivalence
volume (V2) equal to the volume recorded for this data set.
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Sample Description
,..., ,, Calculation
Initial Vx Initial pH*a Procedure
Step
Number
<0 A ..,. 2
>0 1PH62 B 3
>0 >PH62 C 4
SSSS = = ===s = - = - = s= = = = ___ ^
apHe2 is calculated using
Flc = (Vs + V)
F2c = (Vs + V)
Equation 5-4.
CfCrtj + 2 KXK2) Kw
CH+]2 + [H+jKj + KiK2 [H+]
C([H+]2 - K,KP) K
i [ll+]
CH+]2 + [H+lKi + K:K2 L" [H+]
(5-1)
(5-2)
pHei = -log(Hel)
(5-3)
""el
(DIC)Kj
12,011
1/2
= -log(He2)
(5-4)
He2 =
KlKw
12,01]
*-
DIG
1/2
(5-5)
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TABLE 5-2. CONSTANTS AND VARIABLE DESCRIPTIONS
Vs = total initial sample volume
V = cumulative volume of titrant added
C = total carbonate expressed in moles L"1
[H+] = hydrogen ion concentration
Kj_ = 7.079 x 10~7 at 25 °C and 0.1M ionic strength (Butler, 1982)
K2 = 1.202 x 10"10 at 25 °C and 0.1M ionic strength
K,, = 1.660 x 10"14 at 25 °C and 0.1M ionic strength
W
b. Calculate initial estimates of ANC, BNC, and C by:
ANC =
Vsa
BNC =
Vsb
C = ANC + BNC
where
Ca = concentration of acid titrant
Vsa = original sample volume (acid titration)
Ct, = concentration of base titrant
vsb = original sample volume (base titration}
c. Estimate the equivalence point pHei using Equation 5-3. Calcu-
late the Gran function FIC for seven to eight points of the base
titration with pH* spanning pHei using Equation 5-1. Plot FIC
versus Vfo. Perform a linear regression with the points lying on
the linear portion of the plot. Determine the coefficients of
the line F]_c = a + bV. The coefficient r should exceed 0.999.
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If it does not, examine the plot to assure that only points on
the linear portion are used. From the coefficients, calculate a
new estimate of YI by:
Vi = -a/b
d. Calculate the Gran function F2C (Equation 5-2) for data from the
base titration across the current estimate of V2- (Use the
first four to six sets that have a volume less than V2 and the
first six to eight sets greater than V2-) Plot F2C versus Vb.
The data should lie on a straight line with the equation
F2C = a + bV. Perform a linear regression of F2C on Vb and
determine the coefficients of the line. If r does not exceed
0.999, reexamine the data to assure that only points on the
linear portion were used in the regression. Calculate a new
estimate of V2 by:
V2 = -a/b
e. Calculate new estimates of ANC, BNC, and C using the new esti-
mates of Vi and V2 (an asterisk indicates a new value) by:
-VlCb
Vsb
ANC* =
BNC* =
Vsb
C* = ANC + BNC
If C* < 0, then set C* = 0.
f. Compare the latest two,values for total carbonate. If:
C - C*
C + C*
then calculate a new estimate for C by:
C(new)' = (,C + C*)/2 "
g. Using the new value for C, repeat the calculations as above.
Continue repeating the calculations until the relative difference
between C and C* is less than 0.001.
> 0.001
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h. When the expression is less than 0.001, convert the final
values for ANC, BNC, and C to Meq L-i by: ,
ANC (Meq L'1) = ANC (eq L'1) x 106
BNC (Meq L-l) = BNC (eq L'1) x 106
C (Meq I'1) = C (eq I'*) x 106
3. Calculation Procedure B (Initial Yj. >0, Initial pH* <,pHe2)--
a. From the base titration data, determine which data set (V, pH*)
has the pH* nearest, but not exceeding, pHe2 (calculate using
Equation 5-4). As an initial estimate, set the equivalence
volume V2 equal to the volume recorded for this data set. Next
calculate initial estimates of ANC, BNC, and C by:
Calculate the Gran function FIC (Equation 5-1) for data sets from
the acid titration with volumes across the current estimate of YI
(use the first four to six sets with volumes less than Vj. and the
first six to eight sets with volumes greater than YI). Plot FIC
versus Va. The data should lie on a straight line with the equa-
tion FIC = a + bV. Perform a linear regression of FIC on Va and
determine the coefficients of the line. If r does not exceed
0.999, reexamine the data to assure that no outliers were used in
the regression. Calculate a new estimate for YI by:
YI = -a/b
Calculate the Gran function F2c (Equation 5-2) for data sets from
the base titration with volumes across the current estimate of
V2. (Use the first four to six sets with volumes less than V2
and the first six to eight sets with volumes greater than V2).
Plot F2c versus Vb. The data should lie on a straight line with
the equation:
F2c = a + bV.
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Perform a linear regression of F2c on Vb and determine the coeffi-
cients of the line. If r does not exceed 0.999, reexamine the data
to assure that only data on the linear portion 'were included in the
regression. Calculate a new estimate for V2 by:
d.
vsa
V2 = -a/b
Calculate new estimates of ANC, BNC, and C using the latest
estimates of V^ and V2 by:
ANC* =
BNC* =
C* = ANC + BNC
e. Compare the latest two values for total carbonate. If:
C - C*
C + C*
then calculate a new estimate of C by:
C(new) = (C + C*)/2
f. Using the new value of C, repeat the calculations as above.
Continue repeating the calculations until the above expression is
less than 0.001.
g. When the expression is less than 0.001, convert the final values
for ANC, BNC, and C to ueq L-1 by:
ANC (ueq I"1) = ANC (eq L'1) x 106
BNC (ueq l~i) = BNC (eq L~l) x 106
C (ueq L'1) = C (eq L"1) x 106
> 0.001
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4. Calculation Procedure C (Initial Vj >0, Initial pH* > pHe2)
a. Using data sets from the acid titration with pH* values above and
below pH 7 (use four to six sets with a pH* £7 and four to six
sets with a pH* >_7), calculate the Gran function F2a by:
F2a - (Vl - Va)H
b. Plot F2a versus Va. The data should lie on a straight line with
the equation F2a = a + bv- Perform a linear regression of F2a
on Va. The coefficient r should exceed 0.999. If it does not,
reexamine the plot to assure that only data on the linear portion
were used in the calculation. Calculate an estimate for V2 by:
V2 = -a/b
c. Calculate estimates of ANC, BNC, and C by:
Calculate the Gran function FIC (Equation 5-1) for data sets from
the acid titration with volumes across the current estimate of YI
(use the first four to six sets with volume less than V^ and the
first six to eight sets with volumes greater than V^). Plot FIC
versus Va. The data should lie on a straight line with the
equation FIC = a + bV. Perform a linear regression of FIC on Va
and determine the coefficients of the line. The coefficient r
should exceed 0.999. If it does not, reexamine the plot to
assure that only data on the linear portion were included in the
regression. Calculate a new estimate for V^ by:
YI = -a/b.
Calculate the Gran function F2c (Equation 5-2) for data sets from
the acid titration with volumes across the current estimate of V2
(use the first four to six sets with volumes less than V2 and the
first six to eight sets with volumes greater than V2). Plot F2c
versus Va. The data should lie on a straight line with the equa-
tion F2c = a + bV. Perform a linear regression of F2c on Va and
determine the coefficients of the line. The coefficient r should
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f.
Section 5.0
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exceed 0.999. If it does not, reexamine the plot to assure that
only data on the linear portion were included in the regression
Calculate a new estimate of V2 by:
V2 = -a/b.
If V2 <0, use calculation procedure B (step 3).
Calculate new estimates of ANC, BNC, and C using the latest
estimates of V]^ and V2:
ANC* =
BNC* =
sa
> 0.001
Vsa
C* = ANC + BNC
g. Compare the latest two values for total carbonate. If:
C - C*
C + C*
then calculate a new estimate of C by:
C(new) = (C + C*)/2
h. Using this new value of C, repeat the calculations in step 4,
b through d. Continue repeating the calculations until the above
expression is less than 0.001.
i. When the expression is less than 0.001, convert the final values
for ANC, BNC, and C to ueq L'1 by:
ANC (ueq L'1) = ANC (eq L-1) x 106
BNC (ueq I"1) = BNC (eq I'1) x 106
C (ueq L-l) = C (eq L'1) x 106
C* = ANC + BNC
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5.6 QUALITY ASSURANCE AND QUALITY CONTROL
5.6.1 Comparison of Initial Titration pH Values
The values for measured pH at Vtl-trant = 0 (before KC1 spike) of the acid
and base titrations should be within ±0.1 pH unit. If they are not, check
operation to ensure that cross-contamination is not occurring.
For a sample with ANC £ -15 ueq L"1, calculate a value for ANC as follows:
[ANC]CO = 105 x 10~PH* (pH at V=0)
(The pH at Vtjtrant = 0 is taken from the acid titration.) If ANC differs
from [ANC]CO by more than 10 ueq L , check the electrode operation and
calibration.
5.6.2 Comparison of Calculated ANC and Measured ANC
A value for ANC can be calculated from a sample's DIC concentration and
pH. Two sets of pH and DIC values are obtained in the lab: (1) pH* at V=0 of
the base titration and the associated DIC concentration, and (2) pH of the
air-equilibrated sample and the associated DIC concentration. Each set can be
used to calculate a value for ANC. Since ANC is a conservative parameter
(i.e., constant with changing dissolved COg concentrations), the two values
should be equal. The calculated values for ANC can also be compared to the
measured value of ANC. The comparisons are useful in checking both the
validity of assuming a carbonate system and the possibility of analytical
error. ANC is calculated from pH and DIC as follows:
[ANClci = calculated ANC from initial pH and DIC at time of base
titration
[ANC]Q2 - calculated ANC from air-equilibrated pH and DIC^
nip / r u"*" ~ii/ _i_ o i/ !/ \ v
U1U / Ln Jl\i + c. l\il\9 \ Jv
11
[ANC]C (ueq L"1) =
where
12,011
'W
EH+:
x 10C
DIC =
[H+] =
Ki =
K
w
DIC in mg L~l (the factor 12,011 converts mg L"1 to
moles L~M
10-PH
7.0795 x 10~( at 25 °C, 0.1M ionic strength
1.2023 x 10"J" at 25 °C, 0.1M ionic strength
1.6596 x 10"14 at 25 °C, 0.1M ionic strength
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[ANC]ci and [ANC]c2 are compared as follows:
For [ANC]C1 £ 100 ueq L"1, the following condition applies;
[ANC]C1 - [ANC]C2
_< 15 ueq L
-1
-I
For [ANC]C1 > 100 ueq L , the following condition applies:
[ANC]Ci - CANC]C2
(CANC]C1 + [ANC]C2)/2
x 100
< 10%
If either condition is violated, a problem is indicated in either the
pH and/or the DIG determination. In such cases, the problem should be
found, corrected, and the samples reanalyzed.
It is very important that the pH and DIG be measured as closely together
in time as possible. If they are not measured closely in time, acceptable
agreement between [ANC3Q and [ANC]Q2 may not be obtained.
When acceptable values for [ANC]ci and [ANC]c2 are obtained, their average
is compared to the measured ANC as described below. For [ANC]c-ava <
100 ueq L"1 the difference "D" and the acceptance window "w" are:
D = [ANC]c_avg - ANC and,
w = 15 ueq L~l
For CANC]c_avg > 100 ueq L"1:
[ANC]c_avg - ANC
D =
[ANC]C-aVg ,
w = 10%
x 100 and,
If |D| <^ w, it is valid to assume a carbonate system. If D < -w, then the
assumption of a pure carbonate system is not valid and the sample contains
noncarbonate protolytes (soluble reacting species), such as organic
species. If D > w, an analytical problem exists in the pH determination,
DIC determination, Gran analysis calculation, or acid titration (such as
titrant concentration). In this case, the problem should be identified
and the sample should be reanalyzed.
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5.6.3 Comparison of Calculated BNC and Measured BNC
Just as for ANC, pH and DIG values can be used to calculate a BNC value.
Because the BNC of a sample changes with changing dissolved C0£ concentration,
only the initial pH and DIC values measured at the beginning of the base titra
tion are used to calculate a BNC value. This calculated BNC is then compared
to the measured BNC value. BNC is calculated by:
[BNC]C (ueq
DIC
[H+]2
12,011 \[H+]2
[H
+]
CH+]
[BNClc is compared to BNC as described below.
For [BNC]C <_ 100 ueq L"1:
x 10C
D = [BNC]C - BNC and,
w = 10 ueq L~!
For [BNC]C > 100 ueq L
_i
[BNC]C - BNC
0 = x 100 and,
[BNC]C
. w = 10Z
If |D| £ w, then it is valid to assume a carbonate system. If D < -w,
the assumption of a pure carbonate system is not valid, and the sample
contains noncarbonate protolytes, such as organic species. If D > w, an
analytical problem exists in the pH determination, DIC determination, Gran
analysis calculation, or base titration (such as titrant concentration).
In this case, the problem should be identified and the sample should be
reanalyzed.
5.6.4 Comparison of Calculated Total Carbonate and Measured Total Carbonate
If the assumption of a carbonate system is valid, the sum of ANC plus BNC
is equal to the total carbonate. This assumption can be checked by calculating
the total carbonate from the sum of [ANC]Q and [BNC3c, then comparing the
calculated total carbonate to the measured estimate of total carbonate (the sum
of ANC plus BNC). The total carbonate is calculated by:
'1
Cc (umole L') = [ANC]c_avg
is compared to (ANC + BNC) as follows:
[BNC]
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For Cc £ 100 umole L"1:
D = Cc - (ANC + BNC) and w = 10 umole L"1
For Cc >100 umole L"1:
CC - (ANC + BNC)
D = x 100 and,
w = 10% C
If |D| _< w, the assumption of a carbonate system is valid. If D < -w, the
assumption is not valid and the sample contains noncarbonate protolytes.
If D > w, an analytical problem exists. It should be identified and the
sample should be reanalyzed.
5.6.5 Quality Control Checks
1. Duplicate AnalysisAnalyze one sample per batch in duplicate. The
duplicate precision (expressed as %RSD for ANC and BNC and standard
deviation (SD) for pH) should be less than or equal to 10 percent for
ANC and BNC and 0.05 for pH. If the duplicate precision is unaccept-
able (%RSD >10 percent, SD >0.05), then a problem exists in the
experimental technique. Determine and eliminate the cause of the poor
precision prior to continuing sample analysis.
2. Blank AnalysisDetermine the ANC in one blank per batch. The abso-
lute value of the ANC should be less than or equal to 10 ueq, L"1. If
it is not, contamination is indicated. Determine and eliminate the
contamination source (often the source will be the water or the KC1)
prior to continuing sample analysis. A detailed procedure for the
determination of ANC in a blank solution is presented in Appendix E,
Section 6.0. ,
3. pH QC checkPrior to analysis of the first sample in a shift and
every five samples thereafter, or at intervals recommended by the QA
program, the appropriate pH QC sample (pH 4 QC sample for acid
titrations and pH 10 QC sample for base titrations) should be analyzed
using the following procedure:
a. Copiously rinse the electrode with deionized water. Immerse it
in 20 ml of QC sample and stir it for 30 to 60 seconds. Discard
the sample and replace with an additional 40 ml of QC sample.
While the solution is gently stirred, measure and record the pH.
b. From the calibration curve of pH versus pH*, determine the pH*.
If the pH* and theoretical pH of the QC sample differ by more
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than 0.05 pH unit, stop the analysis and repeat the rigorous
calibration procedure in Section 5.4.5.
c. Previously analyzed samples (up to the last acceptable QC sample)
should be reanalyzed. Acceptable values of pH* are reported on a
form similar to NSWS Form 20 (see Appendix D).
5.7 REFERENCES
American Society for Testing and Materials, 1984. Annual Book of ASTM
Standards, Vol. 11.01, Standard Specification for Reagent Water,
D 1193-77 (reapproved 1983). ASTM, Philadelphia, Pennsylvania.
Butler, J. N., 1982. Carbon Dioxide Equilibria and Their Applications.
Addison-Wesley Publications, Reading, Massachusetts.
Gran, G., 1952. Determination of the Equivalence Point in Potentio-
metric Titrations, Part II. Analyst* v. 77, pp. 661-671.
Kramer, J. R., 1982. Alkalinity and Acidity. ln_R. A. Minear and
L. H. Keith (eds.). Water Analysis, Volume 1 Inorganic Species,
Part 1. Academic Press, Orlando, Florida.
Kramer, J. R., 1984. Modified Gran Analysis for Acid and Base Titra-
tions. Environmental Geochemistry Report No. 1984-2. McMaster
University, Hamilton, Ontario, Canada.
McQuaker, N. R., P. D. Kluckner, and D. K. Sandberg, 1983. Chemical
Analysis of Acid Precipitation, pH and Acidity Determinations.
Environ. Sci. Techno!., v. 17, n. 7, pp. 431-435.
National Bureau of Standards, 1982. Simulated Precipitation Reference
Materials IV NBSIR 82-2581. U.S Department of Commerce, NBS,
Washington, D.C.
U.S. Environmental Protection Agency, 1983 (revised). Methods for
Chemical Analysis of Water and Wastes. EPA-600/4-79/020.
U.S. Environmental Protection Agency, Cincinnati, Ohio.
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6.0 PREPARATION OF ALIQUOTS
6.1 OVERVIEW
Changes in chemical parameters may occur in the time interval between sam-
ple collection and analysis. These changes can be minimized by preparing
sample aliquots using a variety of techniques, including filtration and preser-
vation. The particular parameter being measured dictates the type of prepara-
tion and preservation necessary to ensure sample stability until analysis is
complete.
6.1.1 Scope and Application
These procedures are specific to filtration and preservation methods
employed in the NSWS for the parameters listed in Table 6-1,. Preparation of
an extractable aluminum aliquot is described in Section 7.0,,
6.1.2 Summary of Method
Samples may be filtered to remove the biotic and abiotic particles which
exceed 0.45 urn in size. Preservation may include adjustment of aliquot pH to
less than 2 pH units with concentrated acids or storage at 4 °C. Samples
should be processed within 24 to 48 hours from the time of sample collection.
6.1.3 Interferences
The known interferences specific to the parameter being measured are
detailed in the sections containing anlaysis procedures for that parameter.
In preparing aliquots, all interferences are collectively termed contamination.
Measures taken to minimize contamination include processing inside a clean air
station, separation of acid-washed and deionized water-washed apparatus, use of
ultrapure acids, use of Type I reagent grade water (ASTM, 1984), and strict
adherence to laboratory cleanliness rules (see Section 3.5).
6.1.4 Safety
The sample types and most reagents used in preparing aliquots pose no
hazard to the analyst. Protective clothing (lab coat and gloves) and safety
glasses should be worn when handling concentrated acids.
6.2 SAMPLE COLLECTION, PRESERVATION, AND STORAGE
Samples should be collected in deionized water-washed containers of suffi-
cient volume to prepare all necessary aliquots. For the NSWS, 4-L polyethylene
Cubitainers are generally used. Containers should be filled completely to
minimize atmospheric contact and stored at 4 °C in the dark until processed.
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TABLE 6-1. ALIQUOTS, CONTAINERS, PRESERVATIVES, AND CORRESPONDING
PARAMETERS FOR THE NATIONAL SURFACE WATER SURVEY
Al 1quot/(Contai ner)a
Processing and
Preservation*3
Parameters
1
(250 mL, AW)
2
(15 mL, AW)
3
(250 mL, DIW)
4
(125 mL, AW)
5
(500 mL, DIW)
6
(125 mL, AW)
6*
(125 mL, AW)
Fi 1 tered
pH < 2 with HN03C
Filtered
MIBK Extract
Filtered
No Preservative
Filtered
pH <2 with H2S04d
Unfil tered
No Preservative
Filtered
pH <2 with H2S04d
Unfil tered
pH <2 with H2S04d
Ca Na
Mg Mn
K Fe
Total Extractable Al
cr
S04~2
N03
Si02
Dissolved organic carbon
NH4+
pH
BNC
ANC
Conductance
DIC
Dissolved P
Total P
7 Unfiltered
(125 mL, AW) pH <2 with HN03C Total Al
j*AW « acid-washed container, DIW = deionized water-washed container.
bAliquots 2, 3, 4, 5, and 6 should be stored at 4 °C in the dark.
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6.3 EQUIPMENT AND SUPPLIES
6.3.1 Apparatus
Filtration apparatus includes filter holder, vacuum chamber, and vacuum
pump (Figure 6-1).
6.3.2 Reagents and Consumable Supplies
1. Nitric Acid (HNOs, 12M, Baker Ultrex grade or equivalent).
2. 5% Nitric acid washCarefully add 50 ml of concentrated HN03 to 500 ml
water, then dilute to 1 L.
3. Sulfuric Acid (H2S04, 18M, Baker Ultrex grade or equivalent).
4. HaterWater used in all preparations should conform to ASTM specifi-
cations for Type I reagent grade water (ASTM, 1984).
5. Aliquot BottlesClean aliquot bottles are required for the aliquots
prepared from each sample (see Table 6-1 for the sizes used in the
NSWS).
6. Indicating pH Paper (Range 1 to 3).
7. Membrane Filters (0.45-(jm pore size).
8. Capillary tubes.
6.4 PREPARATION
6.4.1 Filtration Unit Assembly
NOTE: A slight positive (blowing into the laboratory) air flow should
be maintained in the clean air station. Check for positive air
flow by taping a Kimwipe strip to the bottom of the glass window.
1. Up to four filtration units may be connected to a single vacuum pump.
Acid-washed and deionized water-washed units may be connected in the
same series. Each type should be clearly labelled. When arranged
in close proximity, a plexiglass barrier should be constructed around
deionized water-washed units to minimize potential contamination
from nitric acid aerosols.
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FUNNElX
CHAMBERS
CAP
BASE-
O-RiNGS
RING
HOLDER
HOSE
Figure 6-1. Filtration apparatus.
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Page 5 of 10
2. Attach the vacuum line from the vacuum pump via a waste filter flask
to the outlet on the first filtration base. Turn on the vacuum.
Adjust the vacuum pump to 10-12 inches mercury (Hg).
CAUTION: Do not exceed 12 inches Hg under any circumstances.
Be sure the waste flask remains upright and is emptied on a regular basis.
3. Two sets of Teflon forceps are needed. One set is acid-rinsed. Label
one pair of this set "ACID-CLEAN" and the other "ACID-DIRTY". One set
is deionized water-rinsed. Label one pair of this set "NONACID-
CLEAN", the other "NONACID-DIRTY". Different color tapes, such as red
for acid and blue for not acid, provide easy identification.
6.4.2 Maintenance
The filter holder and vacuum chamber require periodic cleaning. Acid-
washed apparatus should be soaked in 5 percent nitric acid wash for 24 hours
or longer. Deionized water-washed apparatus should be soaked in deionized
water for a minimum of 48 hours.
The rubber gaskets on the filtration base and the vacuum lines require
periodic replacement due to wear.
6.5 PROCEDURE
6.5.1 Filter Rinsing
NOTE 1: The 0.45-um membrane filter should be replaced before a new sample
is to be filtered. Be sure the filter is centered and lies
smoothly on the filter screen with no tears.
NOTE 2: Make sure the blue filter separators are removed before placing
the filter on the screen. Do not touch the filter to any object
other than clean Teflon forceps or the filter screen. If the
filter does touch another object, discard the filter and obtain
a new one.
NOTE 3: Empty the waste beaker under the filtration apparatus into a
second waste beaker to be dumped outside the hood. Never remove
the apparatus waste beaker from the clean air station.
NOTE 4: If any part of the deionized water-washed apparatus is contami-
nated by acid, replace the entire apparatus with a clean one.
Soak the contaminated unit in deionized water for 48 hours.
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Section 6.0
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Page 6 of 10
3.
4.
Unscrew the filter cup from the filter holder. Make sure it sepa-
rates properly and that the 0-rings are secure and in place.
Lift the cup. Using clean, acid-rinsed Teflon forceps place a
0.45-um membrane filter onto the screen. Moisten the filter with
deionized water (from wash bottle) and apply the vacuum to seal the
filter to the screen. Be sure the filter is centered and lies
smoothly with no tears.
Replace the cup onto the holder without disturbing the filter.
Tighten the ring securely. If the ring is not properly tightened, it
may leak when vacuum is applied. If this happens, obtain a new
aliquot bottle of the same type and reprocess the aliquot.
Rinse the filter with 5 ml of deionized water, followed by 5 ml of
5 percent HN03, followed by two 5-mL rinses with deionized water.
A third rinse with deionized water should cover the sides of the cup
as well as the filter.
NOTE: For deionized water-washed apparatus, eliminate the 5 percent HN03
rinse, rinsing three times with deionized water only.
5. Shut off the vacuum. Break the seal and thoroughly rinse the filter
funnel tip with deionized water.
6.5.2 Sample Filtration
NOTE 1: The cap should be kept on the aliquot bottles until the bottle is
placed under the funnel to avoid any possible contamination from
the chamber.
NOTE 2: If the Cubitainer cap (or its white paper liner) is dropped at
any time, rinse it one time with deionized water and one time
with sample, then continue processing.
NOTE 3: Keep the hood area clean. Wipe up spills as they occur.
1. Agitate the Cubitainer. Pour no more than 10 mL of sample into the
filter cup.
2. Turn on the vacuum and filter the sample into the waste beaker. Turn
off the vacuum.
3. Lift the chamber and remove the waste beaker. Empty the beaker and
place it behind the apparatus, out of the way. Loosen the lid of the
aliquot bottle. Lift the chamber and set the aliquot bottle on the
base. Remove the cap and lower the chamber back onto the base.
Set the cap upright next to apparatus, in a clean spot.
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"_ ' . ' Page 7 of 10
4. Agitate the Cubitainer. Pour no more than 10 ml of sample into the
filter cup.
5. Turn on the vacuum. Filter the sample into the aliquot bottle and
turn off the vacuum. ,
6. Lift the chamber and replace the cap on the aliquot bottle. Remove
the bottle and tighten the cap. Rinse the bottle thoroughly by
shaking and rotating. Pour the rinse sample into the waste beaker.
Loosen the cap, lift the chamber, and replace the bottle under the
funnel. Remove the cap ,and set the chamber on its base.
7. Agitate the Cubitainer. Pour 200 mL of the sample into the filter
cup. Apply vacuum pressure and filter the sample into the aliquot
bottle. Turn off the vacuum. .
8. Use only one aliquot bottle to collect filtered sample. Pour
remaining aliquots of the same type from this bottle. Rinse each
bottle and cap with 5 to 10 mL of filtered sample.
9. If it is necessary to change the filter before filling all aliquots
from one sample because the filter has become clogged, use the
following procedure:
a. Shut off the vacuum. Lift the chamber, cap the aliquot bottle,
remove it, and replace with the waste beaker.
. b. Unscrew the filter cup, remove the dirty filter with .the "DIRTY"
forceps, and replace it with a clean filter using the "CLEAN"
forceps.
c. For aliquots prepared using the acid-rinsed units, rinse the
filter as described in Section 6.5,1. For the filtration unit
which is deionized water-rinsed, follow the same procedure except
eliminate the 5 percent HMOs wash; instead rinse three times
with deionized water.
10. Aliquots which receive added chemical preservatives should be filled
to the bottle shoulder. Aliquots which do not receive added preser-
vatives should be filled to the brim, capped tightly so that no head-
space exists, and immediately refrigerated at 4 °C.
6.5.3 Between Sample Rinsing
1. Place a 250-mL plastic beaker (for waste) under each filter funnel.
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2. Rinse the filter funnel once with deionized water from a 1-L wash
bottle. Be sure water flows evenly over all interior surfaces of
the filter cup; turn the cup one complete revolution while rinsing
the sides.
3. (Acid-Washed Units only). Rinse the filter funnel once with 5 percent
HN03 from a 1-L wash bottle. Turn the cup one complete revolution
while rinsing the sides.
4. Rinse the filter funnel three times with deionized water from a 1-L
wash bottle. Turn the cup one complete revolution for each rinse
and allow the water to drain completely.
6.5.4 Unfiltered Aliquots
1. Thoroughly agitate the Cubitainer and rinse the aliquot bottle once
with a 10-mL portion of sample. Be sure to rotate the bottle so that
the sample contacts all internal surfaces.
2. Agitate the Cubitainer again and fill the bottle to the shoulder with
sample, if preservative is to be added. If unpreserved, fill bottle
completely with sample, cap tightly so that no headspace exists, and
immediately refrigerate at 4 °C.
6.5.5 Preservation
NOTE 1: Dedicate a 40- to 200-uL micropipet for each type of preservative.
Colored tape is recommended for identification (e.g., red tape
for nitric acid, yellow tape for sulfuric acid). It also is
recommended that aliquot labels be color coded to indicate the
type of preservative (e.g., pink for nitric acid, yellow for
sulfuric acid, white for no preservative).
NOTE 2: A row of similarly preserved aliquots (e.g., those preserved with
HN03) may be done at one time. Loosen the aliquot bottle caps
(for the entire row) but do not remove the caps until it is time
for the actual addition of the acid. As long as there is no
contamination to the pi pet tip, one pi pet tip may be used
throughout the preservation procedure for each acid type.
1. Add the appropriate quantity of preservative to the aliquot bottle,
(generally 100 uL).
2. After the preservative is added, tighten the caps and mix thoroughly.
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3. (Acid-preserved aliquots only). Loosen the aliquot bottle caps and
using a fresh capillary tube for each bottle, collect and place a drop
of preserved sample on pH paper (pH range 1.8 to 3.8). The pH should
be less than 2. It may be necessary to add more than 100 uL of acid
for the pH to be less than 2. If this situation occurs, continue
adding the appropriate acid in 100-uL increments until the pH is less
than 2, using a new capillary tube each time the pH is tested.
4. Write the total amount of preservative added to the sample on the
aliquot label and in the logbook.
6.5.6 Shipping Instructions
NOTE: The following procedures are recommended if aliquots are to be
shipped by a commercial carrier or another method which includes
a transfer of physical custody to a third party. Portions of
these procedures may not be applicable when physical custody
of samples remains within a single laboratory.
1. Refrigerate both preserved and preservative-free aliquots for at least
1 hour at 4 °C before shipping. Check that all labels are correct and
tighten the caps firmly. Tape each cap in a clockwise direction with
electrical tape. Place each aliquot to be shipped in an individual
plastic bag and tie with a twist-tie.
NOTE: Aliquot lids may leak if not tightened after refrigeration.
2. Place each set of aliquot bottles (not including extractable aluminum
aliquots) into a 1-gallon Ziploc bag or equivalent. Face the labels
in the same direction for easy sample identification. Remove excess
air from the bag, seal it, and place the bag in the refrigerator, or
directly into the prepared shipping coolers.
3. Line the sides of each shipping container with frozen gel packs.
4. Place numerically sequential sets of aliquots in a container. If
there is excess space, fill with gel packs or newspaper.
5. A shipping form similar to Form 3 (Appendix D), is completed by the
laboratory coordinator and contains all aliquot information for the
batch. At least one copy is placed inside a scalable bag and placed
inside the shipping box. The original is retained in the processing
laboratory until verification of sample receipt at the analytical
laboratory is received.
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6. Securely seal the shipping boxes with strapping tape.
7. Clearly label each box. Information should include:
a. To: Name, address, and telephone number of the analytical
laboratory.
b. From: Name, address, and telephone number of the processing
laboratory.
c. Box of (box number and total number of boxes)
d. Weight
e. Appropriate shipper labels and documentation.
6.6 QUALITY ASSURANCE AND QUALITY CONTROL
There are no specific quality control procedures for aliquot preparation.
The use of laboratory blanks is recommended as a check of possible contamina-
tion during processing.
6.7 REFERENCES
American Society for Testing and Materials, 1984. Annual Book of ASTM
Standards, Vol. 11.01, Standard Specification for Reagent Water,
D 1193-77 (reapproved 1983). ASTM, Philadelpha, Pennsylvania.
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7.0 PREPARATION OF TOTAL EXTRACTABLE ALUMINUM ALIQUOT
7.1 OVERVIEW
7.1.1 Scope and Application
This procedure is for the preparation of a sample extract for subsequent
determination of total extractable aluminum by atomic absorption spectroscopy.
It is applicable to weakly buffered natural waters of low ionic strength.
7.1.2 Summary of Method
A water sample is filtered in a contamination-free environment. Phenol
red is added as a pH indicator. Next, an 8-hydroxyquinoline/sodium acetate
reagent is added. This mixture is then buffered to a pH of 8.3 with an ammonium
acetate buffer. At this pH, any small dissolved aluminum species existing in
the sample will complex with the 8-hydroxyquinoline in the solution.
These organic complexes are removed from the mixture by adding methyl
isobutyl ketone (MIBK), an organic solvent in which the aluminum complexes are
more soluble. Agitation causes the complex to be almost totally transferred
to the organic layer. This organic layer is extracted and stored until it is
analyzed for aluminum content by atomic absorption spectroscopy.
7.1.3 Interferences
Numerous interferences have been observed in the MIBK extraction procedure,
particularly affecting the phenol red color change and organic layer separation.
Suspected interferences include other metals, particularly iron, and, possibly,
organic compounds. Observed colors at the phenol red addition stage include
pink, red, purple, brown, and black. Extracted aliquots have been observed to
range from clear to yellow, green, brown, and black. A bubbly or frothy third
layer has been observed following centrifuging; this layer should be considered
part of the organic layer.
7.1.4 Safety
MIBK is a hazardous organic liquid and should be handled with care. Keep
MIBK in the clean work station at all times. The laminar flow hood must be on,
and a slight negative pressure must be maintained throughout the entire MIBK
procedure. Analysts are required to wear half-mask respirators, safety glasses,
a lab coat, and two pairs of gloves when handling MIBK.
An organic vapor photoionization detector is also employed as a safety
precaution (see Appendix F).
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7.2 SAMPLE COLLECTION, PRESERVATION, AND STORAGE
Water samples are collected in clean, deionized water-washed containers
filled completely to minimize atmospheric contact. Cubitainers or syringes are
recommended for collection of water used in the extractable aluminum aliquot
Collected samples are stored at 4 °C until sample processing; processing should
De as close to the time of sampling as possible (generally within 24 hours).
7.3 EQUIPMENT AND SUPPLIES
7.3.1 Apparatus
1. Centrifuge.
2. Volumetric flasks - 1 or 2 each 2-L, 1-L, and 500-mL.
3. Repipet or equivalent dispensers - 1 each 2.00-mL, 5.00-mL, and 10.0-mL
4. Reagent bottle with dropper - 2 each 60-mL.
5. Polystyrene graduated cylinders - 2 each 25-mL, 100-mL, and 250-mL.
7.3.2 Reagents and Consumable Materials
1.
2.
Phenol RedFill a 60-mL drop-dispenser bottle, labeled "Phenol Red",
with phenol red indicator solution.
Methyl Isobutyl KetoneAttach a labeled ("MIBK") 10.0-mL Repipet
dispenser to a 4-L bottle of methyl isobutyl ketone.
3. 1M NH4OH
NOTE: Always work with NH40H under the hood wearing safety glasses,
double gloves, and a lab coat. Exercise caution when workinq
with concentrated NH40H.
a. Fill a clean 100-mL graduated cylinder with approximately 25 mL
of deionized water.
b. Measure 12 mL of 5M NH4OH (Baker Instra-Analyzed grade or
equivalent) in a clean 25-mL graduated cylinder.
c. Carefully pour NH4OH into the 100-mL graduated cylinder and
dilute to 60 mL. Cover the graduated cylinder with Parafilm and
invert 4 to 5 times to mix thoroughly.
d. Transfer the solution to a 60-mL drop-dispenser bottle labeled
1M NH4OH .
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4. Ammonium Acetate/Ammonia Buffer Solution
a. Fill a clean 2-L Erlenmeyer flask with 200 ml of deionized water.
b. Prepare an ice bath by placing a frozen gel pack into a plastic
pan and filling the pan 1/3 full of tap water. With the flask
sitting in the ice bath, slowly add 112 ml of glacial acetic acid
(Baker Instra-Analyzed grade or equivalent) from a 250-mL gradu-
ated cylinder. Swirl the flask to mix the solution as the acid
is being added. If the solution becomes too hot, allow it to
cool prior to adding more acid.
c. Keep the flask in the ice bath and slowly add 150 mL NfyOH (5M
Baker Instra-Analyzed grade or equivalent) from a 250-mL gradu-
ated cylinder. Swirl during the addition to prevent overheating.
d. Dilute to the 500-mL mark with deionized water and swirl to mix.
e. Place a small amount of the solution into a small beaker. Using
a capillary tube, check the pH of the solution by placing one
drop on pH paper (pH range 8.0 to 9.7). The pH should be near
8.3. If the pH is too high, add glacial acetic acid dropwise
from a disposable pi pet. This may require 20 to 30 drops of
acid. Swirl and test frequently, using a new capillary tube and
a new rinsing of the beaker. If the pH is too low, add 1M NH40H
dropwise from the bottle. It may require 15 to 20 drops to adjust
the pH. Swirl and test frequently, using a new capillary tube
and new rinsing beaker for each test.
f. When the pH has been adjusted, add an additional 32.0 mL of 5M
NH40H. If the solution becomes hot, return the flask to the ice
bath.
g. Dilute with deionized water to the 1-L mark in the Erlenmeyer
flask. Swirl to mix.
h. Pour the NH4OAc/NH3 buffer into a clean, labeled 2.0-mL Repipet.
Rinse the Repipet pump with buffer by depressing it several times.
I. Store any extra buffer in a labeled, capped, 1-L volumetric flask
in the refrigerator.
5. 8-Hydroxyquinoline Solution
NOTE: Make sure 8-hydroxyquinoline is dissolved totally in the glacial
acetic acid before adding water.
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a. Measure 12.5 of mL glacial acetic acid (Ultrex or equivalent
grade) in a clean 25-mL graduated cylinder.
b. Pour into a clean 500-mL volumetric flask labeled "Hydroxyquino-
line Solution".
c. Weigh 5.000 g of 8-hydroxyquinoline in a clean, disposable weigh-
boat. Transfer to the flask containing the glacial acetic acid.
Cap and mix until salt is dissolved completely.
d. Dilute with deionized water to the 500-mL mark and mix thoroughly.
Store the extra solution in the refrigerator.
6. l.OM Sodium Acetate (NaOAc)--
a. Fill a clean 500-mL volumetric flask labeled "l.OM NaOAc" with
approximately 250 mL of deionized water.
b. Weigh 41.0 g anhydrous sodium acetate (ultrapure grade) and add
to flask.
c. When sodium acetate is dissolved, dilute to the 500-mL mark and
mix thoroughly. Store extra solution in the refrigerator.
7. 8-Hydroxyquinoline/Sodium Acetate Solution (HOX)~
NOTE 1: Calibrate the Repipet with deionized water.
NOTE 2: Prepare the HOX reagent daily.
NOTE 3: 140 mL of reagent is enough for 20 samples. Make enough HOX
reagent to process all samples for that day.
a. Place 20 mL l.OM NaOAc solution in a clean 100-mL graduated
cylinder. Rinse the cylinder with a small amount of reagent
prior to measuring the volume.
b. Place 100 mL of deionized water into a clean 250-mL graduated
cylinder.
c. Place 20 mL of 8-hydroxyquinoline solution into a clean 100-mL
graduated cylinder. Rinse the cylinder with a small amount of
reagent prior to measuring the volume.
d. Rinse a 5.0-mL Repipet with deionized water and add the solutions
in the following order: 1M NaOAc, deionized water, and 8-hydroxy-
quinoline; cap and swirl to mix. Flush the plunger with the HOX
reagent.
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8. Consumable Materials
a. 50-mL graduated centrifuge tubes with sealing caps.
b. 10-mL or 15-mL centrifuge tubes with sealing caps.
c. pH indicating paper (pH range 8.00 to 9.7).
d. Capillary tubes.
e. Nucleopore membrane filters and filter holder assemblies.
7.4 PREPARATION :
7.4.1 Calibration and Standardization
Check the calibration of all of the Repipets daily, as directed in
Appendix C, and record the values in the MIBK logbook. Volumes should be
delivered exactly, especially for the MIBK and HOX reagents.
Check the calibration of the analytical balance weekly, as directed in
Appendix C.
7.4.2 Maintenance
Prepare syringe filters as directed in Appendix C. Check the operation of
the organic vapor photoionization detector weekly, as described in Appendix F.
7.5 PROCEDURE . . . .
NOTE 1: Learn how to achieve good reproducibility with a Repipet prior
to sample processing.
NOTE 2: See aluminum extraction flowchart, Figure 7-1.
7.5.1 Filtration
NOTE 1: This section is applicable to samples in syringes. If bulk
sample is used, filter according to the directions for acid-
washed filtration in Section 6.
NOTE 2: A minimal amount of sample is used for rinses to conserve both
sample and filters.
1. Obtain the sample syringes. Record the date and time of collection in
the MIBK logbook (this information should be recorded on the syringe
label).
2. Remove the syringe valve and attach a clean acid-washed Nucleopore
filter assembly (see Appendix C). Only remove the valve from the
sample syringe long enough to filter. When filtration is complete,
replace the valve and set the sample in the refrigerator.
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OBTAIN SAMPLES,
RECORD
TIME AND DATE COLLECTED
IN LOGBOOK.
PLACE FILTER ON SAMPLE
WASH SOmLTUBE 3x
WITH 1-2 mL SAMPLE FILTER
EXACTLY 25 mL OF SAMPLE
INTO TUBE
PLACE SAMPLES IN COOLER
TO KEEP COLD
ADD 10 mL MIBK
AND SHAKE VIGOROUSLY
FOR 10 SECONDS
CENTRIFUGE FOR
90 SECONDS,
EXTRACT TOP LAYER
AND PLACE IN
15 mLTUBE
ANALYSES
COMPLETE
ADD REAGENTS
1...3 DROPS PHENOL
2... 5 mL HOx
3... 2 mL BUFFER
MEASURE AND RECORD
VOLUME IN LOGBOOK
AND ON LABEL
PREPARE
FOR SHIPPING
Figure 7-1. Aluminum extraction flowchart.
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3. Rinse approximately 1 ml of sample through the filter into a waste
beaker. Now filter 1 to 2 ml of sample into an appropriately labeled
acid-washed 50-mL centrifuge tube and cap. Rotate the tube so that
all interior surfaces are rinsed. Repeat this two more times.
4. Filter exactly 25 ml of sample into the rinsed tube. Be sure to fill
all tubes to the same mark. It is crucial that the 25 ml of sample be
measured accurately and reproducibly.
5. Cap the tube and place it in the cooler with gel packs. Filter all
samples prior to beginning the extraction process.
7.5.2 Extraction
NOTE 1: Successful extraction depends thorough agitation after the
addition of MIBK.
NOTE 2: Record in the logbook any abnormalities which appear in the
samples (e.g., color, precipitate).
1. Add three drops of phenol red to the sample in the 50-mL centrifuge
tube.
2. Add 5.0 mL HOX reagent, using the Repipet.
3. Using the 2.0-mL Repipet, add 2.0 mL NH4OAc/NH3 buffer. Mix for
exactly 5 seconds by swirling gently. The tube may be left uncapped.
The solution in the tube should turn red to pink throughout the tube,
indicating that the pH value is 8.3 or greater.
4. If the solution does not change color, rapidly adjust the pH by adding
the 1M NH40H solution dropwise until a red-to-pink color is obtained.
Record number of drops required in the logbook.
NOTE: See comments on color change in Section 7.1.3.
5. Using the 10.0-mL Repipet, add 10.0 mL MIBK to the centrifuge tube.
Cap and shake vigorously for exactly 10 seconds. Time the agitation
with a stopwatch and be sure the time is accurate.
6. Place the centrifuge tube with the filtered sample in a small cooler
with gel packs. After all samples have been processed, centrifuge the
samples, four at a time. Centrifuge the samples for 90 seconds at
medium speed.
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7. Use
a 1-5 ml
pi pet set at 5.0 ml to transfer the top organic layer
(MIBK and HOX-A1 ° complex) to a labeled 15-mL centrifuge tube. Be
careful not to withdraw any of the underlying aqueous layer. A total
of 8.5 to 10.0 ml of MIBK should be extracted. Cap the tube tightly
and check the bottom of the tube to ensure that no water has been
extracted.
8. Compare the sample extract volume to a 15-mL centrifuge tube which has
exact volume markings from 7.0 to 10.0 ml. Record the volume on the
label and in the logbook for each sample. A volume greater than 10.0
ml indicates either the presence of water in the tube pr a faulty
Repipet. A volume less than 8.5 ml indicates improper extraction or
a faulty Repipet. If the Repipet is found to be at fault, the sample
should be refiltered and reprocessed completely. Record volumes in
the logbook.
9. Store the extracted aliquots in a test tube rack in a cooler with a
frozen gel pack until ready to ship. Do NOT store the MIBK sample
extracts in the refrigerator.
10. Dispose of any solid or liquid waste materials as described in Section
/ o o,
7.5.3 Cleanup
NOTE 1: A lab coat, safety glasses, a half-mask respirator, and double
gloves must be worn when handling solid or liquid MIBK waste.
NOTE 2: All waste receptacles should be clearly labeled as MIBK waste.
1. Solid Waste Disposal
a.
b.
c.
During MIBK processing all MIBK solid waste (open centrifuge
tubes and caps, gloves, pipet tips, MIBK-soiled Benchkote)
should be discarded into a labeled metal container lined with a
plastic bag. This container should be located on the floor
beside the clean work station.
At the end of daily processing, this bag containing solid MIBK
waste is emptied into a large, labeled garbage can stored
outside, in a secure area. The gloves being worn also are
discarded.
Vent the large garbage can outside for 5 to 6 days; this aeration
renders the waste acceptable for regular waste disposal. Upon
complete venting of the solid waste, double bag and place in
regular waste disposal canisters.
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2. Liquid Waste Disposal
a. Discard the MIBK liquid waste into a properly labeled solvent
waste can stored in the clean work station.
b. Solvent waste should be emptied daily into a properly labeled
container (e.g., 5-gallon metal gasoline can).
3. Glassware Cleanup
a. Clean all glassware by rinsing in succession with deionized water
(once), 5-percent nitric acid (once), and deionized water (three
times).
/
b. Disassemble the 5.0-mL Repipet daily. Rinse the bottle with
deionized water, then fill it about half full with deionized
water. Replace the dispenser on the bottle and rinse it
copiously by filling it and dispensing about 10 portions of
deionized water. Put the Repipet unit in the clean work station.
Be sure to leave the dispenser full of water to prevent build-up
of air bubbles.
c. Disassemble and rinse the 2.0-mL Repipet whenever the NH40Ac/NH3
buffer is replaced.
d. Store all Repipets in the clean work station.
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8.0 FRACTIONATION AND DETERMINATION OF ALUMINUM SPECIES
8.1 OVERVIEW
8.1.1 Scope and Application
This method is a semi automated colon'metric method applicable to the
determination of reactive aluminum in natural, surface waters. The method
colon'metrically measures in aqueous samples the amount of aluminum which forms
a complex with pyrocatechol violet (PCV). The measurement is performed on two
sample streams, one directly and one after passage through a cation-exchange
column. This method is an adaptation of the method presented by Rogeborg and
Henrikson (1985).
For purposes of this analysis, reactive aluminum is defined as the fraction
of soluble (dissolved) aluminum that reacts with PCV without preliminary
acidification. This fraction is believed to represent the monomeric portion of
the total aluminum pool. This includes free inorganic monomeric aluminum,
various aluminum hydrous oxides, and aluminum bound to various inorganic and
organic ligands. The reactivity of certain aluminum complexes is dependent
upon the strength (stability constant) of the complex in relation to the alumi-
num PCV complex.
Total reactive aluminum is defined as the fraction of the total dissolved
aluminum pool that forms a complex with PCV. Dissolved species are species
that pass through a 0.45-um filter. It is known that some particulate forms of
aluminum are smaller than 0.45 urn. These forms include soils, colloidal alumi-
num complex (monomeric and polymeric), and clay minerals. The reactivity of
these complexes with PCV is unknown.
Reactive nonexchangeable aluminum is defined as the fraction of total
reactive aluminum that is not removed from the sample stream after passage
through the cation-exchange column. This fraction consists primarily of organic-
aluminum complexes whose stability constants are greater than the affinity of
the cation-exchange column for the bound aluminum and yet are less than the
stability constant for the aluminum-PCV complex. This fraction is theoretically
nontoxic to fish, at least in terms of acute effects.
Toxic aluminum is not measured directly but can be estimated by subtracting
reactive nonexchangeable aluminum from total reactive aluminum. This difference
estimates the amount of inorganic monomeric aluminum which is believed to
manifest acute toxic responses in fish.
The method detection limit (MDL) has been determined to be 7.0 ug L"1 for
repetitive measurements of a low aluminum standard. The applicable range of
this method is 0-3500 M9 L'1-
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The method presented here does not distinguish between various inorganic
monomeric aluminum species, nor does it distinguish between the various neutral
organic complexes of aluminum. Furthermore, the definitions of total reactive
and nonexchangeable reactive aluminum are based on commonly accepted usage In
actuality, some charged or weakly bound organic-aluminum complexes will be
removed by the cation exchange column and are regarded as inorganic monomeric
species, and some strongly complexed monomeric aluminum may not be measured in
either fraction.
8.1.2 Summary of Method
f Samples are collected in syringes to minimize diffusion of carbon dioxide
into and out of samples. The aluminum species in each sample are subsequently
determined by flow injection analysis (FIA). Samples are loaded into the FIA
system directly from the syringe via a syringe pump. The sample fills a fixed-
volume (100 uL) sample loop on Channel 1, then passes through a cation exchange
column prior to filling the second sample loop (also 100 uL) on Channel 2 The
contents of each sample loop, total reactive and nonexchangeable reactive
aluminum, respectively, are then injected by operator-prompted computer command.
The sample valve switches by computer activation, engaging the deionized water
carrier stream. The sample (bolus) is flushed by carrier into the reaction
manifold_where it reacts with hydroxylamine hyrochloride/l,10-phenanthroline
eliminating iron interference. The bolus is then reacted with PCV. Optimum
color development is achieved by adjusting the final pH of the aluminum aluminum-
PCV complex to 6.1 by addition of hexamethylene tetraamine buffer. The absorbance
of the complex is subsequently determined at 580 nm. Channel 1 measures total
reactive ( inorganic plus "organic" monomeric) aluminum whereas Channel 2
measures nonexchangeable reactive ("organically bound" monomeric) aluminum.
8.1.3 Interferences
Holding time, storage methods, and changes in temperature, dissolved carbon
dioxide concentrations, and pH may drastically alter aluminum speciation in
!£nf£a??!?P ?!: Soflesofhuu1d be analyzed as soon as possible after collection,
generally within 24 to 36 hours. Samples are stored at 4 °C in the dark during
transit and prior to analysis.
NOTE:
The actual holding time is currently unknown.
stability of aluminum species is ongoing. In
times exceeding 48 hours should be avoided.
Research on the
the interim, holding
TI, I (JJI>.interfei"es with the determination of aluminum using this method,
Therefore, the interference is eliminated by reducing iron (III) to iron (II)
with hydroxylamine hydrochloride and subsequent chelation with 1,10-phenan-
tnronne.
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8.1.4' Safety
The calibration standards and most chemical reagents encountered in this
method pose no serious health hazard due to external contact. Acids and bases
may cause burns and they should be handled only under a fume hood. Protective
clothing (e.g., safety glasses, gloves, lab coats) should be worn. Hands
should be washed thoroughly after handling aluminum standards and reagents.
8.2 SAMPLE COLLECTION, PRESERVATION, AND STORAGE
Samples are collected in 60-mL linear polyethylene syringes with syringe
lock valves affixed to the tips. Use of this type of syringe has been shown to
prevent the diffusion of carbon dioxide into and out of samples if they are
kept at 4 °C. Sample preservation is limited, therefore, to storage at 4 °C in
the dark.
8.3 EQUIPMENT AND SUPPLIES
8.3.1 Equipment Specifications
1. Automated flow injection analyze)A computer-interfaced FIA capable
of automatic injection of samples, mixing of specified reagents for
reaction of PCV with aluminum, and detection unit (colorimeter)
capable of measuring absorbance at 580 nm.
2. Cation-exchange columnA 100-mm (10 mm I.D.) Teflon column with
Teflon fritted inserts.
8.3.2 Consumable Materials
1. Cation-exchange resinAn Amber!ite IR 120 (14 to 50 mesh) exchange
resin is used to separate the inorganic from the organic monomeric
aluminum species.
2. Nucleopore membrane filters and filter holder assemblies or
equivalent.
3. Pump tubes.
4. Teflon tubing.
5. Plastic syringes, 60-mL. ,
8.3.3 .Reagents
1. WaterAll water used in preparing reagents and cleaning labware
should meet the specifications for Type I reagent grade water
(ASTM, 1984).
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NOTE: All reagents, with the exception of the pyrocatechol violet
and degassed DI carrier, may be prepared in large quantities
and refrigerated in polyethylene containers between uses.
2. Hexamethylamine Tetraamine Buffer
a. Label 250-mL disposable beaker "Hexamethylamine Tetraamine
84.0 g". Place the beaker on the balance and ,tare. Be sure the
balance is set on the high range (0 to 300 g).
b. Wearing gloves, use a second labeled beaker to scoop out the
powdered buffer from the container and measure 84.0 g.
c. Obtain a clean 1-L volumetric flask. Label it "Hexamethylamine
Tetraamine Buffer 84.0 g L"1" and add approximately 200 mL of
deionized water.
d. Using a clean funnel, carefully transfer the powdered buffer to
the volumetric flask. It is best to add enough deionized water
to the beaker to form a slurry and then pour it through the
funnel.
e. Rinse the beaker well with deionized water and add it to the
volumetric flask. Bring the volume up to near the 1-L mark with
deionized water and allow the buffer sufficient time to dissolve
prior to filling to the 1-L mark. Mix completely. The buffer is
now ready for filtering. Follow the procedure in Section 8.3.8.
3. Pyrocatechol Violet
NOTE 1: PCV is made daily. If depleted before sample analysis is
completed, a new calibration must be performed.
NOTE 2: Store the PCV in a cool, dark place when not in use. Be sure
the lid is closed tightly.
NOTE 3: Use of an antistatic gun in the empty weighboat will prevent
"climbing" of the PCV powder.
a. Set the balance to the low range (0-30 g) setting. Tare a clean,
dry weighboat.
b. Wearing gloves, use a clean Teflon spatula to place 0.375 g of
pyrocatechol violet powder into the center of the weighboat. Be
sure to weigh it very accurately.
c. Obtain a clean 1-L volumetric flask and label "PCV 0.375 g I'1."
Add approximately 300 mL deionized water to the flask.
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d. Carefully transfer the PCV from the weighboat to the volumetric.
flask by slowly washing the PCV with deionized water into the
flask. Be sure to flush the weighboat completely. Avoid
spilling any solution outside of the flask.
e. Dissolve the PCV in the flask by adding additional deionized
water. Be sure to rinse the mouth and neck of the flask. Bring
the volume up to the 1-L mark and mix thoroughly.
f. Filter this solution following the procedure in Section 8.3.8.
4. Mask
a. Label a clean 250-mL disposable beaker "Hydroxylamine HC1 7.60 g".
Place the beaker on the balance and tare. Be sure the balance
is on the low range (0-30 g).
b. Wearing gloves, use a clean Teflon spatula to scoop 7.60 g
hydroxylamine HC1 into the beaker. This powder scatters easily;
be sure that no powder falls outside of the beaker onto the
balance stage.
c Obtain a clean 1-L volumetric flask and label it "Mask-Hydroxyl-
amine HC1 7.60 g; 1,10-Phenanthroline Monohydrochloride 0.560 g .
Add approximately 300 mL deionized water to the flask.
d. Dissolve the hydroxylamine HC1 in the beaker by adding deionized
water. Carefully transfer it to the volumetric flask, being sure
to flush all the powder from the beaker. Bring the volume in
flask up to about 500 mL with deionized water.
e. Tare a clean weighboat with the balance set on the low range.
Use a clean Teflon spatula to place exactly 0.560 g 1,10-phenan-
throline monohydrochloride into the weighboat.
f. Transfer the powder into the labeled flask by flushing it from
the weighboat with deionized water. Be sure to rinse the
weighboat completely.
g. Swirl the flask to dissolve all solids. The solution may have
a slight pink hue. Now fill to the 1-L mark with deionized
water.
h. Filter this solution following the procedure in Section 8.3.8.
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5. Deionized Water Carrier
NOTE: Be sure to have at least 4 liters of degassed deionized water
prepared before beginning analysis. If the sample load is
greater than 25 samples, increase the volume prepared.
a. Fill a 4-L Cubitainer or other suitable container with fresh
deionized water.
b. Follow the filtration procedure in Section 8.3.8.
6. Cleaning Solution - 0.1N HC1/10 percent Ethyl Alcohol
NOTE: This solution is used to clean tubing as described in Section
8.5.3. It is not involved in the actual aluminum determination.
a. Place 8.3 mL concentrated (Baker Instra-Analyzed or equivalent)
hydrochloric acid into a clean 1-L volumetric flask which
contains approximately 500 ml deionized water.
b. Measure 100 ml 95 percent ethyl alcohol in a graduated cylinder.
Add this to the 1-L flask.
c. Dilute to the 1-L mark with deionized water. Place in a labeled
1-L plastic bottle and store in the refrigerator.
8.3.4 Amber!ite Cation Exchange Resin
NOTE: Prepare as needed.
1. 0.1N HC1
a. Fill a 1-L volumetric flask with about 500 mL deionized water.
b. Add 8.3 mL concentrated (Ultrex or equivalent) hydrochloric acid.
c. Dilute to the 1-L mark with deionized water.
d. Store the solution in the flask until needed.
2. 0.1N NaCl
a. Fill a 1-L volumetric flask with about 500 mL deionized water.
b. Add 5.8 g of sodium chloride.
c. Dilute to the 1-L mark with deionized water.
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3. Hydrogen form of Amberlite
a. Tare a clean 250-mL disposable beaker.
b. Add about 25 g (wet weight) of amberlite cation exchange resin.
c. Remove from the balance and pour in enough 0.1N HC1 to cover the
beads.
d. Stir thoroughly.
e. Rinse with deionized water for approximately 10 minutes, stirring
constantly.
f. Pour off the rinse water from the last rinse into a separate
glass beaker.
g. Check for the presence of chloride ions by adding a few drops of
silver nitrate to the rinse.
CAUTION: Silver nitrate will turn skin black when exposed to sun-
light. Wear gloves during this procedure.
h. If a white precipitate forms (silver chloride), rinse the resin
for another 5 minutes.
i. Check for chloride as in step g above.
j. Repeat steps c through i until no precipitate forms. Store the
prepared resin in a labeled bottle in the refrigerator.
4. Sodium form of Amberlite resinFollow the procedure in step 3, above,
except substitute 0.1N NaCl for 0.1N HC1.
5. One percent hydrogen form of Amberlite resin
NOTE: This is the resin used to pack the cation exchange column in
Section 8.4.4.
a. Tare a 250-mL disposable beaker. Add the desired amount of the
sodium form of amber!ite resin into the beaker. Drain the resin
as much as possible.
b. Record the weight.
c. Take one percent of that value and add that amount of the drained
hydrogen form to the beaker.
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d. Add deionized water and mix thoroughly.
e. Place in a labeled polyethylene bottle (deionized water-washed)
and store in the refrigerator until needed.
8.3.5 Aluminum Stock Solutions
NOTE 1: Use one source of 1,000 mg L"1 aluminum stock solution to make
the standard stock solution and another source to make the
quality control (QC) stock solution.
NOTE 2: These stock solutions can be stored indefinitely and do not
require refrigeration.
1. Standard Stock Solution
a. Fill a clean 1-L volumetric flask with approximately 500 ml of
deionized water.
b. Using a calibrated pipet, add 1.000 ml of concentrated (Ultrex
or equivalent) nitric acid to the flask and mix well.
c. Add 10.00 ml 1,000 mg L"1 aluminum stock solution to the flask
using a calibrated 1-5 ml pipet. Mix thoroughly. Be sure to use
the aluminum stock designated for standard preparation.
d. Bring volume up to the 1-L mark with deionized water and mix
thoroughly. Transfer to a 1-L clean plastic bottle which has been
rinsed one time with a small amount of the stock solution. Label
"10 mg L"1 Calibration Standard Stock".
2. QC Stock SolutionUsing a different source of 1,000 mg L"1 aluminum
stock solution, follow the procedure above. Use a different 10-L
volumetric flask and a new pipet tip. Label the plastic bottle
"10 mg L'1 QC Stock".
8.3.6 Aluminum Calibration Standards
NOTE 1: Flasks used for the standards should never be acid-washed. Wash
only with deionized water. Flasks should be dedicated to a
particular standard.
NOTE 2: Standards should be stored in the refrigerator when not in use.
1. Routine Calibration Standards--
NOTE: Check the calibration of all pipets daily prior to use. Use
the same pipet tip as used for the calibration or recheck the
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calibration if a new tip is required. Be sure to rinse the tip
with the standard prior to use.
a. Fill a clean, labeled 100-mL volumetric flask with approximately
30 ml deionized water. Use one flask per standard.
b. Use the appropriate calibrated pi pet to deliver the correct volume
of stock solution to the flask. See Table 8-1 for values.
c. Mix thoroughly by inversion. Using a disposable pipet, bring
up to the 100-mL mark (exactly) with deionized water.
d. Cap flask and store in the refrigerator when not in use.
2. High-Range Calibration Standards
NOTE: These standards are used for calibration with the "High Al" method.
They require a significant volume of stock solution and should only
be prepared if a sample is found to be out of range on the routine
calibration.
a. These standards are also made in 100-mL volumetric flasks.
Follow the procedure for routine calibration standards, but use
Table 8-2.
b. Be sure to keep an accurate count of 5-mL portions added to each
flask. Standards should be exact.
3. Acidified Blank Preparation
NOTE: The acidified blank is used in the calibration procedure only.
a. Fill a clean 100-mL volumetric flask with about 50 mL of
deionized water. Label "10 percent Nitric Acid".
b. Slowly add 10.0 mL concentrated Ultrex or equivalent nitric acid.
c. Dilute to 100 mL with deionized water. Store in the refrig-
erator. This may be used as a stock solution to prepare the
acidified blank each day.
d. Place 0.1 mL of 10-percent nitric acid in a 500-mL graduated
cylinder containing about 250 mL of deionized water. Dilute to
500-mL mark with deionized water. Label "Acidified Blank".
4. 20 ug L~l Detection Limit StandardFollow the procedure outlined for
routine calibration standards using a 200- to 1000-uL pipet to deliver
200 uL of an aluminum calibration stock solution to the flask.
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TABLE 8-1. VOLUME OF ALUMINUM STOCK STANDARDS REQUIRED TO
PREPARE DAILY STANDARDS
Calibration
Standards
Standard
Concentration
(M9 L'1)
0
25
100
200
350
500
750
1000
Micropipet
Range
40-200 ML
200-1000 ML
200-1000 ML
1-5 mL
1-5 mL
1-5 mL
1-5 mL
1-5 mL
Volume of Standard
Stock Required
See Section 8.3.6
250 ML
1000 ML
2.00 mL
3.50 mL
5.00 mL
7.50 mL
10.00 mL
TABLE 8-2. VOLUME OF ALUMINUM STOCK STANDARDS REQUIRED FOR
HIGH RANGE CALIBRATION STANDARDS
Standard
Concentration
(M9 L-l)
1000
2000
3500
Micropipet
Range
1-5 mL
1-5 mL
1-5 mL
Volume of Standard
Stock Required (mL)
10
20
35
8.3.7 Quality Control Standards
1. 75 ug L"1 Routine QC Standard--
a. Fill a clean, labeled 500-mL volumetric flask with approximately
300 mL of deionized water.
b. Use a calibrated pipet to deliver 3.75 mL of 10-mg-L"1 QC stock
solution to the flask. Be sure to use a new pipet tip.
c. Mix thoroughly. Bring up to exact volume with deionized water
and mix again.
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d. Fill a labeled 60-mL syringe with the standard after rinsing it
with the standard three times. Affix syringe valve.
e. Store standards in the refrigerator.
2. 600 ug L~l Routine QC StandardFollow the above procedure except
substitute a 100-mL flask. Use 6.00 ml of 10-mg L"1 QC stock solution
to prepare this QC solution.
3. 2500 ug L'1 High Range QC Standard
NOTE: This standard is a QC check for the "High Al" method. It requires
a significant volume of stock solution and should only be prepared
.if a sample is found to be out of range on the routine calibration.
a. Fill a clean, labeled 100-mL volumetric flask with approximately
50 mL deionized water.
b. Use a calibrated pi pet to deliver 25.0 ml QC stock solution to
the flask. Be sure to use a new pipet tip.
c. Mix thoroughly. Bring up to the 100-mL mark with deionized water
and mix again.
d. Store flask in the refrigerator.
8.3.8 Reagent Filtering/Degassing
NOTE 1: Glass bell jars are very fragile. Removing the funnel while
vacuum pressure is high may result in breakage.
NOTE 2: Thoroughly wash the filtration apparatus between each reagent
filtration. Rinse with copious amounts of deionized water.
A blue-grey liquid on the filtration apparatus indicates a
reaction between the PCV and buffer, a sign of improper rinsing.
1. Rinse the properly labeled 1-L plastic bottle and cap with deionized
water. Place the bottle under the bell jar on the vacuum filtration
apparatus.
2. For all reagents but the buffer, a 0.45-um Gelman filter in a small
Nalgene filtration funnel should be used. For the buffer, place a
Whatman GF/C filter in a large Buchner funnel. (A glass fiber filter
may be substituted for the Whatman filter. This filter will also
fit into the small Nalgene filtration funnel). Handle the filters
with clean forceps.
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3. Turn on the vacuum pump and pour a small amount of reagent through
the filter and into the 1-L bottle to rinse.
4. Turn off the vacuum and allow the pressure to fall to near zero.
Remove the bottle and replace the cap. Shake the bottle to rinse
interior surfaces. Discard the reagent rinse.
5. Replace the bottle under the filtration apparatus and filter the
remaining reagent into the bottle. Do not overfill the funnel.
For the buffer, one filter is good for about 1 L of reagent.
6. Pour the reagent from the bottle into the appropriate reagent reser-
voir. Store the excess reagents (except PCV) in the refrigerator.
8.4 PREPARATION
NOTE: System assembly is illustrated in Figure 8-l(a) and 8-l(b) for
Channels 1 and 2, respectively.
8.4.1 Precalibration Procedure
1. With pump off, remove reagent lines from deionized water flask.
Place each line in the appropriate reagent reservoir. Be sure the
end is completely submerged in reagent. Cover the opening of each
reservoir with Parafilm. Each reservoir should contain two lines,
one line for each channel.
2. Lock down the pressure arms on the pump. Turn on the pump. Adjust
tension on each line to be sure pptimal pumping is achieved. Worn
tubes will not pump well even at'highest tension. Bubbles oscillat-
ing in a line signal a worn pump tube. Replace it with a pump tube
of the same type.
3. Observe the baseline on both channels. Adjust the zero knobs on
colorimeter to make both channels as close to 100 as possible. Be
sure the baseline is stable for a period of time after adjustment.
4. Recheck the gain knob and be sure it is set to the proper position
and locked into place. Do not adjust this knob once the calibration
has begun or at any time during sample analysis.
5. Check the sample loops. Be sure the proper size loops are in place.
Check all lines for signs of wear.
6. Be sure the waste container is empty and waste is flowing properly.
Turn the pH meter knob to "pH" position. Meter should be calibrated
using procedure in Section 19.4. Record the calibration data in the
logbook. Monitor the waste from one channel by allowing the waste
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mi/min
SAMPLE
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C
R1 .
R2
R3
Key;
1.8
0.8
O.8
1.0
JL
RC3
590>->- pH 6.1
(waste)
Carrier: Deionized water (or 0.1 M HCI)
Rl - Masking solution: Hydroxylammonium chloride
and 1,10 Phenanthroline chloride
R2 Color reagent: Pyrocatacholviolet
R3 Buffer solution: Haxamethylenetatramine and NaOH
RC1- ReactionCoil. 10 cm (0.5 mm i.d.)
RC2- Reaction Coil. 30 cm (0.5 mm i.d.)
RC3ReactionCoil, 60 cm(0.5 mm i.d.)
Sample
Waste
R1
R2
R3
Key:
mi/min
CEC
1.8
0.8
O.8
1.0
Carrier: Deionized water (or 0.1 M HCI)
Rl - Masking solution: Hydroxylammonium chloride
and 1,10 Phenanthroline chloride
R2 - Color reagent: Pyrocatacholviolet
R3 Buffer solution: Haxamethylenetatramine and NaOH
RC1- ReactionCoil, 10 cm (0.5 mm i.d.)
RC2- Reaction Coil, 30 cm (0.5 mm i.d.)
RC3ReactionCoil, 60 cm(0.5 mm i.d.)
CEC-Cation Exchange column
Figure 8-l(a,b). Schematic of flow injection system for aluminum speciation,
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from that channel to flow over the pH probe. Check for a stable
reading. The pH value should be approximately 6.1 ± 0.1.
7. If using a strip chart recorder, adjust prior to sample analysis.
Adjust pen level with zero knob. Check time base and sensitivity
settings also.
8.4.2 Calibration and Standardization
Channels 1 and 2--The dilute calibration standards (including the 0.000 ug
I"1 Al standard) described in Section 8.3.6 are prepared prior to analysis each
day. The cation exchange column is disengaged by turning the 6-port switching
valve to the cl/cal/QC" position, allowing the standards to fill the sample
loop on Channel 2 without passing through the cation exchange column. A low
calibration curve is generated by injecting increasing concentrations of low
calibration standards. Each standard is injected twice during calibration.
The calibration is obtained by printout from the computer, or manually by plot-
ting absorbance (peak area) versus concentration. The best fit line of response
versus concentration is obtained manually or by computer output. Immediately
after the low calibration is performed, high calibration standards are injected
as routine samples and their respective absorbances are recorded for future use
(see "High Calibration" below).
1. Calibration ProceduresOnce the system has attained a steady baseline
with reagents, place the sample intake line into the 100-mL flask
containing the lowest concentration calibration standard (0.00 ug I'1
Al). After two injections of standard, remove the sample line from
the flask, rinse with deionized water and place the sample line in the
next highest standard. Inject this standard twice and continue to
the next highest standard until calibration is complete. Be certain
that the cation exchange column is disengaged during calibration
("cl/cal/QC").
2. High CalibrationThe high calibration standards (500, 750, 1,000 ug
L-J- Al) and high quality control check sample (QCCS) (600 ug L~l Al)
are analyzed daily prior to sample analysis. If a sample exhibits a
measured concentration greater than 350 ug L"1 Al, but less than 600
ug L"A Al, examine the high QCCS for linearity. If the observed con-
centration of the 600 ug L~l QCCS is within 10 percent of its nominal
concentration (540 to 660 ug L"1 Al), the measured concentration of
the high sample may be accepted. If a measured concentration of
greater than 600, but less than 1,000 ug L'1, is observed for a rou-
tine sample, or if the high QC check criteria are not met, a new
calibration line should be calculated from the high standard raw data.
Also, if more than 20 percent of the samples in a batch contain more
than 350 ug L'1 Al, a high calibration should be determined, regardless
of the acceptable high QCCS. The high calibration is determined from
a linear regression of peak area versus concentration of the 350, 500,
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750, and 1,000 ug L"1 Al standards. Check the linearity of the high
calibration by determining the concentration of the high QCCS (600
ug L~l Al) by inserting the peak area into the linear regression
equation. The measured concentration should be within 10 percent of
the nominal value, or the high standards should be reanalyzed and a
new high calibration determined.
If a sample concentration of greater than 1,000 ug L"1 Al is
observed, an expanded calibration may be performed following comple-
tion of the remainder of the batch. Standard concentrations of 1,000,
2,000, and 3,500 Mg L'1 Al and a QCCS of 2,500 ug L"1 Al are used to
calibrate in the expanded range. These standards are prepared by
adding the specified volumes of 10.0 mg L"1 Al standard stock solution
to a clean 100-mL volumetric flask and bringing to a final volume of
100 ml. The 2,500 ug L"1 Al QCCS should be prepared from the
10.0 mg L""1 Al QC stock solution.
ml 10.00
Standard Concentration mg L"1 Al
(ug L'1 Al) required
1,000 10.00
2,000 20.00
2,500 (QCCS) 25.00 (QC stock)
3,500 35.00
Calibration is done by reducing the gain to 1.00 (from 4.00) and
analyzing the 1,000, 2,000, and 3,500 ug L~l Al standards twice each.
This is performed as a separate calibration from the normal calibra-
tion. Analyze the QCCS to ensure linearity (within 10 percent). It
should be noted that the normal limits of linearity have been reported
at 1,000 ug L"1 Al. Also, it is important to change the gain rather
than sample size in order to retain comparable flow charcteristies.
Any samples with aluminum concentrations greater than 3,500 ug L"1 Al
should be diluted with deionized water which has been adjusted to the
pH of the sample with dilute sulfuric acid. This can be done by
titrating deionized water with 0.001N Ultrex or equivalent sulfuric
acid to the pH of the sample and diluting the sample until its PCV
absorbance is on-scale at a gain of 1.00. Return the gain to 4.00
following completion of the high sample analyses. It is very impor-
tant that samples analyzed by high calibrations be rioted as such,
along with their corresponding gain and QC values.
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8.4.3 Maintenance
After completion of all sample analyses for a given day, flush the system
with water for 5 minutes. Next, place the switching valve in the "cl/cal/QC"
position to disengage the cation-exchange column, increase the pump speed by 20
percent, and flush with cleaning solution for 5 minutes. Follow with another
water rinse. Return pump to normal operating speed. Shut off instrument and
computer. If system is not to be used for more than 2 days, pump air through
the lines. Release all pump tubes from the peristaltic pump.
Weekly and daily maintenance is critical in keeping an FIA system in
proper operation. Deviations in flow rate due to worn or constricted lines
alter the flow and mixing characteristics of the system and therefore will
affect the chemistry of the method. Monitor the system constantly for any
changes in flow, replace pump tubes on a regular basis (determined by extent of
use), and release tubes from the pump at the completion of analysis. Spray-
si li cone over the pump rollers weekly to prolong pump tube life. The 0.5-mm
I.D. Teflon tubing is also subject to aging. Crimps in the lines can occur due
to twisting or pinching and are most often observed at the end of mixing coils.
Also, a black precipitate can develop in the lines due to the buffer. Dis-
connecting the coil and injecting cleaning solution from a syringe will augment
the cleaning process. It is also helpful to pass air through the coil with
the syringe. PCV also gradually stains the lines. When a line appears fouled
or damaged, replace it with a line of equal I.D. and length. If a coiled line
is to be replaced, wrap a new coil in a similar fashion. After completing a
coil-wrap, reposition the ends to release any pressure or bends that may lead
to coil-kinking.
Inspect the flow cell regularly for fingerprints, dirt, or scratches. A
dirty flow cell may be cleaned with alcohol, but a scratched or cracked flow
cell should be replaced; therefore, exercise caution when handling flow cells.
Maintain the colorimeter according to manufacturers' instructions. A poorly
functioning colorimeter negates an otherwise properly functioning system;
therefore, the colorimeter should be checked regularly. Turn off the light
source for the colorimeter prior to activating other system components and turn
on after system components to prevent blown fuses.
The rotary valves also require regular maintenance. Weekly (or more fre-
quently if necessary), disassemble the valve by removing the three screws that
hold the valve together and cleaning all of the parts with a soft brush. Check
the^flanged line ends to make sure a good seal is being made and that no con-
strictions exist. Check the valve housing for wear and replace any worn com-
ponents. Put the valve back together by installing the three screws as you
would when changing a tire. Do not over tighten the screws as the Teflon may
become warped. If the valve leaks upon reinstallation, tighten each of the
screws a little more. If the valve still leaks, the flanged ends are probably
not making a good seal. Reinspect the flanges and reassemble the valve.
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8.4.4 Column Packing Procedure
NOTE 1: Soak all reagent lines in deionized water when packing the
column. Turn the pump to "OFF" position.
NOTE 2: Wear gloves while packing the column.
NOTE 3: This procedure is used on initial packing of the column or when
air is introduced into the column.
1. Unscrew the top of the column. This is the outflow for the deionized
water which flushes the column when the valve is in the "CAL"
position.
2. Obtain a 1-5-mL pi pet tip and cut 1-2 mm from the end. Fit the cut
end into the top of the column.
3. If this is the initial packing (or when the Amberlite needs to be
replaced) pour activated Amberlite into the column using a funnel
and proceed to step 5. (See Section 8.3.4 for Amber!ite resin
preparation.)
4. If removing an air pocket from the column, use a disposable pipet to
remove the air pocket, or agitate the beads with a piece of Teflon
tubing to dislodge the air and proceed with step 5.
5. Turn on the pump and allow the deionized water to carry the Amberlite
beads to the pipet tip. Turn off the pump. Allow the beads to fall
and fully pack the column. Be sure that the level of the beads is
flush with the top of the column. If not, add more activated
Amberlite and repeat this step. Remove the excess water with a
disposable pipet.
6. Check for the presence of air pockets. Repeat steps 4 and 5 if any
bubbles persist.
7. Remove the pipet tip and replace the column cap. Be sure that the
cap has all components (washer, Teflon frit) and that there are no
beads on the column threads. If any beads are present on the threads,
dislodge them using a stream of deionized water from a wash bottle.
8. Purge the column deionized water carrier line (preceding the column)
of any air which may have been introduced during the packing
procedure.
9. Turn on the pump and check for any air pockets in the column.
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10. Recharging Amber!ite Cation Exchange Resin--
a.
Pump 0.1N HC1 through the column for 2 minutes. Do not pump the
acid onto the FIA manifold. Collect and discard the effluent
from the column.
b. Pump 0.001N NaCI through the column for 5 minutes. Do not allow
the effluent to pump onto the manifold.
c. Collect 40 mL of effluent in a beaker and measure the pH.
d. The pH value should fall between 4.0 and 5.5. If it does not
repeat steps 2 and 3 until the pH value is within the desired'
range.
8.4.5 Troubleshooting
1.
If the standards used in calibrating do not give a good calibration
after two attempts, remake the standards (recheck pi pet calibrations
Appendix C).
2. If the new standards do not improve the calibration, remake the 10-mg
L -1 aluminum stock solution and prepare new standards.
3. Poorly defined peaks indicate an obstruction in the lines. Flush the
lines with ethyl alcohol. Do not flush alcohol through the column.
4. If flushing fails to correct the problem, check all tubing for kinks
or other objects which could create dispersion.
5. Check all pump tubing for poor pumping efficiencies.
6. An unstable baseline is caused by intermittent flow interruption.
This results in pulsing in the lines and causes baseline fluctuations.
Check all connections for leaks or over tightening.
7. Be sure there is no dead (empty) space in the column. Fill with
appropriate beads.
8.
To check for clogs, place all reagent lines in deionized water. Place
the column in-line on channel 2. Mix a few drops of food coloring
(red is most obvious) in deionized water. Introduce through the sam-
ple inlet line and observe the color progress through the instrument.
Manually switch the valves and continue to observe the color moving
through the lines. Manually switch the valves again and observe
progress through the loops. Switch valves back and observe progress
through the manifolds. This procedure may isolate clogs that are
present in the lines.
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. Page 19 of 24
9. Keep the ambient temperature cool and constant. This will help the
instrument retain its calibration.
10. If the pH is not within the proper range, cheek for:
a. Flow restrictions
b. Drift in the pH meter calibration
c. Incorrect solution preparation
8.5 PROCEDURE
8.5.1 Syringe Pump Setup
1. Release the pressure arm on the sample inlet line at the pump.
Remove the end from the deionized water to prevent siphoning.
2. Disconnect the line at the prevalve fitting.
3. Replace with tubing which has a syringe-adapter fitting on one end.
4. Set the syringe pump near the sample inlet line. The speed knob
should be at "9".
5. Prepare syringes by opening the syringe valve and reducing the volume
to just less than 50 ml. Attach an acid-washed Nucleopore membrane
filter. Rinse the filter by pushing 2-3 ml of sample through. Close
the valve and place the samples in order in the refrigerator; see
Appendix C for filter preparation procedure.
8.5.2 Sample Injection
NOTE 1: The Amber!ite cation exchange column remains in-line for all
sample analyses.
NOTE 2: If any sample exceeds 350 pig Lrl, a 600-ug L-1 QC sample (without
using the column) is analyzed with the next 75-|jg L"1 QC routine
check.
If the value obtained is 600 ± 10 percent, the original sample value is
accepted. If not, a recalibration should be performed using standards
which bracket the value obtained. If the obtained value is in the
1,000-ug L"1 range, the high calibration standards in Table 8-2 should be
prepared.
1. Be sure to monitor the effluent pH and record values on the tally
sheet. pH values should be between 6.0 and 6.2. If the pH starts
to drift, look for possible causes (see Section 8.4.5).
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2. A natural audit sample that contains a known amount of nonexchange-
able aluminum may be analyzed to test the column function.
3. Check baselines and initiate analysis. Run samples in numerical
order.
4. Turn the syringe pump to "OFF" position as soon as the valve lights
return to green.
5. Place the next sample on the pump and affix the inlet line. Check
baseline values between samples. Record any major changes (i.e.,
"glitches") on the tally sheet.
6. Monitor the chart recorder and check for samples that require
reanalysis. Reanalyze any suspect samples (i.e., those with a noisy
baseline, glitches).
7. The 75-ug LT1 QC should be analyzed after every 10 samples, or at
intervals determined by the QA program, once with the column and once
without the column. The acceptable range is 67.5 to 82.5 ug L"1.
8. After the final QC standard has been analyzed, a final natural audit
sample is run with the column. Then the column switch is placed in
the "CAL" position.
9. A final analysis of the 20-ug L~l detection limit and the deionized
water blank is performed.
8.5.3 Cleanup
1. Cap all reservoirs except PCV and store in the refrigerator.
2. Pour PCV into the sink and wash the bottle and cap with deionized
water.
3. Clean all dirty glassware by rinsing three times with deionized water
only.
4. Place inlet lines into the 2-L flask containing deionized water.
5. Remove the syringe adapter line and reattach the pump line.
6. Bypass the column by turning the valve to "CAL" position. Failure to
do this will introduce air into column and repacking the column will
be necessary.
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7. Turn on the pump. Allow lines to flush with deionized water for
5 minutes.
8. Turn the pump off. Place lines in 0.1N HC1/10 percent ethyl alcohol
cleaning solution. Turn the pump on and flush for 5 minutes. Do
not flush the deionized water line leading to the column with the
cleaning solution; this line may be left in the deionized water and
its pressure arm from the pump may be released.
9. Turn the pump off. Replace lines in deionized water and flush for
5 minutes.
10. Turn the pump off. Leave all lines in deionized water. Release
pressure arms on pump. Empty the waste reservoir; failure to do
this will result in waste siphoning back through the manifold and
clogging lines.
11. Remove filters from sample syringes. Remove membranes and discard.
Soak filter parts in deionized water and prepare filters using the
procedure in Appendix C.
12. Save all samples until all laboratory analyses have been completed
and data have been checked by the laboratory supervisor.
13. Turn off power at the monitor, printer, colorimeter., computer, and
injection module. Turn pH meter to "STAND-BY" and store the probe in
3M KC1 solution.
8.6 QUALITY ASSURANCE AND QUALITY CONTROL
8.6.1 Precision and Accuracy
A single operator in a single laboratory analyzed various concentrations
of inorganic monomeric aluminum prepared in distilled/deionized water. The
precision and accuracy estimates are shown in Table 8-3. Similarly, precision
and accuracy were determined for the high calibration range from 350 to 1,000
Mg L-1 Al. These values are displayed in Table 8-4.
Percent recovery was determined for two natural surface water samples,
Big Moose Lake (Adirondack Mountains, New York) and Bagley Lake (Cascade
Mountains, Washington) spiked with 300 and 100 ug L'1 Al, respectively. The
percent recoveries were as shown in Table 8-5.
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TABLE 8-3. PRECISION AND ACCURACY FOR SINGLE OPERATOR AND SINGLE
LABORATORY ANALYSIS OF INORGANIC MONOMERIC ALUMINUM BY
FLOW INJECTION/PYROCATECHOL VIOLET METHOD
Nominal AT
Concentration
Number of
Samples
Avg. Observed
Concentration
(ug L-l)
Precision
(Std. Dev.)
(ug L'1)
Bias
(M9 I"1)
.0
,0
0.0
10.0
15.0
20.
25.
35.0
50.0
75.0
100.0
150.0
350.0
12
13
9
10
10
10
10
10
10
2
5
4.9
9.2
15.0
20.5
24.0
34.2
49.4
70.0
99.1
150.5
350.8
3.3
2.5
2.8
2.5
3.4
2.5
2.8
3.1
2.7
4.8
3.8
4.9
-0.8
0.0
0.5
-1.0
-0.8
-0.6
-5.0
-0.9
0.5
0.8
TABLE 8-4. PRECISION AND ACCURACY FOR SINGLE OPERATOR AND SINGLE
LABORATORY ANALYSIS OF HIGH LEVELS OF INORGANIC MONOMERIC
ALUMINUM BY FLOW INJECTION/PYROCATECHOL VIOLET METHOD
Nominal Al
Concentration
(m L-i)
350.0
500.0
750.0
1000.0
ssss _____
Number of
Samples
5
5
5
5
Avg. Observed
Concentration
(ug L-I)
356.9
494.4
743.9
1004.8
Precision
(Std. Dev.)
(ug L"1)
9.2
11.3
13.3
16.2
Bias
(ug L-l)
6.9
-5.6
-6.1
4.8
8.6.2 Quality Control Checks
1. Detection Limit Quality Control Check Sample (QCCS)Analyze the
detection limit QCCS (20 ug L"l Al) (keep the switching valve in
"cl/cal/QC" position) immediately after low calibration and high cali
bration standards. The high calibration standards are not part of
the computer-generated low calibration. The measured concentration
should be within 20 percent of the actual concentration or the instru
ment detection limit, whichever is greater. If it is not, the reason
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TABLE 8-5. PERCENT RECOVERY OF MONOMERIC ALUMINUM FROM TWO SPIKED
NATURAL SURFACE WATER SAMPLES ANALYZED BY THE FLOW INJECTION/
PYROCATECHOL VIOLET METHOD
Sample
Big Moose
Bagley
Number
of
Samples
6
10
Pre-Spike
Concentration
(ug L-l)
278.2 ± 5.6
3.3 ± 1.5
Spike
Concentration
(ug I'1)
300.0
100.0
Sample + Spike
Concentration
(ug L-l)
575.8 ± 7.7
105.7 ± 2.2
Recovery
(%)
99.6
102.3
for the poor sensitivity and accuracy should be isolated and
eliminated prior to sample analyses.
2. Routine Quality Control Check Sample--If it is not already in posi-
tion, turn the switching valve to "cl/cal/QC" to disengage the cation-
exchange column. Analyze the routine QCCS (75 ug L'1 Al) after the
detection limit QCCS and at intervals determined by the quality
assurance program. The observed concentration should be within
10 percent of the calculated concentration. If the routine QCCS
10-percent window is not met, the reason for the poor accuracy should
be isolated and eliminated prior to sample analyses. A duplicate
injection may be performed, or a QCCS from a freshly prepared batch of
routine QCCS (75 ug L'1 Al) can be injected. If the 10-percent window
again is not met, the FIA should be recalibrated. Reanalyze the
routine QCCS. Continue sample analyses if the QCCS falls within the
10-percent window.
3. BlankAnalyze one blank consisting of water from the same source used
to prepare all reagents and standards. Analyze once at the beginning
and once at the end of analyses for a given day. The blank should be
less than twice the detection limit. If not, the cause for the ele-
vated blank value should be isolated and eliminated.
4. Laboratory DuplicateAnalyze one sample per batch in duplicate
(immediately following the first analysis). The duplicate should be
less than or equal to 10 percent of its corresponding sample for
Channel 1 and Channel 2. If not, the source of the poor precision
should be isolated and eliminated prior to continuing sample analyses.
5. Column Breakthrough SampleThe efficiency of the cation exchange
column (CEC) in removing inorganic monomeric aluminum is determined by
passing a portion of the routine QCCS sample through the CEC every
time the routine QCCS is analyzed as described in step 2. The QCCS
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is passed through the CEC by keeping the switching valve in the
sample position and injecting QCCS. Determine column breakthrough
BEFORE routine QCCS analyses. The CEC should remove all the aluminum
from the QCCS; therefore, Channel 2 should exhibit no detectable
aluminum. If the measured value is greater than 20 percent of the
blank value, perform the column preparation procedure described in
Section 8.4.4.
8.7 References
American Society for Testing and Materials, 1984. Annual Book of ASTM Standards,
i2U\ ?iStnu^r!! Specification for Reagent Water, D 1193-77 (reapproved
1983). ASTM, Philadelphia, Pennsylvania.
Rogeborg, E. 0. S. and A. Henriksen, 1985. An Automated Method for
Fractionation and Determination of Aluminum Species in Freshwaters
Vatten v. 41, pp. 48-53.
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9.0 DETERMINATION OF AMMONIUM
9.1 OVERVIEW
9.1.1 Scope and Application
This method describes the determination of ammonium in natural surface
waters in the range of 0.01 to 2.6 mg L i NH4 . This range is for photometric
measurements made at 630 to 660 nm in a 15-mm or 50-mm tubular flow cell.
Higher concentrations can be determined by sample dilution. Approximately 20
to 60 samples per hour can be analyzed.
9.1.2. Summary of Method
Alkaline phenol and hypochlorite react with ammonia to form an amount of
indophenol blue that is proportional to the ammonium concentration. The
blue color intensifies with sodium nitroprusside (U.S. EPA, 1983).
9.1.3 Interferences
Calcium and magnesium ions may be present in concentration sufficient to
cause precipitation problems during analysis. A 5-percent disodium ethylenedia-
mine tetraacetate (EDTA) solution prevents the precipitation of calcium and
magnesium ions.
Sample turbidity may interfere with this method. Turbidity is removed by
filtration at the processing laboratory. Sample color that absorbs in the
photometric range used also interferes.
9.1.4 Safety
The calibration standards, sample types, and most reagents used in this
method pose no hazard to the analyst. Protective clothing (lab coat and
gloves) and safety glasses should be worn when preparing reagents.
9.2 SAMPLE COLLECTION, PRESERVATION, AND STORAGE
Samples are collected, filtered, and preserved (addition of ^$04 to pH
less than 2). The samples should be stored at 4° C in the dark when not in
use.
9.3 EQUIPMENT AND SUPPLIES
9.3.1 Apparatus and Equipment
Technicon AutoAnalyzer Unit (AAI or AAII) or equivalent, consisting of
sampler, manifold (AAI) or analytical cartridge (AAII), proportioning pump,
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Section 9.0
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heating bath with double-delay coil (AAI), colorimeter equipped with 15-mm
tubular flow cell and 630- to "660-nm filters, recorder, and digital printer for
AAII (optional).
9.3.2 Reagents and Consumable Materials
1. WaterWater should meet the specifications for Type I reagent qrade
water (ASTM, 1984).
2.
3.
5.
Sulfuric Acid (5N), Air Scrubber SolutionCarefully add 139 ml
concentrated sulfuric acid to approximately 500 ml ammonia-free
water. Cool to room temperature and dilute to 1 L with water.
Sodium Phenol ate SolutionUsing a 1-L Erlenmeyer flask, dissolve
83 g phenol in 500 ml water. In small increments, cautiously add
with agitation 32 g NaOH. Periodically cool flask under flowing
tap water. When cool, dilute to 1 L with water.
Sodium Hypochlorite SolutionDilute 150 mL of a bleach solution
containing 5.25 percent NaOCl (such as "Clorox") to 500 ml with
water. Available chlorine level should approximate 2 to 3 percent.
Clorox is a proprietary product and its formulation is subject to
change. The analyst should remain alert to detecting any variation
this product significant to its use in this procedure. Due to the
instability of this product, storage over an extended period should
be avoided.
in
Disodium Ethylenediamine-Tetraacetate (EDTA) (5
50 g EDTA (disodium salt) and approximately six
of water.
percent w/v)Dissolve
pellets NaOH in 1 L
6. Sodium Nitroprusside (0.05 percent w/v)Dissolve 0.5 g sodium
nitroprusside in 1 L deionized water.
7. NH4+ Stock Standard Solution (1,000 mg L'1)Dissolve 2.9654 g anhy-
drous ammonium chloride, NH4C1 (dried at 105 °C for 2 hours) in
water, and dilute to 1,000 mL.
8. Standard Solution A (10.00 mg L"1 NH4+)Dilute 10.0 ml NH/ stock
standard solution to 1,000 ml with water.
9. Standard Solution B (1.000 mg L'1 NH4+)Dilute 10.0 ml standard
solution A to 100.0 ml with water.
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Using standard solutions A and B-, prepare (fresh daily) the following
standards in 100-mL volumetric flasks:
NH/ (mg L'1)
0.01
0.02
0.05
0.10
NH4+ (mg L"1)
0.20
0.50
0.80
00
50
2.00
ml Standard Solution/100 ml
Solution B
1.0
2.0
- 5.0
10.0
mL Standard Solution/100 ml
Solution A
2.0
5.0
8.0 «
10.0
15.0
20.0
9.4 PREPARATION
9.4.1 Calibration and Standardization
Analyze the series of ammonium standards as described in Section 9.5.
Prepare a calibration curve by plotting the peak height versus standard
concentration.
9.5 PROCEDURE .
9.5.1 Standard Operating Procedure
Since the intensity of the color used to quantify the concentration is
pH-dependent, the acid concentration of the wash water and the standard
ammonium solutions should approximate that of the samples. For example, if the
samples have been preserved with 2 mL concentrated HpSO^ L~_;. the wash water
and standards should also contain 2 ml concentrated FSQ L
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1. For a working range of 0.01 to 2.6 mg L"1 NH4+ (AAI), set up the
manlfold_as shown in Figure 9-1. For a working range of 0.01 to
1.3 mg L""1 NH4 (AAII), set up the manifold as shown in Figure 9-2.
Higher concentrations may be accommodated by sample dilution.
2. Allow both colorimeter and recorder to warm up for 30 minutes. Obtain
a stable baseline with all reagents, feeding distilled water through
the sample line.
3. For the AAI system, sample at a rate of 20 hr"1, 1:1. For the AAII
use a 60 hr"1 6:1 cam with a common wash.
4. Load sampler tray with unknown samples.
5. Switch sample line from water to sampler and begin analysis.
6. Dilute and reanalyze samples with an ammonia concentration exceeding
the calibrated concentration range.
9.5.2 Calculations
tration of samples by comparing
A r> A «.«. ...a. .__.. T .1. -_ .? i _L in.
14
Compute concentration of samples by comparing sample peak heights with
the calibration curve. Report results in mg L'1 NH4 .
9.6 QUALITY ASSURANCE AND QUALITY CONTROL
9.6.1 Precision and Accuracy
In a single laboratory (EMSL-Cincinnati), using surface-water samples at
concentrations of 1.41, 0.77, 0.59, and 0.43 mg L"1 NHo-N, the standard
deviation was ±0.005 (U.S. EPA, 1983).
In a single laboratory (EMSL-Cincinnati), using surface-water samples at
concentrations of 0.16 and 1.44 mg L'1 NHo-N, recoveries were 107 percent and
99 percent, respectively (U.S. EPA, 1983). These recoveries are statistically
significantly different from 100 percent.
9.6.2 Quality Control Checks
Quality control checks include blank, duplicate, and matrix spike analyses
and determination of detection limits. Appendix G explains internal quality
control procedures.
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Section 9.0
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Page 5 of 6
SM=SMALL MIXING COIl
LM = LARQE MIXING COIt
HEATING f
BATH 37°C I
WASH WATEf
TO SAMPLER
SM
onoo
LM
CGOOflnfD
LM
mnmnn
SM onm
) f
'
~l
\
PROPORTIONING
PUMP
.
< P B
WASTE
r~
G G
R R
G G
W W
W W
R R
P P
nl/mln.
2.9 WASH
2.0 SAMPLE
0.8 EOTA
2.0 AIR*
0.8 PHENOLATE
0
SAMPLER
20/hr.
1:1
0.6 HYPOCHLORITE
0.6 NITROPRUSSIDE
2.5
> IWASTE
RECORDER
*
SCRUBBED THROUGH
COLORIMETER
5N H2S04
650-660 nm FILTER
Figure 9-1. Ammonia manifold AAI.
PROPORTIONINQ
PUMP
COLORIMETER
50mm FLOW CELL
050-660 nm FILTER
WASTE
SCRUBBED THROUGH
5N H2SO4
Figure 9-2. Ammonia manifold AAII.
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9.7 REFERENCES
American Society for Testing and Materials, 1984. Annual Book of ASTM Standards,
Vol. 11.01, Standard Specification for Reagent Water, D 1193-77 (reapproved
1983). ASTM, Philadelphia, Pennsylvania.
U.S. Environmental Protection Agency, 1983 (revised). Methods for Chemical
Analysis of Water and Wastes. EPA-600/4-79-020. U.S. Environmental
Protection Agency, Cincinnati, Ohio.
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Page 1 of 5
10.0 DETERMINATION OF AMMONIUM BY FLOW INJECTION ANALYSIS
10.1 OVERVIEW
10.1.1 Scope and Application
This method covers the determination of ammonium in the range of 0.01 to
0 150 mg L'1 NH/. This range is for photometric measurements made at 630 to
660 nm in a 10-mm tubular flow cell. Higher concentrations can be determined
by sample dilution. Approximately 60 samples per hour can be analyzed.
10.1.2 Summary of Method
Alkaline phenol and hypochlorite react with ammonia to form an amount of
indophenol blue that is proportional to the ammonium concentration. The blue
color formed is intensified with sodium nitroprusside.
10.1.3 Interferences
Calcium and magnesium ions may be present in concentration sufficient to
precipitate during the analysis. A 5-percent EDTA solution is used to prevent
the precipitation of calcium and magnesium ions.
Sample turbidity may interfere with this method. Turbidity is removed
by filtration at the processing laboratory. Sample color that absorbs in the
photometric range used also interferes. ' .
10.1.4 Safety
The calibration standards, sample types, and most reagents used in this
method pose no hazard to the analyst. Protective clothing (lab coat and
gloves) and safety glasses should be worn when preparing reagents.
10.2 SAMPLE COLLECTION, PRESERVATION, AND STORAGE
Samples are filtered and preserved (addition of H2S04 to pH less than 2)
in the processing laboratory. The samples should be stored at 4 C in the
dark when not in use.
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10.3 EQUIPMENT AND SUPPLIES
10.3.1 Equipment and Apparatus
Tecator FIAstar flow injection analyzer or equivalent consisting of:
1. Sampler.
2. Analytical manifold with 200-uL sample loop
3. In-line heater.
4. Colorimeter equipped with a 10-mm flow cell.
5. Printer.
10.3.2 Reagents and Consumable Materials
1. WaterWater should meet the specifications for Type I reaqent qrade
water (ASTM, 1984).
2. Acidified waterTo a 2-L volumetric flask containing 1500 ml water,
pi pet 0.70 ml of concentrated H2S04 (Ultrex or equivalent). Dilute
to 2 L and mix.
3.
4.
5.
6.
7.
8.
Sodium Phenate SolutionUsing a 400-mL
20.7 g phenol in 200 ml water. Add 8 g
Add water to the 250-mL mark and stir.
a light amber color. Pour the solution
Griffen beaker, dissolve
NaOH, stirring occasionally.
The final solution should be
into a 250-mL amber plastic
bottle and store the bottle in a hood until usedl!
Sodium Hypochlorite SolutionUsing a 500-mL Erlenmeyer flask, dilute
100 mL of a commercial bleach solution (Chlorox or equivalent
5 percent NaOCl, minimum) with 100 mL of water.
Disodium Ethylenediamine Tetraacetate (EDTA)Dissolve 50 g EDTA
(disodium salt) and approximately 6 pellets of NaOH in 1 L of water
and store the solution in a 1-L plastic bottle. To facilitate solu-
tion, use of a mechanical shaker is recommended.
Sodium NitroprussideDissolve 0.5 g sodium nitroprusside in 1 L of
water. Store the solution in a 1-L plastic bottle.
Ammonium Stock Solution (1,000 mg L-1 NH/)In a 1-L volumetric
flask, dissolve 3.6624 g (NH4+)-2S04 (dried at 105 °C for 2 hours) in
water, add 0.35 mL of 18M H2S04 (Ultrex or equivalent), and dilute the
solution to 1 L. Store it in a 1-L plastic bottle.
Standard Solutions (10 mg L"1 NH/)~In a volumetric flask, dilute
l mL of ammonium stock solution to 100 mL with acidified water.
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Section 10.0
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9. Working StandardsUsing the standard solution and diluting with
acidified water, prepare the following standards in 100-mL volumetric
flasks:
4+ (mg L"1) ml standard solution/100 ml
0.010 0.100
0.025 0.250
0.050 0.500
0.100 1.00
0.150 1.50
10.4 PREPARATION
10.4.1 Calibration and Standardization
Analyze the series of standards described above. The calibration curve
is calculated by the instrument. Follow the instructions provided by the
manufacturer for creating calibration curves.
10.5 PROCEDURE
10.5.1 Standard Operating Procedure
1. Turn the power on to the analyzer and to the data station for at least
30 minutes before use.
2. Set up the ammonium manifold, and pump water through the manifold and
lines while making the standards.
3. Prepare the reagents, standards, and QC samples.
4. Check the photometer reference and sample dark current. Consult the
owners manual for specific instructions for this adjustment.
5. Load the standards, QC samples and water samples in the sample trays.
6. Enter the required information about the standards into the analyzer.
7. Begin the analysis.
8. Dilute any samples which are outside the calibration range.
10.5.2 Calculations
The concentrations of the samples are computed by the data station.
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10.6 QUALITY ASSURANCE AND QUALITY CONTROL
10.6.1 Precision and Accuracy
In a single laboratory with standards at concentrations of 0.125, 0 104
(EPA reference sample WP486 No. 1), 0.100, and 0.050 mg L'1 NH/, the averaqe
percent relative standard deviation was 5.65 (Chaloud et al., 1987).
Bias for the same samples were 102, 106, 105, 106, respectively.
10.6.2 Quality Control Checks
A batch is defined herein as the number of samples, excluding the stan-
dards and QC samples, accommodated by the analyzer at any one time. For the
FIAstar, this is approximately 25 samples. The following special sample types
are used for quality control. f JTH«
1. Quality control check solution (QCCS) is a standard having a concen-
tration of approximately the midpoint of the calibration range Use
0.100 mg L HN4 concentration for this procedure. The QCCS is ana-
lyzed after the calibration standards (before any samples), then after
every tenth sample or at intervals determined by the quality assurance
program and as the last sample of any batch of samples. The QCCS
should be within the prescribed accuracy limits (within 10 percent of
actual concentration). If a QCCS is not within the prescribed limit
all samples analyzed since the last good QCCS are reanalyzed. Prepare
the QCCS from an ammonium stock made of ammonium sulfate from a
different lot than that used for the ammonium stock used to prepare
the standards. K
2. Detection limit standard (DL) is a_standard 2 to 5 times the required
detection limit. Use a 0.050 mg L L NH/ solution for this standard.
The DL is analyzed after the first QCCS and before the first sample
and should be within the prescribed accuracy limit (within 20 percent
of actual concentration).
3. A blank is run once per batch of samples. The blank is a sample of
the acidified water used to make up the standards.
4. External standards from the National Bureau of Standards, EPA or
other source should be analyzed twice in any .batch of samples.
5.
An internal standard (IS) or calibration standard is run three times
in a batch; it is run the first time prior to the analysis of the
first sample. The additional IS's are spaced at approximately equal
intervals in the sample batch. The IS assists in compensating for any
drift that may occur during the analysis.
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Section 10.0
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6. One sample in any batch is analyzed in duplicate.
10.7 REFERENCES
American Society for Testing and Materials, 1984. Annual Book of ASTM Stan-
dards, Vol. 11.01, Standard Specification for Reagent Water, D 1193-77
(reapproved 1983). ASTM, Philadephia, Pennsylvania.
Chaloud, D. 0., L. R. Todechiney, R. C. Metcalf, and B. C. Hess, 1987. Wet
Deposition and Snowpack Monitoring Operations and Quality Assurance
Manual. EPA 600/8-87/024. U.S. Environmental Protection Agency, Las
Vegas, Nevada.
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Section 11.0
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Page 1 of 6
11.0 DETERMINATION OF CHLORIDE, NITRATE, AND SULFATE
BY ION CHROMATOGRAPHY
11.1 OVERVIEW
11.1.1 Scope and Application
This method is applicable to the determination of chloride, nitrate, and
sulfate in natural surface waters by ion chromatography (1C). It is recom-
mended for use by or under the supervision of analysts experienced in the use
of ion chromatography and in the interpretation of the resulting ion chromato-
gram. The applicable ranges and method detection limits (MDL) of this method
are:
MDL Range
(mg L-1), (mg L"1)
Chloride 0.01 0.2-10
Nitrate 0.005 0.01-5
Sulfate 0.05 1-20
11.1.2 Summary of Method
1C is a liquid chromatographic technique that combines ion exchange
chromatography, eluent suppression, and conduct!metric detection. A filtered
sample portion is injected into an ion chromatograph. The sample is pumped
through a precolumn, a separator column, a suppressor column, and a conduc-
tivity detector. The precolumn and separator columns are packed with a low-
capacity anion exchange resin. The sample anions are separated in these two
columns based on their affinity for the resin exchange sites.
The suppressor column reduces the conductivity of the eluent to a low
level and converts the sample anions to their acid form. Typical reactions
in the suppressor column are:
Na+ HC03~ + R - H > H2C03 + R - Na
(high-conductivity eluent) (low conductivity)
Na+ A- + R - H > HA + R - Na
Three types of suppressor columns are available: the packed-bed suppres-
sor, the fiber suppressor, and the micromembrane suppressor. The packed-bed
suppressor contains a high-capacity cation exchange resin in the hydrogen form.
The resin is consumed during analysis and has to be regenerated periodically
off-line. The fiber and micromembrane suppressors are based on cation exchange
membranes and are preferred for two reasons. These suppressors are regenerated
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Section 11.0
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continuously throughout the analysis. Also, their dead volume is substantially
less than that of a packed-bed suppressor.
The separated anions in their acid form are measured using a conductivity
cell. Anion identification is based on retention time. Quantification is
performed by comparing sample peak heights to a calibration curve generated
from known standards (ASTM, 1984a; O'Dell et a!., 1984; Topol and Ozdemir,
1981).
11.1.3 Interferences
Interferences can be caused by substances with retention times that are
similar to and overlap those of the anion of interest. Natural surface water
samples are not expected to contain any interfering species. Large amounts of
an anion can interfere with the peak resolution of an adjacent anion. Sample
dilution or spiking can be used to solve most interference problems.
The water dip or negative peak that elutes near, and can interfere with,
the chloride peak can be eliminated by the addition of the concentrated eluent
so that the eluent and sample matrix are similar.
Method interferences may be caused by contaminants in the reagent water,
reagents, glassware, or other sample processing apparatus. These interferences
lead to discrete artifacts or elevated baselines in ion chromatograms.
Samples that contain particles larger than 0.45 microns and reagent solu-
tions that contain particles larger than 0.20 microns should be filtered to
prevent damage to instrument columns and flow systems.
11.1.4 Safety
The calibration standards, samples, and most reagents pose no hazard to
the analyst. Protective clothing and safety glasses should be worn when
handling concentrated sulfuric acid.
11.2 SAMPLE COLLECTION, PRESERVATION, AND STORAGE
Samples are collected in deionized water-washed containers and filtered
without adding any preservative. Aliquot containers are filled completely
(i.e., no headspace) and stored at 4 °C in the dark when not in use.
11.3 EQUIPMENT AND SUPPLIES
11.3.1 Equipment Specifications
1. Ion ChromatographAnalytical system complete with ion chromatograph
and all accessories (conductivity detector, autosampler, data
recording system).
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2. Anion Preseparator and Separator ColumnsDionex Series AG-4A and
AS-4A or equivalents are recommended for use with the ion chromato-
graph. AG-3 and AS-3 columns are suitable for older model ion
chfomatographs.
3. Suppressor Column-Dionex AFS fiber suppressor or AMMS membrane
suppressor have been found to be appropriate.
11.3.2 Reagents and Consumable Materials
Unless stated otherwise, all chemicals should be at least ACS reagent
grade quality. Also, salts used in preparation of standards should be dried at
105 °C for 2 hours and stored in a desiccator.
1. Deionized WaterWater should meet the specifications for Type I
reagent grade water (ASTM, 1984b).
.- 2. Eluent Solution (0.0028M NaHC03/0.0020M Na2C03)Dissolve 0.94 g
sodium bicarbonate (NaHC03) and 0.85 g sodium carbonate (Na2C03) in
water and dilute to 4 L. This eluent strength may be adjusted for
different columns according to the manufactuer's recommendations.
3. Fiber Suppressor Regenerant (0.025N H2S04)Add 2.8 ml concentrated
sulfuric acid (H2S04, Baker Ultrex grade or equivalent) to 4 L water.
4. Stock Standard SolutionsStore stock standards in clean polyethylene
bottles (cleaned with deionized water only, using the procedure
described in Appendix C) at 4 °C. Prepare monthly.
a. Bromide Stock Standard Solution (1,000 mg L-1 Br")Dissolve
1.2877 g sodium bromide (NaBr) in water and dilute to 1.000 L.
b. Chloride Stock Standard Solution (200 mg L'1 Cl~)--Dissolve
0.3297 g sodium chloride (NaCl) in water and dilute to 1.000 L.
c. Fluoride Stock Standard Solution (1,000 mg L~l F~)--Dissolve
2.2100 g sodium fluoride (NaF) in water and dilute to 1.000 L.
d. Nitrate Stock Standard Solution (200 mg L'1 N03~)Dissolve
0.3261 g potassium nitrate (KNOs) in water and dilute to 1.000 L.
e. Phosphate Stock Standard Solution (1,000 mg L~l P)Dissolve
4.3937 g potassium phosphate (KH2P04) in water and dilute to
1.000 L.
f. Sulfate Stock Standard Solution (1,000 mg L'1 S04~2)Dissolve
1.8141 g potassium sulfate (1^504) in water and dilute to 1.000 L.
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5. Mixed Resolution Sample (mg L"1 F , 2 mg L"1 Cl~, 2 mg L
L'-1 P, 2 mg L"1 Br~, 5 mg L"1 S04
2 mg L A P, 2 mg L * Br , 5 mg L SO,/. ^Prepare by appropriate
dilution and mixing of the stock standard solutions.
11.4 PREPARATION
11.4.1 Calibration and Standardization
Each day (or work shift) for each analyte, analyze a blank and a series of
standards which bracket the expected analyte concentration range. Prepare the
standards daily by quantitative dilution of the stock standard solutions.
Suggested concentrations for the dilute standards are given in Table 11-1.
Prepare a calibration curve for each analyte by plotting peak height versus
standard concentration.
TABLE 11-1. SUGGESTED CONCENTRATION OF DILUTE CALIBRATION STANDARDS
Concentration (mg L~l)
Standard Cl N03~ S04
1 0
2 0.020
3 0.10
4 0.50
5 1.00
6 3.00
-2
0
0.020
0.10
0.50
1.00
3.00
0
0.20
, 0.50
2.00
5.00
10.00
11.5 PROCEDURE
11.5.1 Standard Operating Procedure
1. Set up the 1C for operation. Typical operating conditions for a
Dionex 2010i 1C are given in Table 11-2. Other conditions may be used
depending upon the columns and system selected.
2. Adjust detector range to cover the concentration range of samples.
3. Load injection loop (manually or via an autosampler) with the sample
(or standard) to be analyzed. Load five to ten times the volume
required to thoroughly flush the sample loop. Inject the sample.
Measure and record (manually or with a data system) the peak heights
for each analyte.
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TABLE 11-2. TYPICAL ION CHROMATOGRAPH OPERATING CONDITIONS
1C: Dionex 2010ia Eluent Flow Rate: 2.0 ml min"1
Precolumn: AG-4Aa Regenerant: 0.025N H2S04
Separator Column: AS-4Aa Regenerant Flow Rate: 3 mL min"1
Suppressor Column: AMMSa Sample Loop Size: 250 uL
Eluent: 0.75mM NaHC03/2.0mM Na2C03
Typical Ion Retention Time (min)
>,
CT 1.8
N03~ 4.9
S04"2 8.1
aOr equivalent.
4. Dilute and reanalyze samples with an analyte concentration exceeding
the calibrated concentration range.
11.5.2 Calculations
Compute the sample concentration by comparing the sample peak height with
the calibration curve. Report results in mg L"1.
11.6 QUALITY ASSURANCE AND QUALITY CONTROL
11.6.1 Precision and Accuracy
Typical single operator results for surface water analyses are listed in
Table 11-3 (O'Dell et al., 1984).
11.6.2 Quality Control Checks
General QC procedures and QC checks are described in Appendix G. After
calibration, perform a resolution test. Analyze the mixed standard containing
fluoride, chloride, nitrate, phosphate, bromide, and sulfate. Resolution
between adjacent peaks should equal or exceed 60 percent. If it is not,
replace or clean the separator column and repeat calibration.
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TABLE 11-3. SINGLE OPERATOR ACCURACY AND PRECISION (O'Dell et al., 1984)a
Spike Number of Mean Percent Standard
Ion (mg L"1) Replicates Recovery Deviation (mg L"1)
Cl
NO
SO
===
1.0
3~ 0.5
4~2 10.0
ss===ssss= ====== «==
7
7
7
105
100
112
0.14
0.0058
0.71.-.r
aThe chromatographic conditions used by O'Dell were slightly different than
those listed in Table 11-2. However, the results are typical of what is
expected. , .-;...-.
11.7 REFERENCES
American Society for Testing and Materials, 1.984a. Annual Book of ASTM Stan-
dards, Vol. 11.01, Standard Test Method for Anions in Water by Ion
Chromatography, D 4327-84. ASTM, Philadelphia, Pennsylvania.
American Society for Testing and Materials, 1984b. Annual Book of ASTM Stan-
dards, Vol. 11.01, Standard Specification for Reagent Water, D 1193-77
(reapproved 1983). ASTM, Philadelphia, Pennsylvania.
O'Dell, J. W., J. D. Pfaff, M. E. Gales, and G. D. McKee, 1984. Technical
Addition to Methods for the Chemical Analysis of Water and Wastes,
Method 300.0, The Determination of Inorganic Anions in Water by Ion
Chromatography. EPA-600/4-85-017. U.S. Environmental Protection Agency,
Cincinnati, Ohio.
Topol, L. E., and S. Ozdemir, 1984. Quality Assurance Handbook for Air Pollu-
tion Measurement Systems: Vol. V. Manual for Precipitation Measurement
Systems, Part II. Operations and Maintenance Manual. EPA-600/4-82-042b.
U.S. Environmental Protection Agency, Research Triangle Park, North
Carolina.
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12.0 DETERMINATION OF CHLOROPHYLL a
12.1 OVERVIEW
12.1.1 Scope and Application
This procedure is applicable to the determination of chlorophyll ji.and
pheophytin a_ concentrations in natural waters of low ionic strength.
Chlorophyll _a is one of several chlorophylls found in planktonic algae and is
commonly measured as an indicator of algal biomass (Shelske, 1984).
12.1.2 Summary Of Method
Surface-water samples are filtered in the field, and the phytoplankton
retained on a polycarbonate filter are frozen at -20 °C until analysis. The
filters are extracted at 4 °C with 95 percent methanol. The fluorescence
intensity of the extracted pigments at 660 nm is measured and is compared to
the measured intensities of chlorophyll a^ standards (Stainton, et al., 1977).
The extract is then analyzed by reverse-phase, high-performance liquid
chromatography (HPLC) with fluorescence detection to allow differentiation
between fluorescence from chlorophyll a. and from other pigments that fluores-
cence at 660 nm (Reibiz, et al., 1978).
12.1.3 Interferences
With the fluorometer settings recommended, the instrument responds to
chlorophyll a_ in the extract (Stainton, et al., 1977). However, pheophytin a_,
chlorophyll J3, pheophytin b_, and other common pigments also fluoresce at 660 nm,
resulting in an overestimate of chlorophyll £ (Holm-Hansen and Riemann, 1978).
HPLC analysis of the extract allows measurement of the exact, amounts of
chlorophyll a_ and pheophytin _a.
12.1.4 Safety
Diethyl ether can form potentially explosive peroxides when stored; this
can be avoided by storage over a sodium alloy (e.g., Dri-Na). Diethyl'ether
and dimethylamine are very volatile and, along with ethyl acetate, hexane, and
methanol, are extremely flammable (NIOSH/OSHA, 1978; Muir, 1980). All work
with these compounds should be performed in a fume hood. Dimethylamine is
highly toxic; respirators should be worn if ambient concentrations are above
10 ppm. If dimethylamine is used outside a fume hood, laboratory air concen-
trations and personnel exposure should be monitored (NIOSH, 1977).
Analysts should be careful when handling concentrated acids. Eye protec-
tion should be worn, and work should be carried out in a fume hood. Caution
should be exercised to assure that centrifuges and centrifuge heads are firmly
fastened and are stable.
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12.2 SAMPLE COLLECTION, PRESERVATION, AND STORAGE
Surface-water samples are filtered in the field, and the filter pad with
plankton is shipped, frozen, to the processing facility. There the sample is
logged in and is shipped to the analytical laboratory. Chlorophyll is extremely
light-sensitive, and samples must be protected from exposure to light. All
sample-handling operations should be carried out under subdued lighting. In
addition, samples should never be exposed to acid vapors. After collection,
samples should be kept frozen at -20 °C until analysis.
12.3 EQUIPMENT AND SUPPLIES
12.3.1 Equipment Specifications
1. High performance liquid chromatograph, including:
a. Fluorescence detector: Excitation filter - 430-470 nm,
Emission filter - 650-675 nm, blue source.
b. Rheodyne sampling valve, with 10 to 25-uL sampling loop.
c. HPLC pumping system, dual piston, constant flow, capable of 2.0
to 3.0 mL min"1 at 150 bar.
d. IntegratorHewlett Packard 3290 or equivalent.
e. Reverse-phase HPLC column5 micron Spheracil, 250 mm x 2.6 mm
I.D., or equivalent.
f. Guard columnWaters C-18 Guard-Pak, or equivalent.
g. SpectrophotometeiHewlett Packard 8450 photodiode array with
flow cell or equivalent, immediately downstream of the
fluorescence detector.
2. Turner Model III fluorometer, or equivalent, equipped as follows:
a. Cuvettes, 1 cm.
b. Door with standard cuvette holder.
c. Excitation filterKodak Wratten No. 478 (430-450 nm), or
equivalent.
d. Emission filterCorning S2-64 (650-675 nm), or equivalent.
3. Spectrophotometejfor use at 650, 666, and 700 nm, with a spectral
resolution of 2 nm or less and wavelength precision of ±0.05 nm.
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12.3.2 Apparatus
1. Centrifuge, slant-head.
2. Centrifuge tubes15 mL, graduated, with screw cap.
3. Developing chamber for thin-layer chromatography.
4. Filtration equipmentfilters, funnels, filtration flask, vacuum source,
5. SyringesHamilton 1710, or equivalent.
i
6. Vials, with Teflon-lined screw-cap, 10 mL (or greater) capacity.
12.3.3 Reagents and Consumable Materials
1. AcetoneHPLC grade.
2. Chlorophyll aChlorophyll a_ extracted from Anacystis niduluns is
free of chlorophyll J3. Alternatively, chlorophyll from spinach
(which contains chlorophyll tO is available from Sigma Chemical
Company, St. Louis, Missouri. Chlorophyll can also be extracted from
pale green head-lettuce leaves, spinach, or grasses. Chlorophyll a.
can be isolated from extracts by thin-layer chromatographic tech-
niques (Loftus and Carpenter, 1971). The extract, in a mixture of 95
percent methanol and 10 percent NaCI (aq) (50/50, v/v), is extracted
with petroleum ether. The organic phase is freed of water by centri-
fugation and is evaporated to near dryness under a stream of nitrogen.
The remaining solution is spotted on an Eastman 6061 silica-gel
chromatogram sheet (previously dried at 50 °C for 30 minutes). The
chromatogram is developed with 58:30:12 hexane:ethyl acetate:dimethyl-
amine. Chlorophyll a_ (Rf = 7.4) and chlorophyll b_ (Rf = 7.1) spots
are cut out and are extracted into acetone. Store all chlorophyll
standards in the dark at -20 °C.
3. Chlorophyll bChlorophyll _b can be purchased from Sigma Chemical
Company, St. Louis, Missouri, as a crystalline solid. Chlorophyll b_
can also be isolated by the thin-layer chromatographic techniques
described above (Loftus and Carpenter, 1971).
4. Dimethyl amineHPLC Grade.
5. Ethyl AcetateHPLC Grade.
6. HexaneHPLC Grade.
7. Hydrochloric acid, 0.12MAdd 1 volume concentrated HC1 to 100 volumes
deionized water.
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8. MethanolHPLC Grade.
9. Methane"!, 95% (v/v) Add 5 volumes deionized water to 95 volumes
methanol. Mix well.
10. Mobile phase for HPLC-- -Methanol : acetone: water, 68:27:5 by volume.
Store over magnesium carbonate, tightly capped, in a cool, well-
ventilated place. Do not allow prepared mixtures to evaporate.
11. Nitrogen High purity.
12. Petroleum Ether ACS reagent grade.
13. Silica-Gel Chromatography Paper Eastman 6061, or equivalent.
14. Sodium Chloride ACS reagent grade.
15. Water Water used for preparations should conform to the standards for
Type I reagent grade water (ASTM, 1984).
12.4 PREPARATION
12.4.1 HPLC Calibration
Liquid chromatograph operating parameters listed below, or ones which give
resolution equivalent to that shown in Figure 12-1, should be used:
Column: Reverse-phase CIQ, 5 urn
Mobile Phase: Methanol :acetone:water, 68:27:5
(volume)
Detector: Fluorescence
Wavelengths: 440 nm (ex), 660 nm (em)
Flow Rate: 2.0 ml"1 min
Weigh out approximately 1 mg chlorophyll a_. Dissolve the weighed
chlorophyll a_ in 50 ml 95-percent methanol in a stoppered glass bottle which is
wrapped in aluminum foil to prevent exposure of the solution to light. Handle
the stock standard solution with care at all times, and keep it cold (-10°C)
and in the dark when not in use. Exposure to acid vapors should be avoided.
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Figure 12-1. Example high performance liquid chromatography chromatogram.
Measure the ab'sorbances of the stock standard in a 1-cm cuvetts at 650,
666, and 700 nm, with a 1-cm cuvette of 95-percent methanol in the reference
beam. Subtract the absorbance at 700 nm from those at 650 nm and 666 nm to
obtain values corrected for nonspecific light losses (e.g., scattering from
turbidity). Using these corrected values, calculate the chlorophyll a_ and
chlorophyll b concentrations in the solution:
Chlorophyll a_ (mg L"J) 16.5 A666 - 8.3 A650
Chlorophyll b^ (mg L"1) 33.8 A650 - 12.5 K666
If the concentration of chlorophyll b^ is greater than 5 percent of that of
chlorophyll _a, another source of chlorophyll should be used.
Use the procedure described below to prepare mixed calibration standards
of chlorophyll ja and pheophytin j* from the chlorophyll a_ stock solution at five
concentrations spanning the range of 50.0 to 1,000 ug L~l.
NOTE: Prepare all chlorophyll standards under subdued light and store
in the dark.
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1. Add a known volume of the,chlorophyll a. stock solution to a volumetric
flask. Add 1Q percent of that volume o.f 0.12MHC1 to, the flask., ,,.
Swirl the mixture and allow it to stand for 5, minutes.
2. Add 25 mg magnesium carbonate per milliliter of solution and swirl to
mix well. ......
3. After 10 minutes add another measured volume of chlorophyll a^ stock
solution equal to approximately 50 percent of the first volume. Fill
the volumetric flask to 75 percent of its .volume with HPLC mobile
phase.
4. Mix the solution well by inverting the stoppered flask 10 times.
5. Dilute the solution quantitatively and mix well again. Allow the
magnesium carbonate to settle or filter the solution in the dark.
6.
7.
8.
Analyze each calibration standard by injecting a volume through a
nylon sample preparation filter into .the HPLC injection loop and
injecting it on column (-50-uL -injections). - ..,.,,.,, . ... .
Tabulate the peak areas of chlorophyll a_ and pheophytin _a.
Use these results to prepare calibration functions for chlorophyll a.
and pheophytin a.. If the, calibration curve is linear (r >_ 0.99 'for, a
linear regression of area on concentration), the mean response -factor
may be used. - ~
Repeat the calibration each working day using a freshly quantitated stock
solution. If the response for chlorophyll a_ or pheophytin ^ varies from the
expected response by more than 10 percent, prepare fresh stock standards and
repeat the calibration.
12.4.2 Fluorometry Calibration . . .
Use the stock standard described above and 95 percent methanol to prepare
working standards of chlorophyll a_ in volumetric flasks wrapped in aluminum
foil. Use syringes, not air-displacement micropipets, to measure uL volumes.
At least three calibration points should be used for each of the four fluorom-
eter sensitivity ranges -(IX, 3X, 10X, 30X). The fluorometer, should, be.zeroed
against solvent each time there is a scale change, ;
Possible dilutions to be used are given in Table 12-1. It is recommended
to choose standard concentrations which allow measurement of the instrument
response to individual standards on as many scales as possible.
Measure the fluorescence intensity of standard solutions at 660 nm
(Stainton, et al., 1977; Baker, et al., 1983). Prepare intermediate and
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TABLE 12-1. DILUTIONS OF CHLOROPHYLL a. STOCK STANDARD TO MAKE WORKING JTANDARDSa
Working Volume of Concentration (ug L"1)
Standard No. Stock Standard (X = stock standard cone, in mg L~l)
Blank
"1 ' -
2 :
3
4
5
6
7
8
9
10
11
12
aFor each standard,
'OuL
50uL
lOOuL
150uL
200ML
SOOuL
500uL
l.OOmL
2.00mL
S.OOmL
5.00mL
lO.OOmL
20.00mL
final volume is 100 mL.
0.5 X
1.0 X
0.5 X
2.0 X
3.0 X
5.0 X
10 X
20 X
30 X
50 X
100 X
200 X
additional dilutions as necessary to have three readings for each sensitivity
setting (IX, 3X, 10X, 30X). Because of the differences in sensitivity between
individual fluorometers, no concentrations that will work with all instruments
can be specified here. Plot the scale readings of the chlorophyll ^concentra-
tion for each sensitivity factor; if the plot is linear (r _> 0.99 for linear
regression), the mean scale factor (slope) for each sensitivity setting may be
used.
Chlorophyll _a (ug L"1)
F(1X, 3X, 10X, SOX) =
Scale Reading
On some fluorometers there will be curvature for high readings on the IX
sensitivity plot. Although the fluorometer calibration is relatively stable,
the calibration should be checked daily. A change in instrument response of 10
percent or greater necessitates recalibration as described in Section 12.6.2.
The fluorometer should be recalibrated after maintenance, repair, and any
changes in configuration.
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12.5 PROCEDURE
12.5.1 Sample Extraction
NOTE: Perform sample-handling procedures under subdued light.
1. Place the filter in a 10-mL screw-cap vial. Add a measured volume
(3 to 5 ml) of 95 percent (v/v) methanol to the vial to cover the
filter and tightly screw on the cap (with Teflon liner).
2. Record the volume to the nearest 0.1 ml. Allow the mixture to stand
for 1 hour at 4 °C in the dark, inverting it at 15-minute intervals.
3. After 1 hour, decant the methanolic solution from the vial; filtration
or centrifugation of the mixture may be necessary.
4. Store the extract in the dark pending fluorometric and HPLC analysis.
12.5.2 Analysis
From each set of 20 or fewer samples, divide one sample extract into two
aliquots and process the two in parallel. Perform the HPLC analysis before the
measurement of extract gross fluorescence. Record analytical results for all
samples. A form similar to NSWS Form 31, Summary of Analytical Results -
Phytopigments (Appendix D) may be used.
12.5.3 Calculations
Calculate the chlorophyll a_ and pheophytin a_ concentrations from the HPLC
analyses by use of the mean response factor or calibration function (see Section
12.4.1). Calculate the total fluorescence by using the chlorophyll a mean
response factor or calibration curve and the total area of the chromatogram.
Report results in a format similar to NSWS Form 31, Summary of Analytical
Results - Phytopigments (Appendix D) as chlorophyll a_ (ug L~l), pheophytin a
(M9 L"1), and total fluorescence (ug L-1 chlorophyll a_ equivalents). ~
Calculate the concentration of chlorophyll a (from fluorometry) by using
the appropriate scale factor (see Section 12.4.2T. Report results as
chlorophyll a_ (ug L"1 uncorrected, fluorometric).
12.6 QUALITY ASSURANCE AND QUALITY CONTROL
12.6.1 Precision and Accuracy
Although these methods have been used in limnological studies, they are
still in development, and method performances are not well described. Loftus
and Carpenter (1971) report a detection limit of approximately 1 ug L"1 for a
fluorometric method. However, the MDL will depend on the size of the sample
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Section 12.0
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Page 9 of 11
filtered (Holm-Hansen and Riemann, 1978). The HPLC method is estimated to have
a detection limit of 0.2 ug chlorophyll a_ on the filter.
12.6.2 HPLC Analysis Quality Control Checks
1. Before processing any samples, demonstrate through analysis of a
95 percent methanol blank that interferences from glassware and
reagents are under control.
2 From 10 sequential analyses of the methanol blank, calculate the
method detection limit (MDL) using the standard deviation (s) of the
detector signal at the retention time of interest:
MDL (pig L'1) = 3 x s
3. Calibrate the instrument at the start of each working day. In addi-
tion, analyze one calibration standard after every 5 samples or at
intervals dictated by the quality assurance program; if the mean
response changes by more than 10 percent from the initial calibration,
evaluate the response with another standard or recalibrate the instru-
ment. Because the distribution of the HPLC response is not known, the
interim acceptance criterion of 10 percent has been set, pending
availability of better method-performance data.
4. Confirm the identity of peaks identified by HPLC retention time by
evaluating the absorption spectrum from the photodiode array detector
located immediately downstream from the fluorescence detector. Perform
the spectral measurement every 2 seconds.
5. In addition, process a blank daily. A (double-blind) audit sample
should be included with each set of 20 or fewer samples. Results from
this sample should be evaluated to estimate the relative bias of the
measurements. Analyze one extract from each set of 20 or fewer
samples in duplicate. A record of the precision of these duplicate
measurements should be maintained by the laboratory as a check on
analytical precision.
6. Periodically, extracts of phytopigments should be analyzed as a check
on the accuracy of HPLC determinations.
The QC results for the HPLC analyses are recorded in a format similar to
NSWS Form 33, QC Results - Phytopigments - HPLC, and NSWS Form 34, QC Results -
Phytopigments - Time Line (Appendix D).
12.6.3 Fluorometry Quality Control Checks
1. Before analysis of any extracts, make 10 sequential measurements of
,the fluorescence intensity of a 95 percent methanol reagent blank.
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From the estimated standard deviation (SD) of these results, calculate
the method detection limit (MDL) by:
MDL = 3 x SD
2. In addition, on each working day, or with each batch of 15 or fewer
samples, analyze a blank before processing any samples. If the result
of the blank analysis is above the MDL, evaluate the system for
possible sources of contamination.
3. As a check on instrument response, analyze one or more calibration
standards each working day before processing any samples. If the
response changes by more than 10 percent from the initial calibration,
analyze other standards as a check on the stability of the response.
A change of 10 percent-or more in instrument response requires recali-
bration and analysis of two standards each day from that time forward.
Because the exact distribution of the instrument response factor is
not known, acceptance of variation less than or equal to 10 percent
has been set pending better description of method performance. With
each batch of samples, one audit sample should be included as a
(double-blind) check on combined extraction and analysis relative
bias.
4. Analyze one extract from each batch in duplicate. A record of preci-
sion of duplicate measurements should be maintained by the laboratory
as a check on analytical precision.
The QC results for fluorometry are recorded in a format similar to NSWS
Form 32, QC Results - Phytopigments - Fluorometry, and on NSWS Form 34, QC
Results Phytopigments - Time Line (Appendix D).
12.7 REFERENCES
American Society for Testing and Materials, 1984. Annual Book of ASTM Standards
vol. 11.01, Standard Specification for Reagent Water, D1193-77 (reapproved
1983). ASTM, Philadelphia, Pennsylvania.
Baker, K. S., R. C. Smith, and J. R. Nelson, 1983. Chlorophyll determinations
with filter fluorometer: Lamp/filter combinations can cause error.
Limnol. Oceanogr., v. 28 n. 5, pp. 1,037-1,040.
Holm-Hansen, 0., and B. Riemann, 1978. Chlorophyll a. determination: Improve-
ments in Methodology. Oikos; v. 30, pp. 438-477.
Loftus, M. E. and J. H. Carpenter, 1971. A fluorometric method for determining
chlorophylls a_, J3, and £. J. Mar. Res., v. 29, pp. 319-338.
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, Page 11 of 11
Muir, G; D,, 1980. Hazards in the Chemical Laboratory: ;The .Chemical Society,
London, England. ... ; ,
National Institute for Occupational Safety and Health/Occupational Safety and
Health Administration, 1978. NIOSH/OSHA Pocket Guide to Chemical Hazards.
IUS. Government Printing Office, Washington, D.C.
National. Institute for Occupational Safety and Health, 1977. NIOSH Manual of
Analytical Methods, 2nd Ed. (4-volumes),. No. 77-157A. U.S. Department
of Health, Education, and Welfare, Washington, D.C.
Reibeiz, C. A., M. B. Bazzaz, and F. Bel anger, 1978. ln^ Ghromatography Review
v. 4,.n. 2; Spectra Physics. :
Shelske, C. L,, 1984. In Situ and Natural Phytoplankton Assemblage Bioassays
ln^ Algae as Ecological Indicators, pp. 15-47. ' : Academlc Press, London,
England. :;
StaintonrM. P., M. J. Capel, and F. A. J. Armstrong, 1977. The Chemical
Analysis of Fresh Water, 2nd Ed. Fish. ,Mar..'Serv. Spec. Publ. 25,
Canadian Freshwater Institute, Winnipeg, Manitoba, Canada.
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13.0 DETERMINATION OF DISSOLVED INORGANIC CARBON
13.1 OVERVIEW
This procedure is used to measure the amount of dissolved inorganic
carbon (DIG) in natural water and snowpack samples. The amount of carbon in
aquatic systems is largely regulated by the bedrock type and, to a lesser
extent, photosynthesis and respiration. DIC can exist in several forms which
are pH dependent:
pH value Predominant DIC species
<6 free CO2
6-10 HC03"
>10 C03"2
Aquatic environments containing HC03~ and C03~2 generally have a greater buf-
fering capacity than systems containing predominantly free CO;?. DIC content
in combination with pH measurements can, therefore, be a crude indication of
the relative buffering capacity of an aquatic system.
13.1.1 Scope and Application
DIC is determined in NSWS processing laboratories using a Dohrmann DC-80
Carbon Analyzer. This method has been written assuming that the DC-8Q is being
used (Xertex-Dohrmann Corp., 1984). The method, however, can be modified for use
with other instruments meeting the same equipment specifications.
The method detection limit (MDL) for DIC determined from replicate analy-
ses of a calibration blank (approximately 0.1 mg L'1 DIC) is 0.1 mg L'1 DIC.
A 1.00-mL sample volume was used to determine the MDL. The applicable analyte
concentration range is 0.1 to 50 mg L"1 DIC.
13.1.2 Summary of Method
A 1-mL sample is injected into the reaction vessel of the carbon analyzer
where the pH is reduced by phosphoric acid in order to convert the existing
forms of DIC to C02- The C0£ from the sample is purged from the acid reagent
by a continuous flow of nitrogen gas. An infrared (IR) spectrophotometer
detects the amount of C02 present, and the result in parts per million is
displayed and printed.
13.1.3 Interferences
No interferences are known.
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13.1.4 Safety
The calibration standards, sample types, and most reagents used in this
method pose no hazard to the analyst. Protective clothing (lab coat and gloves)
and safety glasses should be worn when handling concentrated phosphoric acid.
The nitrogen cylinder should be secured in an upright position. The line
pressure should be kept below 40 psi. -i =;
13.2 SAMPLE COLLECTION,, PRESERVATION, AND STORAGE
Samples for DIG determination are collected and sealed in syringes; air
bubbles are removed. Sealed syringes.are kept at 4 °C in the dark until analy-
sis. Analysis should be as close to the time of collection as possible,
generally within 24-36 hours. However, a study has shown5that DIG does not
change significantly over a seven-day period if samples are sealed and stored
as described above (Burke, et. al. , 1986).
13.3 EQUIPMENT AND SUPPLIES
13.3.1 Equipment Specifications .. . ,
1. Dohrmann DC-80 Carbon Analyzer or equivalent equipped with high
sensitivity sampler (1.00-mL loop).
13.3.2 ,Apparatus
1. Reagent bottles for DIC standards (equipped with three-valve cap to
permit storage under a C02-free atmosphere, Rainin No. 45-3200 or
equivalent).
2. Luer-Lok syringe valves.
13.3.3 Reagents and Consumable Materials
1. 0.45-um syringe filters. :.-;'
2. 60-mL plastic syringes.""
3. Nitrogen Gas (99.9 percent)C02-free.
4. WaterWater used in all, preparations .should conform to ASTM specifi-
cations for Type I reagent grade water (ASTM, 1984).
5. Phosphoric Acid Reagent-^- , .. .,
a. Fill a clean 1-L-volumetric flask with approximately 500 mL of
deionized water.
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b. Add 50 ml concentrated HsP04 and mix thoroughly.
c. Dilute to the 1-L mark with deionized water, mix well, and
transfer the solution to a Cubitainer labeled "5% ^04". Make
enough to fill a Cubitainer (4 !_)..
d. Fill the reaction vessel with the acid reagent (5% ^04) to just
below the arm of the vessel, using a syringe with Tygon tubing.
6. Calibration Standard Stock (1000 mg L"1 DIC)--
NOTE: All standards are stored under a C0£-free atmosphere and refrig-
erated at 4 °C. Do not allow C02 to enter into any of the stock
reagents; be sure all valves are closed before removing the
syringe from the cap ports.
a. Fill a labeled 1-L volumetric flask with approximately 500 mL of
deionized water.
b. Weigh 8.826 g of anhydrous Na2COa and transfer to the 1-L
volumetric flask. Mix well.
c. After complete dissolution, dilute to the 1-L mark and mix
thoroughly.
d. Turn on the N2 gas and adjust the flowrate to approximately
200 mL min"1 (50 ml per 15 seconds).
e. Use 10-20 mL of the stock solution to rinse a reagent bottle
labeled "Calibration Standard Stock"; then transfer the solution
to a reagent bottle. Tighten the cap firmly and record the
date on the reagent bottle.
f. Attach the purge line from the injector module to the inlet valve
port on the reagent bottle cap. Attach a scrubber line (consis-
ting of first one Mallcosorb, and then one Aquasorb cartridge or
equivalents) to the gas outlet valve on the cap. Open the purge
line and the scrubber line valves (vertical) and close the third,
unused valve (horizontal). Turn the N2 gas line switch (switch
labeled "200") on the injector module to the "UP" position for
external flow. Check the flow of the N£ gas through the system
by placing the end of the scrubber line into a beaker of water
and confirming the presence of bubbles. .
g. Purge the headspace with N2 gas for at least 20 minutes. Be sure
to close all valves before removing the purge line and the
scrubber line, thus preventing C02 contamination.
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7. Daily Calibration Standard (10.00 mg L"1 DIC)
NOTE: Prepare daily, immediately prior to use.
a. Fill a labeled 500-mL volumetric flask with approximately 250 mL
of deionized water.
b. Remove the calibration standard stock from the refrigerator.
Attach a syringe labeled "Calibration Standard Stock" to the out-
let valve of the reagent bottle cap using the female Luer-Lok
adapter. Open the valve and withdraw 5 to 10 ml of the stock
solution. Close the valve. Rinse the syringe with standard, and
empty into a labeled 50-mL beaker. Rinse the beaker. Refill the
syringe with approximately 20 mL of stock solution and empty into
the beaker.
c. Using a calibrated 1 to 5 mL micropipet, rinse the pi pet tip with
the standard solution and add 5.000 mL of calibration standard
stock to the flask and mix well. Dilute to the 500-mL mark with
deionized water and mix thoroughly. Rinse a reagent bottle
labeled "10 mg L"1 Calibration Standard" with 10 to 20 mL of
solution and transfer solution to the reagent bottle. Tighten
the cap and purge headspace as described in steps 6f and 6g.
QC Standard Stock (1,000 mg L~l DIC)~Repeat step 6, calibration
standard stock procedure using a separate source of anhydrous
Label a separate set of glassware "QC Standard Stock".
8.
NOTE 1:
This solution is prepared the same way as the calibration
standard stock. A dilution of the calibration stock is used
to calibrate the carbon analyzer whereas dilutions of the QC
stock are used to check the function of the instrument.
NOTE 2: Prepare weekly.
9. Daily QC Standards--
NOTE 1:
NOTE 2:
Prepare daily, immediately prior to use.
If there are more than 30.samples, make a double batch of
the 2-mg L'1 QC standard in a 1-L volumetric flask.
a. Fill two 500 mL volumetric flasks with approximately 250 mL of
deionized water. Label one flask: "2 mg L'1 QC Standard" and
the other "20 mg L"1 QC Standard."
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b. Follow the procedure for Daily Calibration Standard, step 7b,
substituting the QC standard stock and syringe and beaker labeled
"QC Standard Stock". Use this beaker to prepare the 2-mg L"1 and
20-mg L"1 DIC QC standards.
c. 2-mg L'1 QC StandardUsing a calibrated 200-1,000 \*L micropipet,
rinse the pi pet tip with the QC solution and deliver 1.000 ml QC
Standard Stock to the flask and mix well. Dilute to the 500 mL-
mark and mix again. Rinse a labeled reagent bottle with 10 to
20 mL of solution and transfer the solution to the bottle.
Tighten the cap and purge the headspace for 20 minutes (steps 6f
and 6g).
d. 20-mg I"1 QC StandardUsing a calibrated 1-5 ml micropipet,
rinse the pi pet tip with the QC solution and deliver 10.00 mL of
QC standard stock to the appropriately labeled flask as described
in step c. After rinsing, transfer the solution to a labeled
reagent bottle and purge for at least 20 minutes (steps 6f and
6g).
13.4 PREPARATION
13.4.1 Instrument Setup
CAUTION: Ultraviolet (UV) lamps are not installed for DIC analysis. Do
not turn on UV lamp power switch on the reactor module. The
plug for the lamp (inside reactor module) should be covered
with electrical tape. DO NOT TOUCH - HIGH VOLTAGE.
NOTE 1: See flowcharts for dissolved inorganic carbon analysis (Figures
13-1 and 13-2).
NOTE 2: See Figures 13-3 to 13-5 for illustrations of the Dohrmann carbon
analyzer.
NOTE 3: Allow the IR detector to warm up at least 24 hours prior to
initial use. The IR detector should remain on at all times.
1. Check that all electrical and plumbing connections are complete and
that the tin scrubber is in place. (See instrument manual and Figures
13-3 to 13-5).
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INITIAL
CALIBRATION
LINEARITY
HECK WITHIN RANGE?
2ppm (1.8-2.2ppm)
20ppm(l 8.0-22. Oppm)
RECORD QCCS VALUE
IN LOGBOOK
AND NOTE SAMPLE
ID NUMBERS ASSOCIATED
WITH
UNACCEPTABLE QCCS
MEASURE
CALIBRATION BLANK
IS IT<0.1ppm?
(RUN UP TO THREE
TIMES)
RECORD QCCS
AND BLANK VALUES
IN LOGBOOK
MEASURE
SAMPLES
IDENTIFY ON
PRINTOUT
ENOUGH
OF
PREVIOUS ANALYZED
SAMPLES FOR
REANALYSIS
IS 2ppm IN RANGE
ANALYSES
COMPLETE
PREVIOUS SAMPLES (FROM LAST ACCEPTABLE QCCS)
MUST BE REANALYZED AFTER ACCEPTABLE QCCS
IS OBTAINED.
Figure 13-1. Flowchart for dissolved inorganic carbon analysis.
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CLEAR PREVIOUS
CALIBRATION INFORMATION
REPEAT CALIBRATION
WITH 10 ppm STANDARD
MAKE NEW CALIBRATION
STOCK AND NEW lOppm
STANDARD .
REPEAT CALIBRATION
NO
POSSIBLE INSTRUMENT
MALFUNCTION
CONSULT OPERATION
MANUAL
AND NOTIFY SUPERVISOR
@ REANALYZE. TO TOTAL OF THREE TIMES. '
(2) PREVIOUS SAMPLES (FROM LAST ACCEPTABLE QCCSI
MUST BE REANALYZED AFTER ACCEPTABLE QCCS IS OBTAINED.
Figure 13-2.
Troubleshooting flowchart for dissolved inorganic
carbon analysis.
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O)
N
(0
S-
ro
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TO
WASTE
(SINK)
TO
SAMPLE
LOOP
^"*
BLUE CONNECTOR
------GREEN-GREEN PUMP TUBING
ePURPLE-BLACK PUMP TUBING
5%
H3P04
Figure 13-4. External plumbing of the Dohrmann carbon analyzer
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\ X
REACTION VESSEL
U-TUBE
1
1
\
.
_.-_. ^-OVERFLOW
5%
H3P04
OVERFLOW
SAMPLE FLOW
""---5% H3P04 REAGENT FLOW
«N2 GAS
Figure 13-5. Internal connections of the Dohrmann carbon analyzer.
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. Page 11 of 17
2. Insert the reagent line from the pump into the 5 percent ^04
container.
3. Place the waste line from the injector module into an empty beaker.
Connect the waste!ine from the reactor module to a waste!ine leading
to the sink.
4. Plug the unit in and turn on the IR detector only (switch inside panel
of detector).
5. Select the sample volume switch position (1 ml). Select analysis
mode switch position (TOC).
6. Fill the U-tube with deionized water to the base of the bulb and place
an empty container underneath the U-tube overflow line.
7. Connect the bubble flowmeter with Tygon tubing to the "OUT" port
at the back of the detector module using the magnetic metal clamps
to secure the bubble flowmeter.
13.4.2 Initial Calibration
1. Check the levels of the acid reagent in the Cubitainer and the
reaction vessel. Check the level of deionized water in the U-tube.
Be sure all reagent lines and drain lines are connected.
2. Turn on the white power switches on the reactor and detector modules.
Start the reagent pump (the white switch on the reactor module).
3. Switch the gas from external flow (purge) to internal flow by switch-
ing the N£ gas line switch to the "Down" position. Adjust the flow
rate to 200 ml min"1 (50 mL per 15 seconds) using the bubble flowmeter.
The values should be 15.0 ±0.1 seconds. Record the average flow rate
of three trials in the logbook. If a rotometer is used, use a bubble
flowmeter to set gas flow initially, then attach the rotometer and
record the reading. Thereafter adjust the N£ regulator to the
position giving this reading on the rotometer. Recheck the rotometer
accuracy every 6 months with the bubble flowmeter. Record the N£ tank
and Ng regulator readings (psi) in the logbook.
4. Adjust the detector to a baseline of approximately 0.0100 using the
"ZERO" knob on the panel inside front of detector module. Record the
initial and final baseline readings in the logbook.
5. Fill a syringe labeled "Blank" with deionized water directly from the
outlet on the reverse osmosis system using Tygon tubing.. Let the
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water run about 5 seconds before the collection of water. Avoid any
exposure to air. Attach a syringe valve and evacuate any air bubbles.
Attach the syringe to the syringe port on the injector module.
6. With the injector module knob on "LOAD", rinse the sample loop with
10-15 ml of deionized water. Inject an additional 5 ml of deionized
water. Close the syringe valve and turn knob to "INJECT" and press
the "START" button on the detector module. When the instrument
signals the completion of sample analysis (it beeps), turn knob to
LOAD". Deionized water should read less than 0.100 ppm. Reanalyze a
fresh deionized water sample if this limit is exceeded.
7. Uncalibrate the instrument by pressing the "CALIB" button on the
electronics module until the light goes out.
8. Attach the syringe labeled "10 mg L"1" to the valve on the outlet of
the reagent bottle containing the daily 10 mg L'1 calibration stan-
dard. Open the valve and withdraw 5 to 10 mL of solution. Close the
valve and rinse syringe. Refill the syringe with 40-50 mL of calibra-
tion standard, avoiding exposure to air. Close the valve. Attach the
syringe valve to the syringe and evacuate any air bubbles.
9. Attach the syringe to the injection port. The injector module knob
should be in the "LOAD" position. Load the sample loop by injecting
5 mL of sample. Close the syringe valve, turn the knob to "INJECT",
and press "START". After sample analysis is completed, record the
sample identification number on the printout.
10. The acceptable range for the calibration standard is 7.8 ± 1.5 mg L"1.
The display prints an error message if the value is outside this
range.
11. If the value is out of range, recheck the gas flow and baseline read-
ings. If either of these is the problem, adjust as described in
Section 13.4.2, steps 3 and 4 and depress "CALIB" until the light
comes on. Press "CALIB" again to uncalibrate (light out) and reanalyze
the sample. If the gas flow or the baseline readings are not the
problem, remake the daily 10 mg L'1 calibration standard and recali-
brate the instrument as described above. If the values are still
not in range, remake the weekly calibration stock solution and
prepare fresh 10 mg L"1 standard solution and recalibrate.
12. Repeat step 9 two more times, leaving the syringe in position through-
out the analyses. There is no need to rinse between injections.
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13. After three sample runs of the 10 mg L'1 calibration standard, push
; "CALIB" until the light comes on. The instrument is now calibrated
and the calibration average and adjusted calibration value will
appear on the printout. Record these values in the logbook.
13.4.3 Linearity Check
NOTE 1: Rinse the sample loop with 5 to 10 ml of deionized water between
injections of the standards.
NOTE 2: Close the syringe valve after each injection of a sample.
1. Using the 2 mg L~1 QC standard in a labeled syringe, repeat steps 8
and 9 of Section 13.4.2. The acceptable range is 2.0 ± 0.2 mg L"1.
2. Using the 20-ppm QC standard in a labeled syringe, reipeat steps 8 and
, 9 of Section 13.4.2. The acceptable range is 20.0 ± 2.0 mg L"1.
3. If both values are within acceptable limits, record the sample
identification on the printout and record the values in the logbook.
4. If any value is not within range:
a. Analyze a second sample from the same syringe. If the result
is within limits, see step 5; if is not within limits obtain a
new syringe and analyze a fresh sample. If the analysis of the
sample from the second syringe is within limits, see step 5; if it
is not, see step 4b.
b. Recheck the gas flow and baseline readings. If the baseline or
gas flow has drifted, reset as described in steps 3 and_4 of
Section 13.4.2, and run the following samples: 20 mg L"1, 10 mg
L"1, 2 mg L'1, and a blank. If these values are all within their
acceptable limits, continue with step 5; if they are not, see
step 4c.
c. If the gas flow or baseline reading has not drifted, check the
accuracy of the QC solutions by remaking any daily QC standard
that exceeds the acceptable range and then reanalyzing. If the
values are in the acceptable range, proceed with step 5; if they
are not, see step 4d.
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d. Remake QC standard stock and then remake both of the daily QC
solutions. Analyze both the 2-mg I"1 and 20-mg L'1 QC solutions.
If both sample values are within range, continue with step 5
below. If they are not within range, consult the instrument
operations manual.
5. Repeat steps 5 and 6 of Section 13.4.2 for the analysis of the "Cali-
bration Blank." The value for the blank should be less than 0.100
ppm. Reanalyze a fresh blank sample if the value is outside of
acceptable limits. Record value in logbook and identify on print-
out. K
13.4.4 Maintenance
1. Weekly, replace all of the pump tubes. Remove the reaction vessel and
rinse it with deionized water, then refill it with fresh 5 percent
H3P04. Remove the U-tube, rinse and refill it with fresh deionized
water. Check all tubing connections and replace tubing, connectors,
or septa as necessary.
2. Make new Calibration and QC solutions weekly.
3. Weekly, wipe down the inside of the reactor module and the outside of
the carbon analyzer with a damp Kimwipe to remove any spilled acid
reagent, or dust.
4. Weekly, replace the glass wool and tin beads of the tin scrubber.
5. Change Aquasorb and Mallcosorb cartridges or scrubber lines- when
color change is evident.
6. Periodically check the printer for an adequate paper supply.
7. Disassemble the pump roller pressure plate and inspect, clean, and
lubricate the bearings after 3 months of daily use.
13.5 PROCEDURE
13.5.1 Sample Analysis
NOTE 1: All sample syringes should be refrigerated at 4 °C.
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NOTE 2: A single batch should be analyzed on a single carbon analyzer.
Record the instrument identification number in the logbook.
NOTE 3: Do not remove air bubbles from the sample syringes. These
bubbles may be the result of C02 degassing which may occur
between the time of sample collection and analysis. If bubbles
are present, record this information in the logbook.
NOTE 4: Record information concerning any damage to the syringe or
syringe valve in the logbook.
1. Obtain a sample syringe from the refrigerator and attach a 0.45 urn
Aero-disk or equivalent syringe filter to the syringe valve.
2. Rinse the sample loop with 5 to 7 ml,of deionized water. Inject a
5-mL portion of the sample. Turn the knob to "INJECT" and push the
"START" button to begin analysis. After the sample data is printed,
write the sample identification (ID) number next to its printed
concentration value.
3. Between injections, rinse the sample loop with 5 to 7 ml of deionized
water.
13.5.2 Data Reporting
1. Tape the DIG printout into the logbook and make sure all sample values
are identified with the correct sample ID number.
13.5.3 Cleanup
1. Acid wash all glassware-by rinsing in succession with deionized water
(once), 5 percent nitric acid (once), and deionized water (three
times).
2. After the logbook has been checked by the laboratory supervisor
and all other analyses are complete, discard the syringe filters empty
syringes, and soak all syringe valves in deionized water.
3. Turn off the "PUMP" switch on the reactor module and disengage the
pump roller pressure plate. Turn off the power switches on the
reactor and the detector modules.
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1.
4. Turn off the N£ gas at its source and remove the reagent line from
the acid reagent container (5 percent ^04).
13.6 QUALITY ASSURANCE AND QUALITY CONTROL
13.6.1 Precision and Accuracy
In a multiple lab study using two lake samples containing 0.42 and 9.9
DIC, respectively, the relative standard deviations were 19 percent (n=41) and
5.2 percent (n=7), respectively.
In a single laboratory (EMSL-Las Vegas), using sodium carbonate in
deiomzed water at concentrations of 0.150, 0.500, 2.00, and 30.00 mg L"1 DIC
recoveries were 94, 101, 101, and 98 percent, respectively.
13.6.2 Quality Control Checks
2 mg L~! QC standardAnalyze a 2-mg L'1 QCCS initially, after every
10 sample injections or at intervals determined by the quality
assurance program. Determine if the value obtained is within range
(2.0 ± 0.2 mg L"1). If the value is within range, proceed with sample
analysis. If the value is not in range, inject a second 5-mL aliquot.
If this value still is not acceptable, fill a new syringe with QCCS
and reanalyze. If the reanalyzed value is not within the acceptable
range, refer to Section 13.4.3, steps 4b through 4d.
Detection LimitDetermine the detection limit by analyzing 20 blank
samples. The detection limit is defined as three times the standard
deviation and should be less than 0.100 mg L'1.
Laboratory DuplicateMeasure one sample in duplicate. It is not
necessary to remove the syringe or rinse between injections. The
duplicate value should be within 10 percent of the routine value.
If it is not, reanalyze a third time or analyze another sample in
duplicate.
13.7 REFERENCES
American Society for Testing and Materials, 1984. Annual Book of ASTM
Standards, Vol. 11.01, Standard Specification for Reagent Water,
D 1193-77 (reapproved 1983). ASTM, Philadelphia, Pennsylvania.
Burke, E. M., D. C. Hi 11 man, and E. M. Heithmar, 1986. Stability of pH and
DIC in sealed syringe samples. Presented at the Rocky Mountain Conference
on Analytical Chemistry, August 3-5, Denver, Colorado.
2.
3.
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Xertex-Dohrmann Corporation, 1984. DC-80 Automated Laboratory Total Organic
Carbon Analyzer Systems Manual, 6th ed. Xertex-Dohrmann, Santa Clara,
f^^T T -P S\V%V\ ^ ^
California
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14.0 DETERMINATION OF DISSOLVED ORGANIC CARBON
AND DISSOLVED INORGANIC CARBON
14.1 OVERVIEW
14.1.1 Scope and Application
This method is applicable to the determination of dissolved organic carbon
(DOC) and dissolved inorganic carbon (DIG) in natural surface waters. This
method is written assuming a Dohrmann-Xertex DC-80 Analyzer is being used, but
any instrumentation having similar operating characteristics may be used
instead. . , ,
The method is applicable over the concentration range 0.1 to 30 mg L"1 DIC
or DOC. The method detection limit is approximately 0.8 mg L"1 DOC and
0.1 mg L"1 DIC, as determined from replicate analyses of a blank sample.
14.1.2 Summary of Method
DOC is determined (after external sparging to remove DIC) by ultraviolet
(UV)-promoted persulfate oxidation, followed by infrared (IR) detection. DIC
is determined directly by acidifying to generate C02 followed by IR detection
(U.S. EPA, 1983; Xertex-Dohrmann, 1984).
14.1.3 Interferences
No interferences are known.
14.1.4 Safety
The sample types, standards, and most reagents pose no hazard to the
analyst. Protective clothing (lab coat) and safety glasses should be worn when
preparing reagents and operating the instrument.
14.2 SAMPLE COLLECTION, PRESERVATAION, AND STORAGE
The sample for DOC analysis is filtered and preserved (pH adjusted to less
than 2 with sulfuric acid). The sample is stored at 4 °C when not in use.
The sample for DIC analysis is not filtered or preserved. It is stored at
4 °C in the dark and is filled completely (i.e., no headspace) to minimize
atmospheric exposure.
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14.3 EQUIPMENT AND SUPPLIES
14.3.1 Equipment Specifications
1. Carbon analyzerThis method is based on the Dohrmann DC-80 Carbon
Analyzer equipped with a high-sensitivity sampler. The essential
components of the instrument are a sample injection valve, UV-reaction
chamber, IR detector, and integrator. The injection valve should have
a 5- to 7-mL sample loop and should permit injection with a standard
Luer-Lok syringe. Other instruments having similar performance
characteristics also may be used.
14.3.2 Apparatus
1. Reagent bottle for standard storageHeavy-wall borosilicate glass
bottle with three two-way valves in the cap. Suitable suppliers
include (but are not limited to) Rainin Instrument Co. (Catalog No.
45-3200) and Anspec Co. (Catalog No. H8332).
2. Disposable plastic Luer-Lok syringes or equivalent (for DIC samples)
equipped with Luer-Lok syringe valves.
14.3.3 Reagents and Consumable Materials
1. DOC Calibration Stock Solution (2,000 mg L~l DOC)Dissolve 0.4250 g
potassium hydrogen phthalate (KHP, primary standard grade, dried at
105 °C for 2 hours) in water, add 0.10 mL phosphoric acid (ACS reagent
grade), and dilute to 100.00 mL with water. Store in an amber bottle
at 4 °C. Prepare monthly.
2. Dilute Daily DOC Calibration SolutionsUsing micropipets and volu-
metric pi pets, prepare the following calibration standards daily:
a. 0.500 mg L'1 DOC - dilute 0.125 mL of DOC calibration stock
solution plus 0.5 mL of phosphoric acid to 500.00 mL with water.
b. 1.000 mg L-1 DOC - dilute 0.250 mL of DOC calibration stock
solution plus 0.5 mL of phosphoric acid to 500.00 mL with water.
c. 5.000 mg L^'bOC - dilute 1.250 mL of DOC calibration stock
solution plus 0.5 mL of phosphoric acid to 500.00 mL with water.
d. 10.00 mg L'1 DOC - dilute 2.500 mL of DOC calibration stock
solution plus 0.5 mL of phosphoric acid to 500.00 mL with water.
e. 30.00 mg L'1 DOC - dilute 3.750 mL of DOC calibration stock
solution plus 0.25 mL of phosphoric acid to 250.00 mL with water.
Store calibration standards in amber bottles at 4 °C.
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3. DOC QC Stock Solution (1,000 mg L"1 DOC)Dissolve 0.5313 g of KHP in
water, add 0.25 mL of phosphoric acid, then dilute to 250.00 ml with
water. The QC stock solution should be prepared using an independent
source of KHP. Store in an amber bottle at 4 °C. Prepare monthly.
4. Dilute Daily DOC QC SolutionsPrepare the following QC samples daily:
a. 0.500 mg L'1 DOC (Detection Limit QC Sample) - dilute 0.250 ml of
QC stock solution plus 0.5 ml phosphoric acid to 500.00 ml with
water.
b. 10.00 mg L"1 DOC - dilute 2.500 mL of QC stock solution plus
0.25 mL of phosphoric acid to 250.00 mL with water.
c. 30.00 mg L"1 DOC - dilute 3.000 mL of QC stock solution plus
0.1 mL of phosphoric acid to 100.00 mL with water.
Store QC samples in amber bottles at 4 °C.
5. DIC Calibration Stock Solution (2,000 mg L"1 DIC) Dissolve 4.4131 g
of sodium carbonate (Na2C03, primary standard grade, freshly dried at
105 °C for 2 hours) in water and dilute to 250.00 mL with water. Store
in a tightly capped bottle under a C02~free atmosphere, as described
in Section 13.3.3, step 6. Prepare weekly.
6. Dilute DIC Calibration SolutionsPrepare the following calibration
standards daily:
a. 0.500 mg L"1 DIC - dilute 0.250 mL of DIC calibration stock
solution to 1.000 L with water.
b. 1.000 mg L"1 DIC - dilute 0.250 mL of DIC calibration stock
solution to 500.00 mL with water.
c. 5.000 mg L"1 DIC - dilute 1.250 mL of DIC calibration stock
solution to 500.00 mL with water.
d. 10.00 mg L"1 DIC - dilute 2.500 mL of DIC calibration stock
solution to 500.00 mL with water.
e. 30.00 mg L"1 DIC - dilute 3.750 mL of DIC calibration stock
solution to 250.00 mL with water.
Store calibration standards in tightly capped bottles under a C02-free
atmosphere.
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7. DIC QC Stock Solution (1,000 mg L 1 DIC)Dissolve 2.2065 g of NaoCOq
in water and dilute to 250.00 ml with water. The QC stock solution
should be prepared using an independent source of ^003. Store in a
tightly capped bottle under a C0£-free atmosphere.
8. Dilute DIC QC SolutionsPrepare the following QC samples daily:
a. 0.500 mg L'1 DIC (Detection Limit QC Sample) -dilute 0.250 mL of
QC stock solution to 500.00 ml with water.
b. 10.00 mg L-1 DIC - dilute 2.500 ml of QC stock solution to
250.00 ml with water.
c. 30.00 mg L"1 DIC - dilute 3.000 ml of QC stock solution to
100.00 ml with water.
9.
10.
11.
Potassium Persulfate Reagent (2 percent w/v) Dissolve 20 g of
potassium persulfate (K2S208, ACS reagent grade or better) in water,
add 2.0 ml phosphoric acid, then dilute to 1.0 L with water. This
reagent is used for DOC analyses.
Phosphoric Acid Reagent (5 percent v/v)Dilute 50.0 ml concentrated
phosphoric acid (ACS reagent grade) to 1.0 L with water. This reagent
is used for DIC analyses.
Mate)Water should meet the specifications for Type I reaqent qrade
water (ASTM, 1984).
14.4 PREPARATION
14.4.1 Instrument Setup
1.
DOCSet up the instrument according to the manufacturer's instruc-
tions. Adjust all liquid and gas flow rates. Turn on UY lamp and
allow the system to stabilize. The IR detector should warm up for at
least 2 hours. For best results, leave the IR detector on at all
times.
2. DICSet up the instrument according to the manufacturer's instruc-
tions. Adjust all liquid and gas flow rates, using 5 percent phos-
phoric acid as the reagent. Do not turn on the UY lamp. Allow the
system to stabilize.
14.4.2 DOC Calibration
For the range of interest (0 to 30 mg IT1 DOC), the instrument is designed
to be calibrated with a single 10.00 mg L'1 DOC standard. The linearity of the
calibration is checked with the QC samples. If acceptable results are not
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Section 14.0
Revision 10
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Page 5 of 7
obtained for the QC samples, the instrument should be calibrated using the pro-
cedure described below for routine calibration.
1. Sparge the 10.00-mg L~l calibration standard for 5 to 6 minutes with
C02~free gas.
2. Following the instructions in the operating manual, calibrate the in-
. strument using three replicate analyses of the 10.00-mg L~l standard.
3. Analyze a system blank and a reagent blank. Both should contain less
-than 0.1 mg L~l DOC. If either contains more DOC, then the water is
contaminated. In this case, all standards and reagents should be
prepared again with DOC-free water, and the instrument should be
recalibrated.
4. After sparging for 5 to 6 minutes, analyze the 0.500, 10.00, and
30.00.mg I"1 QC samples. Acceptable results are 0.50,± 0.10, 10.0 ±
6.5, ,and 30.0 ± 1.5 mg L'1, respectively. If acceptable results are
obtained for all QC samples, the instrument calibration is complete.
If acceptable results are not obtained for one or more of the QC
samples, continue with the steps below.
5. Sparge the 0.500, 1.000, 5.000, 10.00, and 30.00 mg L"1 DOC calibra-
tion standards for 5 to 6 minutes with C0£-free gas.
6. Erase the instrument calibration (if present). Analyze each standard
and record the uncalibrated response.
7. Plot the response versus standard concentration. Draw or calculate
(using linear regression) the best calibration curve.
8. Analyze a system blank and a reagent blank. From their response and
the calibration curve, determine their concentrations. Both should
contain less than 0.1 mg L"1 DOC. If either contains more than
0.1 mg L~l DOC, then the water is contaminated. In this case, the
standards and reagents should be prepared again using DOC-free water,
and the instrument should be recalibrated.
9. After sparging for 5 to 6 minutes, analyze the 0.500 and 10.00:mg L"1
QC samples. From their response and the calibration curve, determine
the concentration of each QC sample. Acceptable results are 0.5 ± 0.1
and 10.0 ± 0.5 mg L~l DOC, respectively. If unacceptable results are
obtained for one or more of the QC samples, the calibration standards
should be prepared again and reanalyzed. Acceptable results should be
obtained prior to sample analysis.
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Section 14.0
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14.4.3 PIC Calibration
The calibration procedure is identical to that for DOC with the exception
that the DIC standards are not sparged prior to analysis.
14.5 PROCEDURE
14.5.1 DOC Standard Operating Procedure
1. Calibrate the carbon analyzer for DOC.
2. Sparge samples with C02-free gas for 5 to 6 minutes (sparge gas should
have a flow of 100 to 200 ml min"1). Load and analyze the sample as
directed by the instrument operating manual.
14.5.2 DIC Standard-Operating Procedure
NOTE: For quality assurance reasons, it is very important that the DIC is
measured at the same time pH is measured.
1. Calibrate the carbon analyzer for DIC.
2. Routine DeterminationRinse a clean syringe with sample. Withdraw a
fresh sample portion into the syringe. Attach a syringe filter (0.45
urn) and simultaneously filter the sample and inject it into the carbon
analyzer. Analyze as directed by the instrument operating manual.
3. Air-Equilibrated DeterminationEquilibrate a sample with 300 ppm C02
in air (see Section 5.5.3). Rinse a clean syringe with the air-
equilibrated sample. Withdraw a fresh portion of the air-equilibrated
sample and attach a syringe filter (0.45 urn). Simultaneously filter
and inject the sample into the carbon analyzer. Analyze as directed
by the instrument operating manual.
14.5.3 Calculations
1. If the routine calibration procedure is satisfactory, the instrument
outputs the sample results directly in mg L"1. DOC or DIC calcula-
tions are not necessary.
2. If a calibration curve is necessary, determine the sample concentra-
tion by comparing the sample response to the calibration curve.
Report results as mg L"1 DOC or DIC.
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14.6 QUALITY ASSURANCE AND QUALITY CONTROL
14.6.1 Precision and Accuracy
1. DOCIn a single laboratory (EMSL-Cincinnati), using raw river water,
centrifuged river water, drinking water, and the effluent from a
carbon column which had concentrations of 3.11, 3.10, 1.79, and 0.07
mg L"1 total organic carbon, respectively, the standard deviations
from 10 replicates were 0.13, 0.03, 0.02, and 0.02 mg L"1, respectively
(U.S. EPA, 1983).
In a single laboratory (EMSL-Cincinnati), using potassium hydrogen
phthalate in distilled water at concentrations between 5.0 and
1.0 mg L~l total organic carbon, recoveries were 80 percent and
91 percent, respectively (U.S. EPA, 1983).
2. DIC--In a multiple lab study using two lake samples containing 0.42 and
9.9 DIC, respectively, the relative standard deviations were 19 percent
(n=41) and 5.2 percent (n=7), respectively.
In a single laboratory (EMSL-Las Vegas), using sodium carbonate in de-
ionized water at concentrations of 0.150, 0.500, 2.00, and 30.00 mg L'1
DIC, recoveries were 94, 101, 100, and 98 percent, respectively.
14.6.2 Quality Control Checks
In addition to the QC inherent in the calibration procedures (Section
14.4), the QC procedures described in Appendix G should be performed.
14.7 REFERENCES
American Society for Testing and Materials, 1984. Annual Book; of ASTM
Standards, Vol. 11.01, Standard Specification for Reagent Water,
D 1193-77 (reapproved 1983). ASTM, Philadelphia, Pennsylvania.
U.S. Environmental Protection Agency, 1983 (revised). Methods for Chemical
Analysis of Water and Wastes. EPA-600/4-79-020. U.S. Environmental
Protection Agency, Cincinnati, Ohio.
Xertex-Dohrmann Corporation, 1984. DC-80 Automated Laboratory Total Organic
Carbon Analyzer Systems Manual, 6th ed. Xertex-Dohrmann, Santa Clara,
California.
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Section 15.0
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15.0 DETERMINATION OF TOTAL DISSOLVED FLUORIDE
BY ION-SELECTIVE ELECTRODE
15.1 OVERVIEW
15.1.1 Scope and Application
This method is applicable to the determination of total dissolved fluoride
in natural surface waters. A fluoride ion-selective electrode USE) is used in
this method. The applicable concentration range is 0.005 to 2 mg L L fluoride
(F~). The method detection limit (MDL) is 0.005 mg L'1 F".
15.1.2 Summary of Method
The total dissolved fluoride in a sample is determined e'lectrometrically
using a fluoride ion-selective electrode after addition to the sample of
a total ionic strength buffer solution (TISAB). The TISAB adjusts sample
ionic strength and pH and breaks up fluoride complexes.
The potential of the fluoride ISE varies logarithmically as a function of
the fluoride concentration. A calibration curve is prepared by measuring the
potential of known fluoride standards (after TISAB addition) and by plotting
the potential versus fluoride concentration (on a semi-log scale). Sample
concentrations are determined by comparing the sample potential to the
calibration curve.
This method is based on existing methods (U.S. EPA, 1983; Barnard and
Nordstrom, 1982; Bauman, 1971; LaZerte, 1984; Kissa, 1983; Warner and
Bressan, 1973).
15.1.3 Interferences
The electrode potential is partially a function of temperature. As a
result, standards and samples should be equilibrated to the same temperature
(±1 °C).
The sample pH should be in the range 5 to 7 to avoid complexation of
fluoride by hydronium (pH <5) and hydroxide (pH >7). The addition of TISAB to
samples and standards ensures that the pH is maintained in the correct range.
Polyvalent cations may interfere by complexing fluoride, thereby prevent-
ing detection by the electrode. The TISAB solution contains a decomplexing
agent to avoid potential interferences from polyvalent cations.
Fluoride is ubiquitous. Good laboratory practices and extra care should
be used in order to minimize contamination of samples and standards.
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15.1.4 Safety
The sample types, calibration standards, and most reagents pose no hazard
to the analyst. Protective clothing (lab coat and gloves) and safety
glasses should be worn when handling concentrated sodium hydroxide.
15.2 SAMPLE COLLECTION, PRESERVATION, AND STORAGE
Samples are collected in deionized water-washed containers and are
filtered without adding any preservative. Aliquot containers should be filled
completely (i.e., no headspace). They are stored at 4°C in the dark when not
in use.
15.3 EQUIPMENT AND SUPPLIES
15.3.1 Equipment and Apparatus
1. Digital electrometer (pH/mV meter) with expanded mV scale capable of
reading 0.1 mV.
2. Combination Reference - Fluoride ion selective electrode.
3. Thermally isolated magnetic stirrer and Teflon-coated stir bar.
15.3.2 Reagents and Consumable Materials
Unless otherwise specified, all chemicals should be ACS reagent grade or
better. Use only plasticware (deionized water-cleaned as described in Appendix
C) for reagent preparation.
1.
2.
TISAB SolutionAdd 57 mL glacial acetic acid (Baker Ultrex grade or
equivalent), 4 g of CDTA (1,2-cyclohexylene dinitrilo tetraacetic
acid) and 58 g of sodium chloride (NaCl, ultrapure) to approximately
500 mL water in a 1-L beaker. Stir to dissolve and cool to room
temperature. Adjust the pH of the solution to between 5.0 and 5.5
with 5N NaOH (about 150 mL will be needed). Transfer the solution to
a 1-L volumetric flask and dilute to the mark with water. Transfer
to a clean polyethylene (LPE) bottle. (Note: Alternatively,
commercially available TISAB solution may be used.)
Sodium Hydroxide Solution (5N NaOH)Dissolve 200 g of NaOH in water,
cool, then dilute to 1 L. Store in a tightly sealed LPE bottle.
3. Fluoride Calibration Solutions
a.
Concentrated Fluoride Calibration Stock Solution (1,000 mg L-1
F~) Dissolve 0.2210 g of sodium fluoride (NaF, ultrapure, dried
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Section 15.0
Revision 10
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Page 3 of 5
at 110 °C for 2 hours and stored in a desiccator) in water and
dilute to 100.00 ml. Store in a clean LPE bottle.
b. Dilute Fluoride Calibration Stock Solution (10.00 mg L"1
F-)Dilute 1.000 ml of the concentrated fluoride calibration
stock solution to 100.00 ml with water.
c. Dilute Fluoride Working StandardsUsing mi crop!pets and volu-
metric pi pets, prepare daily a series of dilute working standards
in the range 0.0-2 mg I"1 F~ by quantitatively diluting appropri-
ate volumes of the 10.00 mg L~l F~ solution and TISAB solution to
50.00 ml. The following series may be used:
ml of ml of 10.00 Resulting F~ Concentration When
TISAB mg L"1 F" Solution Diluted to 50.00 mL (mg L"1)
5.00 0.000 0.0000
5.00 0.050 0.0100
5.00 0.100 0.0200
5.00 0.250 0.0500
5.00 0.500 0.100
5.00 2.50 0.500
5.00 10.00 2.000
4. WaterWater should meet the specifications for Type I reagent
grade water (ASTM, 1984).
15.4 PREPARATION
15.4.1. Calibration and Standardization
1. Allow the electrometer to warm up; ensure that the fluoride-ISE
contains adequate internal filling solution.
2. With the electrometer set to measure mV, analyze the dilute fluoride
working standards (in order of increasing concentration, beginning
with the blank), using the procedure described in steps 3 through 5.
3. Prior to use and between determinations, rinse the electrode with
water until a potential of at least 200 mV is obtained. Blot dry to
avoid carryover.
4. Place 20.00 ml of standard in a clean 30-mL plastic beaker. Add a
clean Teflon-coated stir bar, place on a magnetic stirrer, and stir at
medium speed.
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Section 15.0
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Page 4 of 5
5. Immerse the electrode in the solution to just above the stir bar
and observe the potential. Record the potential when a stable reading
is obtained (potential drift less than 0.1 mV min'1). Record the time
required to obtain the reading. (It may take 15 to 30 minutes to
obtain a stable reading for the low standards.)
6. Prepare a calibration curve on semi-logarithmic graph paper. Plot
the concentration of F~ (in mg L"1) on the log axis versus the
electrode potential on the linear axis. Determine the slope of the
line in the linear portion of the plot. The measured slope should be
within ±10 percent of the theoretical slope (obtained from the elec-
trode manual). If it is not, the electrode is not operating properly.
Consult the electrode manual for guidance. (Note: The calibration
curve may be nonlinear below 0.05 mg L"1.)
15.4.2 Maintenance
The fluoride-ISE should be cleaned and the internal filling solution
replaced at regular intervals, as directed by the manufacturer's instructions.
15.5 PROCEDURE
15.5.1 Standard Operating Procedure
NOTE: Use only plasticware when performing fluoride determinations.
Clean using the deionized water washing procedure described in
Appendix C.
1. Allow samples and standards to equilibrate at room temperature.
2. Analyze fluoride standards and prepare calibration curve as described
in Section 15.4.1.
3.
4.
5.
Prior to use and between determinations, rinse the electrode with
water until a potential of at least 200 mV is obtained. Blot dry to
avoid carryover.
Place 10.00 ml of sample in a clean 30-mL plastic beaker. Add a clean
Teflon-coated stir bar, place on a magnetic stirrer, and stir at a
medium speed. Add 1.00 mL of TISAB to beaker. Record the reading
when a stable potential is obtained (drift is less than 0.1 mV min"1).
Also record the time required to reach the stable reading. (It may
take as long as 15 to 30 minutes.) This assists the analyst in
detecting electrode problems.
At the end of the day, thoroughly rinse the electrode and store it in
deionized water.
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Section 15.0
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15.5.2 Calculations
Compute the sample concentration by comparing the sample potential reading
to the calibration curve. Report results in mg L"1.
15.6 QUALITY ASSURANCE AND QUALITY CONTROL
15.6.1 Precision and Accuracy
A synthetic sample containing 0.85 mg L"1 fluoride and no interferences
was analyzed by 111 analysts; the mean result was 0.84 mg L l and the standard
deviation was 0.03 mg L~i {U.S. EPA, 1983).
A synthetic sample containing 0.75 mg L'1 fluoride, 2.5 rng L'1 polyphos-
phate, and 300 mg L'1 alkalinity was analyzed by 111 analysts: the mean result
was 0.75 mg L"1 fluoride, and the standard deviation was 0.036 (U.S. EPA, 1983)
15.6.2 Quality Control Checks ,
The required quality control procedures are described in Appendix G.
15.7 REFERENCES
American Society for Testing and Materials, 1984. Annual Book of ASTM
Standards, Vol. 11.01, Standard Specification for Reagent Water,
D 1193-77 (reapproved 1983). ASTM, Philadelphia, Pennsylvania.
Barnard, W. R., and D. K. Nordstrom, 1982. Fluoride in Precipitation - I.
Methodology with the Fluoride-Selective Electrode. Atmos. Environ.,
v. 16, pp. 99-103.
Bauman, E. W., 1971. Sensitivity of the Fluoride-Selective Electrode
Below the Micromolar Range. Anal. Chim. Acta, v. 54, pp. 189-197.
Kissa, E. W., 1983. Determination of Fluoride at Low Concentrations with
the Ion-Selective Electrode. Anal. Chem., v. 55, pp. 1445-1448.
LaZerte, B. D., 1984. Forms of Aqueous .Aluminum in Acidified Catchments
of Central Ontario: A Methodological Analysis. Can. J. Fish Aquat.
Sci., v. 41, n. 5, pp. 766-776.
U.S. Environmental Protection Agency, 1983 (revised). Methods for Chemical
Analysis of Water and Wastes, EPA-600/4-79-020. U.S. Environmental
Protection Agency, Cincinnati, Ohio.
Warner, T. B-., and D. 0. Bressan, 1973. Direct Measurement of Less Than
1 part-per-billion Fluoride in Rain, Fog, and Aerosols with an Ion-
Selective Electrode. Anal. Chim. Acta, v. 63, pp. 165-173.
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Section 16.0
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Page 1 of 23
16.0 DETERMINATION OF METALS (Al, Ca, Fe, K, Mg, Mn, Na)
BY ATOMIC ABSORPTION SPECTROSCOPY
16.1 OVERVIEW
16.1.1 Scope and Application
Metals in solution may be readily determined by atomic absorption spectro-
scopy. The method is simple, rapid, and applicable to the determination of
Al, Ca, Fe, K, Mg, Mn, and Na in natural surface waters.
Detection limits, sensitivity, and optimum ranges of the metals vary with
the makes and models of atomic absorption spectrophotometers. The data listed
in Table 16-1, however, provide some indication of the actual concentration
ranges measurable by direct aspiration (flame) and furnace techniques. In the
majority of instances the concentration range shown in the table for analysis
by direct aspiration may be extended much lower with scale expansion and, con-
versely, extended upward by using a less sensitive wavelength or by rotating
the burner head. Detection limits by direct aspiration may also be extended
through concentration of the sample and through solvent extraction techniques.
Lower concentrations may also be determined using the furnace techniques. The
concentration ranges given in Table 16-1 are somewhat dependent on equipment
such as the type of spectrophotometer and furnace accessory, the energy source,
and the degree of electrical expansion of the output signal. When using
furnace techniques, however, the analyst should be cautioned that chemical
reactions may occur at elevated temperatures, which may result in either
suppression or enhancement of the signal from the element being analyzed. To
ensure valid data, the analyst should examine each matrix for interference
effects (matrix spike analysis) and, if detected, should analyze the samples by
the method of standard additions.
16.1.2. Summary of Method
In direct aspiration atomic absorption spectroscopy, a sample is aspirated
and atomized in a flame. A light beam from a hollow cathode lamp, which has a
cathode made of the element to be determined, is directed through the flame
into a monochromator and onto a detector that measures the amount of light
absorbed. Absorption depends on the presence of free unexcited ground state
atoms in the flame. Since the wavelength of the light beam is characteristic
of only the metal being determined, the light energy absorbed by the flame is a
measure of the concentration of that metal in the sample. This principle is
the basis of atomic absorption spectroscopy.
When using the furnace technique in conjunction with an atomic absorption
spectrophotometer, a representative aliquot of a sample is placed in the graph-
ite tube in the furnace, evaporated to dryness, charred, and atomized. As a
greater percentage of available analyte atoms are vaporized and dissociated for
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Section 16.0
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Page 2 of 23
TABLE 16-1.
ATOMIC ABSORPTION CONCENTRATION RANGESa
Flame
Furnace'3'0
Metal
Aluminum
Calcium
Iron
Magnesium
Manganese
Potassium
Sodi urn
===========
Detection
Limit
(mg L-l)
0.1
0.01
0.03
0.001
0.01
0.01
0.002
- =^ _sssz:s= =
Sensi-
tivity
(mg L-l)
1
0.08
0.12
0.007
0.05
0.04
0.015
Optimum
Concentration
Range
(mg L-l)
5 to 50
0.2 to 7
0.3 to 5 *
0.02 to 0.5
0.1 to 3
0.1 to 2
0.03 to 1
Detection
Limit
(ug L-l)
3
1
0.2
'.:; Optimum
Concentration
Range
(ug L-i)
20 to 200
5 to 100
1 to 30
1
aThe concentrations shown are obtainable with any satisfactory atomic absorp-
tion spectrophotometer.
&For furnace sensitivity values, consult instrument operating manual.
GThe listed furnace values are those expected when using a 20-uL
injection and normal gas flow.
absorption in the tube than in the flame, the use of small sample volumes or
detection of low concentrations of elements is possible. The principle is
essentially the same as with direct aspiration atomic absorption except a
furnace, rather than a flame, is used to atomize the sample. Radiation from a
given excited element is passed through the vapor containing ground state atoms
of that element. The intensity of the transmitted radiation decreases in
proportion to the amount of the ground state element in the vapor.
The metal atoms to be measured are placed in the beam of radiation by
increasing the temperature of the furnace, thereby causing the injected speci-
men to be volatilized. A monochromator isolates the characteristic radiation
from the hollow cathode lamp and a photosensitive device measures the attenu-
ated transmitted radiation.
Dissolved metals (Ca, Fe, K, Mg, Mn, and Na) are determined in a filtered
sample by flame atomic absorption spectroscopy (U.S. EPA, 1983).
Total Al is determined in an unfiltered, nitric acid preserved sample after
digestion by graphite furnace atomic absorption spectroscopy (U.S. EPA, 1983).
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Total extractable Al is determined in a sample that has been treated with
8-hydroxyquinoline and has been extracted into MIBK (see Section 7) by graphite
furnace atomic absorption spectroscopy (Barnes, 1975; May et al., 1979;
Driscoll, 1984).
16.1.3 Definitions
1. Optimum Concentration RangeThis is a range, defined by limits
expressed in concentration, below which scale expansion should be used
and above which curve correction should be considered. This^range
varies with the sensitivity of the instrument and the operating
conditions employed.
2. SensitivitySensitivity is the concentration in milligrams of metal
per liter that produces an absorption of 1 percent.
3. Dissolved MetalsDissolved metals are those constituents (metals)
which can pass through a 0.45-um membrane filter.
4. Total MetalsThe concentration of metals is determined on an unfiltered
sample following vigorous digestion.
16.1.4 Interferences
1. Direct AspirationThe most troublesome type of interference in atomic
absorption spectrophotometry is usually termed "chemical" and is
caused by lack of absorption of atoms bound in molecular combination
in the flame. This phenomenon can occur when the flame is not suffi-
ciently hot to dissociate the molecule, as in the case of phosphate
interference with magnesium, or because the dissociated atom is
immediately oxidized to a compound that will not dissociate further at
the temperature of the flame. The addition of lanthanum will overcome
the phosphate interference in the magnesium and calcium determinations.
Similarly, silica interference in the determination of manganese can
be eliminated by the addition of calcium. Chemical interferences may
also be eliminated by separating the metal from the interfering
material. While complexing agents are primarily employed to increase
the sensitivity of the analysis, they may also be used to eliminate
or reduce interferences.
lonization interferences occur when the flame temperature is suffi-
ciently high to generate the removal of an electron from a neutral
atom, giving a positively charged ion. This type of interference can
generally be controlled by the addition, to both standard and sample
solutions, of a large excess of an easily ionized element.
Although quite rare, spectral interference can occur when an absorbing
wavelength of an element present in the sample but not being determined
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2.
falls within the width of the absorption line of the element of
interest. The results of the determination will then be erroneously
high, due to the contribution of the interfering element to the atomic
absorption signal. Also, interference can occur when resonant energy
from another element in a multi-element lamp or a metal impurity in
the lamp cathode falls within the bandpass of the slit setting, and
that metal is present in the sample. This type of interference may
sometimes be reduced by narrowing the slit width.
Flame!ess AtomizationAlthough the problem of oxide formation is
greatly reduced with furnace procedures because atomization occurs in
an inert atmosphere, the technique is still subject to chemical and
matrix interferences. The composition of the sample matrix can have
a major effect on the analysis. It is this effect which should be
determined and taken into consideration in the analysis of each
different matrix encountered. To verify the absence of matrix
or chemical interference, a matrix spike sample is analyzed using the
following procedure:
a. Withdraw two equal aliquots from the sample.
b. Add a known amount of analyte and dilute both aliquots to the
same predetermined volume. The dilution volume should be based
on the analysis of the undiluted sample. Preferably, the dilu-
tion should be 1:4 while keeping in mind the optimum concentra-
tion range of the analysis. Under no circumstances should the
dilution be less than 1:1.
c. Analyze the diluted aliquots.
d. Multiply the unspiked results by the dilution factor and compare
to the original determination.
Agreement of the results (within ±10 percent) indicates the absence of
interference. Comparison of the actual signal from the spike to the
expected response from the analyte in an aqueous standard helps con-
firm the finding from the dilution analysis. Those samples which
indicate the presence of interference should be analyzed by the method
of standard additions.
Gases generated in the furnace during atomization may have molecular
absorption bands encompassing the analytical wavelength. When this
occurs, either the use of background correction or selection of an
alternate wavelength outside the absorption band should eliminate this
interference. Background correction can also compensate for non-
specific broadband absorption interference.
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Interference from a smoke-producing sample matrix can sometimes be
reduced by extending the charring time at a higher temperature or utilizing an
ashing cycle in the presence of air. Care should be taken, however, to prevent
loss of the element being analyzed.
The chemical environment of the furnace may cause certain elements to
form carbides at high temperatures. This problem is greatly reduced and the
sensitivity is increased with the use of pyrolytically-coated graphite.
16.1.5 Safety
The calibration standards, sample types, and most reagents pose no hazard
to the analyst. Protective clothing (lab coat and gloves) and safety glasses
shoud be worn when preparing reagents, especially when concentrated acids and
bases are used. The use of concentrated hydrochloric acid, ammonium hydroxide
solutions, and MIBK should be restricted to a hood.
Follow the manufacturer's safety precautions when operating the atomic
absorption spectrophotometers. Store compressed gases in an upright position.
16.2 SAMPLE COLLECTION, PRESERVATION, AND STORAGE
The sample for dissolved metals is filtered through a 0.45-um membrane
filter, then preserved by acidifying to a pH less than 2 with nitric acid.
(NOTE: Preservation is not absolutely necessary if all analyses are completed
within 30. days). The sample for total Al analysis is preserved by acidifying
unfiltered sample to a pH less than 2 with nitric acid. The sample for total
extractable Al is prepared by mixing a portion of sample with 8-hydroxyquinoline
followed by extraction with MIBK (see Section 7).
After processing, the samples are transferred to an analytical laboratory.
For total extractable Al samples, only the MIBK layer from the extraction is
shipped.
16.3 EQUIPMENT AND SUPPLIES
16.3.1 Equipment and Apparatus
1. Atomic Absorption SpectrophotometerThe required spectrophotometer is
a single- or dual-channel, single-or double-beam instrument having a
grating monochromator, photomultiplier detector, adjustable slits, a
wavelength range of 190 to 800 nm, and provisions for interfacing with
a strip chart recorder.
2. BurnerThe burner recommended by the particular instrument manufac-
turer should be used. For certain elements, a nitrous oxide burner is
required.
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4.
5.
3. Hollow Cathode LampsSingle element lamps are preferred, but multi-
element lamps may be used. Electrode!ess discharge lamps may also be
used when available.
Graphite FurnaceAny furnace device capable of reaching the specified
temperatures is satisfactory.
Strip Chart RecorderA recorder is recommended for furnace work so
that there will be a permanent record and so that any problems with
the analysis (i.e., drift, incomplete atomization, losses during
charring, changes in sensitivity) can be recognized easily.
16.3.2 Reagents and Consumable Materials
^General reagents used in each metal determination are listed in this
section. Reagents specific to particular metal determinations are listed in
the particular procedure description for that metal.
Concentrated Hydrochloric Acid (12M HC1)Ultrapure grade (Baker
Instra-Analyzed or equivalent).
HC1 (1 percent v/v)Add 5 ml of concentrated HC1 to 495 mL water.
Nitric Acid (0.5% v/v HN03Carefully dilute Ultrapure grade HN03
(Baker Instra-Analyzed or equivalent) in water in the ratio of 0.5 to
100.
Stock Standard Metal SolutionsPrepare as directed in the individual
metal procedures. Commercially available stock standard solutions may
also be used.
Dilute Calibration StandardsPrepare a series of standards of the
metal by dilution of the appropriate stock metal solution to cover the
concentration range desired.
Fuel and OxidantCommercial grade acetylene is generally acceptable.
Air may be supplied from a compressed air line, a laboratory compres-
sor, or from a cylinder of compressed air. Reagent grade nitrous
oxide is required for certain determinations. Standard, commercially
available argon and nitrogen are required for furnace work.
7. WaterWater should meet the specfications for Type I reaqent grade
water (ASTM, 1984).
1.
2.
3.
4.
5.
6.
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16.4 PREPARATION
16.4.1 Calibration and Standardization
The calibration procedure varies slightly with the various atomic absorp-
tion instruments. For each analyte, calibrate the atomic absorption instrument
by analyzing a calibration blank and a series of standards, following the
instructions in the instrument operating manual. The concentration of stan-
dards should bracket the expected sample concentration; however, the linear
range of the instrument should not be exceeded.
When indicated by the matrix spike analysis, the analytes should be quan-
tified by the method of standard additions. In this method, equal volumes of
sample are added to a deionized water blank and to three standards containing
different known amounts of the test element. The volume of the blank and of
each standard should be the same. The absorbance of each solution is deter-
mined and then plotted on the vertical axis of a graph, with the concentrations
of the known standards plotted on the horizontal axis. When the resulting line
is extrapolated to zero absorbance, the point of intersection of the abscissa
is the concentration of the unknown. The abscissa on the left of the ordinate
is scaled the same as on the right side, but in the opposite direction from the
ordinate. An example of a plot so obtained is shown in Figure 16-1. The
method of standard additions can be very useful; however, for the results to be
valid the following limitations should be taken into consideration:
1. The absorbance plot of sample and standards should be linear over the
concentration range of concern. For best results, the slope of the
plot should be nearly the same as the slope of the aqueous standard
curve. If the slope is significantly different (more than 20 per-
cent), caution should be exercised.
2. The effect of the interference should not vary as the ratio of
analyte concentration to sample matrix changes, and the standard
addition should respond in a similar manner as the analyte.
3. The determination should be free of spectral interference and
corrected for nonspecific background interference.
16.5 PROCEDURE
16.5.1 Flame Atomic Absorption Spectroscopy
Differences among the various makes and models of satisfactory atomic
absorption spectrophotometers prevent the formulation of detailed instructions
applicable to every instrument. The analyst should follow the manufacturer s
operating instructions for a particular instrument. In general, after choosing
the proper hollow cathode lamp for the analysis, the lamp should be allowed to
warm up for a minimum of 15 minutes unless operated in a double-beam mode.
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ZE
ABSOR
A
B
S
0
R
B
A
N
C
RO E^^
BANCE ^>^ y
^^ ^
^^
\
1
. "j»^
>
CONCENTRATION
Cone, of Addn 0 Addn 1 Ad n 2 Addn3"'~
Sample No Addn Addn of 50%. Addn of 100% Addn of 150%
of Expected of Expected of Expected
Amount Amount Amount
Figure 16-1. Standard addition plot.
During this period, align the instrument, position the monochromator at the
correct wavelength, select the proper monochromator slit width, and adjust the
hollow cathode current according to the manufacturer's recommendation. Sub se-
hn^n! y> I19 K ??e fl^e and re9"1ate the flow of fuel and oxidant, adjust the
burner and nebulizer flow rate for maximum percent absorption and stability
and balance the photometer. Run a series of standards of the element under
calate *hS instrument. Aspirate the samples and deterSthe
reads di>ectiy t
16.5.2 Furnace Atomic Absorption Spectroscopy
Furnace devices (flame! ess atomization) are a most useful means of
f10? lim-ts; Because of d1fferences among various makes and
aclory instruments, no detailed operating instuctions can be
nrnn h +h instrfent- Instead, the analyst should follow the instructions
provided by the manufacturer of a particular instrument and use as a guide
?TC Sm£rature,feJt!ngf and other inst^ment conditions listed in Sections
? ^' (wn1ch &re those ^commended for the Perkin-Elmer
In addition, the following points may be helpful-
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1 With fTameless atomization, background correction is important, espe-
cially below 350 rim. This is because certain samples, when atomized,
may absorb or scatter light from the hollow cathode lamp. These
effects can be caused by the presence of gaseous molecular species,
salt particles, or smoke in the sample beam. If no correction is
made, sample absorbance will be greater than it should,be, and the
analytical result will be erroneously high.
2. If all of the analyte is not volatilized during atomization and
removed from the furnace, memory effects will occur. This condition
depends on several factors (i.e., the volatility of the element and
its chemical form, whether pyrolytic graphite is used, the rate of
atomization, and furnace design). If this situation is detected
through blank burns, the tube should be cleaned by operating the
furnace at full power for the required time period at regular
intervals in the analytical scheme.
3. Some of the smaller size furnace devices, or newer furnaces equipped
with feedback temperature control (Instrumentation Laboratories Model
555, Perkin-Elmer Models HGA 2200 and HGA 76B, and Varian Model CRA-90)
employing faster rates of atomization, can be operated using lower
atomization temperatures for shorter time periods than those listed in
this method.
4 In many cases, prior digestion of the sample is not required if a
representative aliquot of sample can be pipeted into the furnace.
However, prior digestion provides a more uniform matrix and possibly
lessens matrix effects.
5 Inject a measured microliter aliquot of the sample into the furnace
and atomize. If the concentration found is greater than the highest
standard, the sample should be diluted in the same acid matrix and
should be reanalyzed. The use of multiple injections can improve
accuracy and can help detect furnace pipetting errors.
16.5.3 Procedure for Determination of Total Aluminum
To determine total aluminum, a portion of sample is digested and the
digestate is analyzed for aluminum by furnace atomic absorption spectroscopy
(U.S. EPA, 1983).
1 Preparation of Aluminum Standard SolutionsAluminum stock solution
(1 000 mg L'1 Al)--Carefully weigh 1.000 g of aluminum metal (analyti-
cal reagent grade). Add 15 ml concentrated HC1 and 5 ml concentrated
HNOs to the metal, cover the beaker, and warm gently. When the metal
is completely dissolved, transfer solution quantitatively to a 1-L
volumetric flask and bring to volume with water. Alternatively, a
commercially available, certified Al standard may be used.
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Prepare dilutions of the stock solution to be used as calibration
standards at the time of analysis. These solutions are also to be
used for standard additions." The calibration standards should be
prepared in 0.5 percent (v/v) HN03.
2. Sample PreparationThe sample should be digested prior to analysis
Due to the low concentrations of analyte expected, contamination from
atmospheric sources can be-a major problem. To avoid contamination
all preparations should be performed in a laminar flow hood. Perform
digestion as follows:
a. Quantitatively transfer a 50.00-mL aliquot of the well-mixed
sample to a Griffin beaker.
b. Add 3.0 ml of concentrated nitric acid.
c. Place the beaker on a hot plate and cautiously evaporate to near
dryness, making certain that the sample does not boil. (DO NOT
BAKE.)
d. Allow the beaker to cool, then again add 3.0 ml of concentrated
nitric acid. Cover the beaker with a watch glass and return to
the hot plate.
e. Increase the temperature of the hot plate until a gentle reflux
action occurs. Continue refluxing, adding acid as necessary,
until the digestion is complete (indicated by a light-colored
residue or no change in appearance with continued refluxing).
f. When complete, evaporate to near dryness. Allow to cool.
g. Add 0.5 ml of 50 percent nitric acid and warm slightly to dis-
solve any precipate or residue resulting from evaporation.
h. Wash down the beaker walls and watch glass with water.
1. Quantitatively filter the sample (to remove silicates and other
insoluble materials) and adjust to 50.00 ml. The sample is now
ready for analysis.
3. Suggested Instrument Conditions (General)
a. Drying time and temperature30 seconds at 125 °C
b. Ashing time and temperature30 seconds at 1,300 °C
c. Atomizing time and temperature10 seconds at 2,700 °C
d. Purge gas atmosphereArgon
e. Wavelength309.3 nm
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Other operating conditions should be set as specified by the particular
instrument manufacturer.
NOTE 1: The above instrument conditions are for a Perkim-Elmer HGA-
2100, based on the use of a 20-uL injection, continuous-
flow purge gas, and nonpyrolytic graphite.
NOTE 2: Background correction may be required if the sample contains a
high level of dissolved solids.
NOTE 3: It has been reported that chloride ion and that nitrogen, used
as a purge gas, suppress the aluminum signal. Therefore, the use
of halide acids and nitrogen as a purge gas should be avoided.
NOTE 4: The ashing temperature can be increased to 1,500 to 1,700 °C by
adding 30 ug magnesium nitrate (MG(N03)2) (Manning, et al., 1982).
NOTE 5: If blanks indicate that sample contamination is occurring, the
use of Teflon labware is recommended.
4. Analysis Procedure
a. Calibrate the instrument as directed by the instrument manufac-
turer.
b. Analyze the samples (including required QC samples).
c. If a sample concentration exceeds the linear range, dilute (with
acidic media) and reanalyze.
d. Report results as mg L"1 Al.
16.5.4 Procedure for Determination of Total Extractable Aluminum
Samples for extractable aluminum are prepared in the processing labora-
tory and are obtained as the 8-hydroxyquinoline complex in MIBK. The MIBK
solution is analyzed for aluminum by graphite furnace atomic absorption (GFAA)
(Barnes, 1975; May et al., 1979; Driscoll, 1984).
1. Preparation of Reagents
a. Glacial acetic acid (HOAc, 18M)Baker Ultrex grade or equivalent.
b. Ammonium hydroxide (NH4OH, 5M)Baker Ultrex grade or equivalent.
c. Sodium acetate solution (NaOAc, l.OM) Dissolve 8.2 g NaOAc (Alfa
Ultrapure grade or eqivalent) in 100 mL of water.
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d. Methyl isobutyl ketone (MIBK)--HPLC grade or equivalent.
e. Phenol red indicator solution (0.04 percent w/v)ACS reagent
grade.
f. Hydrochloric acid (HC1, 12M) Baker Ultrex grade or equivalent.
g. 2.5M HCl--Dilute 208 mL of 12M HC1 to 1.0 L.
h. NH4+/NH3 bufferAdd 2.5M HC1 to 21 mL of 5M NH>,OH until the
pH = 8.3, then dilute to 100 mL. *
NOTE: Do this cautiously in a fume hood.
i. 8-hydroxyquinoline solution (10 g L"1)Dissolve 5 grams of 8-
hydroxyquinoline (99 plus percent purity) in 12.5 mL HOAc, then
dilute to 500 mL.
j. 8-hydroxyquinoline sodium acetate reagentMix, in order, 10 mL
of l.OM NaOAc, 50 mL of water, and 10 mL of hydroxyquinoline
solution.
NOTE: This reagent should be prepared daily.
2. Preparation of Aluminum Standard Solutions
a. Aluminum stock solutionSee Section 16.5.3, Preparation of
Aluminum Standard Solutions.
b. Dilute calibration standardsEach day, quantitatively dilute the
Al stock solution to prepare a series of calibration standards
over the range 0 to 0.1 mg L'1 Al. A blank should be prepared.
Prior to analysis, the blank, standards, and any QC samples
should be extracted using the following procedure:
1) Pi pet 25.00 mL of a calibration standard (or calibration
blank or QC sample) into a clean 50-mL separatory funnel (or
a clean 50-mL disposable centrifuge tube with cap).
2) Add 2 to 3 drops phenol red indicator and 5.00 mL 8-hydroxy-
quinoline NaOAc reagent. Swirl to mix.
3) Rapidly adjust the pH to 7 by dropwise additions of 5M NHaOH
until the solution turns red. Immediately add 2.0 mL of
NH4 /NH3 buffer and 10 mL of MIBK. Cap and shake vigorously
for 10 seconds using a rapid, end-to-end motion. Be careful
of pressure buildup.
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4) Allow the phases to separate (10 to 15 seconds) and isolate
the MIBK layer. If an emulsion forms, separation can be
hastened by centrifugation. Keep the MIBK layer tightly
capped to prevent evaporation.
3. Suggested Instrument Conditions (General)
a. Drying cycleRamp 10 seconds, hold 10 seconds
b. Drying temperature 100 °C
c. Ashing cycleRamp 5 seconds, hold 20 seconds
d. Ashing temperature--!,500 °C
e. Atomization cycleHold 5 seconds (no ramp, power heating)
f. Atomization temperature2,500 °C
g. Purge gasArgon at 20 cc/minute
h. LampAl HC1 at 25 mA
i. Wavelength309.3 nm
j. Graphite tubeNonpyrolytic
k. Sample size25 uL
These operating conditions are for a Perkin-Elmer 5000 with a HGA-500
graphite furnace and AS-40 autosampler.
4. Analysis Procedure
a. Calibrate the instrument as directed by the instrument
manufacturer.
b. Analyze the samples (including required QC samples).
c. If a sample concentration exceeds the linear range, dilute with
MIBK, and reanalyze.
d. Report results as mg L"1 Al.
NOTE: By using the same volumes for standards as for samples, concen-
tration factors are taken into account.
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16.5.5 Procedure for Determination of Dissolved Calcium
Samples for determination of dissolve calcium (filtered and preserved
with nitric acid; see comment in Section 16.2) are analyzed by flame atomic
absorption spectroscopy for calcium (U.S. EPA, 1983).
1. Preparation of Lanthanum chloride matrix modifier solution (LaCU)
Dissolve 29 g of La203, slowly and in small portions, in 250 ml of
concentrated HC1 (Caution: Reaction is violent) and dilute to 500 ml
with water.
2. Preparation of Calcium Standard Solutions
a. 'Calcium stock solution (500 mg L'1 Ca)Suspend 1.250 g of CaCOo
(analytical reagent grade, dried at 180 °C for 1 hour before
weighing) in water and dissolve cautiously with a minimum of
dilute HC1. Dilute to 1,000 ml with water.
b. Dilute calibration standardsEach day, quantitatively prepare a
series of dilute Ca standards from the calcium stock solution to
span the desired concentration range.
3. Suggested Instrumental Conditions (General)
a. LampCa, hollow cathode
b. Wavelength422.7 nm
NOTE: The 239.9 nm line may also be used. This line has a relative
sensitivy of 120.
c. Fuelacetylene
d. Oxidantair
e. Flamereducing
4. Analysis Procedure
a. To each 10.0-mL volume of dilute calibration standard, blank,
and sample add 1.00 mL of LaCl3 solution (e.g., add 2.0 mL of
LaCl3 solution to 20.0 mL of sample).
b. Calibrate the instrument as directed by the manufacturer.
c. Analyze the samples, including QC samples.
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d. Dilute and reanalyze any samples with a concentration exceeding
the calibrated range.
e. Report results as mg L~l Ca.
NOTE 1: Phosphate, sulfate, and aluminum interfere but are masked by the
addition of lanthanum. Because low calcium values result if the
pH of the sample is above 7, both standards and samples are
prepared in dilute acid solution. Concentrations of magnesium
greater than 1,000 mg L"1 also cause low calcium values. Concen-
trations of up to 500 mg L~^ each of sodium, potassium, and
nitrate cause no interference.
NOTE 2: Anionic chemical interferences can be expected if lanthanum
is not used in samples and standards.
NOTE 3: The nitrous oxide-acetylene flame will provide two to five times
greater sensitivity and freedom from chemical interferences.
lonization interferences should be controlled by adding a large
amount of alkali to the sample and standards. The analysis
appears to be free from chemical suppressions in the nitrous
oxide-acetylene flame.
16.5.6 Procedure for Determination of Dissolved Iron
The samples for determination of dissolved iron (filtered and preserved
with nitric acid; see note in Section 16.2) are analyzed by flame atomic
absorption spectroscopy (U.S. EPA, 1983).
1. Preparation of Iron Standard Solutions
a. Fe stock solution (1,000 mg L"1 Fe)Carefully weigh 1.000 g of
pure iron wire (analytical reagent grade) and dissolve in 5 ml of
concentrated HN03, warming if necessary. When iron is completely
dissolved, bring the volume of the solution to 1 L with water.
b. Dilute calibration standardsEach day, quantitatively prepare
a series of calibration standards spanning the desired concentra-
tion range. Match the acid content of the standards to that of
the samples (ca. 0.1 percent (v/v) HNO^).
2. Suggested Instrumental Conditions (General)
a. LampFe, hollow cathode
b. Wavelength248.3 nm
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NOTE: The following lines may also be used: 248.8 nm, relative
sensitivity 2; 271.9 nm, relative sensitivity 4; 302.1 nm,
relative sensitivity 5; 252.7 nm, relative sensitivity 6;
372.0 nm, relative sensitivity 10.
c. Fuelacetylene
d. Oxidantair
e. Flameoxidizing
i
3. Analysis Procedure
a. Calibrate the instrument as directed by the instrument manufac-
turer.
b. Analyze the samples.
c. Dilute and reanalyze any samples with concentrations exceeding
the calibrated range.
d. Report results in mg L~l Fe.
16.5.7 Procedure for Determination of Dissolved Magnesium
The samples for determination of dissolved magnesium (filtered and
preserved with nitric acid, see note in Section 16.2) are analyzed by flame
atomic absorption spectroscopy for magnesium.
1. Preparation of Lanthanum chloride solution (LaCla)Dissolve 29 g of
13303, slowly and in small portions, in 250 mL concentrated HC1
(Caution: Reaction is violent), and dilute to 500 mL with water.
2. Preparation of Magnesium Standard Solutions
a. Stock solution (500 mg L"1 Mg)Dissolve 0.829 g of magnesium
oxide (MgO, analytical reagent grade), in 10 mL of HN03 and
dilute to 1 L with water.
b. Dilute calibration standardsEach day, quantitatively prepare
from the Mg stock solution a series of Mg standards that span the
desired concentration range.
3. Suggested Instrumental Conditions (General)
a. LampMg, hollow cathode
b. Wavelength285.2 nm
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NOTE: The line at 202.5 nm may also be used. This line has a relative
sensitivity of 25.
c. Fuelacetylene
d. Oxidantair
e. Flameoxidizing
4. Analysis Procedure
a. To each 10.0 ml of dilute calibration standard, blank, and
sample, add 1.00-mL of LaCl3 solution (e.g., add 2.0 ml LaCl3
solution to 20.0 mL of sample).
b. Calibrate the instrument as directed by the manufacturer.
c. Analyze the samples.
d. Dilute and reanalyze any samples with a concentration exceeding
the linear range.
e. Report results as mg L"1 Mg.
NOTE 1: The interference caused by aluminum at concentrations greater
than 2 mg L"1 is masked by additional lanthanum. Sodium,
potassium, and calcium cause no interference at concentrations
less than 400 mg L"1.
NOTE 2: To cover the range of magnesium values normally observed in
surface waters (0.1 to 20 mg L~l), it is suggested that either
the 202.5-nm line be used or that the burner head be rotated.
A 90 ° rotation of the burner head will produce approximately
one-eighth the normal sensitivity.
16.5.8 Procedure for Determination of Dissolved Manganese
The samples for determination of dissolved manganese (filtered and pre-
served with nitric acid, see note in Section 16.2) are analyzed by flame atomic
absorption spectroscopy for manganese (U.S. EPA, 1983).
1. Preparation of Manganese Standard Solutions
a. Mn stock solution (1,000 mg L'1 Mn)Carefully weigh 1.000 g of
manganese metal (analytical reagent grade) and dissolve in 10 ml
of HN03- When the metal is completely dissolved, dilute the
solution to 1 L with 1 percent (v/v) HC1.
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b. Dilute calibration standardsEach day, quantitatively prepare a
series of calibration standards spanning the desired concentra-
tion range. Match the acid content of the standards to that of
the samples (ca. 0.1 percent (v/v) HN03).
2. Instrumental Conditions (General)--
a. Lamphollow cathode
b. Havel ength279.5
NOTE: The line at 403.1 nm may also be used. This line has a relative
sensitivity of 10.
c. Fuelacetylene
d. Oxidantair
e. Flameoxidizing
3. Analysis Procedure
a. Calibrate the instrument as directed by the manufacturer.
b. Analyze the samples.
c. Dilute and reanalyze any samples with a concentration exceeding
the calibrated range.
d. Report results as mg L~l Mn.
16.5.9 Procedure for Determination of Dissolved Potassium
The samples for determination of dissolved potassium (filtered and pre-
served with nitric acid, see note in Section 16.2) are analyzed by flame atomic
absorption spectroscopy for potassium (U.S. EPA, 1983).
1. Preparation of Potassium Standard Solutions
a. Potassium stock solution (100 mg L"1 K)Dissolve 0.1907 g of KC1
(analytical reagent grade, dried at 110 °C) in water and bring
the volume of the solution to 1 L.
b. Dilute calibration standardsEach day, quantitatively prepare a
series of calibration standards spanning the desired concentra-
tion range. Match the acid content of the standards to that of
the samples (ca. 0.1 percent (v/v) HN03).
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2. Suggested Instrumental Conditions (General)
a. LampK, hollow cathode
b. Wavelength766.5
NOTE: The 404.4 nm may also be used. This line has a relative sensitivity
of 500.
c. Fuelacetylene
d. Oxidantair
e. Flameslightly oxidizing
3. Analysis Procedure
a. Calibrate the instrument as directed by the manufacturer.
b. Analyze the samples.
c. Dilute and reanalyze any samples with a concentration exceeding
the calibrated range.
d. Report results as mg L~l K.
NOTE 1: In air-acetylene or other high-temperature flames (greater than
2,800 °C), potassium can experience partial iorn'zation which
indirectly affects absorption sensitivity. The presence of other
alkali salts in the sample can reduce this ionization suppressive
effect and thereby enhance analytical results. The ionization
suppressive effect of sodium is small if the ratio of Na to K is
under 10. Any enhancement due to sodium can be stabilized by
adding excess sodium (1,000 ug mL'1) to both sample and standard
solutions. If more stringent control of ionization is required,
the addition of cesium should be considered. Reagent blanks
should be analyzed to correct for potassium impurities in the
buffer stock.
NOTE 2: To cover the range of potassium values normally observed in
surface waters (0.1 to 20 mg I-"1), it is suggested that the
burner head be rotated. A 90 ° rotation of the burner head
provides approximately one-eigth the normal sensitivity.
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16.5.10 Procedure for Determination of Dissolved Sodium
The samples for determination of dissolved sodium (filtered and preserved
v/ith nitric acid, see note in Section 16.2) are analyzed by flame atomic
absorption spectroscopy for sodium (U.S. EPA, 1983).
1. Preparation of Sodium Standard Solutions
a. Sodium stock solution (1,000 mg L"1 Na)--Dissolve 2.542 g of NaCl
(analytical reagent grade, dried at 140 °C) in water and bring
the volume of the solution to 1 L.
b. Dilute calibration standardsEach day, quantitatively prepare a
series of calibration standards spanning the desired concentra-
tion range. Match the acid content of the standards to that of
the samples (ca. 0.1 percent (v/v)
2. Suggested Instrumental Conditions (General )
a. Lamp~Na, hollow cathode
b. Wavelength 589.6 nm
NOTE: The 330.2 nm resonance line of sodium, which has a relative
sensitivity of 185, provides a convenient way to avoid the need
to dilute more concentrated solutions of sodium.
c. Fuel acetylene
d. Oxidant air
e. Flame oxidizing
3. Analysis Procedure
a. Calibrate the instrument as directed by the manufacturer.
b. Analyze the samples.
c. Dilute and reanalyze any samples with a concentration exceeding
the calibrated range.
d. Report results as mg L"1 Na.
NOTE: Low-temperature flames increase sensitivity by reducing the
extent of ionization of this easily ionized metal. lonization
may also be controlled by adding potassium (1,000 mg L"1) to both
standards and samples.
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16.5.11 Calculations
Generally, instruments are calibrated to give sample results directly in
concentration units. If they do not, then a manual calibration curve must be
prepared and sample concentrations are determined by comparing the sample
signal to the calibrated curve. If dilutions were performed, the appropriate
factor should be applied to sample values. Report results as; mg L"-1 for each
analyte.
16.6 QUALITY ASSURANCE AND QUALITY CONTROL
16.6.1 Precision and Accuracy
1. Determination of Total Aluminum
In a multiple laboratory study using 84 lake samples; containing 0.03
to 5 mg L"1 Al, the overall duplicate relative standard deviation was
10.5 percent (note that this represents the overall within-laboratory
precision).
In a multiple laboratory study using synthetic, simulated lake samples
containing 0.02 and 0.19 mg L"1 Al, respectively, recoveries of 115
(n=21) and 103 (n=21) percent were obtained.
2. Determination of Total Extractable Aluminum
In a multiple laboratory study using 74 lake samples containing 0.005
to 3 mg L"1 extractable Al, the overall duplicate relative standard
deviation was 7.4 percent (note this is the overall within-laboratory
precision).
Accuracy data are not available.
3. Determination of Dissolved Calcium
In a single laboratory (EMSL-Cincinnati). using distilled water spiked
at concentrations of 9.0 and 36 mg Ca L~s the standard deviations
were ±0.3 and ±0.6, respectively. Recoveries at both these levels
were 99 percent.
4. Determination of Dissolved Iron
An inter!aboratory study on trace metal analyses by atomic absorption
was conducted by the Quality Assurance and Laboratory Evaluation
Branch of the EPA Environmental Monitoring Systems Laboratory in
Cincinnati, Ohio (EMSL-Cincinnati). Six synthetic concentrates con-
taining varying levels of aluminum, cadmium, chromium, copper, iron,
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manganese, lead, and zinc were added to natural water samples. The
statistical results for iron were as follows:
Number
of Labs
77
78
71
70
55
55
Number
of Labs
82
85
78
79
57
54
True Value
(ug L-l)
840
700
350
438
24
10
Mean Value
(ug L-l)
855
680
348
435
58
48
Standard
Deviation
(ug L-l)
173
178
131
183
69
69
Accuracy as
Percent Bias
1.8
-2.8
-0.5
-0.7
141
382
5. Determination of Dissolved Magnesium-"-
In a single laboratory (EMSL-Cincinnati), using distilled water spiked
at concentrations of 2.1 and 8.2 mg L"l Mg, the standard deviations
were ±0.1 and ±0.2, respectively. Recoveries at both of these levels
were 100 percent.
6. Determination of Dissolved Manganese
An inter!aboratory study on trace metal analyses by atomic absorption
was conducted by the Quality Assurance and Laboratory Evaluation
Branch of EMSL-Cincinnati. Six synthetic concentrates containing
varying levels of aluminum, cadmium, chromium, copper, iron, manganese,
lead, and zinc were added to natural water samples. The statistical
results for manganese were as follows:
True Value
(ug L-l)
426
469
84
106
11
17
Mean Value
(ug L-l)
432
474
86
104
21
21
Standard
Deviation
(ug L-l)
70
97
26
31
27
20
Accuracy as
Percent Bias
1.5
1.2
2.1
-2.1
93
22
7. Determination of Dissolved Potassium--
In a single laboratory (EMSL-Cincinnati), using distilled water sam-
ples spiked at concentrations of 1.6 and 6.3 mg L"l K, the standard
deviations were ±0.2 and ±0.5, respectively. Recoveries at these
levels were 103 percent and 102 percent, respectively.
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Section 16.0
Revision 10
Date: 8/87
Page 23 of 23
8. Determination of Dissolved Sodium
In a single laboratory (EMSL-Cincinnati), using distilled water sam-
ples spiked at levels of 8.2 and 52 mg L~l Na, the standard deviations
were ±0.1 and ±0^8, respectively. Recoveries at these levels were
102 percent and 100 percent.
16.6.2 Quality Control Checks
The required QC procedures are described in Appendix G.
16.7 REFERENCES
American Society for Testing and Materials, 1984. Annual Book of ASTM
Standards, Vol. 11.01, Standard Specification for Reagent Water, D 1193-77
(reapproved 1983). ASTM, Philadelphia, Pennsylvania.
Barnes, R. B., 1975. The Determination of Specific Forms of Aluminum in
Natural Water.s Chem. Geol., v. 15, pp. 177-191.
Driscoll, C. T., 1984. A Procedure for the Fractionation of Aqueous
Aluminum in Dilute Acidic Waters. Int. 0. Environ. Anal. Chem., v. 16,
pp. 267-283.
Manning, D. C., W. Slavin, and G. R. Carnick, 1982. Investigation of
Aluminum Interferences Using the Stabilized Temperature Platform Furnace.
Spectrochim. Acta,.Part B, v. 37b, n. 4, pp. 331-341.
May, H. M., P. A. Helmke, and M-.. L. Jackson, 1979. Determination of
Mononuclear Dissolved Aluminum in Near-Neutral Waters. Chem. Geol.,
v. 24, pp. 259-269.
U.S. Environmental Protection Agency, 1983 (revised). Methods for Chemical
Analysis of Water and Wastes. EPA 600/4-79-020. U.S. Environmental
Protection Agency, Cincinnati, Ohio.
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Section 17.0
Revision 10
Date: 8/87
Page 1 of 10
17.0 DETERMINATION OF DISSOLVED METALS (Ca, Fe, Mg, and Mn) BY
INDUCTIVELY COUPLED PLASMA EMISSION SPECTROSCOPY
17.1 OVERVIEW
17.1.1 Scope and Application
This method is applicable to the determination of dissolved Ca, Fe, Mg,
and Mn in natural surface waters.
Table 17-1 lists the recommended wavelengths and typical estimated instru-
mental detection limits using conventional pneumatic nebulization for the
specified elements. Actual working detection limits are sample-dependent, and
as the sample matrix varies, these concentrations may also vary.
17.1.2 Summary-of Method
The method describes a technique for the simultaneous or sequential deter-
mination of Ca, Fe, Mg, and Mn in natural water samples. The method is based
on the measurement of atomic emission by optical spectroscopy. Samples are
nebulized to produce an aerosol. The aerosol is transported by an argon carrier
stream to an inductively coupled argon plasma (ICP), which is produced by a
radio frequency (RF) generator. In the plasma (which is at a temperature of
6,000 to 10,000 °K), the analytes in the aerosol are atomized, ionized, and
excited. The excited ions and atoms emit light at their characteristic wave-
lengths. The spectra from all analytes are dispersed by a grating spectrometer
and the intensities of the lines are monitored by photomultiplier tubes. The
photocurrents from the photomultiplier tubes are processed by a computer system.
The signal is proportional to the analyte concentration and is calibrated by
analyzing a series of standards (U.S. EPA, 1983; Fassel, 1982).
A background correction technique is required to compensate for variable
background contribution to the determination of trace elements. Background
should be measured adjacent to analyte lines during sample analysis. The posi-
tion selected for the background intensity measurement, on either or both sides
of the analytic line, is determined by the complexity of the spectrum adjacent
to the analyte line. The position used should be free of spectral interference
and should reflect the same change in background intensity as occurs at the
analyte wavelength measured. Generally, each instrument has different back-
ground handling capabilities. The instrument operating manual should be
consulted for guidance.
The possibility of additional interferences listed in Section 17.1.3
should also be recognized and appropriate corrections should be made.
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Section 17.0
Revision 10
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Page 2 of 10
TABLE 17-1. RECOMMENDED WAVELENGTHS AND ESTIMATED
INSTRUMENTAL DETECTION LIMITS
Element
Wavelength (nm)a Estimated detection limit (ug
Calcium
Iron
Magnesium
Manganese
317.933
259.940
279.079
257.610
10
7
3.0
2
aThe wavelengths listed are recommended because of their sensitivity and over-
all acceptance. Other wavelengths may be substituted if they can provide the
needed sensitivity and are treated with the same corrective techniques for
spectral interference.
bThe estimated instrumental detection limits as shown are taken from Fassel
(1982). They are given as a guide for an instrumental limit. The actual
method detection limits are sample-dependent and may vary as the sample matrix
varies.
17.1.3 Interferences -
The following types of interference effects may contribute to inaccuracies
in the determination of trace elements:
1.
Spectral InterferencesSpectra! interferences can be categorized as
(a) overlap of a spectral line from another element; (b) unresolved
overlap of molecular band spectra; (c) background contribution from
continuous or recombination phenomena; and (d) background contribution
from stray light from the line emission of high-concentration elements.
The first of these effects can be compensated by utilizing a computer
correction of the raw data which requires the monitoring and measure-
ment of the interfering element. The second effect may require selec-
tion of an alternate wavelength. The third and fourth effects usually
can be compensated by a background correction adjacent to the analyte
line. In addition, users of simultaneous multi-element instrumenta-
tion should assume the responsibility of verifying the absence of
spectral interference from an element that could occur in a sample but
for which there is no channel in the instrument array. Table 17-2
lists some interference effects for the recommended wavelengths given
in Table 17-1. The interference information is expressed as analyte
concentration eqivalents (i.e., false analyte concentrations) arising
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Section 17.0
Revision 10
Date: 8/87
Page 3 of 10
-------
Section 17.0
Revision 10
Date: 8/87
Page 4 of 10
from 100 mg I"1 of the interfering element. The values in the table
are only approximate and should be used as a guide for determining
potential interferences. Actual values should be determined for each
analytical system when necessary.
Only those interferences listed were investigated. The blank spaces
in Table 17-2 indicate that measurable interferences were not observed
for the interferent concentrations listed in Table 17-3. Generally,
interferences were discernible if they produced peaks or background
shifts corresponding to 2 to 5 percent of the peaks generated by the
analyte concentrations (also listed in Table 17-3).
2. Physical InterferencesPhysical interferences generally are con-
sidered to be effects associated with the sample nebulization and
transport processes. Changes in viscosity and surface tension can
cause significant inaccuracies, especially in samples that contain
high dissolved solids or acid concentrations. The use of a peristal-
tic pump may lessen these interferences. If these types of interfer-
ences are operative, they can be reduced by dilution of the sample
or utilization of standard addition techniques.
High dissolved solids may also cause salt buildup at the tip of the
nebulizer. This affects aerosol flow rate, causing instrumental
drift. Wetting the argon prior to nebulization, using a tip washer,
or diluting the sample can be used to control this problem. Better
control of the argon flow rate improves instrument performance. This
is accomplished with the use of mass flow controllers.
3. Chemical InterferencesChemical interferences are characterized by
molecular compound formation, ionization effects, and solute vapori-
zation effects. Normally these effects are negligible with the ICP
technique. If observed, they can be minimized by careful selection of
operating conditions (i.e., incident power, observation position),
by buffering of the sample, matrix matching, and standard addition
procedures. These types of interferences can be dependent on matrix
type and the specific analyte element.
17.1.4 Interference Tests
Whenever a new or unusual sample matrix is encountered, a series of tests
should be performed prior to reporting concentration data for analyte elements.
These tests, as outlined below, ensure that neither positive nor negative
interference effects are operative on any of the analyte elements, thereby
distorting the accuracy of the reported values.
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Section 17.0
Revision 10
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Page 5 of 10
TABLE 17-3. INTERFERENCE AND ANALYTE ELEMENTAL CONCENTRATIONS
USED FOR INTERFERENCE MEASUREMENTS IN TABLE 17-2
Analytes (mg L"1) Interferences (mg L"1)
Ca
Fe
Mg
Mn
1
1
1
1
Al
Ca
Cr
Cu
Fe
Mg
Nn
Ni
Ti
V
1,000
1,000
200
200
1,000
1,000
200
200
200
200
1. Serial DilutionIf the analyte concentration is sufficiently high
(minimally a factor of 10 above the instrumental detection limit after
dilution), an analysis of a dilution should agree within 5 percent of
the original determination (or within some acceptable control limit
that has been established for that matrix). If it does not, a chemi-
cal or physical interference effect should be suspected.
2. Spiked AdditionThe recovery of a spiked addition added at a minimum
level of 10X the instrumental detection limit (maximum 100X) to the
original determination should be recovered to within 90 to 110 percent
or within the established control limit for that matrix. If not, a
matrix effect should be suspected. The use of a standard addition
analysis procedure can usually compensate for this effect.
NOTE: The standard addition technique does not detect coincident
spectral overlap. If overlap is suspected, use of computerized
compensation, an alternate wavelength, or comparison with an
alternate method is recommended.
3. Comparison with Alternate Method of AnalysisWhen investigating a
new sample matrix, a comparison test may be performed with other
analytical techniques, such as atomic absorption spectrometry or other
approved methodology.
4. Wavelength Scanning of Analyte Line RegionIf the appropriate equip-
ment is available, wavelength scanning can be performed to detect
potential spectral interferences.
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Section 17.0
Revision 10
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Page 6 of 10
17.1.5 Safety
Generally, the calibration standards, sample types, and most reagents pose
no hazard to the analyst. Protective clothing (lab coats and gloves) and
safety glasses should be worn when handling concentrated acids. Follow the
instrument manufacturer's safety recommendations for the operation of the ICP.
The toxicity or carcinogenicity of each reagent used in this method has
not been defined precisely. Each chemical compound should be treated as a
potential health hazard. From this viewpoint, exposure to these chemicals
should be reduced to the lowest possible level by whatever means available.
The laboratory is responsible for maintaining a current awareness file of
Occupational Safety and Health Administration (OSHA) regulations regarding the
safe handling of the chemicals specified in this method. A reference file of
material data handling sheets also should be made available to all personnel
involved in the chemical analysis. Additional references to laboratory safety
are available and have been identified (DHEW, 1977; OSHA, 1976; ACS, 1979) for
the information of the analyst.
17.2 SAMPLE COLLECTION, PRESERVATION, AND STORAGE
For the determination of trace elements, contamination and loss are a
prime concern. Dust in the laboratory environment, impurities in reagents, and
impurities on laboratory apparatus which the sample contacts are sources of
potential contamination. Sample containers can introduce either positive or
negative errors in the measurement of trace elements by (a) contributing con-
taminants through leaching or surface desorption and (b) depleting concen-
trations through adsorption. Thus the collection and treatment of the sample
prior to analysis requires particular attention. Labware should be washed
thoroughly as described in Appendix C.
Samples are filtered and acidified (0.1-mL increments) with nitric acid
until the pH is less than 2. The processed samples are analyzed for dissolved
metal (Ca, Fe, Mg, Mn) content.
17.3 EQUIPMENT AND SUPPLIES
17.3.1 Equipment Specifications
1. Inductively Coupled Plasma-Atomic Emission Spectrometer.
2. Computer-controlled ICP emission spectrometer with background
correction capability.
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Section 17.0
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Page 7 of 10
17.3.2 Reagents and Consumable Materials
1. Acids used in the preparation of standards and for sample processing
should be ultra-high purity grade or equivalent(e,g., Baker Ultrex
grade or, SeaStar Ultrapure grade).
a. Hydrochloric Acid, concentrated (sp. gr. 1.19).
' ' b. Hydrochloric Acid (50 percent v/v)Add 500 ml of concentrated
HC1 to 400 mL of water and dilute to 1 L.
c. .Nitric Acid, concentrated (sp. gr. 1.41).
d. Nitric Acid (50 percent v/v)Add 500 ml concentrated HN03 to
. 40,0 ml of water and dilute to ,1 L. . .. -
2. WaterWater should meet the specifications for Type I reagent
grade water (ASTM, 1984).
3. Standard Stock SolutionsSolutions may be purchased or prepared from
ultra-high purity grade chemicals or metals. All salts should be
dried for 1 hour at 105 °C unless otherwise specified.
CAUTION: Many metal salts are extremely toxic and may be fatal if
swallowed. Wash hands thoroughly after handling.
a. Calcium Stock Standard Solution (100 mg L-!)--Suspend 0.2498 g of
" . V CaC03 (dried at 180 .°C for 1 hour before weighing) in water and
dissolve cautiously with a minimum amount of 50 percent HN03.
Add 10.0 mL of concentrated HN03 and dilute to 1 L with water.
b. Iron Stock Standard Solution .(100 mg L"l)Dissolve 0.1430 g of
Fe?03 in a warm mixture of 20 ml of 50 percent HC1 and 2 mL of
concentrated HN03. Cool, add an additional 5 mL of concentrated
HN03, and dilute to 1 L with water.
c. Magnesium Stock Standard Solution (100 mg L"1)Dissolve 0.1658 g
of MgO in a minimum amount of 50 percent HN03. Add 10.0 mL of
concentrated HN03 and dilute to 1 L with water.
d. Manganese Stock Standard Solution (100 mg L'1)Dissolve 0.1000 g
- of manganese metal in an acid mixture consisting of 10 mL of
concentrated HC1 and 1 mi of concentrated HN03 and dilute to
1 L with water.
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Section 17.0
Revision 10
Date: 8/87
Page 8 of 10
17.4 PREPARATION
17.4.1 Calibration and Standardization
Prepare a calibration blank and a series of dilute calibration standards
from the stock solutions spanning the expected sample concentration range.
Match the acid content of the standards to that of the samples. A multi-
element standard may be prepared.
The calibration procedure varies with the various ICP instruments. Cali-
brate the ICP for each analyte following the instrument operating conditions.
17.5 PROCEDURE
Because of the differences among makes and models of satisfactory instru-
ments, no detailed instrumental operating instructions can be provided.
Instead, the analyst should refer to the instructions provided by the manu-
facturer of the particular instrument.
17.5.1 Standard Operating Procedure
1.
2.
3.
4.
Set up instrument as recommended by the manufacturer or as experience
dictates. The instrument should be allowed to become thermally stable
before beginning (10 to 30 minutes).
Profile and calibrate instrument according to instrument
manufacturer's recommended procedures. Flush the system with the
calibration blank between each standard. (The use of the average
intensity of multiple exposures for both standardization and
sample analysis has been found to reduce random error.)
Begin sample analysis, flushing the system with the calibration blank
solution between each sample. Analyze required QC samples at
intervals determined by the quality assurance program.
Dilute and reanalyze any samples with a concentration exceeding
the calibration range.
17.5.2 Calculations
Generally, instruments are calibrated to output sample results directly in
concentration units. If not, then a manual calibration curve should be pre-
pared and sample concentrations determined by comparing the sample signal to
the calibrated curve. If dilutions were performed, the appropriate factor
should be applied to sample values. Report results as mg L~l for each analyte
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Section 17.0
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Page 9 of 10
17.6 QUALITY ASSURANCE AND QUALITY CONTROL
17.6.1 Precision and Accuracy
In an EPA round-robin Phase I study, seven laboratories applied the ICP
technique to acid-distilled water matrices that had been dosed with various
metal concentrates. Table 17-4 lists the true value, ttemean reported value,
and the mean percent relative standard deviation URSD) (U.S. EPA, 198.3).
17.6.2 Quality Control Checks
The required QC procedures are described in Appendix 6.
17.7 REFERENCES
American Chemical Society, 1979. Safety in Academic Laboratories, 3rd ed.
Committee on Chemical Safety, ACS, Washington, D.C.
American Society for Testing and Materials, 1984. Annual Book of ASTM
Standards, Vol. 11.01, Standard Specification for Reagent Water, D 1193-77
(reapproved 1983). ASTM, Philadelphia, Pennsylvania.
Department of Health, Education, and Welfare, 1977. Carcinogens - Working with
Carcinogens. No. 77-206. DHEW, Public Health Service, Center for Disease
Control, National Institute for Occupational Safety and Health,
Cincinnati, Ohio.
Fassel, V. A., 1982. Analytical Spectroscopy with Inductively Coupled Plasmas
- Present Status and Future Prospects. J.n Recent Advances in Analytical
Spectroscopy. Pergamon Press, Oxford and New York.
Occupational Safety and Health Administration, 1976. OSHA Safety and Health
Standards, General Industry. OSHA 2206 (29 CFR 1910). OSHA, Washington,
D.C.
U S Environmental Protection Agency, 1983 (revised). Methods for Chemical
Analysis of Water and Wastes, EPA-600/4-79-020. U.S. Environmental
Protection Agency, Cincinnati, Ohio.
-------
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-------
Section 18.0
Revision 4
Date: 8/87
Page 1 of 10
18.0 DETERMINATION OF TOTAL NITROGEN
18.1 OVERVIEW
18.1.1 Scope and Application
This method is applicable to the determination of total nitrogen in natural
surface waters. Total nitrogen includes inorganic nitrogen compounds (nitrate,
nitrite, and ammonia) as well as organically fixed nitrogen (proteins, etc.).
This method is applicable to the determination of total nitrogen in the
range of 0.01 to 20 mg L"1 N. The minimum detection limit is approximately
0.007 mg L"1 (three times the standard deviation of replicate blank analyses).
This method may give poor recoveries for organic compounds which contain
nitrogen-to-nitrogen double bonds as well as terminal nitrogen groups (e.g.,
HN = C).
18.1.2 Summary of Method
Samples are oxidized in an autoclave at 120 °C with an alkaline persulfate
mixture. The oxidation process converts all nitrogen-containing compounds to
nitrate. The nitrate is subsequently determined col orimetrically by flow
injection analysis (FIA). During FIA, nitrate is reduced to nitrite by cadmium
reduction; the nitrite is determined by diazotizing with sulfanil amide and
coupling with N-(l-napthyl)ethylenediamine dihydrochloride to form a highly
colored azo dye, which is measured col orimetrically at 540 nm. The procedure
is based on the published methods of Ebina et al. (1983), Smart et al. (1981),
D'Elia et al. (1977), Nydahl (1978), and Tecator (1983).
18.1.3 Definitions
Total Persulfate NitrogenIn a water sample, this is the total nitrogen
present that is digested by the persulfate method, including organic N, NH4.-N,
N03-N, and N02-N.
18.1.4 Interferences
Turbidity may interfere with this method. If the digestate is turbid, it
should be filtered through a 0.45-Mm membrane prior to analysis. Ethylenedia-
mine tetraacetate (EDTA) is used to reduce interference from iron, copper, and
other metals.
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Section 18.0
Revision 4
Date: 8/87
Page 2 of 10
18,1.5 Safety
The calibration standards, sample types, and most reagents used in this
method do not pose a hazard to the analyst. Protective clothing (lab coat,
gloves, and safety glasses) should be worn when preparing reagents.
WARNING
Cadmium present in the reduction column is poisonous. Extreme
caution should be taken when handling grains and solutions.
18.2 SAMPLE COLLECTION, PRESERVATION, AND STORAGE
An unfiltered 100-mL sample contained in a bottle washed with HC1
(wash as described in Appendix C, substituting HC1 for HHO^) is preserved with
0.05 mL Ultrex or equivalent grade concentrated H2S04 to pH less than 2. Store
sample at 4 °C in the dark when not in use.
18.3 EQUIPMENT AND SUPPLIES
18.3.1 Equipment and Apparatus
1. Flow injection analyzerAnalyzer consists of injection valve,
spectrophotometer, printer/integrator, cadmium reduction column, and
recorder/computer data handler.
2. Autoclave.
3. Teflon-lined screw-top digestion vessels.
NOTE: Clean all labware with hot 5 percent HC1 and rinse copiously with
nitrogen-free water. Keep labware tightly sealed from the atmos-
phere to reduce contamination.
18.3.2 Reagents and Consumable Materials
Reagents should be ACS reagent grade unless otherwise stated.
1. Ammonium chloride-EDTA solutionDissolve 85 g reagent grade ammonium
chloride and 0.1 g disodium ethylenediamine tetraacetate (CASRN 60-00-
4) in 900 mL water. Adjust the pH to 8.5 with concentrated ammonium
hydroxide and dilute to 1 L.
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Section 18.0
Revision 4
Date: 8/87
Page 3 of 10
2. Copper sulfate solution (2% w/v) Dissolve 20 g CuS04'5H20 in 500 ml
water, then dilute to 1 L.
3. Hydrochloric acid (HC1)Concentrated (d = 1.19, 37 percent, Baker
Ultrex grade or equivalent).
4. Dilute HC1 (1 + DAdd 50 ml concentrated HC1 (Baker Instra-Analyzed
grade or equivalent) to 50 mL water.
5. NED solutionDissolve 0.5 g N-(l-naphthyl)-ethylenediamine dihydro-
chloride (CASRN 551-09-7) in 500 ml water. Filter and degas. Store
in an amber bottle at 4 °C. Prepare fresh weekly.
6 Oxidizing reagentDissolve 3.0 g sodium hydroxide (NaOH) and 20.0 g
potassium persulfate (K2$2Q8> N<0.001%) in 1 L of water. If the total
nitrogen in a reagent blank is too high (>0.010 ppmh then the
potassium persulfate may be purified by recrystallization. Recrys-
tallize potassium persulfate as follows:
a. Dissolve 75 g potassium persulfate (reagent grade containing
less than 0.001% N) in 500 ml water heated to 60 °C.
b. Filter rapidly through loosely stoppered Pyrex wool and cool in
ice water to about 4 °C while stirring continuously.
c. Isolate the crystals by vacuum filtration on a sintered-glass
filter. Wash with small amounts of ice water (4 °C).
d. Dry in vacuum over anhydrous calcium chloride. Rapid drying in
an efficient vacuum is essential in minimizing sulfuric acid
formation on the crystals.
e. Store the crystals in a vacuum desiccator over calcium chloride.
7. Sodium hydroxide(NaOH)Crystals (98.00%, Baker Instra-Analyzed
grade or equivalent, N<0.0003%).
8. Sodium hydroxide (50% w/w) Dissolve 50 g sodium hydroxide in 50 mL
water. Cool to room temperature. Separate supernatant from any
precipitate by transferring supernatant to a clean plastic bottle.
Store bottle tightly capped.
9. Sodium hydroxide (0.36N)Dilute 7.2 ml 50% NaOH to 250 ml. Store
in a borosilicate glass reagent bottle equipped with an Ascarite
or equivalent C0£ trap.
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Section 18.0
Revision 4
Date: 8/87
Page 4 of 10
10.
11.
Sulf anil amide solutionDissolve 5 g of sulf anil amide
CASRN 63-74-1) in a mixture of 26 mL of concentrated HC1 and 300
of water, then dilute to 500 ml. Filter and degas. Store at 4
This solution is stable for several months.
ml
°C.
WaterAll water used in preparing reagents and in cleaning labware
should meet the specifications for Type I reagent grade water (ASTM,
1984) .
18.3.3 Reduction Column and Reagents
WARNING
Cadmium is poisonous. Handle with extreme caution. Dispose of
solution from the following treatments as hazardous wastes.
1. Granulated cadmium40 to 60 mesh.
2. Copperized cadmiumPrepare copperized cadmium as described below:
2.
a.
Wash the cadmium with dilute HCT and rinse with water.
color of the cadmium so treated should be silver.
The
Swirl 10 g of cadmium in 100 ml copper sulfate solution for 5
minutes, or until the blue color partially fades. Decant and
repeat with fresh copper sulfate solution. Continue washings
until a brown colloidal precipitate forms.
Wash the cadmium-copper with water (at least 10 times) to remove
all the precipitated copper. The color of the cadmium so treated
should be black.
18.3.4 Standard Solutions
-1
Concentrated stock standard solution (1,000 mg L"1 N03-N total
nitrogen)Dissolve 0.60681 g sodium nitrate (NaNOs, ultrapure grade,
dried at 110 °C for 2 hours and stored in a desiccator) in water and
dilute to 100.00 ml with water. Store at 4 °C. Prepare weekly.
Dilute stock standard solution (10.00 mg L"1 N03-N total nitrogen)
Dilute 1.000 ml of the 1,000-mg L'1 total-nitrogen solution to 100.00
ml with water. Store at 4 °C.
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Section 18.0
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3. Daily calibration standardsDaily, prepare the calibration standards
listed in the table below by adding the appropriate volume of
10.00-mg -I"1 total-nitrogen standard and diluting to 100 ml.
Total-nitrogen ml of 10.00-mg L'1 Total-nitrogen ml of 10.00-mg L"1
standard total-nitrogen ' standard total-nitrogen
(ing L-!) standard required (mg L"1) standard required
0.000 0.000 0.100 1.000
0 010 0.100 0.500 5.000
0.030 0.300 1.000 10.000
0.050 0.500
4. Concentrated column efficiency (CE) stock standard solution (100 mg
L"1 NOo-TN)Dissolve 0.4502 g sodium nitrite (NaNOo, ACS reagent
grade, dried at 100 °C for 2 hours and stored in a desiccator) in
water and dilute to 100.00 ml. Prepare daily.
5. CE standard,(5.000 mg L~1N02-TN)Daily, dilute 0.500 ml of the
1,000-mg L'1 N02-TN solution to 100.00 ml with water.
18.3.5 Quality Control (QC) Standards
1. QC stock solution (1,000 mg L"1 total nitrogen)Dissolve 0.60681 g
of NaNOs (ultrapure grade, dried at 110 °C for 2 hours and stored in
a desiccator) in water and dilute to 100.00 ml. Store at 4 °C. NaN03
should be from a source independent of that used to prepare the con-
centrated stock standard solution.
2. Detection limit QC sample (0.030 mg L-1 total nitrogen)Daily, dilute
0.0300 of ml QC stock solution to 1.000 L with water.
3. Routine QCCS (0.500 mg L"1 total nitrogen)Daily, dilute 0.0500 ml
of QC stock solution to 100.00 ml with water.
4. CE QC stock solution (100 mg L'1 N02-TN)Dissolve 0.4502 g of NaN02
(ACS reagent grade, dried at 110 °C for 2 hours and stored in desic-
cator; should be from a source independent of that used to prepare the
concentrated CE stock standard solution) in water and dilute to 100.00
ml. Store at 4 °C.
5. CE QCCS (0.500 mg L'1 N02-TN)Daily, dilute 0.0500 ml of CE QC stock
solution to 100.00 ml with water.
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18.4 PREPARATION
18.4.1 Calibration and Standardization
The colorimeter is calibrated before each batch of samples is analyzed.
The seven daily total-nitrogen calibration standards (including 0.000 mg L"1)
are analyzed, and a calibration curve is generated from their responses.
18.4.2 Preparation of Reduction Column
The reduction column is an 8-mm by 50-mm low-pressure glass chromatography
column. Pack the reduction column with copperized cadmium as follows:
1. Insert a fritted Teflon bed support into one end of the column.
Place a column plug in the same end. Fill the column with water.
2. Add copperized cadmium granules to the column while gently vibrating
the column with an electric engraving pencil or similar device.
This procedure will ensure even column packing. When the column is
completely packed, insert another fritted Teflon bed support on the
top of the column.
3. Insert the packed column into the flow system using standard
1/4-28 chromatography fittings. The column is now ready for use.
Keep the column filled with water at all times. If air bubbles become
trapped in the column, they can be dislodged by vibrating the column while
pumping carrier through the system. Repack the column if void volumes are
apparent.
18.5 PROCEDURE -
18.5.1 Standard Operating Procedure
1. Set up the FIA system as indicated in Figure 18-1.
2. Allow all reagents to run through the system for 10 minutes.
3. Analyze a 0.500-mg L'1 NOo-N standard on an ion chromatograph to
determine if any nitrate is present.
4. Add 5.00 ml oxidizing reagent to 5.00 ml of sample (routine samples,
calibration standards, reagent blank, and QC samples included) in a
Teflon digestion vessel, and cap the vessel.
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Key;
Cd - red
S-
B-
C-
Rl-
R2-
Cd-red-
RC1-
RC2-
RC3-
Sample
.Neutralizing Stream (0.36N NaOH)
Carrier (ammonium chloride - EDTA solution)
Diazotizing Reagent (Sulfanilamide solution)
Color Reagent (NED solution)
Cadium Reduction Column
Reaction Coil, 12 cm (0.5 mm i.d.)
Reaction Coil. 30 cm (0.5 mm i.d.)
Reac.tion Coil, 60 cm (0.5 mm i.d.)
Figure 18-1. Schematic of flow injection system for
determination of total nitrogen.
5.
6.
7.
Autoclave sample at 120
temperature.
-1
°C for 30 minutes, then cool to room
-1
Analyze a 0.500-mg l~l N02-N sample and a 0.500-mg L * NOo-N sample.
Calculate the column efficiency as described in Section 18.6.3. If
the column is less than 95 percent efficient, reactivate or replace
the column until 95 percent or greater efficiency is achieved.
Load the autosampler of the FIA system, and start the analysis.
Analyze the samples in the following order:
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a. Calibration Standards f. CE QCGS
b. CE QCCS and 0.500-mg L"1 g. Ten Samples, or interval
N03-TN standard determined by the quality
assurance program
c. Reagent Blank , h. Routine QCCS
d. Detection Limit QCCS i. 0.500-mg-'I'1 Calibration
Standard
e. Routine QCCS j. Calibration Blank
8. Repeat steps 7e through 7i until all samples are analyzed.
9. Dilute and reanalyze all samples that exceed the calibrated range.
18.5.2 Calculations
Construct a calibration curve for total nitrogen by plotting the measured
response for the calibration standards versus concentration. From the calibra-
tion curve and response for the samples, calculate the sample concentration.
Report results as mg L"1 total nitrogen.
18.6 QUALITY ASSURANCE AND QUALITY CONTROL
18.6.1 Precision and Accuracy
In previous studies (Ebina et al., 1983; Tecator, 1983) for total nitrogen
concentrations within the range 0.14 to 2.0 mg L'1, the relative precision of
the method ranged from 0.4 to 2.5 percent. In a single laboratory (Ebina et
al., 1983). using river water spiked with total nitrogen in the range 2.5 to
10.0 M9 L'1, the recovery (accuracy) varied from 99 to 103 percent.
18.6.2 Quality Control Checks
1. Laboratory DuplicateAnalyze one sample per batch in duplicate
(including digestion). Duplicate precision (expressed by percent
relative standard deviation) should not exceed 10 percent.
2. Reagent BlankPrepare and analyze one reagent blank per batch. A
reagent blank contains only the reagents used in processing. It
should contain less than 0.010 mg L'1 total nitrogen.
3. Detection Limit QC CheckAnalyze the detection limit QCCS once per
batch prior to sample analysis. The measured result should be within
20 percent of the actual concentration.
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4. Routine QC checkAnalyze the routine QCCS prior to sample analysis,
after every 10 samples are analyzed or at intervals determined by
the quality assurance program, and after the final sample is analyzed.
The measured concentration should be within 10 percent of the actual
concentration.
18.6.3 Reduction Column Quality Control Checks
To ensure that the reduction column completely reduces nitrate to nitrite,
nitrite samples (CE standards and CE QCCS) should be analyzed.
1. CE-StandardAnalyze a 5.000-mg L"1 N02-N standard after the calibra-
tion standards have been run. Determine the efficiency of the column
using the equation below:
N03 peak height
Column Efficiency (%) = x 100
N02 peak height
If the column is less than 95 percent efficient, reactivate or replace
the column so that 95 percent or greater efficiency is achieved.
2. CE QC CheckAnalyze the CE QCCS after every routine CE standard
analysis. The measured concentration should be within 10, percent of
the actual concentration. If it is not, check the instrument
operation and sample preparation.
18.7 REFERENCES
ASTM, 1984^ Annual Book of ASTM Standards, Vol. 11.01, Standard Specification
for Reagent Water, D 1193-77 (reapproved 1983). ASTM, Philadelphia,
Pennsylvania.
D'Elia, C. F., P. A. Stendler, and N. Corwin, 1977. Determination of Total
Nitrogen in Aqueous Samples Using Persulfate Digestion.
Limnol. Oceanogr., v. 22, pp. 760-764.
Ebina, J., T. Tsutsui, and T. Shirai, 1983. Simultaneous Determination of
Total Nitrogen and Total Phosphorus in Water Using Peroxodisulfate
Oxidation. Water Res., v. 17, pp. 1721-1726.
Nydahl, F., 1978. On the Peroxodisulfate Oxidation of Total Nitrogen in Waters
to Nitrate. Water Res., v. 12, pp. 1123-1130.
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Section 18.0
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Smart, M. M., F. A. Reid, and J. R. Jones, 1981. A Comparison of Persulfate
Digestion and the Kjeldahl Procedure for Determination of Total Nitroqen
in Freshwater Samples. Water Res., v. 15, pp. 19-21.
Tecator, 1983. Determination of the Sum of Nitrate and Nitrite in Water by
Flow Injection Analysis. Technical Sub Note ASN62-01/83g Tecator
Httgancls, Sweden.
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19.0 DETERMINATION OF pH (CLOSED SYSTEM)
19.1 OVERVIEW
The pH of an aquatic environment is regulated by both abiotic (inorganic
C02 equilibria, surficial geology, and anthropogenic pollutants) and biotic
(photosynthesis, respiration, and decomposition) factors. A pH balance is
usually maintained by the presence of buffering reactions within the aquatic
system. If this balance is shifted, both chemical and biotic repercussions may
result.
The pH is defined as the negative logarithm of the activity of hydrogen
ions (H+). The H+ activity is a measure of the "effective" concentration of
hydrogen ions in solution; it is always equal to or less than the true concen-
tration of hydrogen ions in solution. Values usually range from pH 1 to pH 14,
with pH 1 being most acidic, pH 7 neutral (at 25 °C), and pH 14 most alkaline.
Each pH unit represents a tenfold change in H+ activity, i.e., a pH 4 solution
is 10 times as acidic as a pH 5 solution.
When the pH of a sample solution is measured, the hydrogen ions come into
equilibrium with the ion exchange surface (glass) of a calibrated pH electrode
which creates an electrical potential. This voltage difference is measured by
the pH meter in millivolts, then is converted and displayed as pH units.
19.1.1 Scope and Application
This method is applicable to the determination of pH in surface waters of
low ionic strength. For the AERP studies, pH is determined in the processing
laboratory using an Orion Model 611 pH meter and an Orion Ross combination pH
electrode. The method has been written assuming that the Orion meter and
electrode are used (Orion, 1983). The method, however, can be modified for use
with other instrumentation meeting equivalent specifications.
The applicable pH range is 3.0 to 11.0.
19.1.2 Summary of Method
pH is measured in a closed system on a sample collected without exposure
to the atmosphere to prevent gaseous exchange between the samples and the
atmosphere. The measurement is performed by attaching the sample syringe to
the pH sample chamber (Figures 19-1 and 19-2), injecting the sample, and deter-
mining the pH using a pH meter and electrode.
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Section 19.0
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Figure 19-1. Schematic of pH measurement system.
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Section 19.0
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Page 3 of 16
TO
WASTE
INLET
Figure 19-2. pH sample chamber.
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Section 19.0
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Page 4 of 16
19.1.3 Interferences
No interferences are known.
19.1.4 Safety
The calibration standards, sample types, and reagents used in this method
pose no hazard to the analyst. Protective clothing (lab coat and gloves) and
safety glasses should be worn when handling sulfuric acid.
19.2 SAMPLE COLLECTION, PRESERVATION, AND STORAGE
Samples are collected and sealed without air bubbles in 60-mL plastic
syringes. They are stored at 4 °C in the dark until used. Analysis should be
as close to the time of collection as possible, generally within 24-36 hours,
although a study has shown that pH does not change significantly over a
seven-day period if samples are sealed and stored as described above (Burke,
et a!., 1986).
19.3 EQUIPMENT AND SUPPLIES
19.3.1 Apparatus and Equipment
1. Orion Model 611 pH meter or equivalent.
2. Orion Ross combination pH electrode or equivalent.
NOTE: Only combustion electrodes are recommended.
3. pH sample chamber.
4. 60-mL plastic syringes.
5. Luer-Lok or equivalent syringe valves.
19.3.2 Reagents and Consumable Materials
1. pH Calibration Buffers (pH 4 and 7) Commercially available pH
calibration buffers (NBS- traceable) at pH values of 4 and 7.
2. Potassium Chloride (3M) Dissolve 75 g KC1 in 1 L of Water.
3. pH 4.00 Quality Control Check Solution (QCCS) (0.0001N HeSO^ Add
1.000 mL of 0.1N H2S04 to a volumetric flask, dilute to 1 L.
Prepare daily.
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4. Dilute pH 7.00 Buffer Intermeter Comparability SolutionDilute 5.000
± 0.001 g of NBS-traceable pH 7.00 buffer to 1 L in a volumetric
flask. Prepare daily.
NOTE: The dilute buffer is used only when more than 1 pH meter is being
used; see Section 19.5.4.
5. WaterWater used in all preparations should conform to ASTM specifi-
cations for Type I reagent grade water (ASTM, 1984).
19.4 PREPARATION
19.4.1 Instrument Preparation
1. Plug in the instrument and verify that the control knob is on "STD
BY." Allow at least 30 minutes for instrument warm-up prior to use.
NOTE: If instrument is used frequently, leave on and in "STD BY" mode
between uses.
2. Connect the combination electrode to the meter. Consult the pH
electrode manual for the proper procedure.
3. Verify that the level of reference filling solution (3M KC1) in the
electrode is just below the fill hole and that the fill hole is
uncovered during measurement (slide the plastic sleeve down).
4. Calibrate the meter for temperature weekly using a two-point
standardization (one point at approximately 5 °C to 10 °C and the
other point at room temperature).
a. Room TemperaturePlace the electrode and an NBS-traceable
thermometer into deionized water which is at room temperature.
Swirl the electrode for 5 to 10 seconds.
b. Turn the knob on the meter to "TEMP." Using a small screwdriver,
adjust the display, using the "TEMP ADO" screw on back of the pH
meter, to the temperature reading of the thermometer.
c. Cold TemperaturePlace the probe and the NBS-traceable thermom-
eter into a 250-mL beaker containing cold deionized water (5 to
10 °C). Repeat Step b by adjusting the display with the "TEMP
SLOPE" screw on the back of the meter.
d. Continue steps a through c until no further adjustments are
necessary and record all values in the logbook.
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Section 19.0
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19.4.2 Calibration and Standardization
1.
2.
3.
4.
Check the meter temperature calibration daily with a beaker of
room temperature deionized water and an NBS-traceable thermom-
eter. If the display differs from the NBS-traceable thermometer
by more than 1.0 °C, complete adjustments as described in Section
19.4.1, step 4.
Pour fresh pH 7.00 and pH 4.00 buffer solutions into labeled
50-mL beakers (one "RINSE," one "CALIBRATION," and one "CHECK"
beaker for each buffer). Rinse all beakers three times and fill
with the appropriate buffer solutions.
Rinse the electrode with deionized water. Place the electrode
into the pH 7.00 "RINSE" beaker and swirl for 30 seconds. Place
the electrode into the "CALIBRATION" beaker, turn the knob to
"pH", swirl for 30 to 60 seconds (or until the pH reading is
stable), and read the value on the display. Consult the pH-
temperature chart, Table 19-1. Use the "CALIBRATE" knob to
adjust the pH reading on the meter to the theoretical pH of the
buffer solution at the appropriate temperature.
Repeat step 3 for pH 4.00 buffer using the "% SLOPE" knob to
adjust the pH reading.
Repeat steps 3 and 4 until both the pH 7.00 and the pH 4.00
buffers agree with the theoretical pH of the buffer solution at
the appropriate temperature.
Check the standardization using the buffer solutions in the
"CHECK" beakers. If the values differ by more than ±0.03 units
from the theoretical value, repeat the standardization process.
When the meter standardization is acceptable, record the pH and
temperature readings for each .buffer solution in the pH logbook.
19.4.3 Maintenance
1.
2.
Weekly, drain the 3M KC1 filling solution from the electrode using a
disposable pi pet with Teflon tubing attached.
Refill the electrode chamber with the 3M KC1 filling solution and
rinse by inverting the electrode. Drain the solution as in step 1.
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Section 19.0
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Page 7 of 16
TABLE 19-1. pH VALUES OF BUFFERS AT VARIOUS TEMPERATURES
(from Orion Research Instruction Manual, 1983)
NBS buffer,
nomi nal
value
at 25 °C
1.68
3.78
4.01
6.86
7.00
7.41
9.18
10.01
0 °C
1.67
3.86
4.00
6.98
7.11
7.53
9.46
10.32
5
1
3
4
6
7
7
9
10
°C
.67
.84
.00
.95
.08
.50
.40
.25
10 °C
1.67
3.82
4.00
6.92
7.06
7.47
9.33
10.18
20 °C
1.67
3.79
4.00
6.87
7.01
7.43
9.23
10.06
: = =: = = = = = === = = = = = ===:=: = ==: = ==.= ===:==== =
Temperature
30 °C
1.68
3.77
4.02
6.85
6.98
7.40
9.14
9.97
40
1.
3.
4.
6.
6.
7.
9.
9.
°C
69
75
03
84
97
38
07
89
50
1.
3.
4.
6.
6.
7.
9.
9.
°C 60 °C
71 1.72
75
06 4.08
83 6.84
97 '
37
01 8.96
83
70 °C 80 °C 90 °C
1.74 1.77 1.79
4.13 4.16 4.21
6.85 6.86 6.88
8.92 8.89 8.85
3. Refill the electrode with the filling solution to just below the fill
hole.
4. Gently spin the electrode overhead for approximately 1 minute by the
leader to remove any air bubbles. Be careful to stand clear of any
obstacles when swinging the electrode.
19.4.4 pH Meter Electronic Checkout
NOTE: This procedure should be performed whenever a new pH meter is set
up or when calibration problems occur.
1. Connect the shorting strap as outlined in the Orion pH meter manual.
2. Turn the "TEMP ADJ" and "TEMP SLOPE" screws fully counterclockwise and
record the display pH value (turn knob to "pH" position).
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3. Turn the "TEMP SLOPE" screw 7.5 turns clockwise and record the display
pH value. The difference between the "TEMP SLOPE" value in step 2 and
step 3 should be between 7.0 to 15.0.
4. Turn the "TEMP ADJ" screw until a value between 50.0 ±0.1 appears on
display.
5. Press the test button. A value of 42.2 ± 2.0 should appear on the
display when the knob is in the "TEMP" position. If this value is not
displayed, keep depressing the test button and use the "TEMP SLOPE"
screw to adjust the reading to 4.0 ± 0.1. Release the test button and
use the "TEMP ADJ" screw to obtain a reading of 50.0 ± 0.1. Press the
test button again. The reading should be 42.2 ± 2.0. Repeat this
procedure several times if the value is not in range.
19.4.5 Electrode Etching Procedure
NOTE 1: Use Extreme Caution when using the NaOH pellets. Be sure to wear
gloves, eye protection, and a rubber apron.
NOTE 2: If the electrode response is sluggish or if the instrument cannot
be standardized, the following procedure is recommended for
cleaning the ceramic junction of the electrode and improving the
electrode response time.
NOTE 3: Etch electrodes in groups of three when possible. Prepare a
fresh NaOH solution for each group of electrodes.
1. Drain the filling solution from the electrode.
2. Rinse the filling chamber with deionized water and drain it.
3. Refill the chamber with deionized water.
4. Prepare a 50 percent (w/v) NaOH solution by slowly adding 30 g of NaOH
to 30 mL of deionized water.
5. Gently stir the solution with up to three electrodes to dissolve
the NaOH. The solution will be very hot and may boil and splatter,
caution must be_ used.
6. Stir the solution an additional 2 minutes with the electrodes.
7. Rinse the electrodes with deionized water.
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8, Rinse the electrodes in pH 7.00 buffer for 2 minutes.
9. Drain the deionized water from the filling chambers.
10. Refill each electrode with 3M KC1, agitate the electrodes, and drain
the chambers.
11. Refill the chambers once more with 3M KC1 and spin each electrode
from the leader to remove air bubbles.
19.5 PROCEDURE
19.5.1 Sample Chamber Assembly
1. Using a 3-pronged clamp, attach the pH sample chamber to the ringstand
so that the overflow from the chamber will drain into the sink.
2. Insert the electrode through the rubber silicone stopper. Rinse the
electrode and the chamber copiously with deionized water.
19.5.2 Initial Quality Control Check
NOTE: Refer to Figures 19-3 and 19-4.
1. Rinse and fill a beaker with pH 4.00 QCCS. Rinse the syringe with
QCCS. Fill the syringe with 50 ml of QCCS and attach a syringe valve.
2. Attach the syringe to the inflow tubing of the pH sample chamber.
Inject enough standard to fill the chamber. Rinse the electrode by
swirling it in the chamber for 15 to 30 seconds. Drain the chamber.
Repeat.
3. Fill the chamber a third time. Loosely insert the electrode and inject
it with an additional 5 to 10 ml of QCCS to expel air bubbles. Seal the
electrode into chamber. Check for air bubbles.
4. Turn the knob to "pH" and start the stopwatch. Record the initial pH,
temperature, and time (0:00) in the pH logbook (see Figure 19-5,
Column 1).
5. Wait until the readings seem fairly consistent and then note the time
and pH values on a loose sheet of paper. If the pH reading does not
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INITIAL
STANDARDIZATION
AND CHECK
QCCS
WITHIN ± 0.1 pH
UNITS OF THEORETICAL
VALUE
ENOUGH
OLUME REMAININ
N PREVIOUSLY ANALYZE
SAMPLES TO
REANALY2
QCCS
WITHIN 0.1 pH
UNITS
Ci) PREVIOUS SAMPLES (FROM LAST ACCEPTABLE QCCS)
MUST BE REANALYZED AFTER ACCEPTABLE QCCS IS
RECORD QCCS VALUE IN
LOGBOOK AND NOTE
SAMPLE ID NUMBERS
ASSOCIATED WITH
UNACCEPTABLE QCCS.
(See Figure 19^1 if an
unacceptable QCCS
is not attained.)
Figure 19-3. Flowchart for pH determination.
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©PREVIOUS SAMPLES (FROM LAST ACCEPTABLE
QCCS) MUST BE REANALYZED AFTER
ACCEPTABLE QCCS IS OBTAINED.
Figure 19-4. Troubleshooting flowchart for pH detemination,
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Section 19.0
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INJECT
INJECT
INJECT
SAMPLE ID
INTIAL
PH
INITIAL
TEMP
INITIAL
TIME
PH
TEMP
TIME
PH
TEMP
TIME
PH
TEMP
TIME
PH
TEMP
TIME
NOTE 1: DO NOT COMPARE SUCCESSIVE pH VALUE UNTIL
DATA COLUMN 4. ALL EARLIER DATA ARE INDEPENDENT.
NOTE 2: SOME pH DETERMINATIONS MAY REQUIRE CONTINUATION
ON TO THE NEXT LINE.
Figure 19-5. pH logbook and example page; organization of raw data.
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Section 19.0
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vary by more than 0.02 pH units in one direction throughout a 1-minute
interval, the reading is considered stable. Record the stable pH and
temperature readings, and the total elapsed time in the logbook (see
Figure 19-5, Column 2).
6. Inject a 5-mL portion of QC solution into the chamber. Repeat step 5.
Record the first stable pH reading, temperature, and time in the
logbook (see Figure 19-5, Column 3).
7. Inject a second 5-mL portion of QC solution into the chamber. Repeat
step 5 and record the data in the logbook (see Figure 19-5, Column 4).
8. Check the pH values from Column 3 and Column 4 in the logbook. If
they agree within ±0.03 pH units, the sample measurement is completed.
If they do not, continue to inject 5-mL portions of solution into the
chamber and record the first stable pH, temperature, and elapsed^time
values in additional columns until two successive stable pH readings
agree within ±0.03 units.
19.5.3 Sample Measurement
NOTE: Allow syringe samples to warm to room temperature before
measuring pH.
1. Rinse the sample chamber and electrode copiously with deionized water.
2. Attach a pH syringe to the chamber and determine the sample pH as
described in Section 19.5.2, steps 2 through 8.
3. Measure and record the value of the QCCS at predetermined intervals.
a. If the measured QCCS pH is acceptable (pH 4.00 ± 0.10), proceed
with routine sample pH determinations.
b. If the QCCS pH is not acceptable, follow the steps below until an
acceptable value is obtained.
1) Repour the pH 4.00 QCCS into a beaker, refill a new rinsed
syringe, and reanalyze.
2) Remake the pH 4.00 QCCS (see Section 19.3.2) and reanalyze.
3) Repeat the standardization steps (see Section 19.4.2) and
reanalyze the QCCS. If the pH meter requires recalibration
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c.
to obtain an acceptable QCCS reading, make a notation in the
pH logbook. Determine which of the samples have sufficient
volume to reanalyze. .Reanalyze all samples which have suffi-
cient sample volume back to the last acceptable QCCS.
Obtain an acceptable QCCS pH measurement prior to continuing
analysis.
19.5.4 Additional Procedures Using Two pH Meters
1. Analyze a dilute buffer intermeter comparability check sample (see
Section 19.3.2) after each QCCS is analyzed. The acceptable range
for the dilute buffer is pH 7.31 ± 0.07. If the values are not
acceptable, follow the steps below (for initial comparability only):
a. If both meter values are out of range, remake the dilute buffer
and reanalyze on both meters.
b. If only one meter is out of range, check the meter calibration
and recalibrate if necessary. If the calibration is correct,
reanalyze a new syringe of dilute buffer. If the calbration still
does not come within range, perform the electronic checkout
described in Section 19.4.4 and repeat calibrations.
2. The dilute buffer values of both meters should agree within 0.05 pH
unit. If they do not, follow the steps below (for initial compar-
ability only): ~~~~ : '
a. Check the calibration of both meters. Recalibrate one or both
meters if necessary.
b. If the calibrations of both meters are accurate, obtain new
syringes and reanalyze the dilute buffer.
c. If intermeter comparability cannot be obtained, all samples
should be analyzed on the meter with the pH values closest to
7.31.
3. If the dilute buffer comparability checks that are analyzed mid-
batch after the QCCS are within limits, but do not agree within
0.05 pH unit, follow the steps below:
a. Obtain a new syringe and reanalyze the dilute buffer.
b. If the values are within 0.05 pH unit, continue with sample
analysis.
-------
Section 19.0
Revision 10
Date: 8/87
Page 15 of 16
c. If the values are still not within 0.05 pH unit, recalibrate the
meter which deviates the most from 7.31 pH units and reanalyze
the dilute buffer. If the values agree within 0.05 pH unit, two
meters can be used but reanalyze all samples which were analyzed
on the recalibrated meter back to the last acceptable QCCS and
the last dilute buffer check.
d. If the meters still are not within the 0.05 pH unit limit, sam-
ples should be analyzed on one meter; use the meter with the pH
value closest to 7.31. All samples on the deviant meter should
be reanalyzed, back to the last acceptable QCCS and the last
dilute buffer values on the acceptable meter.
19.5.5 Cleanup
1. Copiously rinse the sample chamber and glassware with deionized water.
2. Remove the electrode from the silicone stopper of the sample chamber.
Cover the fill hole of the electrode with the plastic sleeve and store
the electrode in 3M KC1.
3. Make sure the meter is on "STO BY."
19.6 QUALITY ASSURANCE AND QUALITY CONTROL
19.6.1 Precision and Accuracy
A single laboratory, using a 5.00 x 10~5 H2S04 solution for 485 chronologi-
cal pH measurements by seven different operators and nine different electrodes
of the same model (Orion Ross 81-04b combination electrode), achieved a preci-
sion of ±0.05 pH units and an accuracy of +0.03 pH units. (Metcalf, 1987).
19.6.2 Quality Control Checks
1. Laboratory DuplicateOne sample is analyzed in duplicate (without
rinsing the chamber). The pH value of the duplicate sample should be
within 0.1 pH unit of the routine sample value. If the value is out-
side the acceptable range, reanalyze a third time, if sample volume
permi ts.
2. Field-Laboratory pH comparisonIf, for a given sample the laboratory
value differs from the in situ pH value by 0.5 pH unit or more,
reanalyze the sample.
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Section 19.0
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Page 16 of 16
19.7 REFERENCES
American Society for Testing and Materials, 1984. Annual Book of ASTM
Standards, Vol. 11.01, Standard Specification for Reagent Water,
D 1193-77 (reapproved 1983). ASTM, Philadelphia, Pennsylvania.
Burke, E. M., D. C. Hillman, and E. M. Heithmar, 1986. Stability of pH and
DIG in sealed syringe samples. Presented at the Rocky Mountain
Conference on Analytical Chemistry, August 3-5, Denver, Colorado.
Metcalf, R. C., 1987. The accuracy of Ross pH combination electrodes in
dilute sulphuric acid standards. Analyst, v. 112, no. 10, in press.
Orion Research Incorporated, 1983. Instruction Manual - Model 611
pH/millivolt meter., Orion, Cambridge, Massachusetts.
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Section 20.0
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Page 1 of 7
20.0 DETERMINATION OF pH (OPEN SYSTEM)
20.1 OVERVIEW
The pH is defined as the negative logarithm of the activity of hydrogen
ions (H+). The H+ activity is a measure of the "effective" concentration of
hydrogen ions in solution; it is always equal to or less than the true concen-
tration of hydrogen ions in solution. Values usually range from pH 1 to pH 14,
with pH 1 being most acidic, pH 7 neutral (at 25 °C), and pH 14 most alkaline.
Each pH unit represents a tenfold change in H+ activity, i.e., a pH 4 solution
is 10 times as acidic as a pH 5 solution.
When the pH of a sample solution is measured, the hydrogen ions come into
equilibrium with the ion exchange surface (glass) of a calibrated pH electrode
which creates an electrical potential. This voltage difference is measured by
the pH meter in millivolts, then is converted and displayed as; pH units.
20.1.1 Scope and Application
This method is applicable to the determination of pH in samples which are
at equilibrium with respect to C02 gas transfer between the sample and the
ambient atmosphere (e.g., snowpack and precipitation samples). For the AERP
studies, pH is determined in the processing laboratory using an Orion Model 611
pH meter and an Orion Ross combination pH electrode. The method has been
written assuming that the Orion meter and electrode are used (Orion, 1983).
The method, however, can be modified for use with other instrumentation meeting
equivalent specifications.
The applicable pH range is 3.0 to 11.0.
20.1.2 Summary of Method
The measurement is performed by immersing the electrode in a portion of
the sample. The pH reading is considered stable when it does not vary more
than 0.02 pH units in one direction throughout a one-minute interval.
20.1.3 Interferences
Atmospheric C02 will cause an interference if the sample is not at
equilibria with the atmosphere or if the laboratory atmosphere is subject
to variations in C0£ concentration.
20.1.4 Safety
The calibration standards, sample types, and reagents used in this method
pose no hazard to the analyst. Protective clothing (lab coat and gloves) and
safety glasses should be worn when handling sulfuric acid.
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Section 20.0
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20.2 SAMPLE COLLECTION, PRESERVATION, AND STORAGE
Samples should be collected in clean, deionized water-washed containers.
Approximately 60 mL of sample is needed. No special preservation procedures
are necessary, although it is recommended samples be kept at 4 °C in the dark
until analysis. Measurement of pH should be completed as soon as possible
following sample collection, generally within 24 to 36 hours.
20.3 EQUIPMENT AND SUPPLIES
20.3.1 Apparatus and Equipment
1. Orion Model 611 pH meter or equivalent.
2. Orion Ross combination pH electrode or equivalent.
NOTE: Only combination electrodes are recommended.
3. Centrifuge tubes or small plastic beakers, deionized water-washed as
described in Appendix C.
20.3.2 Reagents and Consumable Materials
1. pH Calibration Buffers (pH 4 and 7)Commercially available pH
calibration buffers (NBS-traceable) at pH values of 4 and 7.
2. Potassium Chloride (3M)Dissolve 75 g KC1 in 1 L of water.
3. pH 4.00 QC Solution (0.0001N H2S04)~add 1.000 ml of 0.1N HpSOa
to a volumetric flask, dilute to 1 L. Prepare daily.
4. WateiWater used in all preparations should conform to ASTM specifi-
cations for Type I reagent grade water (ASTM, 1984).
20.4 PREPARATION
20.4.1 Instrument Preparation
Instrument preparation is identical to that described for closed system
pH measurements (see Section 19.4.1).
20.4.2 Calibration and Standardization
Calibration is identical to that described for closed system pH measure-
ments (see Section 19.4.2).
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Section 20.0
Revision 2
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Page 3 of 7
20.4.3 Maintenance
Maintenance is identical to that described for closed system pH measure-
ments (see Section 19.4.3).
20.4.4 pH Meter Electronic Checkout
The pH meter electronic checkout is identical to that described for closed
system pH measurements (see Section 19.4.4).
20.4.5 Electrode Etching Procedure
The electrode etching procedure is identical to that described for closed
system pH measurements (see Section 19.4.5).
20.4.6 Sample Preparation
NOTE: Sample preparation should be done in the clean air station by an
. .analyst wearing a lab coat and sterile gloves.
Obtain two 50-mL centrifuge tubes (deionized water-washed) which addi-
tionally have been leached in deionized water for at least 24 hours. ; Swirl the
contents of the sample container and mix. Rinse the tubes three times with
sample (if the samp.le volume is low, rinse twice with deionized water and a
third time with sample). Swirl the sample container and pour approximately
25 ml of sample into each tube. Cap the tubes and label one "R" to be used as
a rinse of the electrode.
20.5 PROCEDURE .
NOTE: Refer to Figures 20-1 and 20-2.
20.5.1 Initial Quality Control Check
1. Rinse and fill two beakers with pH 4.00 QC solution.
2. Rinse the electrode by swirling it in the rinse beaker for ,15 to 30
seconds.
3. Insert electrode into the measurement beaker. : "
4. Turn the knob to "pH" and start.the stopwatch. Record the initial pH,,
temperature, and time (0:00) in the pH logbook.
5. Wait until the reading seems fairly consistent, then note the
time and pH values on a loose sheet of paper. If the pH reading
does not vary by more than 0.02 pH units in one direction after
a 1-minute interval, the reading is considered stable. Record the
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Section 20.0
Revision 2
Date: 8/87
Page 4 of 7
INITIAL
STANDARDIZATION
AND CHECK
QCCS
WITHIN ± 0.1 PH
UNITS OF THEORETICAL
VALUE
CHECK QCCS
STANDARD
RECORD IN
LOGBOOK
MEASURE pH
OF
SAMPLES
ENOUGH
OLUME REMAININ
N PREVIOUSLY ANALYZE
SAMPLES TO
REANALYZ
7
QCCS
WITHIN 0.1 pH
UNITS
MORE
SAMPLES
) PREVIOUS SAMPLES (FROM LAST ACCEPTABLE QCCS)
MUST BE REANALYZED AFTER ACCEPTABLE QCCS IS
OBTAINED.
RECORD QCCS VALUE IN
LOGBOOK AND NOTE
SAMPLE ID NUMBERS
ASSOCIATED WITH
UNACCEPTABLE QCCS.
(See Figure 20-2 if an
unacceptable QCCS
is not attained.)
Figure 20-1. Flowchart for pH determination.
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Section 20.0
Revision 2
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Page 5 of 7
CONSULT
OPERATIONS
MANUAL AND
NOTIFY SUPERVISOR
©PREVIOUS SAMPLES (FROM LAST ACCEPTABLE
QCCS1MUST BE REANALYZED AFTCR
ACCEPTABLE QCCS IS OBTAINED.
Figure 20-2. Troubleshooting flowchart for pH determination.
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Section 20.0
Revision 2
Date: 8/87
Page 6 of 7
stable pH and temperature readings and the total elapsed time in
the logbook.
20.5.2 Sample Measurement
1. Rinse the electrode copiously with deionized water, then rinse
it in the sample tube marked "Rinse." -
2. Determine sample pH by following the instructions in Section 20.5.1.
20.5.3 Routine Quality Control Check
NOTE: The pH 4.00 QC solution is analyzed at the beginning of a batch and
at the end of a batch. The QCCS also is analyzed at intervals
within the batch as specified by the quality assurance program.
1. Measure and record the QC solution by following the instructions in
Section 20.5.1.
2. If the measured QC solution pH is acceptable (pH 4.00 ± 0.10), proceed
with routine sample pH determinations.
3. If the QC solution pH is not acceptable, follow the steps below until
an acceptable value is obtained:
a. Repour the pH 4.00 QC solution into a beaker and reanalyze.
b. Remake the pH 4.00 QC solution (see Section 20.3.2) and reanalyze.
c. Repeat the standardization steps (see Section 20.4.3) and reana-
lyze the QC solution.
4. If the pH meter requires recalibration to obtain an acceptable QC
reading, make a notation in the pH logbook. Determine which samples
should be reanalyzed. Reanalyze all samples back to the last accept-
able QC check.
20.5.4 Cleanup
1. Copiously rinse the electrode and glassware with deionized water.
2. Cover the fill hole of the electrode with the plastic sleeve and
store the electrode in 3M KC1.
3. Make sure the meter is on "STD BY."
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Section 20.0
Revision 2
Date: 8/87
Page 7 of 7
20.6 QUALITY ASSURANCE AND QUALITY CONTROL
See Section 19.6.
20.7 REFERENCES
American Society for Testing and Materials, 1984. Annual Book of ASTM
Standards, Vol. 11.01. Standard Specification for Reagaent Water,
D 1193-77 (reapproved 1983). ASTM, Philadelphia, Pennsylvania.
Orion Research Incorporated, 1983. Instruction Manual - Model 611 pH/milli-
volt meter. Orion, Cambridge, Massachusetts.-
-------
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Section 21.0
Revision 10
Date: 8/87
Page 1 of 7
21.0 DETERMINATION OF TOTAL PHOSPHORUS
21.1 OVERVIEW
21.1.1 Scope and Application
This method may be used to determine concentrations of total phosphorus in
natural surface waters in the range from 0.001 to 0.200 mg L"1 P.
NOTE: Samples preserved with HgCl£ should not be analyzed using this
method.
21.1.2 Summary of Method
All forms of phosphorus, including organic phosphorus, are converted to
orthophosphate by an acid-persulfate digestion.
Orthophosphate ions react with ammonium molybdate in acidic solution to
form phosphomolybdic acid, which upon reduction with ascorbic acid produces an
intensely colored blue complex. Antimony potassium tartrate is added to
increase the rate of reduction (Skougstad, et al., 1979; Gales, et al., 1966;
Murphy and Riley, 1962).
21.1.3 Interferences
Barium, lead, and silver interfere by forming a precipitate. There is a
positive interference from silica when the silica-to-total-phosphorus ratio
exceeds about 400:1 (Table 21-1).
TABLE 21-1 PERCENT RECOVERY OF TOTAL PHOSPHORUS IN THE PRESENCE OF SILICA
(Skougstad, et al., 1979)
Total P mg L"1
0.200
0.100
0.050
0.010
0.005
0.002
_______ .
20
98
103
104
144
160
550
15
100
104
133
140
350
Si02 (mg L"1
10
100
102
122
120
250
)
5
102
102
111
120
250
1
101
103
102
100
100
100
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Section 21.0
Revision 10
Date: 8/87
Page 2 of 7
HgClg-NaCI-preserved samples give inconsistent results and, therefore, should
21.1.4 Safety
The calibration standards, sample types, and most reagents used in this
method pose no hazard to the analyst. Protective clothing (lab coat and
gloves) and safety glasses should be worn when handling concentrated sulfuric
acid. Use proper care when operating the autoclave. Follow manufacturer's
safety precautions.
21.2 SAMPLE COLLECTION, PRESERVATION, AND STORAGE !
Samples are preserved with concentrated H2S04 until the pH is less than 2
Samples are stored at 4 °C in the dark when not in use.
21.3 EQUIPMENT AND SUPPLIES
21.3.1 Equipment Specifications
1. Technicon AutoAnalyzer II or equivalent, consisting of sampler car-
tridge manifold, proportioning pump, heating bath, colorimeter,
voltage stabilizer, recorder, and printer. With this equipment the
following operating conditions have been found satisfactory for the
range from 0.001 to 0.200 mg L'1 P:
Absorption cell50 mm
Wavelength880 nm
Cam30 h'1 (1:1)
Heating bath temperature37.5 °C.
21.3.2 Apparatus
1. Autoclave.
2. Glass tubes with plastic caps, disposable18 mm by 150 mm.
21-3.3 Reagents and Consumable Materials
All reagents should be ACS reagent grade or equivalent.
1. Ammonium Molybdate Solution (35.6 g L-l)~Dissolve 40 g of ammonium
molybdate [(NH4)6Mo7024'4H20] in 800 mL of water and dilute to 1 L.
2. Ascorbic Acid Solution (18 g L-l)-Dissolve 18 g of ascorbic acid
(C6H804) in 800 mL of water and dilute to 1 L.
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Section 21.0
Revision 10
Date: 8/87
Page 3 of 7
3.
4.
Antimony Potassium Tartrate Solution (3 g L'1)--Dissolve 3.0 g of
antimony potassium tartrate [K(SbO)C4H406-1/2H20] in 800 ml of water
and dilute to 1 L. ,
Combined Working ReagentCombine reagents in the order listed below.
(This reagent is stable for about 8 hours. The stability is increased
if kept at 4 °C):
50 ml
15 ml
30 ml
5 ml
Sulfuric acid, 2.45M
Ammonium molybdate solution
Ascorbic acid solution
Antimony potassium tartrate solution
5.
6.
7.
8.
Phosphate Stock Standard Solution (100 mg L'1 P)Dissolve 0.4394 g of
potassium acid phosphate (KH2P04, dried for 12 to 16 hours over
concentrated ^$04, sp. gr. 1.84) in water and dilute to 1.000 L.
Phosphate Standard Solution I (10.00 mg L"1 P)Quantitatively dilute
100.0 ml phosphate stock standard solution to 1.000 L with water.
Phosphate Standard Solution II (1.000 mg L"1 P)Quantitatively dilute
10.00 mL phosphate stock standard solution to 1.000 L with water.
Dilute Phosphate Working StandardsPrepare a blank and 1.000 L each
of a series of working standards by appropriate quantitative dilution
of phosphate standard solutions I and II. For example:
Phosphate standard
solution II
(ml)
0.0
1.00
5.00
10.00
Phosphate standard
solution I
(ml)
0.0
5.0
10.0
20.0
Total P
concentration
in working
standard
(mg L"1)
0.000
0.001
0.005
0.010
0.050
0.100
0.200
9. Potassium Persulfate Solution (4 g L"1)Dissolve 4.0 g potassium of
persulfate (^2°8^ in water and dilute to 1 L.
10. Sulfuric Acid (2.45M)Slowly, and with constant stirring and cooling,
add 136 ml of concentrated sulfuric acid (sp. gr. 1.84) to 800 mL
water. Cool and dilute to 1 L with water.
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Section 21.0
Revision 10
Date: 8/87
Page 4 of 7
11. Sulfuric Acid (0.45M)Slowly, and with constant stirring and cooling,
add 25.2 mL of concentrated sulfuric acid (sp. gr. 1.84) to 800 mL
water. Cool and dilute to 1 L with water.
12. Sulfuric Acid-Persulfate Reagent (1 + 1)Mix equal volumes of 0.45M
sulfuric acid and potassium persulfate solution.
13. Water DiluentAdd 1.0 mL Levor IV (Technicon No. 21-0332 or equiva-
lent) to 1 L water.
14. WaterWater should meet the specifications for Type I reagent qrade
water (ASTM, 1984).
21.4 PREPARATION
21.4.1 Calibration and Standardization
Analyze the series of total P standards as described in Section 21.5.
Prepare a calibration curve by plotting the peak height versus standard
concentration. ,
21.5 PROCEDURE
21.5.1 Standard Operating Procedure
NOTE: It is critical that the colorimeter is optically peaked prior to
first analysis.
1. Mix each sample, pipet a volume of it containing less than 0.002 mg
total P (10.0 ml maximum) into a disposable glass tube, and adjust
the volume to 10.0 mL.
\
2. Prepare blank solutions and several standards bracketing the expected
concentration range and adjust the volume of each to 10.0 mL.
3. Add 4.0 mL acid-persulfate reagent to samples, blanks, and standards.
4. Place plastic caps gently on top of tubes, but do not push down.
Autoclave for 30 minutes at 15 psi pressure and 121 °C. After the
samples have cooled, the caps may be pushed down.
5. Set up manifold as shown in Figure 21-1.
6. Allow the colorimeter, recorder, and heating bath io warm up for at
Ieasto30 minutes or until the temperature of the heating bath reaches
37.5 C. Zero the recorder baseline while pumping all reagents
through the system.
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Section 21.0
Revision 10
Date: 8/87
Page 5 of 7
Coil Nc
157-8273-
>.
-03 5 -turn
0COOO
37.5°C
Colorimeter
880 nm .
50 mm cellx^
r-jJ
Y
coils
i
Waste
4
To sampler 4
T
wash
receptacle^
0.030 in
0.32 mL/min
0.030 in
0.32 mL/min
0.035 in
0.42 mL/min
0.030 in
0.32 mL/min
0.073 in
2.00 mL/min
0.040 in
0.60 mL/min
Air
Wats>r
Samole
Combined
reaqent
Wash
solution
Waste
Proportioning pump
Recorder
Sampler -
30/h
1/1 cam
Figure 21-1. Total Phosphorus Manifold.
7 Beqinning with the most concentrated standard, place a complete set of
' standards in the first positions of the first sample tray with blank
solution between each standard. Fill remainder of each tray alter-
nately with unknown samples and blank solution.
8. Begin analysis. When the peak from the most concentrated standard
appears on the recorder, adjust the "STD CAL" control until the flat
portion of the peak reads full scale. Using the baseline control,
adjust each blank in the tray to read zero as it is analyzed.
9. Dilute and reanalyze samples with a total P concentration exceeding
the calibrated range.
21.5.2 Calculations
Compute the concentration of total P in each sample by comparing its peak
height to the calibration curve. Report results as mg L A P. .
21.6 QUALITY ASSURANCE AND QUALITY CONTROL
21.6.1 Precision and Accuracy
Data for the determination of the precision and accuracy of the method
are given in Tables 21-2 and 21-3.
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Section 21.0
Revision 10
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Page 6 of 7
TABLE 21-2. PRECISION AND ACCURACY OF THE PHOSPHORUS METHOD FOR
NATURAL WATER SAMPLES (Skougstad, et al.', 1979).
(All data in mg L'1 P)
Sample
Mean
Std. Dev.
Rel. Std.
4-065070
4-065080
4-066060
10
10
10
0.0347
0.1435
0.0902
0.0012
0.0031
0.0027
3 34
2 16
2.99
TABLE 21-3. PRECISION AND ACCURACY OF THE PHOSPHORUS METHOD
FOR ANALYST-PREPARED STANDARDS (Skougstad, et al., 1979).
(All data in mg L'1 P)
Sample
Mean
Std. Dev.
0.040
0.030
0.020
0.004
0.001
9
10
10
9
9
====;
0.0424
0.0322
0.0172
0.0033
0.0013
0.0007
0.0006
0.0004
0.0007
0.0005
J.71
1.96
2.45
21.21
37.5
It is estimated that the percent relative standard deviation URSD)
(coefficient of variation) of this method is 38 percent at 0.001 mg L'1,
2.5 percent at 0.020 mg L"1, and 2.2 percent at 0.144 mg L"1.
21.6.2 Quality Control Checks
The required quality control procedures are described in Appendix G.
21.7 REFERENCES
American Society for Testing and Materials, 1984. Annual Book of ASTM
Standards, Vol. 11.01, Standard Specification for Reagent Water, D 1193-77
(reapproved 1983). ASTM, Philadelphia, Pennsylvania.
Gales, M. E., Jr., E. C. Julian, and R. C. Kroner, 1966. Method for
Quantitative Determination of Total Phosphorus in Water. J. Am. Water
Works Assoc., v. 58, pp. 1363-1368.
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Section 21.0
Revision 10
Date: 8/87
Page 7 of 7
Murphy, J., and J. P. Riley, 1962. A Modified Single-Solution Method for
the Determination of Phosphate in Natural Waters. Anal. Chim. Acta,
v. 27, pp. 31-36.
Skougstad, M. W., M. J. Fishman, L. C. Friedman, D. E. Erdman, and S. S.
Duncan (eds.), 1979. Method 1-4600-78, Automated Phosphomolybdate
Col orimetric Method for Total Phosphorus. ln_ Methods for Deter-
mination of Inorganic Substances in Water and Fluvial Sediments:
Techniques of Water-Resources Investigations of the United States
Geological Survey, Book 5, Chapter Al. U.S. Government Printing
Office, Washington, D.C.
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Section 22.0
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Page 1 of 7
22.0 DETERMINATION OF DISSOLVED SILICA
22,1 OVERVIEW
22.1.1 Scope and Application
This method is applicable for the determination of dissolved silica in
natural surface waters in the concentration range from 0.1 to 10 mg L"1.
22.1.2 Summary of Method
The procedure utilizes automated technology and is based on existing
methodology (Skougstad, et al., 1979).
Silica reacts with molybdate reagent in acid media to form a yellow
silicomolybdate complex. This complex is reduced by ascorbic acid to form the
molybdate blue color. The silicomolybdate complex may form either as an alpha
or beta polymorph, or as a mixture of both. Because the two polymorphic forms
have absorbance maxima at different wavelengths, the pH of the mixture is kept
below 2.5, a condition which favors formation of the beta polymorph (Govett,
1961; Mullen and Riley, 1955; Strickland, 1962).
A 1-hour digestion with l.OM NaOH is required to ensure that all the
silica is available for reaction with the molybdate reagent.
22.1.3 Interferences
Interference from phosphate, which forms a phosphomolybdate complex, is
suppressed by the addition of oxalic acid. Hydrogen sulfide should be removed
by boiling the acidified sample prior to analysis. Large amounts of iron
interfere; however, neither hydrogen sulfide nor iron is expected in
appreciable quantities in natural surface water samples.
22.1.4 Safety
The calibration standards, samples, and most reagents used in this method
pose no hazard to the analyst. Protective clothing (lab coat and gloves) and
safety glasses should be worn when handling concentrated sulfuric acid and
performing sample digestions.
22.2 SAMPLE COLLECTION, PRESERVATION, AND STORAGE
Samples are collected and filtered using only deionized water-washed con-
tainers and apparatus. Sample containers are completely filled (i.e., no head-
space) and are stored at 4 °C in the dark when not in use.
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Section 22.0
Revision 10
Date: 8/87
Page 2 of 7
22.3 EQUIPMENT AND SUPPLIES
22.3.1 Equipment Specifications
1. Technicon AutoAnalyzer II or equivalent consisting of sampler, car-
tridge manifold, proportioning pump, colorimeter, voltage stabilizer,
recorder, and printer.
With this equipment, the following operating conditions are recommended:
Absorption cell15 mm
Wavelength660 nm
Cam 60 hour-1(6/1)
22.3.2 Reagents and Consumable Materials
1. Ammonium Molybdate Solution (9.4 g L"1)Dissolve 10 g of ammonium
molybdate ((NH^)gMo7024'4H20) in 0.05M H2S04 and dilute to 1 L with
0.05M H2S04. Filter and store in an amber plastic container.
2. Ascorbic Acid Solution (17.6 g L'1)Dissolve 17.6 g of ascorbic acid
(CsHsOg) in 500 mL of water containing 50 mL acetone. Dilute to 1 L
with water. Add 0.5 mL Levor IV solution. The solution is stable for
1 week if stored at 4 °C.
3. Hydrochloric Acid (50 percent v/v)Slowly add 500 mL of concentrated
HC1 to 500 mL water.
4. Hydrochloric Acid (2 percent v/v)Add 10 mL of concentrated HC1 to
490 mL water.
5. Hydrofluoric Acid (HF, ACS reagent grade).
6. Levor IV SolutionTechnicon No. 21-0332 or equivalent.
7. Oxalic Acid Solution (50 g L'1)Dissolve 50 g of oxalic acid
(C2H204-2H20) in water and dilute to 1 L.
8. Silica Standard Solution (500 mg L'1 Si02)Dissolve 2.366 g of sodium
metasilicate (Na2Si03'9H20) in water and dilute to 1.000 L. The con-
centration of this solution should be verified by standard gravimetric
analysis (described in Section 22.4). Store in a plastic bottle.
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Section 22.0
Revision 10
Date: 8/87
Page 3 of 7
9.
Silica Working StandardsPrepare a blank and 500 ml each of a series
of silica working standards by appropriate quantitative dilution of
the silica stock standard solution. The following series is suggested:
Silica stock
solution
standard
(mL)
0.0
0.200
0.500
1.00
5.00
10.0
Silica concentration in
working standard (mg L~*)
0.0
0.200
0.500
1.00
5.00
10.0
10.
11.
12.
Sodium Hydroxide Solution (l.OM NaOH)Dissolve 4 g of sodium hydrox-
ide (NaOH) in water and dilute to 1 L.
Sulfuric Acid Solution (0.05M ^04) (50% v/v ^$04)--Cautiously add
2.8 mL of concentrated sulfuric acid (H2S04, sp. gr. 1.84) to water
and dilute to 1 L. Cautiously and slowly add 500 mL H2S04 to 500 mL
of water. Beware of excessive heat buildup.
WaterWater should meet the specifications for Type I reagent grade
water (ASTM, 1984).
22.4 PREPARATION
22.4.1 Calibration and Standardization
Verify the concentration of the silica stock standard solution using the
gravimetric procedure detailed in steps 1 through 7 (APHA, 1980).
1. Sample EvaporationAdd 5 mL of 50 percent v/v HC1 to 200.0 mL silica
stock standard. Evaporate to dryness in a 200-mL platinum evaporat-
ing dish, in several portions if necessary, on a water bath or
suspended on an asbestos ring over a hot plate. Protect against
contamination by atmospheric dust. During evaporation, add a total of
15 mL of 50 percent HC1 in several portions. Evaporate sample to
dryness and place dish with residue in a 110 °C oven or over a hot
plate to bake for 30 minutes.
2. First FiltrationAdd 5 mL of warm 50 percent HC1 and add 50 mL of hot
water. While hot, filter sample through an ashless medium-texture
filter paper, decanting as much liquid as possible. Wash dish and
residue with hot 2 percent HC1, then with a minimum volume of water
until washings are chloride-free. Save all washings. Set aside
filter paper with its residue.
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Section 22.0
Revision 10
Date: 8/87
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3. Second Filtration Evaporate filtrate and washings from the above
operations to dryness in the original platinum dish. Bake residue in
a 110 °C oven or over a hot plate for 30 minutes. Repeat step 2. Use
a separate filter paper and a rubber policeman to aid in transferring
residue from dish to filter.
4. Ignition Transfer the two filter papers and residues to a covered
platinum crucible, dry at 110 °C, and ignite at 1,200 °C to constant
weight. Avoid mechanical loss of residue when first charring and
burning off the paper. Cool in desiccator, weigh, and repeat ignition
and weighing until constant weight is attained. Record weight of
crucible and contents.
5. Volatilization with HF Thoroughly moisten weighed residue with water.
Add 4 drops of 50 percent v/v ^$04 followed by 10 mL of concentrated
HF, measuring the latter in a plastic graduated cylinder or pouring an
estimated 10 mL directly from the reagent bottle. Slowly evaporate to
dryness over an air bath or hot plate in a hood, and avoid loss by
splattering. Ignite crucible to constant weight at 1,200 °C. Record
weight of crucible and contents.
6. Blank Repeat steps 1 through 5 with a blank sample.
7. Perform the following calculations for both the standard and blank
samples:
X = weight of crucible plus contents before HF treatment (mg)
Y = weight of crucible plus contents after HF treatment (mg)
Z » weight of silica in sample (mg) = X - Y
8. Calculate the silica concentration in the stock standard by:
mg Si Q£ Z (standard) - Z (blank) mg
9.
L 0.200 L
Analyze the series of silica standards as described in Section 22.5
(including digestion).
10. Prepare a calibration curve by plotting the peak height versus
standard concentration.
22.5 PROCEDURE
22.5.1 Standard Operating Procedure
1. Set up the manifold as shown in Figure 22-1.
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Section 22.0
Revision 10
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Page 5 of 7
22-turn coll
20-turn coil
UBfi&il£9£i_
Colorimeter
660 ran Waste
15-ran
To sampler 4
wash ~"
receptacle
0.030 in
0.32 mL/rain
0.035 in
0.42 niL/min
0.025 1n
0.23 ml/ml n
0.030 in
0.32, mL/min
0.035 1n
0.42 mL/min
0.073 1n
2.00 mL/rain
0.045 in
0.80 mL/min
Air
Molybdate
Reaaent
Samel e
Oxalic
Acid:
Ascorbic
Acid
Water
Waste
Recorder
Proportioning pump
Sampler 4
60/hour
6/1 cam
Figure 22-1. Silica manifold.
2. Allow colorimeter and recorder to warm up for at least 30 minutes.
Zero the recorder baseline while pumping all reagents through the
system.
3. Add 5.00 ml of l.OM NaOH to 50.00 ml of sample. Digest for one hour.
4. Beginning with the most concentrated working standard, place a com-
plete set of standards in the first positions of the first sample
tray, followed by a blank. Fill remainder of each sample tray with
unknown and QC samples.
5. Begin analysis. When the peak from the most concentrated working
standard appears on the recorder, adjust the "STD GAL" control until
the flat portion of the curve reads full scale.
6. Dilute and reanalyze any sample with a concentration exceeding the
calibrated range.
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Section 22.0
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Page 6 of 7
22.5.2 Calculations
Compute the silica concentration of each sample by comparing its peak
height to the calibration curve. Any baseline drift that may occur should be
taken into account when computing the height of a sample or standard peak.
Report results as mg L * Si02.
22.6 QUALITY ASSURANCE AND QUALITY CONTROL
22.6.1 Precision and Accuracy
In_a multiple laboratory study using 111 lake samples containing 0.05 to
10 mg L"1 Si 02 the duplicate relative standard deviation was 1.6 percent (note
that this is the overall within-laboratory precision).
In a multiple laboratory_study using two synthetic, simulated lake samples
containing 10.7 and 1.07 mg L l Si02, respectively, recoveries obtained were 88
(n=21) and 95 (n=21) percent, respectively.
22.6.2 Quality Control Checks
The required QC is described in Appendix G.
22.7 REFERENCES
American Public Health Association, American Water Works Association, and Water
Pollution Control Foundation, 1980. Standard Methods for the Examination
of Water and Wastewater, 15th Ed. APHA, Washington, D.C.
American Society for Testing and Materials, 1984. Annual Book of ASTM Stan-
dards, Vol. 11.01, Standard Specification for Reagent Water, D 1193-77
(reapproved 1983). ASTM, Philadelphia, Pennsylvania.
Govett, 6.J.S., 1961. Critical Factors in the Colorimetric Determination of
Silica. Anal. Chim. Acta, v. 25, pp. 69-80.
Mullen, 0. B., and J. P. Riley, 1955. The Colorimetric Determination of
Silica with Special Reference to Sea and Natural Waters. Anal. Chim.
Acta, v. 12, pp. 162-176.
Skougstad, M. W., M. J. Fishman, L. C. Friedman, D. E. Erdman/ and S. S. Duncan
(eds.), 1979. Method 1-2700-78, Automated Molybdate Blue Colorimetric
Method for Dissolved Silica. Ir^ Methods for Determination of Inorganic
Substances in Water and Fluvial Sediments: Techniques of Water-Resources
Investigations of the United States Geological Survey, Book 5, Chapter AI.
U.S. Government Printing Office, Washington, D.C.
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Section 22.0
Revision 10
Date: 8/87
Page 7 of 7
Strickland, J.D.H., 1962. The Preparation and Properties of Silicomolybdic
Acid: I. The Properties of Alpha Silicomolybdic Acid. J. Am. Chem.
Soc., v. 74, pp. 852-857.
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Section 23.0
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Page 1 of 10
23.0 DETERMINATION OF SPECIFIC CONDUCTANCE
23.1 OVERVIEW
Specific conductance is a measure which often can be linearly correlated
with the ionic strength of a solution. Conductivity can be used to generate a
synthetic ionic balance which can be used as a check of measured ionic
concentrations.
23.1.1 Scope and Application
This method is applicable to natural surface waters of low ionic strength.
Most freshwater lakes sampled in the AERP stuides have a specific conductance
in the range 10 to 100 uS cm"1; AERP-sampled streams generally have a specific
conductance in the range 10 to 500 uS cm"1.
23.1.2 Summary of Method
The specific conductance in samples is measured using a conductance meter
and conductivity cell. The meter and cell are calibrated using potassium
chloride standards of known specific conductance (U.S. EPA, 1983). Standards
and samples are analyzed at 25 °C. A temperature-controlled water bath is
recommended to maintain a constant temperature.
23.1.3 Interferences
Temperature variations represent the major source of potential error in
specific conductance determinations. To minimize this error, calibration stan-
dards and samples should be measured at the same temperature. A temperature-
controlled water bath is recommended.
Natural surface waters contain substances (humic and fulvic acids, sus-
pended solids, etc.) which may build up on the conductivity cell. Such a
buildup interferes with the operation of the cell and should be removed perio-
dically, following the cell manufacturer's recommendations.
23.1.4 Safety
The calibration standards and sample types pose no hazard to the analyst.
23.2 SAMPLE COLLECTION, PRESERVATION, AND STORAGE
Samples are collected in clean, deionized water-washed containers. The
container washing procedure is described in Appendix C. Specific conductance
should be determined as close to sample collection time as possible, generally
within 24 hours. Samples should be kept at 4 °C until analysis.
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Section 23.0
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23.3 EQUIPMENT AND SUPPLIES
23.3.1 Equipment Specifications
Digital specific conductance meter with the following minimum
specifications:
Range: 0.1 to 1,000 uS cm"1
Readability: 0.1 uS cm"1
Maximum Error: 1 percent of reading
Maximum Imprecision: 1 percent of reading
23.3.2 Apparatus
1. Conductivity CellHigh-quality glass cell with a cell constant of
1.0 or 0.1. Cells containing platinized electrodes are recommended.
2. ThermometerNBS-traceable thermometer with a range of 0 to 40 °C and
divisions of 0.1 "C.
3. Constant Temperature Water Bath (Optional)Controlled to a -tempera-
ture of 25.0 ± 0.1 °C.
4. Centrifuge Tubes50 ml, deionized water-washed. Soak in deionized
water for a minimum of 24 hours between uses.
23.3.3 Reagents and Consumable Materials
1. Potassium Chloride Stock Solution (1M KC1)
NOTE 1: Prepare as needed and refrigerate at 4 °C.
NOTE 2: This stock solution is used to make the following standards:
147 uS cm"1 calibration standard
14.7, 74, 147 MS cm"1 QC standards.
NOTE 3: This stock solution should be made up in at least 1-L batches
to minimize weighing and dilution errors. The 1M KC1 stock
solution has a theoretical specific conductance of 111,900
uS cm"1 at 25 °C. This value should be verified by measuring
at least three 35-mL samples contained in 50-mL centrifuge
tubes.
a. Fill a clean 1-L volumetric flask with approximately 500 mL of
deionized water. Water should meet the specifications for Type I
reagent grade water (ASTM, 1984).
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. Section 23.0
Revision 4
Date: 8/87
Page 3 of 10
b. Weigh 74.553 g of potassium chloride(KC1, ultrapure, dried for
2 hours at 105 °C and ampulated).
c. Completely dissolve the KC1 in deionized water arid dilute to the
1-L mark. Mix again thoroughly. . , . ,
d. Store the stock solution in 500-mL bottles (deionized water-
washed) which have been rinsed three times with the 1M KC1 solu-
tion. Label the bottles "1M KC1 Stock Solution" and refrigerate
at 4 °C. ......-.-.
2. Calibration Blank Rinse two clean, labeled 50-mL centrifuge tubes
three times with deionized water, then fill with 30 to 40 ml of
deionized water.
NOTE 1: .Two centrifuge tubes (leached in deionized water for a minimum
of 24 hours) are needed for each calibration, QC and blank
solution. Label accordingly and designate one of each set as the
rinse.
NOTE 2: It cannot be assumed that the deionized water has a negligible
conductivity; therefore, the blank conductivity value is sub-
tracted from all standards.
NOTE 3: Be consistent in obtaining deionized water.; Obtain deionized
water from the same source from which all standards are made.
3. Calibration Standard - 147 pS cm"1--
NOTE: Prepare daily
a. Fill a clean, labeled 1-L volumetric flask with approximately
500 mL of deionized water. Obtain a 50-mL disposable beaker,
rinse three times with 1M KC1 stock solution and pour 5 to 10 mL
of stock solution. Use this stock solution to make calibration
and QC solutions.
b. Use a calibrated 100- to 2,000-uL pipet (rinse pipet tip one time
with solution) to deliver 1.000 mL of stock solution to the 1-L
flask. Mix and dilute to 1-L mark and mix again.
c. Rinse two clean labeled 50-mL pentrifuge tubes three times with
calibration standard and pour 30 to 40 mL in each tube.
4, Quality Control Standards - 14.7, 74, 147 uS cnT1
NOTE: Prepare daily.
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Section 23.0
Revision 4
Date: 8/87
Page 4 of 10
a. Fill three clean, labeled 500-mL volumetric flasks with approxi-
mately 250 ml deionized water.
b. Use the 1M KC1 stock solution to prepare the following solutions:
1) 14.7 pS cm~1~Use a calibrated 40- to 200-uL pipet to deliver
0.050 ml of stock solution to the volumetric flask labeled
"14.7 uS cnT1 QC Standard". Alternately, weigh 50 mg of
stock solution. Low-range standards can generally be pre-
pared more accurately by weight than by volume.
2) 74 uS cm"1Use a calibrated 200- to 1,000-uL pipet to
50 ml
labeled "74 uS cm
deliver 0.250 ml of stock solution to the volumetric flask
i"1 QC Standard".
3) 147 pS cm"1Use a calibrated 200- to 1,000-ML pipet to
deliver 0.500 ml of stock solution to the volumetric flask
labeled "147 MS cm"1 QC Standard".
c. Mix and dilute each of the three standards to the 500-mL mark and
mix again.
d. Rinse each clean, labeled centrifuge tube three times with the
appropriate standard (2 centrifuge tubes for each standard, with
one tube designated as rinse). Fill each tube with its corres-
ponding standard (30 to 40 mL).
e. Cap and store each standard and all poured centrifuge tubes at
room temperature.
23.4 PREPARATION
NOTE: See Figure 23-1.
23.4.1 Electronics Check
1. Unscrew both of the leads connecting the probe to the conductance
meter to break the circuit and to prevent capacitance shunting between
calibrating resistors and probe.
2. Check the electronic function of the conductance meter by plugging in
the resistors and reading the specific conductance at these ranges:
Resistor Value (Mmho)
1.000
10.00
100.0
Range (Mmohms = MO)
2 MO
200 MO
2 MO
-------
ELECTRONICS
CHECK
WITH RESISTORS
YES
CALIBRATION
PROCEDURE
TO CHECK
PROBE CELL
CONSTANT
1
MEASURE
SAMPLES AND
RECORD IN LOGBOOK
Section 23.0
Revision 4
Date: 8/87
Page 5 of 10
VALUES
WITHIN 1% OF
THEORETICAL
VALUES
7
STANDARD(10%)
AND BLANK
CONSULT CONDUCTIVITY
METER OR CONDUCTIVITY
PROBE OPERATIONS MANUAL
AND NOTIFY SUPERVISOR
REMAKE AND
REMEASURE
SOLUTIONS
]NO
FINAL CELL
CONSTANT CHECK
ANALYSES
COMPLETE
(j) PREVIOUS SAMPLES (FROM LAST ACCEPTABLE QCCS)
MUST BE REANALYZED AFTER ACCEPTABLE QCCS
IS OBTAINED.
Figure 23-1. Flowchart for specific conductance measurement.
-------
Section 23.0
Revision 4
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Page 6 of 10
Readings should be within 1.0 percent of the theoretical value.
Record the values in the logbook. If the values are not within
1.0 percent, consult the manufacturer's guide.
23.4.2 Conductivity Cell Calibration Check
NOTE 1: Turn conductance meter "OFF" when removing probe from solution.
NOTE 2: Gently mix all solutions in the centrifuge tubes by inverting
them three times.
NOTE 3: When measuring the specific conductance of a solution, do not
allow the probe to touch the sides or the bottom of the
plasticware. Hold the cell upright. Be sure the vent holes
are covered by solution and that there are no air bubbles
around the probe.
NOTE 4: Rinse the probe and NBS-traceable thermometer in deionized water
between each measurement.
NOTE 5: Measure the blank first.
1. Make sure the probe is connected properly.
2. Obtain a NBS-traceable thermometer. (A temperature probe may be
substituted when approved and calibrated against an NBS-traceable
thermometer).
3. Rinse the probe in the blank rinse solution for 10 to 15 seconds.
Place the probe in the blank solution to be measured. The range
should be set at 2u .
4. Following manufacturer's directions, determine the specific conduc-
tance of the calibration blank. Allow the reading to stabilize.
Record values in the logbook. The value should be less than 1.000 at
this range; if not, repour and measure it again.
5. Rinse the NBS-traceable thermometer in the blank rinse and measure the
temperature of the solution to the nearest 0.1 °C. Record the value
in the logbook.
6. Measure the specific conductance of the 147 uS/cm"1 calibration stan
dard as described for the blank. The range should be set at 200
7. The cell constant (K) of the conductivity cell is a commercially
certified standard which is checked daily in the laboratory. For
samples with a specific conductance greater than 20 uS cm~S use a
cell with a theoretical cell constant value of 1.0. For samples
-------
Section 23.0
Revision 4
Date: 8/87
Page 7 of 10
with a specific conductance of less than 20 uS cm"1, use a cell
with a theoretical cell constant value of 0.1.
8. The cell constant is checked using the blank and 147-uS cm"1 calibra-
tion standard measurements. All theoretical values for the specific
conductance standards are at 25 °C. A temperature correction table
(Table 23-1) with the appropriate muiHi plication factors permits
the conversion of a measured value at any temperature (° C) to the
value at 25 °C. The chart is read to the nearest 0.1 °C. Calculate
the cell constant by:
147 (Theoretical Value of Standard at 25 °C)
K - _ . , _..- .
/Measured Value x Temperature\ - /Measured x Temperature\
of Calibration Correction I Value of Correction j
\ Standard (from Table/ \ Blank (from Table/
x 23-1) ' \ 23-1) '
Record this value as K-j, the initial cell constant, showing all calcula-
tions.
23.4.3 Quality Control Check
1. Measure the specific conductance of the three QC solutions as
described in Section 23.4.2, steps 3 through 6.
2. To complete the temperature corrected conductance value, use the
following equation:
Cell Temperature
Temperature = Meter x Constant x Correction
Correction Reading Value (K-j) Value (from
Value Table 23-1)
Do this calculation for the 14.7, 74, and 147 uS cm"1 and the blank
solutions. Subtract the temperature-corrected blank value from each
of the temperature-corrected QC check values and determine if the
final values fall within the specified ranges:
QC Standard (uS cm"1) Range (uS cm"1)
14.7. 13.23-16.17 (10%)
74 70.30-77.70 (5%)
' ' '. 147 139.65-154.35 (5Z.)
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Section 23.0
Revision 4
Date: 8/87
Page 8 of 10
TABLE 23-1. TEMPERATURE CORRECTION FACTORS TO COMPUTE SPECIFIC CONDUCTANCE
VALUES AT 25.0 °C (from Dobos, 1975)
Multiplication factor
0 c
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
0
1.521
1.491
1.462
1.433
1.405
1.377
1.350
1.323
1.297
1.271
1.246
1.221
1.197
1.173
1.150
1.129
1.106
1.084
1.062
1.041
1.020
1.000
0.980
0.961
0.942
0.923
0.905
0.1
1.518
1.488
1.459
1.430
1.402
1.374
1.347
1.320
1.294
1.268
1.243
1.219
1.195
1.171
1.148
1.125
1.103
1.081
1.060
1.039
1.018
0.998
0.978
0.959
0.940
0.921
0.903
0.2
1.515
1.485
1.456
1.427
1.399
1.371
1.344
1.318
1.292
1.266
1.241
1.216
1.192
1.169
1.146
1.123
1.101
1.079
1.058
1.037
1.016,
0.996
0.976
0.957
0.938
0.919
0.901
0.3
1.512
1.482
1.453
1.424
1.396
1.369
1.341
1.315
1.289
1.263
1.238
1.214
1.190
1.166
1.143
1.121
1.099
1.077
1.056
1.035
1.014"
0.994
0.974
0.955
0.936
0.918
0.899
0.4
1.509
1.479
1.450
1.421
1.393
1.366
1.339
1.312
1.286
1.261
1.236
1,212
1.188
1.164
1.141
1.118
1.096
1.075
1.053
1.033
1.012
0.992
0.972
0.953
0.934
0.916
0.898
0.5
1.506
1.476
1.447
1.419
1.391
1.363
1.336
1.210
1.284
1.258
1.234
1.209
1.185
1.162
1.139
1.116
1.094
1.073
1.051
1.031
1.010
0.990
0.971
0.951
0.932
0.914
0.896
0.6
1.503
1.474
1.444
1.416-
1.388
1.360
1.333
1.307
1.281
1.256
1.231
1.207
1.183
1.159
1.136
1.114
1.092
1.070
1.049
1.028
1.008
0.988
0.969
0.949
0.931
0.912
0.894
'0.7
1.500
1.471
1.442
1.413
1.385
1.358
1.331
1.304
1.279
1.253
1.229
1.204
1.180
1.157
1.134
1.112
1.090
1.068
1.047
1.026
1.006
0.986
0.967
0.947
0.929
0.910
0.892
0.8
1.497
1.468
1.439
1.410
1.382
1.355
1.328
1.302
1.276
T.251
1.226
1.202
1.178
1.155
1.132
1.110
1.088
1.066
1.045
1.024
1.004
0.984
0.965
0.946
0.927
0.908
0.890
0.9
1.494
1.465
1.436
1.407
1.380
1.352
1.325
1.299
1.274
1.248
1.224
1.199
1.176
1.153
1.130
1.107
1.085
1.064
1.043
1.022
1.002
0.982
0.963
0.944
0.925
0.907
0.889
23.4.4 Maintenance
1.
2.
Never acid-wash any containers used for specific conductance measure-
ment. Rinse the containers three times with deionized water or soak
them in deionized water overnight before use.
Store the conductivity cell in fresh deionized water daily. Sub-
stances which build up on the probe (e.g., humic and fulvic acids and
suspended solids) should be removed periodically according to the
manufacturer's recommendati ons.
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Section 23.0
Revision 4
Date: 8/87
Page 9 of 10
3. Probe replatinization is required periodically. Consult the instruc-
tion manual for the proper method.
23.5 PROCEDURE
Follow manufacturer's instructions for the operation of the meter and
cell.
1. Place the calibration standards, QC solutions, and samples in the
/ constant-temperature water bath (25.0 ± 0.1 °C) to allow the samples
and standards to equilibrate to 25.0 °C.
2. Rinse the cell thoroughly with water.
3. Rinse the cell with a portion of the sample to be measured. Immerse
the electrode in a fresh portion of sample and measure its
conductance.
4. Rinse the cell thoroughly with water after use. Store cell in water.
NOTE: If the readings become erratic, the cell may be dirty or may need
replatinizing. Consult the manufacturer's operating manual for
guidance.
5. Compute specific conductance by the equation given in Section 23.4.3,
step 2.
23.6 QUALITY ASSURANCE AND QUALITY CONTROL
23.6.1 Precision and Accuracy
Forty-one analysts in seventeen laboratories analyzed six synthetic
samples containing increments of inorganic salts, with the following results
(U.S. EPA, 1983):
Increment, as Precision, as Accuracy
Specific Conductance Standard Deviations -
(MS cm"1) (MS cm"1) Bias (%) Bias (uS cm"1)
100 7.55 -2.02 -2.0
106 8.14 -0.76 -0.8
808 66.1 -3.63 -29.3
848 79.6 -4.54 -38.5
1,640 106 -5.36 -87.9
1,710 119 -5.08 -86.9
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Section 23.0
Revision 4
Date: 8/87
Page 10 of 10
In a single laboratory (EPA-Cincinnati) using surface-water samples with
an average conductance of 536 uS cm'1 at 25 °C, the standard deviation was
6 US cm"1 (U.S. EPA, 1983).
23.6.2 Quality Control Checks
1. Use the three QC solutions described previously (see Section 23.3.3).
These solutions should be measured before sample analysis, following
sample analysis, and at intervals in between as recommended by the
quality assurance program.
2. Measure one sample in duplicate (i.e., prepare four centrifuge tubes).
The routine and duplicate values should agree to within ±10 percent.
If they do not, prepare new sample portions and reanalyze.
23.7 REFERENCES
American Society of Testing and Materials, 1984. Annual Book of ASTM Standards,
Vol. 11.01, Standard Specification for Reagent Water, D 1193-77 (reapproved
1983). ASTM, Philadelphia, Pennsylvania.
Dobos, D., 1975. Electrochemical Data: A Handbook for Electrochemists in
Industries and Universities. Elseyier Scientific Publishing Company,
Amsterdam, The Netherlands.
U.S. Environmental Protection Agency, 1983 (revised). Methods for Chemical
Analysis of Water and Wastes, EPA 600/4-79-020. U.S. Environmental
Protection Agency, Cincinnati, Ohio.
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Section 24.0
Revision 10
Date: 8/87
Page 1 of 5
24.0 DETERMINATION OF TRUE COLOR
24.1 OVERVIEW
The amount of color in natural surface waters has been demonstrated to be
closely correlated to the amount of dissolved organic carbon (DOC). The major
sources of DOC are (1) photosynthetic products of algae and macrophytes, (2)
humic compounds of terrestrial origin, and (3) excretions from zooplankton and
larger animals. Thus a lake with a large pool of DOC might be a productive
lake and would probably be more highly colored than an unproductive lake.
Color analysis, in conjunction with other analytical methods, can yield infor-
mation concerning the productivity of the water system.
Dissolved organic compounds also act as chelators for metals like aluminum.
A colored lake may have high concentrations of aluminum, but the concentration
of toxic forms is reduced due to the formation of alumino-organic complexes.
24.1.1 Scope and Application
This method is applicable to the determination of true color in natural
surface waters. For AERP studies, true color is measured in the processing
laboratory using a Hach Model CO-1 color test kit. The value obtained through
the scale window is the sample's apparent color. This method has been written
assuming that the Hach Color Determination Kit is used. However, the method
may be modified for use with other instrumentation meeting equivalent
specifications.
The applicable color range is 0 to 1000 APHA platinum-cobalt color units
(PCUs) (APHA, 1985; U.S. EPA, 1983).
24.1.2 Summary of Method
The true color is determined after centrifuging a sample and comparing
its color to APHA color standards.
24.1.3 Interferences
No interferences are known.
24.1.4 Safety
The sample types pose no hazard to the analyst. Tinted glass should not
be worn when performing color measurements.
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24.2 SAMPLE COLLECTION, PRESERVATION, AND STORAGE
The sample portion for true color determination is taken from the sample
container used to prepare aliquots. It is raw (unfiltered) sample.
24.3 EQUIPMENT AND SUPPLIES
24.3.1 Apparatus and Equipment
1. Hach Model CO-1 Color Determination Kit or equivalent.
2. Sample cuvettes.
3. Centrifuge.
24.3.2 Reagents and Consumable Materials
1. WaterWater used to rinse cuvettes should conform to ASTM specifica-
tions for Type I reagent grade water (ASTM, 1984).
2. Centrifuge tubes, 50-mL.
24.4 PREPARATION
24.4.1 Sample Preparation
1. Rinse a labeled 50-mL plastic centrifuge tube and lid with three
5-mL portions of sample from the appropriate sample container.
2. Fill the tube with 50-mL sample. Prepare additional centrifuge tubes
for laboratory duplicates or replicates.
3. Place four sample tubes in the centrifuge at a time. If there are
less than four samples, balance the centrifuge by placing a 50-mL
centrifuge tube filled with deionized water into the empty port.
4. Centrifuge samples for 10 minutes with the centrifuge dial set at a
medium speed (40).
5. Repeat steps 1 through 4 above for all samples in the batch. Make
sure tubes are labeled with sample identification (ID) numbers.
6. Rinse a color-viewing tube with three 2-mL portions of supernatant
from the centrifuge tube.
7. Fill the rinsed color-viewing tube to the top with supernatant and
cover with Parafilm. Label the Parafilm with the sample ID.
8. Repeat steps 6 and 7 for all samples in the batch and for any dupli-
cates prior to beginning color determinations.
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24.4.2 Color Kit Preparation
Fill a tube with deionized water. Insert the plastic stopper in such a
way as to expel air bubbles. Secure the stopper with a piece of scotch tape
around the mouth of the tube. This tube is a blank which is used as a com-
parison. The color wheel is adjusted so that the color selected on the wheel
along with the blank matches the color of the sample.
24.5 PROCEDURE
24.5.1 Low Range Sample Color Determination
NOTE: If the sample exceeds 100 color units, remove tubes from the com-
parator, cover, and set aside until low range samples have been
analyzed.
1. Place lengthwise viewing adapter in comparator as shown in instruc-
tion manual for color determination kit.
2. Insert the plastic stopper into the top of the sample tube, making
sure that no air bubbles are created. Insert the sample tube into
the opening nearest the center on the back of the comparator.
Rotate and push downward to prevent breakage. Be sure the outside
of the tube is clean and dry.
3. Insert tube containing deionized water into the other opening on the
back of the comparator.
4. Hold the comparator up to a white background and view through the
openings of the comparator. (NOTE: To keep source constant, a piece
of white Benchkote should be taped to the wall; the comparator should
be viewed using it as a backdrop.) View the comparator at the same
height above the floor each time.
5. Rotate the disc until a color on the dial matches the sample color.
6. Record the reading obtained by viewing through the scale window to the
nearest 5 units. Record the value in the color logbook. Reading is
expressed as APHA PCU's. {1000 platinum-cobalt units = color from
mixing 2.492 g KoPtClg + 2 g CoCl2'6H20 + 200 mL HC1 (cone) + 800 ml
H20). If reading exceeds 100 platinum cobalt units, proceed with high
range determination as described below.
24.5.2 High Range (100-500 PCD) Sample Color Determination
1. Using a disposable Pasteur pi pet, extract the sample to the bottom
line of each color tube. Also extract the deionized water in the
comparison tube to the bottom line of the color tube.
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2.
3.
4.
5.
6.
24.5.3
1.
2.
3.
4.
25.5.4
1.
Remove lengthwise viewing adapter from the comparator.
Insert the tube containing the sample vertically into the top right
opening of comparator, as shown in the instruction manual-for the
color determination kit.
Insert the tube containing deionized water into the top left opening
of comparator.
Proceed as in Section 24.5.1 steps 4 through 6, for low-range deter-
minations.
Multiply the reading obtained by five and record the results in the
color logbook. Be sure to include the calculations.
High Range (500-1000 PCU) Sample Color Determination
Be sure the volume of both the sample and the deionized water is
level with the bottom line on the color tubes.
Fill another color tube to the bottom line with deionized water. Add
this to the sample and invert the tube to mix (cover the tube with
Parafilm). Using a disposable pi pet, extract the solution to the
bottom line of the color tube. Also extract the deionized water in
the comparison tube to the bottom line of the color tube.
Proceed as in Section 24.5.1, steps 4 through 6.
Multiply the value by ten and record in the logbook. Recofd the
initial value and document which procedure was followed.
Cleanup
When all samples have been analyzed for color, rinse the color viewing
tubes and caps copiously with deionized water. Place the tubes upside
down in a tube rack and allow them to dry in the clean air station.
2. Rinse all dirty centrifuge tubes and caps copiously with deionized
water. Set all tubes upside down in tube rack and allow to dry in the
clean air station (tubes are reusable). The caps can be placed upside
down on Kimwipes and allowed to dry.
3. Place the color disc in its plastic cover and store it.
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24.6 QUALITY ASSURANCE AND QUALITY CONTROL
24,6.1 Precision and Accuracy
As no calibration or QC standards are used in this method, precision and
accuracy information are not available.
24.6.2 Quality Control Checks
1. Laboratory DuplicateOne sample per batch is measured in duplicate
(two samples poured and analyzed from the same sample container). The
duplicate sample is analyzed at the end of the batch; the value of the
duplicate sample should agree within 10 color units of the routine
sample. If the values do not agree within 10 color units, reanalyze
both tubes.
24.7 REFERENCES
American Public Health Association, 1985. Standard Methods for the Examination
of Water and Wastewater, 16th ed. APHA, Washington, D. C.
American Society for Testing and Materials, 1984. Annual Book of ASTM
Standards, Vol. 11.01, Standard Specification for Reagent Water,
D 1193-77 (reapproved 1983). ASTM, Philadelphia, Pennsylvania.
U.S. Environmental Protection Agency, 1983 (revised). Methods for Chemical
Analysis of Water and Wastes. EPA-600/4-79-020. U.S. Environmental
Protection Agency, Cincinnati, Ohio.
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Section 25.0
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25.0 DETERMINATION OF TURBIDITY
25.1 OVERVIEW
Turbidity is a measure of suspended organic and inorganic material in the
water column which affects light transmission. High turbidity may be the
result of phytoplankton bloom or sediment from watershed runoff. Acidified
bodies of water may be less productive and are often less turbid.
25.1.1 Scope and Application
This method is applicable to the determination of turbidity in natural
surface waters. For AERP studies, turbidity is determined in the processing
laboratory using a Monitek Model 21 nephelometer. As a result, the method has
been written assuming that the Monitek nephelometer is used (Monitek, 1977).
The method may.be modified for use with other instrumentation meeting equiva-
lent specifications.
The applicable turbidity range is 0 to 200 nephelometer turbidity units
(NTUs).
25.1.2 Summary of Method
The nephelometer measuring system works by projecting an optical beam
through the unfiltered sample contained in a special optical cuvette. A photo-
detector measures the intensity of the light scattered by particles in
the solution. A ditigal reading is displayed which is proportional to the
concentration of particles in the solution.
25.1.3 Interferences
Air bubbles in the sample cuvette interfere with the determination and
cause a positive bias.
25.1.4 Safety
The calibration standards and sample types pose no hazard to the analyst.
25.2 SAMPLE COLLECTION, PRESERVATION, AND STORAGE
The sample portion for turbidity determination is taken from the sample
container used to prepare aliquots. It is raw (unfiltered) sample which is
permitted to warm to room temperature.
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25.3 EQUIPMENT AND SUPPLIES
25.3.1 Equipment and Apparatus
1. Monitek Model 21 nephelometer or equivalent
2. Sample cuvettes
25.3.2 Reagents and Consumable Materials
1. Certified Turbidity Calibration StandardsCommercially available
certified turbidity standards with values 5.0, 10.0, and 20.0 NTu.
Additional certified turbidity standards with values of 50.0, 100,
and 200 NTU may be required for high range calibration (See Section
25.5.2). Repour all standards weekly; refrigerate between uses.
Prepare standards as follows:
NOTE 1: A 5 NTU standards is used as the QC check for the 20.0 NTU
range. Prepare two cuvettes from two separate stock bottles.
Label one as the QC sample.
NOTE 2: Allow all standard cuvettes to warm to room temperature
before using.
NOTE 3: Stock bottles containing NTU standards should always be stored
in the refrigerator.
a. Obtain a clean, scratch-free cuvette.
b. Rinse the cuvette three times with 5 mL of the appropriate
standard. Cap cuvette and gently invert so that the rinse
contacts all surfaces. The cuvettes used for the standards are
screw cap cuvettes. If this type is unavailable, use a Parafilm
cover.
c. Fill the cuvette with standard and cover or cap tightly. Dry the
exterior with a Kimwipe to-remove fingerprints or liquid.
d. Using a permanent marker pen, label the cap with the appropriate
NTU value.
2. Prepared Turbidity StandardsIn addition to the certified standards,
above, standards with values of 2.0 NTU and 175 NTU (high range only)
can be prepared as follows:
a. 2.0 NTU - Place 5.0 mL of the 10.0 NTU standard in a 100-mL
graduated cylinder. Add 20.0 mL of deionized water and mix.
Rinse the cuvette three times prior to filling the cuvette with
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Section 25.0
Revision 10
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Page 3 of 9
the 2.0 NTU standard. Check the value on the calibrated
nephelometer. Replace this standard weekly as with all other
standards.
b. 175 NTU - Place 12.5 ml of deionized water into a 100-mL
volumetric flask. Fill to the 100-mL mark with the 200 NTU
standard. Remake solution weekly.
3. WaterAll water used in preparing reagents, in dilutions, and in
cleaning labware should meet the specifications for Type I reagent
grade water (ASTM, 1984).
25.4 PREPARATION , .
25.4.1 Daily Calibration ,
NOTE 1: The following procedure is written for the 0 to 20.0 NTU range.
NOTE 2:' All cuvettes should be checked for optical comparability
prior to use for both standards and samples (see Section 25.4.2).
1. If the instrument has been off, allow it to warm up for at least
15 minutes before using.
2. With the lamp on .and the cuvette well empty, set the "RANGE" switch
to 2 NTU. .';'.",...'
3. Set the instrument display to read 0.00 by adjusting the "ZERO"
control knob. The minus sign will flash on and off.
4i Insert the 10,0 NTU cuvette and align the index marks.
5. Set the instrument "RANGE" switch to the 20-NTU position. Adjust the
"STANDARDIZE" control knob so the display reads 10.0 (or the standard
value if another standard is used).
6. Insert the 2.0, 5.0, and 20.0 NTU standards in succession. Record
each reading in the turbidity logbook. Do not adjust the instrument
in any way to read these samples. Measure the 2.0 and 5.0 NTU on
range 20 and the 20.0 NTU on range 200.
7. The measured values should be 2.0 ±0.2, 5.0 ± 0.5, and 20.0 ± 2.0 NTU.
If the measured values are unacceptable, wipe the cuvettes with a
clean Kimwipe and reanalyze. If the values are still unacceptable,
repeat steps 2 through 7. If the reanalyzed values are not within the
acceptable range, repour the standards and repeat steps 2 through 7.
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Section 25.0
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25.4.2 Maintenance
1. Cuvette Comparability
a. Clean all cuvettes by rinsing them three times with deionized
water.
b. Rinse the cuvette to be checked three times with the 10.0 NTU
standard. Fill with approximately 25 mL of the standard.
c. Follow Section 25.4.1, steps 3 through 5, using the original
cuvette containing the 10.0 NTU standard to be sure the
nephelometer is calibrated.
d. Now place the cuvette to be compared into the cuvette well.
Observe the reading and slowly rotate cuvette to obtain a reading
which is as close as possible to the value obtained using the
standard cuvette.
e. The value should be 10.0 ± 0.2 NTU for a given location on the
cuvette. Once the best acceptable alignment has been located,
place an index mark on the cuvette at the index mark on the
instrument.
f. The cuvette is now considered comparable to the standard cuvette
Turbidity readings should be taken only with the index marks
aligned.
25.5 PROCEDURE
NOTE 1: Refer to Figure 25-1 for the flowchart for turbidity measure-
ments.
NOTE 2: Avoid rigorous agitation to minimize introduction of air bubbles
which interfere with measurement. Allow sample containers to
come to room temperature prior to pouring samples for turbidity
analysis.
NOTE 3: Samples with numerous, large particulates will have readings
which decrease as the particles settle out. Record the highest
stable reading as the sample value.
25.5.1 Low Turbidity Samples
1. Gently swirl the sample container to evenly distribute any settled
particles.
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Section 25.0
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Page 5 of 9
"ZERO" THE
NEPHELOMETER
CHECK INSTRUMENT
OPERATION AND
STANDARD QUALITY
INITIAL CALIBRATION
10 NTU STANDARD
NO
ARE
ALUES WITHIN
10% OF THEORETICAL
VALUES
LINEARITY CHECK
WITH 2.0.5.0 AND
20'.0 NTU STANDARDS
RECORD VALUES
IN LOGBOOK AND RECORD
VALUE FOR 5.0 NTU QCCS
ANALYSES COMPLETE
ANALYZE SAMPLES
AND RECORD IN LOGBOOK
RECORD VALUE
IN LOGBOOK
CHECK INSTRUMENT,
RECALIBRATE AND NOTE IN
LOGBOOK. REANALYZE ALL
SAMPLES BACK TO LAST
ACCEPTABLE QCCS
AFTER ACCEPTABLE QCCS
IS OBTAINED.
ANALYZE 5.0 NTU QCCS
AND RECORD IN LOGBOOK
CCEPTABL
VALUE ?
(5.0±0.5
TU
Figure 25-1. Flowchart for turbidity.
2. While wearing disposable, dust-free gloves, rinse the cuvette with
three 5-mL portions of sample. It is not necessary to swirl the
container between rinses.
3. Cap the sample container and swirl. Immediately fill the cuvette.
Cover with Parafilm and label with the sample identification number.
Wipe the cuvette with a Kimwipe to remove any liquid or fingerprints.
4. Invert the cuvette three times and place the sample into the cali-
brated nephelometer. Measure all values on range 20 unless the read-
ing exceeds 20 NTU; then see steps 6 and 7. Record results in the
turbidity logbook. If the reading is not stable, remove the cuvette
and gently invert. Check for air bubbles, wipe, and reinsert into
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Section 25.0
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5.
6.
the nephelometer. Record the stable reading or flag the unstable
readings if a stable reading cannot be obtained.
Analyze the 5.0 NTU QC standard after every 10 samples or at intervals
recommended by the quality assurance program. If the measurement is
within acceptable limits, record the value in the logbook and continue
sample analysis. If the measurement is not within acceptable limits,
wipe the cuvette with a clean Kimwipe and reanalyze. If the reana-
lyzed value still is not within the acceptable range, see Section
25.4.1, step 7.
If the sample readings exceed 20 NTU, switch the "RANGE" selection
knob to the 200 position and measure a 50-NTU standard. If the 50 NTU
value is within 5 percent (47.5-52.5) of the theoretical value,
remeasure the sample and record the value in the logbook along with
the reading for the 50-NTU standard. Note in the logbook that no
recalibration was required.
7. If the 50 NTU is not within acceptable limits, remove the high sample
and set aside. Analyze the rest of the samples using the above
procedure, setting aside all the samples with readings that exceed
20 NTU. After all low turbidity samples have been read, and .the final
QC sample has been analyzed, the nephelometer should be recalibrated
for high turbidity samples.
25.5.2 High Turbidity Samples r
1. If a sample reading exceeds 20 NTU and the 50-NTU value is not within
acceptable limits (Section 25.5.1, steps 6 and 7), the nephelometer
should be recalibrated as follows:
a. DO NOT make any adjustments using the "ZERO" knob.
b. Set the "RANGE" selector to 200. Place the 100-NTU standard into
the cuvette well and adjust the "STANDARDIZE" knob until the
display reads 100.
c. Check the 20, 50, and 175 NTU standards and record the values in
the logbook. If the values are not within range (20 ± 2.0,
50 ± 5.0, 175 ± 17.5) go back to Step Ib.
d. Measure all high turbidity samples at one time. Run a QC check
before, in the middle, or after every 10 samples, and at the end
of a set. Analyze one high sample in duplicate, i.e., pour a
second cuvette. Results should agree within 10 percent or
reanalyze the pair.
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Section 25.0
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e. Choose the QC sample value according the the chart below. Do not
use the same standard that was used to calibrate the meter; pour a
second standard from a separate stock bottle.
Sample Values (NTU) QC solution (MTU)
20-50 20
50-175 50
175-199 175
2. If any sample reading exceeds 200 NTU, a dilution should be made.
Obtain- some fresh filtered sample by using a 60-mL disposable sterile
syringe and an Acrodisc or equivalent syringe filter. Filter a small
amount of sample into a clean cuvette and rinse thoroughly. Rinse the
cuvette a total of three times.
3. Filter approximately 25 to 30 ml of sample into a cuvette. Place in
the nephelometer and read the turbidity value. Record the value in
the logbook noting the range used.
4. Rinse a clean 50-mL centrifuge tube three times with a small amount
of unfiltered sample. Fill the tube with exactly 5.0 ml of unfiltered
sample. Using a disposable pi pet, add exactly 45 mL of filtered
sample by filling the tube to the 50.0 ml mark (previously filtered
sample from the cuvette may be used). Invert the centrifuge tube
three times to mix thoroughly. Place a small amount of this diluted
sample into a clean cuvette and rinse three separate times.
5. Fill the cuvette with the diluted sample. Read the turbidity value
and record the value in the logbook noting the range used.
6. Calculate the actual turbidity value using the following equation:
(Turbidity of DilutedX /Turbidity of Filtered'
Sample \ [ Sample
I - 9 1.-*
10 / \ 10
Record the actual turbidity value and the calculations in the logbook.
25.5.3 Cleanup
1. Clean the turbidity cuvettes by rinsing copiously with deionized
water. Place upside down in the tube rack in the clean work station
to dry.
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Section 25.0
Revision 10
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Page 8 of 9
2. Turn off the lamp. Leave the power on if the nephelometer is used
daily. Follow the manufacturer's instructions for complete care.
25.5.4 General Precautionary Notes for Procedure
1. Check the optical comparability of all cuvettes,monthly using the
procedure in Section 25.4.2. Always align index~ijiarks when making
readings.
2. Always wear gloves when handling cuvettes. Check that all cuvettes
are clean and free of fingerprints or smudges. Avoid handling in
the region of light path.
3. If the standards or samples have been cooled, allow them to warm to
room temperature before analysis to avoid cuvette fogging.
4. If air bubbles are present in the sample, allow the sample to sit
uncovered for about 20 minutes; gently tap the sides of the cuvette
after covering it to release the bubbles. Mix gently prior to
reading.
5. Perform a linear calibration check at least every 6 months.
6. To minimize the contamination of a standard, do not introduce any
object into a standard bottle or pour the used standard back into the
bottle. The foil lid on a bottle may fall into the standard but will
not harm the solution in any way. Do not remove it.
25.6 QUALITY ASSURANCE AND QUALITY CONTROL
25.6.1 Precision and Accuracy
No information available at this time.
25.6.2 Quality Control Checks
1. Routine QC check
a. Insert the 5.0-NTU standard into the calibrated nephelometer.
b. The measured value should be 5.0 ± 0.5 NTU. Record the accept-
able value in the logbook and continue with sample measurement.
c. If the value is not acceptable, wipe the cuvette with a clean
Kimwipe and reanalyze. If the value is still not acceptable,
refill the cuvette with a fresh portion of 5.0-NTU standard and
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Section 25.0
Revision 10
Date: 8/87
Page 9 of 9
repeat Section 25.4.1, steps 3 through 6. Reanalyze all samples
back to the last acceptable QCCS value. Record procedure and
reanalyzed values in the logbook.
2. Laboratory DuplicateOne sample per batch is analyzed in duplicate
(two cuvettes from the same sample container). The cuvette designated
as the duplicate is analyzed at the end of the sample analysis before
the final QC check. The values obtained from the routine and dupli-
cate samples should agree within 10 percent. If they do not, repour
both the routine and duplicate cuvettes and reanalyze.
25.7 REFERENCES
American Society for Testing and Materials, 1984. Annual Book of ASTM
Standards, Vol. 11.01, Standard Specification for Reagent Water, D 1193-77
(reapproved 1983). ASTM, Philadelphia, Pennsylvania.
Monitek, Inc., 1977. Model 21 Laboratory Nephelometer, Preliminary Operating
and Maintenance Instructions. Monitek, Hayward, California.
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Appendix A
Revision 4
Date: 8/87
Page 1 of 5
APPENDIX A
NATIONAL SURFACE WATER SURVEY MOBILE LABORATORY SPECIFICATIONS
A commercially available, insulated, heavy-duty cargo trailer shell (Wells
Cargo) was modified and outfitted to produce a field laboratory facility for
the Eastern Lake Survey. The design of the trailer took several factors into
consideration. The trailers would be towed by 1-ton pickup truck driven by a
non-professional driver. Electrical and water requirements had to be within
the supply capabilities of utility companies located in rural or remote areas.
The laboratory had to support field sampling and sample processing operations
with cold storage space and reagent grade water. Workspace was required for
four to five scientists and specific analytical instrumentation. Storage space
was required for equipment, reagents, and supplies. A work area which mini-
mized contamination (from metals, anions) was needed to conduct sample pro-
cessing. Standard laboratory safety features for storing chemicals and
protecting personnel were necessary.
Schematic drawings of the trailer are shown in Figures 1 and 2. Each
trailer was 9.4 m long, 2.4 m wide, and 3.9 m high. These dimensions required
a fifth-wheel type hitch configuration (i.e., where the hitch is attached to
the bed of the tow vehicle over the rear axle, rather than to the rear bumper)
to ensure road safety and stability. There were 146 m^ of compartment storage.
The interior work space of each trailer was 6.1 m long, 2.3 m wide, and 2.3 m
high. Each trailer contained approximately 5.5 linear m of counterspace. Each
trailer required both 110 V and 220 V alternating current, single-phase
80-amp electrical power, a minimum feed water pressure of 40 psi, and access
to a sewer drain or leach field.
A 1.8 m-wide laminar flow hood (Continental Control Systems) was installed
at the rear of each trailer to provide a contamination-free work area. The
hood contained a high efficiency purification apparatus (HEPA filters, 0.3-um
pore size) capable of delivering Class 100 air (as defined by Federal Standard
20913, 1973, Government Services Administration) into the work area. The hood
also had adjustable flow vents that allowed a static, positive, or negative
pressure to be maintained within the work area.
A reverse osmosis and deionization system provided high-quality water for
each trailer. Tap water was pretreated by filtration (5-um pore size) and
reverse osmosis (Mi Hi pore Milli-RO, 4-L per hour output), and was stored in a
95-L reservoir. Water from the reservoir was deionized on demand (Millipore
Milli-Q system). The end product at the point of use met ASTNi Type I specifi-
cations for reagent grade water (ASTM, 1984).
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Appendix A
Revision 4
Date: 8/87
Page 2 of 5
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Appendix A
Revision 4
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Appendix A
Revision 4
Date: 8/87
Page 4 of 5
Each trailer was equipped with two 2.4 m3 freezers and one 9.1 m3 com-
bination refrigerator and freezer- Two roof-mounted heater/air conditioning
units (5,000 BTU heating capacity and 13,200 BTU cooling capacity per unit)
provided temperature control for the laboratory interior. Laboratory safety
features included an eyewash station, first aid kit, two Halon fire extin-
guishers, a vented storage cabinet for flammable chemicals, racks for compressed
gas cylinders, and a safety shower mounted outside the trailer door. A steel
cabinet under the laminar flow hood provided vented storage for acids and other
corrosive chemicals. '
Each mobile laboratory trailer was equipped with identical instrumentation
to allow for standardized sample processing and analysis. This instrumentation
included a total carbon analyzer (0.001 mg L'1 C resolution) a pH meter with
combination electrode (± 0.01 pH unit resolution), an electronic balance
(± 0.001 g resolution), a nephelometer (± 0.1 NTU resolution), a benchtop
5 APHA platinum-cobalt unit resolution), and
instruments used in the trailers are
Other laboratory equipment and supplies
centrifuge, a color test kit (±
vacuum filtration equipment. Specific
described in Linthurst et al. (1986).
used are listed in Appendix B.
Once on site; a mobile laboratory trailer could be made operational within
48-72 hours. During field operations, water samples were analyzed and processed
using standardized methods and quality assurance procedures (Hillman et al.,
1986, and Drousl et al., 1986). Dissolved inorganic carbon (DIG), pH, turbidity,
and true color were measured at the field laboratory. Water samples were
processed in the laminar flow hood into several distinct aliquots and were
preserved. They were shipped to an analytical laboratory the following day.
Where appropriate, the processing procedure included filtration, preservation
with ultrapure acid, and the preparation of a dissolved monomeric aluminum
fraction. The laboratory also provided reagent grade water, frozen chemical
refrigerant packs, and reagents for use by the field sampling crews.
Researchers who require the use of a trailer similar to that described
here should consider several aspects of the design. Power, water, and-drainage
requirements preclude operating these trailers as truly self-sufficient units.
Advance arrangements with utility companies may be necessary to prepare a
site for setting up a mobile laboratory trailer. The internal environment of
these trailers could not always be maintained during extreme weather conditions
(i.e., subfreezing temperatures or high humidity). Alternative heating and
air-conditioning units should be investigated if trailers are to be set up in
areas subject to extremes in temperature and humidity.
The work and storage areas of the trailers were well organized and per-
mitted four to five people to work comfortably without undue interference from
each other. For extended periods in the field, additional on-site storage space
for backup equipment and supplies is recommended.
-------
Appendix A
Revision 4
Date: 8/87
Page 5 of 5
Trailers involved in supporting a large operation, consisting of many
field teams or a large daily sample load, may require larger-capacity water
purification systems than those used during the Eastern Lake Survey. Each
trailer used in the Eastern Lake Survey supported one or two helicopter
teams and processed 20 to 30 samples per day. The amount of reagent grade
water needed for this effort was just within the supply capability of the
system in most locations. ,
Finally, the location of the trailer is important in terms of the proper
operation of the laminar flow hood. Areas subjected to gusty winds and
blowing dust, or heavy vehicular traffic should be avoided to reduce the
possbility of sample contamination from particulate matter or organic vapors.
REFERENCES
American Society for Testing and Materials, 1984. Annual Book of ASTM
Standards, Vol. 11.01, Standard Specification for Reagent Water, D 1193-77
(reapproved 1983). ASTM, Philadelphia, Pennsylvania.
Drouse, S. K., D. C. Hillman, L. W. Creelman, and S. J. Simon, 1986. National
Surface Water Survey: Eastern Lake Survey (Phase I-Synoptic Chemistry).
Quality Assurance Plan. EPA 600/4-86-008. U. S. Environmental Protection
Agency, Las Vegas, Nevada.
Hillman, D. C., J. F. Potter, and S. J. Simon, 1986. National Surface Water
Survey: Eastern Lake Survey (Phase I-Synoptic Chemistry). Analytical
Methods Manual. EPA 600/4-86-009. U. S. Environmental Protection Agency,
Las Vegas, Nevada.
Linthurst, R. A., D. H. Landers, J. M. Eilers, D. F. Brakke, W. S. Overton,
E. P. Meier, and R. E. Crowe, 1986. Characteristics of Lakes in the
Eastern United States. Vol. I: Population Descriptions and Physico-
Chemical Relationships. EPA 600/4-86-007A. U. S. Environmental Protection
Agency, Washington, D.C.
-------
-------
Appendix B
Revision 4
Date: 8/87
Page 1 of 6
APPENDIX B
PROCESSING LABORATORY EQUIPMENT LIST
1. Mobile processing laboratory facilities and supplies
a. Electrical and water inputs
b. Water outlet
c. Source of water capable of meeting ASTM specifications for Type I
reagent grade water (such as Barnstead NANOpure/ROpure 40 or Mi Hi pore
Mill.i-RO/Super-Q System)
d. Heating and cooling system
e. Freezer/Refrigerator
f. Laminar flow hood capable of delivering class 100 (Federal Standard
209 B 1973, Government Services Administration) air
g. Solvent storage cabinet
h. Standard laboratory countertops and sink
i. Analytical balance (±0.001 g) and plastic weighing boats
j. Vacuum pump
k. Centrifuge (capable of holding four 50-mL tubes)
1. Field data forms, shipping forms, batch forms, logbooks
m. Class 100 air filtration filters
n. Spare water treatment cartridges
o. Coolers
p. Clean 20-L Cubitainers with spigots
(continued)
-------
Appendix B
Revision 4
Date: 8/87
Page 2 of 6
PROCESSING LABORATORY EQUIPMENT LIST (Continued)
2. Total extractable aluminum supplies
a. Clean 50-mL graduated centrifuge tubes with sealing caps
b. Clean 10-mL centrifuge tubes
c. Clean sealing caps for 10-mL centrifuge tubes
d. HPLC-grade methyl isobutyl ketone (MIBK) .. ,
e. Sodium acetate
f. 8-hydroxyquinoline (99+ percent purity)
g. NlfyOH (30 percent - Baker Instra-Analyzed grade or equivalent)
h. Clean 1-L, 500-mL, and 100-mL volumetric flasks
1. Glacial acetic acid (Baker Instra-Analyzed grade or equivalent)
j. Hydrochloric acid (12 M - Baker Instra-Analyzed grade or equivalent)
k. Phenol-red indicator solution (0.04 percent w/v)
1. 2.00-mL Repipet dispensers
m. 3.00-mL Repipet dispensers top for 1-gallon bottle
n. 5.00-mL Repipet dispensers
o. 100-mL reagent bottles with droppers
p. Polystyrene graduated cylinders (25-, 100-, 250-mL sizes)
3. PCV-Reactive Aluminum Supplies
a. Clean 250-mL beakers
b. Clean 100-mL beakers
(continued)
-------
Appendix B
Revision 4
Date: 8/87
Page 3 of 6
PROCESSING LABORATORY EQUIPMENT LIST (Continued)
c. Flow-injection analyzer
d. Micropipets, variable-volume, 1-5 uL
e. Micropipets, variable-volume, 40-200 uL
f. Micropipets, variable-volume, 200-1,000 uL
g. Disposable micropipet tips, 1-200 uL
h. Disposable micropipet tips, 600-1,000 uL
i. Disposable micropipet tips, 1-5,000 uL
j. Polyethylene bottles, 1-L capacity
k. Volumetric flasks, 100-mL capacity
1. Filter paper, Whatman GF/C or equivalent
m. Cation-exchange resin (Amberlite IR-120, 14-50 mesh or equivalent)
n. Hydrochloric acid, concentrated (Baker Ultrex grade or equivalent)
o. Ammonium hydroxide, concentrated (Baker InstraAnalyzed grade or
equivalent)
p. Hydroxylammonium chloride
q. 1,10-phenanthroline
r. Hexamethylene tetramine
s. Stock Al calibration standard solutions, 1,000 mg L"'1
t. Stock Al QC solution (1,000 mg L"1), certified standard from different
source than the calibration standard solution
u. Sodium chloride (ACS reagent grade)
v. Pyrocatechol violet
(continued)
-------
Appendix B
Revision 4
Date: 8/87
Page 4 of 6
PROCESSING LABORATORY EQUIPMENT LIST (Continued)
4. True color determination supplies
a. Color determination kit
b. Color determination kit spare supplies
1. Color discs
2. Color viewing tube
3. Hollow polyethylene stoppers
c. Color-blindness test kit
5. Filtration apparatus and supplies
a. Membrane filters, 0.45 urn, 47 mm diameter
b. Teflon or plastic forceps
c. Filtrators - low form (Fisher or equivalent)
d. Acrylic vacuum chambers (custom made)
e. Clean filter holders
f. Spare rubber stoppers
g. Vacuum pump with regulator
h. Clean polyethylene amber wide-mouth bottles (125-, 250-, and 500-mL
sizes)
i. Disposable gloves (talc-free)
j. Digital micropipets (5-40 uL, 40-200 uL, 200-1,000 uL, 1,000 -
5,000 uL)
(continued)
-------
Appendix B
Revision 4
Date: 8/87
Page 5 of 6
PROCESSING LABORATORY EQUIPMENT LIST (Continued)
k. Micropipet metal-free pi pet tips (in four sizes corresponding to
micropipet sizes in [j] above)
1. Indicating pH paper (Type CS, range 1.8 to 3.8)
m. HN03 and ^$04 (Baker Ultrex grade or Seastar Ultrapure grade)
n. Frozen freeze gel packs
o. Styrofoam-lined shipping containers
-v-,
6. DIG determination supplies
a. Dohrmann DC-80 carbon analyzer or equivalent
b. 50-mL polypropylene syringes
c. Syringe valves (Mininert or equivalent)
d. Zero-grade nitrogen gas
e. Anhydrous Na£C03 (ACS Primary Standard Grade)
f. Syringe membrane filters (Gelman Acrodisc 4218, 0.45 urn or equivalent)
g. Spare carbon analyzer parts (nuts, ferrules, tubing)
7. pH determination supplies
a. pH meter (Orion Model 611 or equivalent)
b. Orion Ross epoxy body combination pH electrode
c. 3M KC1 filling solution for combination pH electrode
d. pH sample chamber (custom made)
e. 0.100N H2S04
f. Ringstand (to hold pH apparatus) and clamps
(continued)
-------
Appendix B
Revision 4
Date: 8/87
Page 6 of 6
PROCESSING LABORATORY EQUIPMENT LIST (Continued)
g. NBS-traceable pH buffers (pH 4 and 7)
h. 50-mL disposable beakers
8. Turbidity determination supplies
a. Nephelometer (Monitek Model 21 or equivalent)
b. 5-, 10-, 20-, 50-, 100-, 200-NTU standards
c. Cuvettes
9. Snowpack and bulk precipitation supplies
a. Racksto hold buckets during sample-melting process '.
b. Sample buckets
c. Syringes (60 mL, plastic)
d. Syringe valves (Luer-Lok or equivalent)
e. Scale, capable of accurate measurement within ±1 g
-------
- . - Appendix C
Revision 4
Date: 8/87
Page 1 of 6
APPENDIX C
GENERAL LABORATORY PROCEDURES
NOTE 1: Logbooks should be kept for each procedure or instrument.
The lab supervisor should review and sign the logbook at the
completion of daily analyses. There should als;o be an instrument
calibration logbook including a record of the dates that; new
chemicals are opened.
NOTE 2: If an error is made in a logbook, use one line to cross out and
initial. Always use ink when recording in the logbook.
NOTE 3: Gloves, lab coats, and lab glasses should be worn when contacting
sample, acids, or hazardous materials.
C.I ELECTRONIC BALANCE : ; .
C.I.I Balance Standardization
NOTE 1: Check standardization weekly.
NOTE 2: Be sure to check the calibration over range for which the balance
is used.
1. While wearing gloves, use the calibration weights to standardize the
balance. Do not touch the weights with anything but the forceps
included in the weight set. Tare the balance and record the reading
for each weight in the instrument calibration logbook.
2. If weight values and balance readings do not agree, consult the
manufacturer's guide for adjustments.
C.I.2 Weighing Procedures
NOTE 1: Use a dry Teflon spatula. Do not use same spatula for successive
weighings of different chemicals.
NOTE 2: Remember to weigh the substance with the lid on the balance if
it had been originally tared with the lid on the balance.
1. While wearing gloves, pour the approximate amount of substance needed
into a weighboat. Do not put the spatula into the bottle.
2. Obtain a second weighboat, place it on the balance and tare.
-------
Appendix C
Revision 4
Date: 8/87
Page 2 of 6
3. Using a spatula, transfer the substance to the weighboat on the
balance until the desired amount is obtained.
4. Dispose of any unused substance; do not return to bottle.
C.I.3 Cleanup
1. Rinse the spatula with deionized water after use and allow to air dry.
2. Do not leave any spilled chemicals on the balance. Use a damp Kimwipe
to clean the balance pan and wipe dry.
C.2 MICROPIPET
NOTE 1: The following instructions refer to the Finn continuous volume
micropipets used in AERP studies. These procedures can be
modified for use with other digital micropipets.
NOTE 2: Keep pi pet vertical at all times to prevent contamination.
C.2.1 Pi pet Calibration
Note: Check the calibration of each pi pet weekly and record data in the
instrument calibration logbook. Each procedure requires a daily
calibration check of all pipets used. This data is recorded in
the corresponding procedural logbook.
1. Calibrate pipets as follows, setting the volume as instructed below:
Pi pet Volume Range Set Volume to: Permitted Ranges
40-200 uL 50 ML 0.049-0.051 g
200-1000 pL 1000 ML 0.990-1.010 g
1000-5000 ML 2000 ML 1.990-2.010 g
2. While wearing gloves, place the appropriate size pi pet tip onto the
end of the pi pet.
3. Using the balance, set for low range (0-30g), place a weighboat on the
balance and tare. Use fresh deionized water and pi pet the specified
volume-into weighboat. Weigh deionized water a total of five times
and average to the nearest 0.1 mg and compare this average with the
permissible ranges in step 1. Record all measurements in the
instrument calibration logbook.
4. If the mean in step 3 lies outside of the permitted range, the volume
setting is adjusted as follows: remove the cap of the micropipet
to expose the adjustment dial. If the adjustment dial is turned in
-------
Appendix C
Revision 4
Date: 8/87
Page 3 of 6
the same direction as the thicker side of the arrow marking on the
cap, the volume delivered by the micropipet will increase. Turn the
dial toward the thinner side of the arrow marking to decrease the
delivered volume.
C.2.2 Pi pet Operation - Forward Technique
NOTE 1: Operate the thumb button slowly and steadily. Do not let the
thumb button snap back. Deliver the volume smoothly.
1. While wearing gloves, place a clean pipet tip on pipet.
2. Keep the pipet as vertical as possible during up-take of solution.
Depress thumb button to first stop. Dip the pipet tip slightly
below the solution surface and slowly release the thumb button.
3. Deliver the liquid by gently depressing the thumb button to the
first stop. Touch the pipet tip to side of the container (except
when preserving aliquots) while simultaneously depressing the thumb
button to the second stop. Slowly release the thumb button.
4. Remove the used pipet tip by pressing the tip ejector down. Dispose
of the pipet tip in a proper waste receptacle.
C.2.3 Pipet Operation - Reverse Technique
NOTE: Use this technique to pipet viscous liquids.
1. Apply a pipet tip and depress thumb button to second stop. Dip the
pipet tip slightly below the surface of the solution and slowly
release the thumb button.
2. Deliver the liquid by gently depressing the button to the first stop.
Release the thumb button. Remove and dispose of the pipet tip.
C.2.4 Care of Pi pets
1. If any liquid is sucked into the barrel, immediately consult the
manufacturer's guide and clean as directed. Do not use pipet until
it is cleaned.
2. For leakage or inaccuracies refer to the manufacturer's trouble-
shooting guide.
C.3 REPIPET DISPENSER INSTRUCTIONS
NOTE 1: These instructions are specific to the Reference Lab Industries'
Repipet used in the AERP studies. These procedures may be
modified for use for other equivalent apparatus.
-------
Appendix C
Revision 4
Date: 8/87
Page 4 of 6
NOTE 2: Do not include the drops that are dispensed when pulling up on
the Repipet dispenser in the delivery volume.
C.3.1 Calibration of 2.0-mL and 5.0-mL Repipet Dispensers
NOTE: Use clean air station.
1. Set the Repipet to dispense 2.0 or 5.0 ml of solution as directed by
manufacturer.
2. Place the weighboat on the balance and tare. Fill the Repipet bottle
with deionized water and dispense 2.0 or 5.0 ml of deionized water into
the weighboat.
3. Return the weighboat to the balance and weigh contents. Acceptable
limits are:
Repipet Limits
2.0 mL 2.0 ± 0.02 g
5.0 ml 5.0 ± 0.05 g
If weight is outside range, adjust dispenser as directed by manufac-
turer and recheck.
C.3.2. Calibration of 10.0-mL Repipet
NOTE: The 10.0-mL Repipet is used only for MIBK in AERP studies; it
should always remain under the hood.
1. Set the Repipet to dispense 10.0 mL as directed by the manufacturers's
manual.
2. Obtain a 50-ml centrifuge tube with its cap and place on balance and
tare.
3. Dispense 10.00 mL of MIBK into the centrifuge tube and weigh. The
acceptable range is 7.98 ± 0.05 g at 20 °C. If the weight is not
within acceptable limits, adjust the dispenser as directed by the
manufacturer and recheck.
C.4 PREPARATION OF 5 PERCENT NITRIC WASH
NOTE 1: Use Baker-Analyzed grade HN03 or equivalent for general glassware
cleaning.
NOTE 2: The 5 percent HN03 wash is used both to clean glassware and in
filtration to rinse the acid units.
-------
Appendix C
Revision 4
Date: 8/87
Page 5 of 6
1. Partially fill a 1-L volumetric flask with deionized water.
2. Add 50 ml of concentrated HNC>3 and mix well.
3. Dilute to the 1-L mark with deionized water. Mix arid transfer to a
1-L wash bottle labeled "5% HN03".
C.5 SYRINGE FILTER PREPARATION
NOTE: These procedures are specific to the Nucleopore Swin-lok filter
assemblies used in the AERP studies for syringe filtration of
extractable aluminum and PCV-reactive aluminum samples. These
procedures may be modified for use with other filter assemblies,
except disposable types.
C.5.1 Cleaning
1. Used filter assemblies are cleaned by discarding the Nucleopore mem-
brane, placing the parts in a beaker and rinsing the parts three times
with deionized water.
C.5.2 Assembly
1. Refer to the Nucleopore Swin-lok filter instructions for part descrip-
tions.
2. Place the disc in the filter base with the coarse grid down (away from
filter). Place an 0-ring in the groove around the disc, and seat the
0-ring carefully.
3. Using gloves and clean Teflon forceps, obtain a Nucleopore membrane,
discarding the blue separator papers. Dip the membrane into a beaker
of deionized water and place it on top of the 0-ring, being sure to
center the membrane.
4. Obtain a filter stem and place a second disc into this part, being
sure the coarse side is up (away from filter). The top and bottom
discs are interchangeable but the smooth side of each filter should
always face the membrane filter.
5. Place the filter stem on the filter base; aligning the notches to
secure the membrane. Place the top onto the assembly and screw down
tightly.
C.5.3 Acid-Wash Procedure
1. Attach an assembled filter onto a syringe containing deionized water.
Inject approximately 2-3 mL through the filter. Check the filter for
leaks.
-------
Appendix C
Revision 4
Date: 8/87
Page 6 of 6
2. Repeat the procedure using a syringe containing 5 percent nitric acid.
3. Repeat step 1, but rinse with three separate 2 to 3-mL portions of
deionized water.
C.5.4 Filter Storage
1. Place wet filters in a large sealable bag and seal. This will prevent
the membranes from drying out. The bag may then be stored in the
refrigerator if desired.
2. Each filter may now be used to filter a sample syringe for MIBK
extraction or FIA aluminum analysis.
C.6 CLEANING OF PLASTICWARE
Plasticware, depending on its use, is cleaned by either an acid-washing
procedure or deionized water-washing procedure.
C.6.1 Acid-Washing Cleaning Procedure
All plasticware (with the exceptions given in Section C.6.2) is rinsed
three times with deionized water, three times with 3N HN03 (prepared from Baker
Instra-Analyzed HNC-3 or equivalent), and six times with deionized water. It is
then filled with deionized water and allowed to stand for 48 hours. Next, it
is emptied, dried in a laminar flow hood, delivering Class 100 air (when dry
containers are necessary), and placed in clean plastic bags (bottles are capped
first). The procedure in Section C.6.3 is used to check the cleaning procedure.
C.6.2 Deionized-Hater-Leaching Cleaning Procedure
Plasticware to be used for pH, acidity, alkalinity, and anion determina-
tions is rinsed three times with deionized water, filled with deionized water,
allowed to stand for 48 hours, then emptied and sealed in clean plastic bags.
The procedure in Section C.6.3 is used to check the cleaning procedure.
NOTE: The deionized water used in cleaning the plasticware should meet or
exceed specifications for ASTM Type I reagent grade water.
C.6.3. Cleaning Procedure Quality Control Check
After the initial cleaning (by either procedure), 5 percent of the con-
tainers are checked to ensure that rinsing has been adequate. The check is
made by first adding 500 ml (or the maximum amount) of deionized water to a clean
container, sealing the container with a cap or Parafilm, and slowly rotating it
so that the water touches all surfaces. The specific conductance of the water
is then measured. It should be less than 1 uS cm~l. If any of the containers
fail the check, all of the containers are rerinsed and 5 percent are retested.
-------
Appendix D
Revision 4
Date: 8/87
Page 1 of 21
APPENDIX D
NATIONAL SURFACE WATER SURVEY BLANK DATA FORMS
The National Surface Water Survey forms shown in this appendix are
facsimiles of the forms used in the processing and analytical laboratories.
Form Number Form Title Page
2/5 Batch/QC Field Data Form 2 of 21
3 Shipping 3 of 21
11 Summary of Sample Results 4, 5 of 21
13 ANC and BNC Results 6 of 21
14 QC Data for ANC and BNC Analyses 7 of 21
15 Conductivity 8 of 21
16 Anion-Cation Balance Calculation 9 of 21
17 1C Resolution Test 10 of 21
18 Detection Limits 11 of 21
19 Sample Holding Time Summary 12, 13 of 21
20 Blanks and QCCS 14, 15 of 21
22 Duplicates 16, 17 of 21
31 Summary of Analytical Results -
Phytopigments 18 of 21
32 QC Results - Phytopigments Flurometry 19 of 21
33 QC Results - Phytopigments HPLC 20 of 21
34 QC Results - Phytopigments Time Line 21 of 21
-------
Appendix D
Revision 4
Date: 8/87
Page 2 of 21
NATIONAL SURFACE WATER SURVEY
BATCH/QC FIELD DATA FORM
DATE RECEIVED
DYDATAMGT
ENTERED
RE-ENTERED
D FORM 2 LAKES
OR
D FORM 5 STREAMS
LAKE
OR
STREAM
10
CONDUCTIVITY
(US cm -*
NO SAMPLES
IMOATCII___
LAD TO WHICH
DATCH SENT _
DATE SHIPPED
QIC (mg/L)
OCCS LIMITS
SAMPLE UCL 2.2
CODE LCL1.B
STATION pH
QCCS LIMITS
UCL4.1
LCL 3.9
TURDIDITY (NTUJ
QCCS LIMITS
UCL S.S
LCL 4.5
COMMENTS:
SAMPLE ID
DATE PROCESSED-
AIR-DILI. NO ,
DATA QUAUFICnS X. Y »nd Z ARE AVAILABLE FOB USE OH THIS FORM.
QUALIFIER COMMENT
BASE SITE ID ,
LAD CREW ID .
MOBILE LABORATORY
SUPERVISOR
'CV ALUMINUM PCV ALUMINUM
(Ppm) (ppm)
UCL UCL
LCL LCL
DISSOLVED ORGANIC
WHITE - OnHL COPY VEUOW - FIELD COPY
PINK - EMSU-LV COPY
NSWS Form 2/5
-------
Appendix D
Revision 4
Date: 8/87
Page 3 of 21
NATIONAL SURFACE WATER SURVEY
SAMPLE MANAGEMENT OFFICE
P.O. BOX 818
ALEXANDRIA, VA 22314
NSWS
FORM 3
SHIPPING
RECEIVED BY
IF INCOMPLETE IMMEDIATELY NOTIFY:
SAMPLE MANAGEMENT OFFICE
(703) 557-2490
FROM
(STATION ID): '
SAMPLE
ID
01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
1
TO
(LAB):
BATCH
ID
OATE PROCESSED
ALIOUOTS SHIPPED
(FOH STATION USE ONLY)
2
3
4
5
6
7
a
DATE SHIPPED DATE RECEIVED
AIR-BILL NO.
PUTS
SAMPLE CONDITION UPON LAB RECEIPT
(FOR LAB USE ONLY)
QUALIFIERS:
V:
ALIQUOT SHIPPED
ALIQUOT MISSING DUE TO DESTROYED SAMPLE
WHITE -FIELD COPY
PINKLAB COPY
YELLOW SMO COPY
GOLD LAS COPY FOR RETURN TO SMO
NSWS Form 3
-------
Appendix D
Revision 4
Date: 8/87
Page 4 of 21
CM
CD
DD
as
6
1 X
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00
3:
00
-------
Appendix D
Revision 4
Date: 8/87
Page 5 of 21
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-------
Appendix D
Revision 4
Date: 8/87
Page 6 of 21
NATIONAL SURFACE WATER SURVEY
Form 13
Lab Name
ANC AND BNC RESULTS
Batch ID
Lab Manager's Signature_
= = S333 = = := = :23;: = :=::=::= =
RESULTS
Sample ID
Analyst
[ANC] =
[C02-BHC] -
DATA
ueq/L
CB
eq/L
eq/L
Initial Sample Volume =
Blank ANC =
DATE STANDARDIZED
DATE STANDARDIZED'
Page 1 of 1
mL
ueq/L
ACID TITRATION
BASE TITRATION
VOLUME HC1
(mL)
0.00
0.00 (with KC1)
MEASURED
PH1
CALCULATED
PH
VOLUME NaOH
(mL)
0.00
0.00 (with KC1)
MEASURED
PH1
CALCULATED
PH
NSWS Form 13
-------
Appendix D
Revision 4
Date: 8/87
Page 7 of 21
NATIONAL SURFACE WATER SURVEY
Form 14*
Page 1 of 1
LAB NAME
QC DATA FOR ANC AND BNC ANALYSES
BATCH ID
LAB MANAGER'S SIGNATURE
SAMPLE
ID
01
02
03
04
05
06
07
08
09
10
11
12 ,
13
14
15 :'
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
ANC
Meq/L
C02-BNC
ueq/L
CALCULATED ANC
RESULT
.__,.
DIFFERENCE3
%xb
*Form not required in data package but recommended for internal QC requirements.
aDifference = Calculated ANC-Measured ANC
b /DIG (in umoles/LHCANC] + [Cb2-BNC])
X 100
DIC
NSWS Form 14*
-------
Appendix D
Revision 4
Date: 8/87
Page 8 of 21
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fO
c
u
S 1
t.
o
H-
"O
i
o
£
3
(U *
TO
tO
CL
(tJ
4-» C
^ i
c
r~ C
u.
o ^
OJ «r
3 (
CT C.
fT
4-
ti ^
c i:
E c
t.
j_ ^
K
LO
r-1
D
3 E
K 0
U-
00
r<
CO
tu ;z;
(O
4->
3
o
c
o
o
GJ
L.
5?
s
u
1
J
3
j
^
3
3
J
»
-------
Appendix D
Revision 4
Date: 8/87
Page 9 of 21
NATIONAL SURFACE HATER SURVEY
Form 16*
Page 1 of 1
LAB NAME
ANION-CATION BALANCE CALCULATION
BATCH ID
LAB MANAGER'S SIGNATURE
Sample
10
01
02
03
1 04
05
06
07
08
09
10
11
12
13
14
' 15
16
1? '"
' 19
20
21
22
23
24
25-
26 "'
27
28
29
30
31
32
33
34'"
35"""
" 36 '
37 '
38
" 3d
40
% Ion
Difference**
Factor to Convert
mq/L to neq/L
*Form not required i
**% Ion Difference =
***[H+] = (io-pH) x
Ions Uieq/L)
Ca2+
49.9
Cl"
28.2
Mg21"
82.3
N03"
16.1
K+
25.6
Na+
43.5
S042-
20.8
n data package but recommended for internal y
ANC + E Anions - £ Cations (except H*)
1 Anions + £ Cations + ANC + 2[H+]
105 peq/L
F"
52,6
NH4+
55.4
ANC
___-
[{+***
__--
Z requirements
o
NSWS Form 16
-------
Appendix D
Revision 4
Date: 8/87
Page 10 of 21
NATIONAL SURFACE WATER SURVEY
Form 17 Page 1 of 1
1C RESOLUTION TEST
LAB NAME
BATCH ID
LAB MANAGER'S SIGNATURE .
1C Resolution Test
1C Make and Model:_
Date:
Concentration: S042~ Ug/mL, N03~___
Column Back Pressure (at max. of stroke): psi
Flow Rate: mL/min
Column Model: Date of Purchase:
Column Manufacturer:
Column Serial No:
Is precolumn in system Yes No
(a) cm (b) cm
Percentage Resolution: 100 x (1-a/b)
The resolution must be greater than 60%
Test Chromatogram:
NSWS Form 17
-------
Appendix D
Revision 4
Date: 8/87
Page 11 of 21
NATIONAL SURFACE WATER SURVEY
Form 18
Page 1 of 1
DETECTION LIMITS
LAB NAME
BATCH ID
LAB MANAGER'S SIGNATURE
Parameter
Ca
Mg
K
Na
- Mn .
Fe
AT, total
extractable
CT
S°42-
N03~
Si02
F~, total
NH4+
DOC
Specific
Conductance
DIC
P, total
Al , total
Units
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
uS/cm
mg/L
mg/L
mg/L
Instrumental
Contract Required Detection Date Determined
Detection Limit Limit (DD MMM YY)
0.01
0.01
0.01
0.01
0.01 . -
0.0,1
0.005
0.01
0.05
0.005
0.05
0.005
0.01
0.1
*
0.05
0.002
0.005
*Report the X, which must not exceed 0.9 uS/cm, Of six nonconsecuti ve blanks.
Note: Report with four significant figures or down to IDL.
NSWS Form 18
-------
Appendix D
Revision 4
Date: 8/87
Page 12 of 21
NATIONAL SURFACE WATER SURVEY
FORM 19
Page 1 of 2
LAB NAME
BATCH ID
DATE* PROCESSED
SAMPLE HOLDING TIME SUMMARY
LAB MANAGER'S SIGNATURE
DATE* RECEIVED
Parameter
Molding
Time
Holding Time
Plus
Date Samplcc
Sample ID:
01
U?
03
Di
"US
U(i
o/
on
UJ
1U
11
12
~n
rt
Ib
Ib
T7
in
l!>
-------
Appendix D
Revision 4
Date: 8/87
Page 13 of 21
NATIONAL SURFACE WATER SURVEY
FORM 19
Page 2 of 2
LAB NAME
DATE* PROCESSED
SAMPLE HOLDING TIME SUMMARY
BATCH ID LAB MANAGER'S SIGNATURE _
DATE* RECEIVED
Parameter
Holding
Time
Holding Time
Plus
Date Sampled
Sample ID:
01
02
03
04
05
06
07
Od
09
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
3?
38
39
40
DOC
14
NH4+
28
Eq. OH
7
ANC
14
BNC
14
Specific
Conductance
14
Eq. DIC
14
Init. DIC
14
Total P
28
Total Al
28
Date* Analyzed**
*Report these dates as Jul an dates
**If parameter was reanalyzed due to QA problems, report the last date analyzed.
NSWS Form 19 (Continued)
-------
I
Appendix D
Revision 4
Date: 8/87
Page 14 of 21
OJ
u-
o
cn
UJ
UJ
so
o sr
u_ o
oiu:
t^
0-
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<_)
3: s-
O 1
_J
S- 4->
0. E
CL'r-
O 0
O !_
cy )->
o o
_i
U*.
S'i
O -i-
1 _1
O- 4J
s o
o o
_J
to
c
O!
c
13
c
C=
O
o
01
c
c
c
o
(_J
01
c
c
c
3
cn
c
c
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3
c
13
3
c
LJ_
t/1 .
0 >
cr
o
cn t.
re
QJ 4-»
CX-r-
0. E
oo
0 0
o- s-
i: c
cn o
o
in
QJ 4-3
o 'i
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CO
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cn o
r- O
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cn
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o
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c
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r
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c:
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tu
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ructions
c:
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in
14
cr
03
o
o
s_
CL
CL
OJ
O
o
CM
5-
O
-------
Appendix D
Revision 4
Date: 8/87
Page 15 of 21
o
CM
-
LU
5>
Di
UJ
3= o
CM
UJ
o s:
0. -~.
4-> O _1
C O Cn
0 _1
UJ CD cn
0 13 E
C O
0. O ~-
00 <_> 00
CO O.
o
a: o.
CT3C
UJ O.
rn cn
z. E
0 _J
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Q cn
ameter
ra
CL.
z.
=
z.
c:
0
(XJ
o
13
f !-
0 H-
0) -r-
3 S
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c
cn
c
c
o
cn
c
13
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O
cn
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en
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cn
c
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0. E
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1
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cn o
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§1
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01
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err s-
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cn o
r- O
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c
cn
c:
5
4J
C
O
cn
c
5
c
c
o
o
cn
c
5
o
o
cn
c
5
c
c
o
cn
d
5
c
c
o
o
ca
c
o
-------
Appendix D
Revision 4
Date: 8/87
Page 16 of 21
Q)
O1
tO
CL.
LU
OH
LU
CM
gl S
U- O Q
co
_l
3:
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z:
1
C9
r~«
to
~C£.
UJ
5S
§
E
CO
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CD
5
2:
00
o
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£
=3
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F-l
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to to cn
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o
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o
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2:
oo
-------
Appendix D
Revision 4
Date: 8/87
Page 17 of 21
00
q-
o
o>
en
UJ
00
LU
<:
o
o_
ZD
O
3 CM
CM
UJ
O E
0 _J
' /^ cr
1-1 e
O _1
Ld Q CT1
E
U T3 E
at c 0
Q. o -~-
GO CJ GO
f ^ J
= cr
<; -!
te
O i
r C
O. a
0
01
at
o
E
GO
(0 +J
U i
3 a;
Q
X
Q
G'
**
ai Q
1C ""*
(J 0)
-0 <- r-
C i Q.
0 ex. E
O 3 1C
O> O GO
GO
C
"a
E
its
GO
(U
1C 4->
O i
"a. a
3 GC
a
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a:
**
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S- E=
a> o
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c:
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00
3
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-------
Appendix D
Revision 4
Date: 8/87
Page 18 of 21
NATIONAL SURFACE WATER SURVEY
FORM 31
BATCH ID:
SUMMARY OF ANALYTICAL RESULTS - PHYTOPIGMENTS
LAB NAME:
LAB MANAGER'S SIGNATURE:
ul
u
£)
^a
ii)
JO
jl
J2
Jj
J4
Jt>
Jb
jy
JB
Jii
40
SAMPLE
ID
,
EXTRACT
VOLUME
(mL)
CHLa (ng/L)
FLUUROMETRIC
UHCORRECTEO
CHLa (pg/L)
~HPLC
... .
PHEa (pg/L)
HPLC
OTHERS,
COMMENTS
NSWS Form 31
-------
Appendix D
Revision 4
Date: 8/87
Page 19 of 21
NATIONAL SURFACE WATER SURVEY
FORM 32
QC RESULTS - PHYTOPIGMENTS
FLUOROMETRY
BATCH ID: LAB MANAGER'S SIGNATURE:
DATE:
ITEM RESULT* COMMENTS
METHOD DETECTION LIMIT 'pig/I CHLa*
BLANK pg'/L CHLa*
RESPONSE FACTORS~
XI
X3
X10
X30
CALIBRATION CHECK \ig/L'
Standard cone. ' CHLa* pg/L CHLa*
DUPLICATES
SAMPLE ID
a) M9/L CHLa*
b) jjg/L CHLa*
MEAN pg/L CHLa*
*Calculate as for a 200-mL sample
NSWS Form 32
-------
Appendix D
Revision 4
Date: 8/87
Page 20 of 21
TTEM~
NATIONAL SURFACE WATER SURVEY
FORM 33
QC RESULTS - PHYTOPIGMENTS
HPLC
RESULT*
COMMENTS
METHOD DETECTION LIMIT
Ug/L CHLa
~ug/L PHEef
BLANK
Ug/L CHLa
~M9/L PHEeT
RESPONSE FUNCTIONS
CHLa:
PHEa:
CALIBRATION CHECK
Standard cone.
Standard cone.
Standard cone.
CHLa
M9/L
"M9/L
"M9/L
Standard cone.
Standard cone.
Standard cone.
ug/L
PHEa
Standard cone. (jg/L pg/L Standard cone. pg/L pg/L
Standard cone. pg/L pg/L Standard cone. uq/L uq/L
Standard cone. pg/L pg/L Standard cone. ug/L uq/L
DUPLICATES
a)
b)
SAMPLE ID
ug/L CHLa*
Mg/L CHLa*
Ug/L PHEa*
ug/L PHEa*
MEAN :
a)
b)
SAMPLE ID
ug/L CHLa*
pg/L CHLa*
Ug/L PHEa*
Ug/L PHEa*
MEAN :
*Calculate as for a 200-mL sample
NSWS Form 33
-------
Appendix D
Revision 4
Date: 8/87
Page 21 of 21
NATIONAL SURFACE WATER SURVEY
FORM 34
QC RESULTS - PHYTOPIGMENTS
TIME LINE
RUN
NUMBER
01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
SAMPLE
(STANDARD) ID
EXTRACTION
TIME
FLUOR.
ANALYSIS
TIME
HPLC
ANALYSIS
TIME
NSWS Form 34
-------
-------
Appendix E
Revision 4
Date: 8/87
Page 1 of 22
APPENDIX E
EXAMPLES OF CALCULATIONS REQUIRED FOR
ACIDITY AND ALKALINITY DETERMINATIONS
E.1.0 HC1 STANDARDIZATION (SECTION 5.4.1)
1.00 ml of 0.01038N Na2C03, 4.00 mL of l.OM KC1, plus 36.00 mL of C02-
free deionized water are titrated with HC1 titrant. The titration data are
given below:
mL HC1 added
PH
mL HC1 added
0.00
0.100
0.200
0.300
0.400
0.500
0.600
0.700
10.23
9.83
9.70
9.54
9.28
8.65
7.20
6.71
PH
mL HC1 added
0.800
0.900
1.000
1.100
1.200
1.300
1.400
1.500
6.37
6.03
5.59
4.91
4.48
4.26
4.11
4.00
_pH
1.700
1.900
2.100
2.300
3.84
3.72
3.63
3.56
2.500
3.49
is calculated for the data sets (V, pH) that are within the pH range
4 to 7 using the equation:
'lb
= (Ve + V)
vsc
(Vs + V) \[H+]2
where
C
CH+]
Ki
initial sample volume (41.00 mL)
volume of HC1 added (mL)
4 = (N ,/(2 x 41)
= 1.266 x
= 10~PH
= 7.079 x 10
= 1.202 x 10
= 1.660 x 10
2C03
-10
The (V, Fib) values are tabulated below:
V Flb (x ID'3)
0.700
0.800
0.900
1.000
3.57
2.59
1.60
0.64
100
200
300
400
(x 10~3)
-0.34
1.
2.
3.
33
28
26
1.500
-4.23
-------
Appendix E
Revision 4
Date: 8/87
Page 2 of 22
The plot of F^t, versus V is shown in Figure E-l. The data lie on a
straight line and are analyzed by linear regression to obtain the coefficients
of the line Fib = a + bV. From the regression:
Then
and
r = 1.0000
a = 0.01038 ± 0.00001
b = -0.009747 ± 0.000012
= -a/b = 1.065 ml
NHC1 =
oCOo x v NaoCO-,
c. o c, o
(0.01038) (1.00)
1.065
= 0.009743 eq L'1
CO
o
T
x
vx
JO
uT
4
3-
2-
1-
-3-
-4-
-5-1
0.2
0.6
V
I
1.8
Figure E-l. Plot of
versus V for HC1 standardization.
-------
Appendix E
Revision 4
Date: 8/87
Page 3 of 22
E.2.0 INITIAL NaOH STANDARDIZATION WITH KHP .(SECTION 5.4.2)
5.00 ml of 9.793 x 10"4N KHP, 2.00 ml of l.OM KC1, plus 18.0 ml of C02-free
deionized water are titrated with approximately 0.01N NaOH. The titration
data and appropriate Gran function values are given below:
Volume NaOH
(ml)
0.000
0.050
0.100
0.150
0.200
0.250
0.300
0.350
0.400
0.450
0.500
0.550
0.600
0.700
0.900
1.100
1.300
The Gran function
calculated by:
F3b(x 10~3)
90
39
86
34
82
29
.14
.66
0.79
0.26
-0.25
-0.77
-1.28
-2.29
-4.40
1S calculated for data with pH 5 to 10.
'3b
(Vc + V)
vsc
2[H+]2
k(Vc + V)
V = volume NaOH added (ml)
Vs = initial sample volume (25.00,ml)
C = N|
-------
I
Appendix E
Revision 4
Date: 8/87
Page 4 of 22
F35 versus V is plotted in Figure E-2. The data lie on a straight line
with the equation F^ = a + bV. The coefficients are calculated by linear
regression. From the regression:
r = 1.0000
a = 0.004931 ± 0.000008
b = -0.01036 ± 0.00002
From this, YS and
are calculated by:
Y3 = -a/b = 0.4760 mL
x VKHP
'NaOH
= 0.01028 eq L'1
E.3.0 NaOH-HCl STANDARDIZATION CROSSCHECK (SECTION 5.4.3)
0.500 ml of 0.00921N NaOH, 2.50 ml of l.OM KC1, plus 22.0 ml of COp-free
deionized water are titrated with 0.0101N HC1 (standardized with Na2C03).
The titration data and appropriate Gran function values are given below:
Volume HC1
(mL)
0.000
0.100
0.200
0.250
0.300
0.350
0.400
0.450
0.500
0.550
0.600
0.650
0.700
0.800
(x 10"3)
2.
2.
1.
1.
.46
.15
.60
.06
0.59
0.057
-0.44
-0.93
-1.41
-1.95
-2.34
-------
Appendix E
Revision 4
Date: 8/87
Page 5 of 22
2-
1-
05
° o-
* X
u.05
"1 * '
-2-
-3-
-4-
C _
0.3
Figure E-2. Plot of
versus V for initial NaOH standardization with KHP.
-------
Appendix E
Revision 4
Date: 8/87
Page 6 of 22
The Gran function Fj_ is determined for data in the pH range 4 to 10.
is calculated by:
71 =
-------
2-
1-
-1-
-2-
_3_J
0.2
0.4
V
Appendix E
Revision 4
Date: 8/87
Page 7 of 22
0.8
Figure E-3. Plot of F^ versus V for NaOH-HCl standardization cross-check.
-------
Appendix E
Revision 4
Date: 8/87
Page 8 of 22
E.4.0 DAILY NaOH STANDARDIZATION WITH STANDARDIZED HC1 (SECTION 5.4.4)
1.000 ml of an approximately 0.01N NaOH solution, 2.50 ml of l.OM KC1, and
21.50 ml of COa-free deionized water are titrated with 0.009830N HC1. The
titration data are given below:
ml HC1 added
pH
ml HC1 added
pH
0.00
0.200
0.400
0.600
0.650
0.700
10.24
10.10
9.90
9.51
9.32
8.97
0.750
0.800
0.850
0.900
1.000
1.100
5.44
4.65
4.37
4.22
4.02
3.88
ml HC1 added
PH
1.200
1.400
3.78
3.62
FI is calculated for each data pair (V, pH) in the pH range 4 to 10 using
the equation:
(V
- CH+]
where
V
D&
The new data pairs (V,
initial sample volume (25.00 + 1.00 = 26.00 ml)
volume of HC1 added
1.660 x 10~14
IO-PH
are tabulated below:
V
0.400
0.600
0.650
0.700
0.750
0.800
A plot of FI
ilumes from Y
F1 (x 10"3)
3.35
1.38
0.89
0.40
-0.093
-0.58
versus V is shown i
- 0.40 to V = 1.10
V
0.850
0.900
1.000
1.100
n Figure E-4. The
lie on a straight 1
FJL (x 10~3)
-1.10
-1.56
-2.48
-3.44
data sets correspond!
ine with the equation
FI = a + bV.
-------
Appendix E
Revision 4
Date: 8/87
Page 9 of 22
4-1
3-
2-
1-
CD
T
X
+~*
uT
Q--/
-1-
O _
-3-
-4-1
0.4
0.7
1.2
Figure E-4. Plot of FI versus V for daily NaOH standardization.
-------
Appendix E
Revision 4
Date: 8/87
Page 10 of 22
The coefficients are obtained by linear regression. The results are:
r = 1.000
a = 0.00720 ± 0.00004
b = -0.009710 ± 0.00047
From these results:
Vx = -a/b = 0.741
and
x vx (o.oogsso) (0.741)
= " - = 0.00728
VNaOH 1-000
E.5.0 ELECTRODE CALIBRATION (SECTION 5.4.5)
This section describes the electrode calibration procedure. The tables
below (E-l and E-2) tabulate the titration data (V and pH), the calculated pH
values (pH*), and the coefficients for the line pH = a + b pH*.
TABLE E-l. ACID TITRATION
V = 50.00 mL N = 0.00983
Volume HC1 Volume HC1
(mL) _ pH pH* (mL) _ pH pH*
0.000 5.87 --- 0.450 4.05 4.06
0.025 5.25 5.31 0.500 4.00 4.02
0.050 4.97 5.01 0.600 3.92 3.94
0.100 4.68 4.71 0.800 3.80 3.81
0.150 4.51 4.54 1.000 3.71 3.72
0.200 4.38 4.41 1.200 3.64 3.64
0.250 4.29 4.31 1.500 3.55 3.55
0.300 4.22 4.24 1.700 3.50 3.50
0.350 4.15 4.17 2.000 3.43 3.43
0.400 4.10 4.11
1.00 a = 0.10 ± 0.01 b = 0.971 ± 0.002
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Appendix E
Revision 4
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Page 11 of 22
TABLE E-2. BASE TITRATION
vs -
50.0 ml
Volume NaOH
(ml)
0
0
0
0
0
0
0
V* :£
.000
.050
.200
.300
.400
.500
.600
0.99
== =-===-===== ===-================================
NNaOH = 0.00804
PH
6
8
9
9
9
9
9
a
.66
.67
.28
.34
.40
.66
.74
= 0
pH*
8
9
9
9
9
9
.08
.68 .
.29
.46
.58
.68
.76
± 0.27
Volume NaOH
(ml)
0
0
1
1
1
1
1
.820
.940
.080
.200
.300
.400
.500
pH
9.
9.
9.
10.
10.
10.
10.
87
93
99
04
07
11
13
pH*
9
9
10
10
10
10
10
.89
.95
.01
.06
.09
.12
.15
b = 0.99 ± 0.03
The data in Tables E-l and E-2 are plotted in Figure E--5. Except for two
points in the base titration (at V = 0.3 and 0.4), the data lie on a straight
line. (NOTE: the lines calculated for each titration are essentially coinci-
dent as indicated by their coefficients.) Excluding these two points, the data
are fit to the line with the equation pH = a + b pH*. The coefficients of the
line (obtained by linear regression) are:
r = 1.0000
a = -0.014 ± 0.0011
b = 0.999 ± 0.002
E-ll
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Appendfx £
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Page 12 of 22
Figure E-5. Plot of pH* versus pH for electrode calibration.
E.6.0 BLANK ANALYSIS - ANC DETERMINATION (SECTION 5.6.5)
This section describes the determination of ANC in a blank solution. The
blank is prepared by adding 4.00 mL of 0.10M NaCl to 36.00 mL of deionized
water. It is titrated with 0.00983N HC1. The titration data are given below
(both measured and calculated pH* values are included):
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Appendix E
Revision 4
Date: 8/87
Page 13 of 22
Volume HC1
(ml)
0.000
0.080
0.120
0.200
0.300
0.400
pH*
5.84
4.69
4.52
4.31
4.14
4.01
5.85
4.70
4.53
4.32
4.14
4.02
0.00192
0.00292
0.00386
Volume HC1
(ml) pH
0.500
0.600
0.700
1.000
1.200
1.500
_piH_ pH*
91
84
3.77
3.62
3.55
3.,45
91
84
3.77
3.62
3.55
3.45
0.00498
0.00587
0.00691
0.00984
0.0116
0.0147
The Gran function
'la
V) CH+]
is calculated for pH* values less than 4.5; the values are included in the
table.
Fla versus V is plotted in Figure E-6. The data are linear and fit the
line Fia = a + bV using linear regression. The resulting coefficients are:
CO
b
14-
12-
10-
8-
6-
4-
2-
| 1 1 1 1 1 I
0.2 0.4 0.6 0.8 1-0 1.2 1.4
V
Figure E-6. Plot of FI& versus V for ANC determination of blank.
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Appendix £
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Page 14 of 22
r = 0.9999
a = (-0.3 ± 5.0) x 10~5
b = 0.009777 ± 0.000061
From this:
and
ANC
-a/b = 3.07 x 10~4 mL
V1CHC1 eq
= 7.6 x 10-8
Vsa L
= 0.08 ueq L~l
This value for ANC is acceptable.
E.7.0 SAMPLE ANALYSIS
E.7.1 Titration Data (Section 5.5.)
A natural lake sample was titrated as described in Section 5.5. The
^Jr?*10" data are g1ven below- Also included are values for the calculated pH
(pH*).
Acid Titration
'sa
36.00 mL
0.00983 eq L
pH
-1
vsalt = 4.00 mL
pH*
pH
pH*
0.000
0.040
0.080
0.120
0.140
0.160
0.260
0.280
0.380
5.10
4.89
4.71
4.56
4.50
4.44
4.24
4.21
4.08
5.11
4.90
4.72
4.57
4.51
4.44
4.24
4.21
4.08
0.460
0.550
0.650
0.750
0.900
1.100
1.400
1.700
*
3.99
3.91
3.84
3.77
3.69
3.61
3.50
3.42
3.99
3.91
3.84
3.77
3.69
3.61
3.50
3.42
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Appendix E
Revision 4
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Page 15 of 22
Base Titration
Vsb =
cb = o
Vb
0.00
0.015
0.030
0.050
0.080
0.120
0.160
0.200
0.240
0.280
0.320
0.340
0.360
0.380
0.400
36.00 ml
.00702 eq I'1
PH
5.08
5.13
5.26
5.35
5.57
5.78
6.06
6.30
6.65
6.98
7.29
7.46
7.62
7.83
8.03
Vsalt = 4.00
pH*
5.09
5.14
5.27
5.36
5.58
5.79
6.07
6.31
6.66
7.00
7.31
7.48
7.64
7.85
8.05
ml
vb
0.425
0.470
0.500
0.540
0.560
0.600
0.660
0.700
0.780
0.900
1.000
1.100
1.405
1.700
2.200
2.500
PK
8.30
8.66
8.85
9.01
9.10
9.21
9.35
9.44
9.57
9.72
9.83
9.92
10.12
10.26
10.43
10.51
pH*
8.32
8.68
8.87
9.03
9.12
9.23
9.37
9.47
9.60
9.75
9.86
9.95
10.15
10.29
10.43
10.54
E.7.2 Initial Estimate of Vi (Section 5.5.4)
The Gran function FI& is calculated for each data pair from the acid
titration that has a pH* less than 4. The values are given below:
va
0.460
0.550
0.650
0.750
Fla(xl
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Appendix E
Revision 4
Date: 8/87
Page 16 of 22
Fla versus Va is plotted in Figure E-7. A regression of Fia on Va is
performed to fit the data to the line Fla = a + bV. The resulting coefficients
are:
r = 0.9999
a = -0.000241 ± 0.000051
b = 0.009496 ± 0.000050
From this, the initial estimate of YI is calculated by:
V]. = -a/b = 0.0254 ml
0.2 0.4
Va
Figure E-7. Plot of Fia versus Va for initial determination of
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Appendix E
Revision 4
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Page 17 of 22
Because YI > 0 and the initial sample pH*x 7.6, calculation procedure B
(section 5.5.4, step 3) is used to determine the ANC and BNC of the sample.
E.7.3 Initial Estimates of V?. ANC. BNC, and C (Section 5.5.4)
From the base titration data, Y£ is estimated to be 0.40 ml (the first
point with a pH* <_ 8.2). Now that initial estimates of YI and Y£ have been
obtained, estimates of ANC, BNC, and C can be calculated:
vl ca ' ' R ,
ANC = . -r-r - = 6.9 x 10"b eq l~L
vsa
V2 Cb c i
BNC = - = 7.80 x 10~b eq L'1
C = ANC + BNC = 8.49 x lO'5 eq L'1
E.7.4 Refined Estimates of VT and V? (Section 5.5.4)
The Gran function FIC (equation 5-1) is calculated for acid titration data
with volumes across the current estimate of YI. The values are given below:
va
0.000
0.040
0.080
0.120
Ff v 1 0 i
1 r* \ A A v /
-0.26
-3.23
-6.42
-9.93
Va
0.140
0.160
0.260
0.280
0.380
Flc(xlO-4)
-11.6
-13.9
-22.8
-24.4
-33.3
FIC versus Va is plotted in Figure E-8. A regression of F^ on Va is
performed. The regression results are:
r = 0.999
a = -0.000032 ± 0.00019
b = -0.00882 ± 0.0010
A new estimate of YI is:
YI = -a/b = -0.0036 ml
Next the Gran function ?2c (Equation 5-2) is calculated from data sets
from the base titration with volumes across the current estimate of Y£. The
values are given below:
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Appendix E
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Page 18 of 22
F?r(x 1CT4)
F?r(x 10"4)
0.340
0.360
0.380
0.400
1.22
0.61
-0.087
-0.78
0.425
0.470
0.500
0.540
-2.01
-4.98
-7.73
-11.1
Va
-0.04 0 0.04
J iU ' i
0.44
-35 -J
Figure E-8. Plot of FIC versus Va for Vi determinati
on.
F2C versus Vb is plotted in Figure E-9. A regression of F2c on Vh is
performed. (NOTE: data with Vb > 0.4 are not used in the regression.) The
regression results are:
r = 0.999
a = 0.00126 ± 0.00003
b = -0.003348 ± 0.000073
A new estimate of Y2 is:
V2 = -a/b = 0.376 ml
1
E.7.5 New Estimates of ANC, BNC, and C (Section 5.5.4)
From the new estimates of Y! and V2, new estimates of ANC, BNC, and C are
calculated:
-------
I
o
1
X
\^f
o
Appendix E
Revision 4
Date: 8/87
Page 19 of 22
0.70
Figure E-9. Plot of F£C versus V^ for V2 determination.
ANC* - = o.99 x 10'6 eq L'1
Vsa
V2 Cb
BNC* = = 7.36 x ID'5 eq L'1
Vsb
C* = ANC + BNC = 7.45 x 10~5 eq L'1
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Appendix E
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Page 20 of 22
£7.6 Comparison of Latest Two Estimates of Total Carbonate (Section 5.5.4)
= 0.065 > 0.001
Because C and C* do not agree, a new C is calculated from their average:
C(new) = (C + C*)/2 = 7.97 x 1Q-5 eq i'l
The calculations in Sections E.7.4 through E.7.6 are repeated until
successive iterations yield total carbonate values which meet the criteria
given above. The results from each iteration (including those already shown)
are given below. Note that all decimal values used are not shown.
Iteration V1(mL)
1
2
3
4
5
6
7
8
9
10
0.0254
0.0036
0.0022
0.0014
0.0010
0.0008
0.0007
0.0006
0.0006
0.0005
V2(mL)
0.400
0.377
0.376
0.376
0.375
0.375
0.375
0.375
0.375
0.375
ANC
(ueq L'1)
6.9
0.99
0.60
0.40
0.28
0.22
0.18
0.16
0.15
0.15
BNC
(ueq L'1)
78.0
73.6
73.4
73.3
73.2
73.2
73.1
73.1
73.1.
73.1
c
(ueq L J
84.9
74.5
74.0
73.7
73.5
73.4
73.3
73.3
73.3
73.3
C - C*
) C + C*
0.065
0.037
0.021
0.012
0.007
0.004
0.002
0.001
0.0006
New C
(ueq L'1)
79.7
76.8
75.2
74.4
73.9
73.6
73.4
73.4
73.3
uo,,o r- The,f1nal values for ANC and BNC are reported in a format similar to
NSWS Form 11 (see Appendix D).
E.8.0 QUALITY CONTROL CALCULATIONS
Examples of the quality control calculations are described in this
section.
£8.1 Comparison of Calculated ANC and Measured ANC (Section 5.6.5)
For the sample analyzed in Section E.7.0, the following data were obtained:
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Appendix E
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Page 21 of 22
Initial pH = 5.09
Dissolved Inorganic
Carbon (DIG) = 59 mg L"1
Air-equilibrated pH = 5.06
Air-equilibrated DIG = 0.36
From these data, the calculated ANC values are computed using the equation:
DIG [H+]K1 + 2 ^2
[ANC]. (peq I.1) =
12,011 UH+]2
Kw
- [H+]
x 105
The results are:
[ANC]
cl
= -4.2
-1
[ANC]C2 = -6.4 ueq L
-1
Then
|[ANC]C1 - [ANC]C2| = 2.2 ueq L"1 < 15 |jeq L'
Because [ANC]ci and [ANC]Q2 are in agreement, their average value is used
for comparison to the measured value:
[ANC]c_avg = -5.3 Meq L"1 ANC = 0.15 Meq L"1
D = |ANCC - ANCj = 5.4 Meq L"1 < 15 Meq L"1
The calculated and measured ANC values agree, which backs up the assump-
tion of a carbonate system.
E.8.2 Comparison of Calculated and Measured BNC (Section 5.6.3)
For the sample analyzed in Section E.7.0, the following data were
obtained:
Initial pH = 5.09
DIG = 0.59 mg L'1
BNC = 73.1
From these data, the BNC is computed using the equation:
DIC / [H+]2 - KiK9
[BNC]C (Meq L'1) =
The result is:
12,011
[BNC]r = 53.3 Meq L"1
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Appendix E
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Page 22 of 22
This value is compared to the measured value:
D = [BNC]C - BNC = -19.8 ueq L'1 < -10 ueq L"1
This value of D is indicative of other protolytes in the system which are
contributing to the measured BNC. This might be expected because the sample
also contains 3.2 mg L'1 dissolved inorganic carbon (DOC).
E.8.3 Comparison of Calculated Total Carbonate and Measured Total Carbonate
(Section 5.6.4) ~~~ ~~
For the sample analyzed in Section E.7.0, the following data were obtained:
ANC = 0.15 ueq L'1 = 0.15 umole \_~l
[ANC]c_avg = -5.3 ueq L'1 = -5.3 umole L"1
BNC = 73.1 ueq L'1 = 73.1 umole L-I
[BNC]C = 53.3 ueq L'1 = 53.3 umole L'1
From the DIC value, the total carbonate is calculated:
Cc - [ANC]c_avg + [BNC]c_avg = 48.0 umole L"1
This calculated value is then compared to the measured value:
D = Cc - (ANC + BNC) = -25.2 umole L'1 < -10 umole L'1
This value of D is indicative of other protolytes in the system. This
might be expected because the sample also contains 3.2 mg L~l DOC. Notice that
the same conclusion was reached in the BNC comparison.
In general, noncarbonate protolytes are significant (i.e., contribute
significantly to the total protolyte concentration), when indicated by one (or
both) of the individual comparisons (ANC and BNC comparisons) and by the total
carbonate comparison.
-------
Appendix F
Revision 4
Date: 8/87
Page 1 of 1
APPENDIX F
THE PHOTOIONIZATION DETECTOR FOR USE AS A METHYL ISOEIUTYL KETONE
DETECTION SYSTEM
NOTE: These procedures are specific to the AID photoiorn'zation detector
installed in the NSWS mobile laboratories. These procedures can be modified
for use with other photoionization detectors.
The AID photoionization detector should be used as a danger-level alert
system for MIBK. This detector was field tested during the MSWS and was found
to be useful in alerting laboratory personnel to the presence of potentially
hazardous levels of MIBK in the work area. The full instructions for calibra-
tion are included with the detector, but an alternative weekly method is
described below. The instrument should be calibrated to emit its warning
signal at 25 ppm. MIBK odor is noticeable at levels much below 25 ppm.
The detector should be calibrated outside the laboratory and should be
plugged into an AC outlet using the supplied adapter. Batteries may be used,
but should be fully charged prior to use. Obtain a polyethylene bag and flush
with standard MIBK gas. Empty the bag outside and refill with standard MIBK
gas. The exact concentration of MIBK in the gas is shown on the certification
tag attached to the tank. Turn on the meter and allow reading to stabilize
with the inlet tube in the open air. Be sure that no higher than normal levels
of organic vapors are present and adjust the reading to zero using a small
screwdriver to turn the zero set screw on the rear of the meter.
Place the detector inlet tube into the bag filled with MIBK standard gas
and turn on meter. Adjust the meter reading to the value which is recorded on
the tank certification tag by turning the "SENS CAL" knob (bottom front). Be
sure the reading has stabilized. Remove the tube from the bag and be sure the
meter reading returns to near zero. Set the alarm level by adjusting the ppm
set knob (top front) to 25 ppm on the scale of the knob. The meter reading
should not change. Test the sensitivity by placing the inlet tube in the bag.
Place the calibrated instrument on the shelf near the clean workstation
with the inlet tube placed near the sash opening. Record the calibration
information in the MIBK logbook. If the ambient air level exceeds 25 ppm at
the inlet site, the alarm will sound, warning personnel to put on respirator
masks. If the indicator meter exceeds 50 ppm, the laboratory should be evacu-
ated until the level drops to an acceptable limit. For specific questions
concerning proper operation procedures, consult the instrument manufacturer's
manual.
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Appendix G
Revision 10
Date: 8/87
Page 1 of 10
APPENDIX G
INTERNAL QUALITY CONTROL REQUIREMENTS
Quality control (QC) is an integral part of sample analysis. QC
requirements common to all analytical methods are detailed in this section.
QC requirements specific to a single method are detailed in the section for
that method.
G.I METHOD QUALITY CONTROL
Each method contains specific QC steps which should be performed to ensure
data quality. Table G-l is a brief summary of the required QC checks as well
as control limits and corrective actions for QC checks outside control limits.
QC steps common to all (or most) of the methods are detailed in Sections 6.1.1
through G.I.4, while QC steps specific to a single method are detailed in the
method section.
6.1.1 Calibration Verification QC Check Sample
After performing the calibration step for a method, verify the calibration
(to ensure proper standard preparation) prior to sample analysis by analyzing a
calibration QC check sample (QCCS). The QCCS is a known sample containing the
analyte of interest at a concentration in the low- to mid-calibration range.
Furthermore, the QCCS should be prepared from an independent source of that
used for preparation of the calibration standards.
For each batch of samples, analyze the calibration QCCS immediately after
calibration, after every 10 sample analyses or at intervals determined by the
quality assurance program, and after the final sample analysis. Plot the
measured analyte concentration of the QCCS on a control chart and develop the 95
percent and 99 percent confidence intervals. The 99 percent confidence interval
should be within the limits given in Table G-2. (The limits in Table G-2 may
be used as initial limits until enough data are obtained to generate a control
chart.) If the 99 percent confidence interval is not within those limits, a
problem exists with the experimental technique or with the QCCS itself.
The measured analyte concentration in the QCCS should be within the 99
percent confidence interval. An acceptable result should be obtained prior to
continuing sample determinations. If unacceptable results are obtained, repeat
the calibration step and reanalyze all samples analyzed since the last
acceptably analyzed QCCS.
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Appendix G
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Page 2 of 10
TABLE G-l. SUMMARY OF INTERNAL METHOD QUALITY CONTROL CHECKS
Parameter or Method
Quality Control Check
Control Limits
Corrective' Action4
Acidity.
Alkalinity, pll
1. Tltrant standardization cross- 1. Relative difference <5%.
check.
2. Electrode calibration (Hernstian 2. Slope = 1.00 ± 0.05.
response check).
3. pH QCCSb (pH 4 and 10) analysis. 3. pH 4 « 4.00 ± 0.05.
pH 10 = 10.00 ± 0.05.
4. Blank analysis (salt spike). 4. |Blank| £10 ueq L"1.
5. Duplicate analysis. 5. SRSDC <10i.
1. Restandardize tltrants.
2. Recalibrate or replace
electrode.
3. Recalibrate electrode.
6. Protolyte comparison.
4. Prepare fresh spike
solution.
_ 5. Refine analytical
technique. Analyze
another duplicate.
6. See method (Section 5). 6. See method (Section 5).
Ions (cr.F". HH4*. la.
H03-. S04-ZI.
Metals (Al, Ca. Fe,
K. Kg, Hn. b.
Ha).
Sdici. Total Phos-
phorus, Dissolved 2a.
Inorganic Carbon
(D1C). Dissolved
Organic Carbon b.
(DOC)
Specific Conductance
3.
Initial QCCSb analysis
(calibration and verification).
Continuing QCCS° analysis
(every 10 samples).
Detection limit (DL) determina-
tion (weekly).
OL QCCSb analysis (daily, metals
and total P only).
Blank analysis.
la.b. The lesser of the 991
confidence interval
or value given in
1n Table G-2.
2a.
DL < values in
method.
b. XRecovery = 100 ±20Z.
3a. Blank £2 x DL (except
sp. cond.).
b. Blank £0.9 pS cm"1
(sp. cond. only).
4. Duplicate analysis.
4. Duplicate precision URSD)
<_ values given in Method.
5. Matrix spike (except total ext. 5. %Recovery = 100 ± 151.
Al, DIC, and sp. cond.).
6. Resolution test (ion chroma-
tography only).
6. Resolution >60l.
la. Prepare new standard
and recalibrate.
b. Recalibrate. Reanalyze
associated samples.
2a,b. Optimize instru-
mentation and
technique.
3a,b. Determine and eliminate
contamination source.
Prepare fresh blank
solution. Reanalyz
associated samples.
4. Investigate and eliminate
source of imprecision.
Analyze another duplicate.
5. Analyze 2 additional
spikes. If one or both
outside control limits,
analyze sample batch
by method of standard
additions.
6. Clean or replace separator
column. Recalibrate.
*Assuaing QC check is outside control limits.
"QCCS Quality control check sample.
CIRSO percent relative standard deviation.
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Appendix G
Revision 10
Date: 8/87
Page 3 of 10
TABLE G-2. MAXIMUM CONTROL LIMITS FOR QUALITY CONTROL SAMPLES
Maximum Control Limit for QC Sample (% Deviation from
Parameter Theoretical Concentration of QC Sample)
Al, total extractable ±20%
Al, total ±20%
Ca ±5%
Cl~ ±5%
Dissolved Inorganic Carbon ±10%
Dissolved Organic Carbon ±10%
F~, total ±5%
Fe ±10%
K ±5%
Mg ±5%
Mn ±10%
Na ±5%
NH4+ ±10%
NOo" ±10%
«J
P, total ±20%
Si02 ±5%
S04~2 ±5%
Specific conductance ±2%
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Appendix G
Revision 10
Date: 8/87
Page 4 of 10
G.I.2 Detection Limit Determination and Verification
Determine the detection limit weekly for all parameters (except pH, alka-
linity, acidity, and specific conductance for which the term detection limit
does not apply). The detection limit is defined as three times the standard
deviation of 10 nonconsecutive reagent or calibration blank analyses. In the
case where a signal is not obtained for a blank analysis (such as in ion
chromatographic analyses or autoanalyzer analyses), a low-concentration stan-
dard (concentration about three to four times the detection limit) is analyzed
rather than a blank. Detection limits should not exceed the values listed in
Table G-3. If a detection limit is not met, refine the analytical technique
and optimize any instrumentation variables until the detection limit is
achieved.
To verify the detection limit for the determination of metals, PCV-reactive
aluminum, and total P, daily, analyze a detection limit QCCS after calibration
and prior to sample analysis. The detection limit QCCS should contain the
analyte of interest at two to three times the detection limit. The measured
concentration should be within 20 percent of the true concentration. If it is
not, the detection limit is questionable. Determine the detection limit as
described above.
G.I.3 Blank Analysis
Once per batch analyze a calibration blank as a sample. The calibration
blank is defined as a "0" mg L"1 standard (contains only the matrix of the cali-
bration standards). The measured concentration of the calibration blank should
be less than twice the instrumental detection limit. If not, the blank is
contaminated or the calibration is in error at the low end. Prior to sample
analysis, investigate and eliminate any contamination source and repeat the
calibration.
Prepare and analyze a reagent blank for the three methods which require
sample preparation (dissolved SiO£, total P, and total Al). A reagent blank
contains all the reagents (in the same quantities) used in preparing a real
sample for analysis. Process in the same manner (digestions) as a real sample.
The measured concentration of the reagent blank should be less than twice the
required detection limit (Table G-3). If it is not, the reagent blank is con-
taminated. Investigate and eliminate the contamination source. Prepare and
analyze a new reagent blank and apply the same criteria. Reanalyze'all samples
associated with the contaminated blank after the contamination is eliminated.
Contact the laboratory supervisor or QA manager if a contaminated reagent blank
problem cannot be rectified.
Prepare one reagent blank with each set of samples processed at one time.
For example, if two sample batches are processed together, only one reagent
blank is necessary. Report the concentration of the single reagent blank for
both batches. On the other hand, if a sample batch is split into groups that
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TABLE G-3. REQUIRED MINIMUM ANALYTICAL DETECTION LIMITS, EXPECTED RANGES,
AND INTRALABORATORY RELATIVE PRECISION
Parameter3
Acidity
Alkalinity
Al , Total Extractable
Al, PCV-reactive
Al, Total
Ca
Cl~
DIC
DOC
F~, Total
Fe
K
Mg
Mn
Na
NH4+
N03
P, Total
pH, Processing
Laboratory
pH, Laboratory
sto2
so4~2
Specific Conductance
True Color
Turbidity
Units
ueq L-l
ueq L"1
mg L"1
mg L"1
mg L"1
mg L"1
mg L-1
mg L~j
mg L -1
mg L-l
mg L~j
mg L 1
mg L j-
mg L"1
mg L~|
mg L |
mg L"1
mg L~l
pH units
pH units
mg L"1
mg L'1
pS cm"1
PCUe
NTUf
Require
Detectio
Limit
_
-
0.005
0.007
0.005
0.01
0.01
0.05
0.1
0.005
0.01
0.01
0.01
0.01
0.01
0.01
0.005
0.002
-
-
0.05
0.05
d
0
2
d
n Expected
Range
10-150
-100-1000
0.005-1.0
0.000-5.0
0.005-1.0
0.5-20
0.2-10
0.05-15
0.1-50
0.01-0.2
0.01-5
0.1-1
0.1-7
0.01-5
0.5-7
0.01-2
0.01-5
0.005-0.07
3-8
3-8
2-25
1-20
5-1000
0-200
2-15
Relative
Intral ababoratory
Precision Goal (%)b
10
10
10(A1>0.01),20(A1<0
10(A1>0.01),20(A1<0
10(A1>0.01),20(A1<0
5
5
10
5(DOO5),10(DOC<5)
5
10
5 . - -
5
10
5
5
10
. 10(P>0.01),20(P<0.0
±0.1C
±0.05C
5
5
1
±5C
10 ,
.01)
.01)
.01)
1)
aDissolved ions and metals are being determined, except where noted.
^Unless otherwise noted, this is the relative precision at concentrations
above 10 times instrumental detection limits.
GAbsolute precision goal is in terms of applicable units.
dBlank should be <0.9 uS cm"1
ePCU = platinum-cobalt units.
= nephelometer turbidity units.
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are processed at different times, a reagent blank is necessary for each group.
In this case, report all reagent blank values for the batch.
G.I.4 Duplicate Sample Analysis
Prepare and analyze one sample per batch in duplicate. If possible,
choose a sample for duplicate analysis containing analyte at a concentration
greater than five times the detection limit. Calculate the percent relative
standard deviation (%RSD) between duplicates. The duplicate precision URSD)
should not exceed the value given in Table G-3. If duplicate %RSD values fall
outside the values given in Table G-3, a problem exists (such as instrument
malfunction, calibration drift). After finding and resolving the problem,
analyze a second sample in duplicate. Acceptable duplicate sample results
should be obtained prior to continuing sample analysis.
% RSD =
x 100
x
S =
Z(x - x)2\ 1/2
n-1
G.I.5 Matrix Spike Analysis
Prepare one matrix spike with each batch by spiking a portion of a sample
with a known quantity of analyte. The spike concentration should be the larger
of two times the endogenous level or ten times the required detection limit.
Also, the volume of the spike added should be negligible (less than or equal to
0.001 of the sample aliquot volume). Calculate the percent recovery of the
spike as follows:
% spike recovery =
/ measured
/concentration
I of sample
\ plus spike
measured \
concentration!
of unspiked I
sample /
(actual concentration of spike added)
x 100
The spike recovery should be 100 ± 15 percent. If the recovery is not
acceptable, spike and analyze two additional, different samples. If either
recovery is unacceptable, analyze the entire batch by the method of standard
additions. The method of standard addition involves analyzing the sample,
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the sample plus a spike at about the endogenous level, and the sample plus a
spike at about twice the endogenous level.
NOTE: Matrix spikes for graphite furnace atomic absorption spectro-
scopy (6FAA) analyses may not be added directly in the furnace.
The concentration of the matrix spike should not exceed the
instrument linear dynamic range. For this reason, the matrix
spike concentration for furnace analyses should be chosen
judiciously and may be different than suggested above.
Similarly, care should be taken to avoid exceeding the linear
range when performing standard additions for GFAA analyses.
The samples may be diluted and the spike levels may be adjusted
so that the linear range is not exceeded.
G.2 OVERALL INTERNAL QUALITY CONTROL
Once each parameter in a sample has been determined, two procedures exist
for checking the correctness of analyses. These procedures are outlined in
Sections G.2.1 and G.2.2.
G.2.1 Anion-Cation Balance
Theoretically, the acid neutralizing capacity (ANC) of a sample equals the
difference between the concentration (eq L~l) of cations and the anions in a
sample (Kramer, 1982). In practice, this is rarely true due to analytical
variability and to ions that are present but not measured. For each sample,
calculate the percent ion difference (%ID) as follows:
ANC + z anions - Z cations
% Ion Difference = x 100
TI
TI (Total ion strength) = £ anions + X cations + ANC + 2[H+]
X anions = [Cl~] + [F~] + [N03~] + [S04~2]
Z cations = [Na+] + [K+3 + [Ca+2] + [Mg+2] + [NH4+]
ANC = [ALK]
[H+3 = (10-PH) x 106 ueq L-*
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All concentrations are expressed as microequivalents per liter (ueq L'1).
Table G-4 lists factors for converting mg L~l to ueq L~l for each of the
parameters.
The %ID should not exceed the limits given in Table 6-5. An unacceptable
value for %ID indicates the presence of unmeasured ions or an analytical error
in the sample analysis. For the surface waters sampled, the ions included in
the %ID calculation are expected to account for 90 to 100 percent of the ions
in a sample. Note that the ANC term in the calculation accounts for protolyte
ions that are not specifically determined (such as organic acids and bases).
Examine the data from samples that do not meet the %ID criteria for possi-
ble causes of unacceptable %ID. Often, the cause is improper data reporting
(misplaced decimal point, incorrect data reduction, switched sample identifi-
cations). After examining the data, redetermine any parameter that is suspect.
If an explanation for the poor %ID cannot be found and the problem cannot be
corrected, contact the laboratory supervisor or QA manager for further guidance,
TABLE G-4. FACTORS TO CONVERT mg L"1 TO ueq L~l
Factor
Ion (ueq L~l per mg/L~l)
Ca+2
cr
F~
K+
Mg+2
Na+
^NH4+
N03-
SOA"2
49.9
28.2
52.6
25.6
82.3
43.5
55.4 ;
16.1
20.8
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TABLE G-5. CHEMICAL REANALYSIS CRITERIA
A. Anion-Cation Balance
Maximum
Total Ion Strength (ueq L"1) % Ion Difference5
<50 .. 60
>;50<100 30
>100 15
B.. Specific Conductance
..'.- Maximum
Measured Conductance (uS cm"1) % Conductance Difference5
<5 50
>_5<30 , 30
>30 20
alf the absolute value of the percent difference exceeds these values,
the sample should be reanalyzed. When reanalysis is indicated, the data
for each parameter are examined for possible analytical error. Any
suspect results are then redetermined and the above percent differences
are recalculated (Peden, 1981). If the differences are still unaccept-
able or no suspect data are identified, the laboratory supervisor or QA
manager should be contacted for guidance.
G.2.2 Conductivity Balance
Estimate the specific conductance of a sample by summing the equivalent
conductances for each measured ion. Calculate the equivalent conductance for
each ion by multiplying the ion concentration by the appropriate factor in
Table G-4 (only major ions are included in the calculation). Calculate the
percent conductance difference (%CD) as follows:
calculated cond. - measured cond.
% Conductance Difference = ; : x 100
measured conductance
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The %CD should not exceed the limits listed in Table G-5. As with the
calculation, an unacceptable value for %CD indicates either the presence
of unmeasured ions or an analytical error in the sample analysis. For the
surface waters sampled, the ions included in the %CD calculation are expected
to account for 90 to 100 percent of the ions in a sample. However, in contrast
to the %ID calculation, there is no term in the %CD calculation to account for
protolytes not specifically determined.
Examine the data from samples that do not meet the %CD criteria for
possible causes of the unacceptable %CD, such as improper data reporting or
analysis. The presence or absence of unmeasured protolytes can be tested by
the procedures described in Section 5. Note that the absence of unmeasured
protolytes is positive evidence that the %CD exceeds the maximum difference due
to analytical error. Redetermine any parameter that is identified as suspect.
If an explanation for the poor %CD cannot be found and the problem cannot be
corrected, contact the laboratory supervisor or QA manager for further guidance.
G.3 DATA REPORTING
Record the results from each method on the proper data form (blank NSWS
data forms are included in Appendix D). Report results to the number of
decimal places in the actual detection limit. However, report no more than
four significant figures. Sample results from reanalyzed samples or from
standard additions should be annotated. After the forms are completed, the
laboratory supervisor should sign them, indicating he has reviewed the data and
that the samples were analyzed in accordance with the method protocol.
G-4 References
Kramer, J. R., 1982. Alkalinity and Acidity. lr± R. A. Minear, L. H.
Keith (eds.), Water Analysis. Vol. 1. Inorganic Species, Part 1.
Academic Press, Orlando, Florida.
Peden, M. E., 1981. Sampling, Analytical, and Quality Assurance Protocols
for the National Atmospheric Deposition Program. Paper presented at
October 1981 ASTM D-22 Symposium and Workshop on Sampling and Analysis
of Rain. ASTM, Philadelphia, Pennsylvania.
frU.S. GOVERNMENT PRINTING OFFICE: 1987-516-002/80505
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