Federal Water Pollution Control Administration
Division of Water Quality Research
Analytical Quality Control Laboratory
Cincinnati, Ohio
FWPCA METHODS FOR CHEMICAL ANALYSIS
OF
WATER AND WASTES
NOVEMBER, 1969
U.S. DEPARTMENT OF THE INTERIOR
-------
FWPCA METHODS FOR CHEMICAL ANALYSIS
OF WATER AND WASTES
NOVEMBER 1969
U.S. DEPARTMENT OF THE INTERIOR
FEDERAL WATER POLLUTION CONTROL ADMINISTRATION
DIVISION OF WATER QUALITY RESEARCH
ANALYTICAL QUALITY CONTROL LABORATORY
1014 BROADWAY
CINCINNATI, OHIO
-------
PREFACE
This manual describes the analytical procedures selected for use
in FWPCA laboratories for the chemical analysis of water and waste
samples. The methods were chosen by a committee of senior chemists
from within the Administration, using Standard Methods for the
Examination of Water and Wastewater, 12th Edition (1965) and ASTM
Standards, Part 23, Water; Atmospheric Analysis (1968) as basic
references. Where acceptable methods were not available from these
sources, detailed descriptions of suitable procedures are included
in this manual.
In order to provide reliable water quality and waste constituent
data for use by FWPCA, these procedures will be used in all
Administration laboratories except under very unusual circumstances.
Other agencies and individuals are encouraged to use these methods,
in the interest of uniformity throughout the water pollution control
effort.
5avid G. Stephan
Assistant Commissioner
Research £ Development
Allan Hirsch
Acting Assistant Commissioner
Office of Operations
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INTRODUCTION
This 1969 edition of "FWPCA Methods for Chemical Analysis of Water and
Wastes" describes chemical analytical procedures to be used in FWPCA
laboratories. The methods were selected by a team of senior scientists
within FWPCA based on the following criteria:
(1) The method should measure the desired constituent with precision
and accuracy sufficient to meet the data needs of FWPCA, in the
presence of the interferences normally encountered in polluted
waters.
(2) The procedures should utilize the equipment and skills normally
available in the typical water pollution control laboratory.
(3) The selected methods are in use in many laboratories or have been
sufficiently tested to establish their validity.
(4) The methods should be sufficiently rapid to permit routine use for
the examination of a large number of samples.
Except where noted under "Scope and Application" for each constituent,
the methods are useful for the measurement of the indicated constituent
in both water and wastewaters and in both saline and fresh water samples,
Table I lists the parameter to be measured, the basis of the analytical
method, the reference volume which contains a detailed description of
the procedure, and the STORET number to be used in recording the final
result. The reader should note that most of the detailed analytical
procedures found in this manual will ultimately appear in Standard
Methods for the Examination of Water and Wastewater, 13th Edition',
and/or ASTM Standards, Part 23. A majority of the procedures have been
111
-------
accepted for future publication and adoption by these organizations or
are under consideration by the appropriate subcommittees.
The 1969 edition contains a number of procedures not included in pre-
vious publications of FWPCA methods. In particular, procedures are
included for the use of the AutoAnalyzer for the determination of alka-
linity, chloride, fluoride, hardness, Kjeldahl nitrogen, ammonia nitrogen,
nitrate nitrogen, phosphorus, and sulfate. In certain cases two pro-
cedures are offered, since definitive data are not presently available
to indicate a choice. Detailed instructions are also given for the
measurement of metals by atomic absorption spectroscopy. The dissolved
oxygen probe and the fluoride specific ion electrode are included as
alternative methods.
Certain changes in recommended FWPCA methods have been made, notably
(a) the use of the pyridine pyrazalone method for the determination of
cyanide replacing the benzidine pyridine method; (b) the use of glass
fiber filters instead of membrane filters in the determination of sus-
pended solids; and (c) a drying temperature of 180°C in place of the
previously recommended 105°C for dissolved solids measurement.
Specific instructions for the handling and preservation of samples
cannot be given because of the wide variability in types of samples
and local sampling situations. However, certain general principles
should be followed. Wherever possible, the sampling program should
be designed to provide for the shortest possible interval between
sample collection and analysis. Positive steps should be taken to
IV
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maintain both the concentration and the physical state of the consti-
tuents to be measured. Where both total and dissolved concentrations
are to be determined, the dissolved concentration is the amount present
after filtration through a 0.45 micron membrane filter. When the dis-
solved concentration is to be determined, filtration should be carried
out as soon as possible after collection of the sample, preferably in
the field. Where field filtration is not practical, the sample should
be filtered as soon as it is received in the laboratory.
In situations where the interval between sample collection and analysis
is long enough to produce significant changes in either the concen-
tration or the physical state of the constituent to be measured, the
preservatives listed in Table II are recommended.
Although every effort has been made to select methods which are appli-
cable to the widest range of sample types, circumstances may require
that alternative procedures be used in place of the methods recommended
herein. In these situations, the analyst is urged to define the nature
of the interference with the FWPCA method and bring this information to
the attention of the Analytical Quality Control Laboratory through the
appropriate Regional AQC Coordinator. The analyst should also suggest
alternative procedures which have been found to be superior for this
kind of sample condition. In this manner, any weaknesses in the selected
methods and the preferable alternatives can be called to the attention
of all laboratories utilizing the FWPCA methods.
-------
The methods described herein were selected with the assistance of the
following Regional Analytical Quality Control Coordinators:
Richard T. Dewling
AQC Coordinator
Hudson-Delaware Basins Office
Northeast Region, FWPCA
Edison, New Jersey 08817
Kenneth R. Tinsley
AQC Coordinator
Middle Atlantic Region, FWPCA
918 Emmet Street
Charlottesville, Virginia 22901
William T. Donaldson
AQC Coordinator
Southeast Water Laboratory
Southeast Region, FWPCA
College Station Road
Athens, Georgia 30601
Jacob D. Dumelle
ATTN: LeRoy E. Scarce
AQC Coordinator
Great Lakes Region, FWPCA
1819 West Pershing Road
Chicago, Illinois 60605
Theodore 0. Meiggs
AQC Coordinator
Missouri Basin Region Laboratory
Missouri Basin Region, FWPCA
7300 Rochester Road, Box 4963
Kansas City, Missouri 64120
Robert E. Crowe
AQC Coordinator
Kerr Water Research Center
South Central Region, FWPCA
P. 0. Box 1198
Ada, Oklahoma 74820
Daniel F. Krawczyk
AQC Coordinator
Pacific Northwest Water Laboratory
Northwest Region, FWPCA
200 South 35th Street
Corvallis, Oregon 97330
John C. Merrell, Jr.
AQC Coordinator
Southwest Region, FWPCA
Phelan Bldg., 760 Market Street
San Francisco, California 94102
Robert L. Booth
AQC Coordinator
Analytical Quality Control Laboratory
Ohio Basin Region, FWPCA
1014 Broadway
Cincinnati, Ohio 45202
VI
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FWPCA METHODS FOR CHEMICAL ANALYSIS
OF WATER AND WASTES
JULY, 1969
TABLE I
Parameter
Acidity, Total (mg/1 as CaCO_)
Alkalinity, Total (mg/1 as CaCO )
Aluminum, Total (yg/1
, Dissolved (yg/1)
Arsenic, Inorganic (yg/1)
Biochemical Oxygen Demand,
5 day mg/1)
Cadmium, Total (yg/1)
, Dissolved (yg/1)
Calcium, Total (mg/1)
Chemical Oxygen Demand (mg/1)
Low Level (mg/1)
Saline Waters (mg/1)
Storet
Number
00435
00410
01105
01000
00310
01025
00915
00340
00335
00340
Method
Electrometric titration - pH 8.3
Electrometric titration - pH 4.5
Technicon - Methyl Orange
Atomic Absorption
Filtration through 0.45y MF
Silver diethyldithiocarbomate
Winkler-azide or DO analyzer
Atomic Absorption
Filtration through 0.45y MF
Atomic Absorption
Dichromate reflux - 0.25N
- 0.025N
- Chloride, correction
Referenc
Std. Meth.
12th Ed.
(1965)
This Ma
This Ma
This Ma
p. 56-57
This Ma
This Ma
This Ma
p. 510-514
This Ma
This Ma
es to be Used
ASTM Stds.
Part 23
(1968)
lual
p. 155
lual
mal
lual
lual
lual
p. 244
lual
mal
uses
*
*
*
*
*
*
:(See USGS Reference, last page of index)
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FWPCA METHODS FOR CHEMICAL ANALYSIS
OF WATER AND WASTES
Parameter
Chloride (mg/1)
Chlorine Demand,
15 min. (mg/1)
1 hr. (mg/1)
2 hr. (mg/1)
24 hr. (mg/1)
Chlorine Residual (mg/1)
Chromium, Total (yg/1)
, Dissolved (pg/1)
Color, Units
Copper, Total (yg/1)
, Dissolved (yg/1)
Cyanide (mg/1)
Storet
Number Method
00940
00365
00370
00375
00380
50060
01030
00080
01040
00720
Mercuric nitrate titration
Technicon - Ferricyanide
Amperometric titration
Amperometric titration
Atomic Absorption
Filtration through 0.45y MF
Platinum-cobalt visual
Atomic Absorption
Filtration through 0.45y MF
Silver nitrate titration or pyridine-
pyrazalone
Referei
Std. Meth.
12th Ed.
(1965)
p. 87-90
This M;
p. 381-383
p. 378
This M;
This M;
This M;
This M;
ices to be Used
ASTM Stds.
Part 23
(1968)
p. 24
nual
nual
nual
nual
nual
uses
*
*
*
*
*
:(See USGS Reference, last page of index)
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FWPCA METHODS FOR CHEMICAL ANALYSIS
OF WATER AND WASTES
CO
Parameter
[ f
I References to be Used
Std* Meth.
Storet i 12th Ed.
Number Method (1965)
ASTM Stds.
i
Dissolved Oxygen
Fluoride (mg/1)
(mg/1) 00300 ; Winkler-azide or DO analyzer i This
00950 ; SPADNS, with distillation i p. 144-146
1 Technicon - complexone This
Probe i This
Hardness, 1 ;
Total, (mg/1 as CaCO ) 00900 j EDTA titration p. 147-152
j Technicon - E.B.T. This
Iron, Total (yg/1)
, Dissolved (yg/1) 01046
Lead, Total (yg/1)
, Dissolved (yg/1)
Magnesium, Total
(mg/1)
Manganese, Total (yg/1)
, Dissolved (yg/1)
01049
00925
01055
Calculation - Ca + Mg by atomic absorption j This
Atomic Absorption '.
Filtration through 0.45y MF i This
Atomic Absorption
Filtration through 0.45y MF This
Atomic Absorption This
Atomic Absorption
Filtration through 0.45 MF This
M
Part 23 '•
(1968)
uses
mual
1
p. 212-217 [
Manual ;
Manual
Manual
Manual
j
Manual
M
M
M
mual
mual
mual
*
*
*
*
*
*
r(See USGS Reference, last page of index)
-------
FWPCA METHODS FOR CHEMICAL ANALYSIS
OF WATER AND WASTES
Parameter
References to be Used
Storet
Number
Method
jStd. Meth. ASTM Stds..
j 12th Ed. ; Part 23
I (1965) j (1968) USGS
MBAS (mg/1)
38260 Methylene Blue
p. 297-299
Nitrogen, Ammonia (mg/1)
00610 Distillation (pH 9.5) - Nesslerization
Technicon - sodium phenolate
This Manual
This Manual
i
Nitrogen, Kjeldahl, Total (mg/1)
00625 Digestion - distillation
Technicon - digestion + phenolate
This Manual
This M4nual
Nitrogen, Nitrate (mg/1)
00620 I Brucine sulfate
j Technicon - hydrazine reduction
This Manual
This Manual
Nitrogen, Nitrate - Nitrite (mg/1)
Technicon - cadmium reduction
This M
nual
Nitrogen, Nitrite (mg/1)
00615
Diazotization
Technicon - diazotization
This Mdnual
This M; nual
Nitrogen, Organic + Ammonia (mg/1)
00635
Technicon - digestion + phenolate
This Mi
nual
Oil § Grease (mg/1)
00550
Hexane soxhlet extraction
This M;
nual
'(See USGS Reference, last page of index)
-------
FWPCA METHODS FOR CHEMICAL ANALYSIS
OF WATER AND WASTES
Parameter
Organic Carbon, Total (mg/1)
, Dissolved (mg/1)
pH (units)
Phenolics (mg/1)
Phosphorus , (mg/ 1 )
Hydrolyzable (mg/1)
Orthophosphate (mg/1)
Phosphorus, Dissolved
Potassium, Total (mg/1)
, Dissolved (mg/1)
Storet
Number
00680
00681
00400
32730
00665
70507
00666
00935
Method
Dow Beckman (MOD #915) or Carbonaceous
Analyzer
Filtration through 0.45y MF
Electrometric
4-aminoantipyrine
Persulfate - digestion + single reagent
Technicon - manual digestion + automated
single reagent or stannous
chloride
Sulfuric acid digestion + single reagent
Technicon - manual digestion + automated
single reagent or stannous
Direct single reagent chloride
Technicon - single reagent or stannous
chloride
Filtration through 0.45p MF
Atomic Absorption
Titration through 0.45p MF
References to be Used
Std. Meth.
12th Ed.
(1965)
This M
This M
p. 226-228
p. 516
This N
This N
ASTM Stds.
Part 23 !
(1968) !
E
inual
inual
p. 284
p. 517
anual
anual
*
*
*
:(See USGS Reference, last page of index)
-------
FWPCA METHODS FOR CHEMICAL ANALYSIS
OF WATER AND WASTES
Parameter
Selenium, Total ( g/1)
, Dissolved ( g/1)
Silica, Total (yg/1)
, Dissolved (ug/1)
Sodium, Total (mg/1)
, Dissolved (mg/1)
Solids, Total (mg/1)
, filterable
, non-filterable
, Volatile (mg/1)
Specific Conductance
Sulfate (mg/1)
Sulfide (mg/1)
Storet
Number
.
01145
00955
00930
00500
00515
00530
00505
00095
00945
00745
Method
i
Diaminobenzidiue
Filtration through 0.45p MF
1
Molybdate
Filtration through 0.45y MF
Atomic Absorption
Filtration through 0.45y MF
Gravimetric, 105° C
Filtration through glass fiber, 180°C
Glass-fiber filtration, 105°C
Gravimetric, 550°C
Wheatstone Bridge
Turbidimetric
Technicon - Barium chloranilate
lodometric
Referen
Std. Meth.
12th Ed.
(1965)
p. 251-253
This N
This M
p. 425
p. 280
p. 291-293
This M
p. 428
ces to be Us
ASTM Stds.
Part 23
(1968)
anual
mual
p. 183
p. 56-58
mual
ed
USGS
*
*
*
*
*
(See USGS Reference, last page of index)
-------
FWPCA METHODS FOR CHEMICAL ANALYSIS
OF WATER AND WASTES
Parameter
Storet
Number
Method
Std. Meth.
12th Ed.
(1965)
References to be Used
ASTM Stds.
Part 23
(1968)
USGS
Temperature (°C)
00010
Mercury, dial, or thermistor
p. 311
Threshold Odor - 60°C
- Room Temp.
00085
Dilution series
Dilution series
p 304
Turbidity, Nephelometric (JCU)
00070
Hach 2100 or equivalent
This MJ
nual
Zinc, Total (ug/1)
, Dissolved (ug/1)
01090
Atomic Absorption
Filtration through 0.45u MF
This Mi
nual
Techniques of Water Resources Investigations of the U.S. Geological Survey, Book 5, Chap AI: Laboratory Analysis
of Water, Dissolved Minerals and Gases (to be published)
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Table II - Sample Preservation
Parameter
Acidity-Alkalinity
Biochemical Oxygen Demand
Calcium
Chemical Oxygen Demand
Chloride
Color
Cyanide
Dissolved Oxygen
Fluoride
Hardness
Metals, Total
Metals, Dissolved
Nitrogen, Ammonia
Nitrogen, Kjeldahl
Nitrogen, Nitrate - Nitrite
Oil and Grease
Organic Carbon
pH
Phenolics
Phosphorus
Preservative
Refrigeration at 4°C
Refrigeration at 4°C
None required
2 ml H2S04 per liter
None required
Refrigeration at 4°C
NaOH to pH 10
Determine on site
None required
None required
5 ml HNOg per liter
Filtrate: 3 ml 1:1 HN03 per liter
40 mg HgCl2 per liter - 4°C
40 mg HgCl2 per liter - 4°C
40 mg HgCl- per liter - 4°C
2 ml H2S04 per liter - 4°C
2 ml H2S04 per liter (pH 2)
Non e avai 1 ab 1 e
1.0 g CuS04 + H3P04 to
pH 4.0 - 4°C
40 mg HgCl2 per liter - 4°C
Maximum
Holding Period
24 hours
6 hours
7 days
24 hours
24 hours
No holding
6 months
6 months
7 days
Unstable
7 days
24 hours
7 days
24 hours
7, days
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Table II - Sample Preservation
(continued)
Maximum
Parameter Preservative Holding Period
Solids None available
Specific Conductance None required
Sulfate Refrigeration at 4°C 7 days
Sulfide 2 ml Zn acetate per liter 7 days
Threshold Odor Refrigeration at 4°C 24 hours
Turbidity None available
References:
Jenkins, David, "A Study of Methods Suitable for the Analysis and Preserva-
tion of Phosphorus Forms in an Estuarine Environment." Report for the
Central Pacific River Basins Project, Southwest Region, FWPCA (1965).
Jenkins, David, "A Study of Methods for the Analysis and Preservation of
Nitrogen Forms in an Estuarine Environment." Report for Central Pacific
River Basins Project, Southwest Region, FWPCA (1965).
Howe, L. H. and Holley, C. W. "Comparisons of Mercury (II) Chloride and
Sulfunic Acid as Preservatives for Nitrogen Forms in Water Samples."
Env. Sci. £ Techn. 3:478 (1969).
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ACIDITY
1. Scope and Application
1.1 The method recommended is identical to the procedure des-
cribed in ASTM Standards, Part 23, pp 155-158, except that
the sample is titrated to a final pH of 8.3 and results re-
ported as mg/1 CaCO .
O
1.2 This method is not applicable to analysis of acid samples
from mine drainage. It is the decision of the AQC staff to
delay the method selection for measurement of acidity in
acid mine drainage samples until such time that a more com-
prehensive review of the problem can be made.
1.3 Methods for analysis of mine drainage samples for all con-
stituents contributing to acidity of such samples may be
selected at the option of the respective laboratory directors,
2. Calculation
2.1 Acidity is reported as calcium carbonate CaCO, according to
> o
the following formula:
Acidity as mg/1 CaCO = A x N x 50,-OOP
ml sample
where:
A - ml of base used for titration
N = normality of base
3. Precision
3.1 A synthetic sample containing 21 mg/1 acidity as CaCO, was
analyzed by 55 laboratories with a standard deviation of
±1.73 mg/1.
11
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TOTAL ALKALINITY
(Automated Methyl Orange Method)
1. Scope and Application
1.1 This automated method is applicable to surface and saline
waters. The applicable range is 10 to 200 mg/1 as CaCO,.
2. Summary of Method
2.1 Methyl orange is used as the indicator in this method be-
cause its pH range is in the same range as the equivalence
point for total alkalinity, and it has a distinct color
change that can be easily measured. .The methyl orange is
dissolved in a weak buffer at a pH of 3.1, just below the
equivalence point, so that any addition of alkalinity causes
a color change directly proportional to the amount of alka-
linity.
3. Sample Handling and Preservation
3.1 Sample should be refrigerated at 4°C and run as soon as
practical.
4. Interferences
4.1 No significant interferences.
5. Apparatus
5.1 Technicon AutoAnalyzer consisting of:
12
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(Total Alkalinity)
5.1.1 Sampler I.
5.1.2 Manifold.
5.1.3 Proportioning pump.
5.1.4 Colorimeter equipped with 15 mm tubular flow cell
and 550 my filters.
5.1.5 Recorder equipped with range expander.
6. Reagents
6.1 Methyl Orange: Dissolve 0.125 g of methyl orange in 1 liter
of distilled water.
6.2 pH 3.1 Buffer: Dissolve 5.1047 g of potassium acid phthalate
in distilled water and add 87.6 ml 0.1 N HC1 and dilute.to 1
liter. Stable for one week.
6.3 Methyl Orange-Buffered Indicator: Add 1.0 liter of pH 3.1
buffer to 200 ml methyl orange solution and mix well. Stable
for 24 hours.
6.4 Stock Solution: Dissolve 1.0000 g of pre-dried anhydrous
sodium carbonate in distilled water and dilute to 1.0 liter.
1.0 ml = 1.00 mg Na2C03.
6.4.1 Prepare a series of standards by diluting suitable
volumes of stock solution to 100.0 ml with distilled
water. The following dilutions are suggested:
13
-------
(Total Alkalinity)
ml of
Stock
Solution
1.
2.
4.
6.
8.
10.
14.
18.
20.
0
0
0
0
0
0
0
0
0
Cone, mg/1
10
20
40
60
80
100
140
180
200
7. Procedure
7.1 No advance sample preparation is required. Set up manifold
as shown in Figure 1.
7.2 Allow both colorimeter and recorder to warm up for 30 minutes.
Run a baseline with all reagents, feeding distilled water
through the sample line. Adjust dark current and operative
opening on colorimeter to obtain stable baseline.
7.3 Place distilled water wash tubes in alternate openings on
sampler and set sample timing at 2.0 minutes.
7.4 Place working standards in sampler in order of decreasing
concentration. Complete filling of sampler tray with unknown
samples.
7.5 Switch sample line from distilled water to sampler and begin
analysis.
8. Calculation
8.1 Prepare standard curve by plotting peak heights of processed
standards against known concentrations. Compute concentration
of samples by comparing sample peak heights with standard curve.
14
-------
(Total Alkalinity)
"9. Precision and Accuracy
9.1 In a single laboratory (AQC), using surface water samples
at concentrations of 15, 57, 154, and 193 mg/1 as CaC03, the
standard deviation was ±0.5.
9.2 In a single laboratory (AQC), using surface water samples
at concentrations of 31 and 149 mg/1 as CaCO.j, recoveries
were 100% and 99%, respectively.
References
1. Technicon AutoAnalyzer Methodology, Bulletin 1261, Technicon Con-
trols, Inc., Chauncey, N.Y. (1961).
2. Standard-Methods, APHA, 12th Ed., p. 48, New York, N.Y. (1965).
15
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LARGE MIXING COILS
oooooooo
'i'i'l'I' ' '!'
1/2 DELAY COIL
•*- WASTE -*•
PURPLE
GREEN
RED
BLUE
SAMPLER 1
SAMPLE
CONTINUOUS FILTER
AIR
BUFFER + INDICATOR
B^ WASTE
PROPORTIONING PUMP
-il?
2X
COLORIMETER RECORDER
15mm TUBULAR f/c
550 mn FILTERS
SAMPLING TIME: 2.0 MINUTES
WASH TUBES: ONE
FIGURE 1. ALKALINITY MANIFOLD
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BIOCHEMICAL OXYGEN DEMAND
1. Scope and Application
1.1 It is the opinion of the Analytical Quality Control Program
and its advisors that present BOD test procedures are in-
herently nonreproducible and that the unpredictable nature
of the test results make their interpretation difficult.
Therefore, no specific procedure has been selected as the
FWPCA standard test for Biochemical Oxygen Demand.
1.2 The traditional BOD test is empirical, employing standard-
ized laboratory conditions in an attempt to yield repro-
ducible results. Since the actual environmental conditions
of temperature, biological population, water movement,
sunlight, and oxygen concentrations cannot be accurately
reproduced in the laboratory, the results obtained from the
empirical test have little relationship to stream oxygen
demands.
1.3 The test may be useful for determining the relative waste
loadings to treatment plants and the degree of oxygen demand
removal provided by primary treatment. Because of the com-
plex changes in oxygen-demanding materials during secondary
treatment, the use of the test to measure secondary plant
efficiency is questionable.
1.4 At the present time, there are no other procedures that
adequately replace the BOD test. There are, however, other
17
-------
(BOD)
measurements available which furnish useful information.
These tests include Total Organic Carbon (TOC) and Chemical
Oxygen Demand (COD).
2. Procedure
2.1 Directions for conducting the BOD test are found in:
Standard Methods for the Examination of Water and
Wastewater, 12 Edition (1965), pp. 415-421.
ASTM Standards (1968) Part 23, Water; Atmospheric
Analyses, pp. 727-732.
2.2 Determinations of dissolved oxygen in the BOD test may be
made by use of Dissolved Oxygen (Probe Method) or Dissolved
Oxygen (Modified Winkler with Full-Bottle Technique) in this
manual.
3. Precision and Accuracy
3.1 In 34 laboratories, the standard deviation of the BOD test,
using a glucose-glutamic acid mixture, was ±31 mg/1 at a mean
BOD concentration of 184 mg/1. In a single laboratory, the
precision was ±11 mg/1 at a BOD of 218 mg/1 (Analytical Refer-
ence Service, PHS).
3.2 There is no method available to determine the accuracy of the
BOD test.
18
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CHEMICAL OXYGEN DEMAND
(Low Level)
1. Scope and Application
1.1 The scope of this modification of the Chemical Oxygen Demand
(COD) test is the same as for the high level test. It is
applicable to the analysis of surface waters, domestic and
industrial wastes with low demand characteristics.
1.2 This method (low level) is applicable for samples having a
COD in the range of 5-50 mg/1 COD.
2. Summary of Method
2.1 Organic and oxidizable inorganic substances in an aqueous
sample are oxidized by potassium dichromate solution in 50
percent (by volume) sulfuric acid solution. The excess
dichromate is titrated with standard ferrous ammonium
sulfate using orthophenanthroline ferrous complex (ferroin)
as an indicator.
3. Sampling and Preservation
3.1 Collect the samples in glass bottles, if possible. Use of
plastic containers is permissible if it is known that no
organic contaminants are present in the containers.
3.2 Biologically active samples should be tested as soon as
possible. Samples containing settleable material should be
well mixed, preferably homogenized, to permit removal of
representative aliquots.
19
-------
(Chemical Oxygen Demand)
(Low Level)
3.3 Samples may be preserved with sulfuric acid at a rate of
2 ml of cone. H2S04 per liter of sample.
4. Interferences
4.1 Traces of organic material either from the glassware or
atmosphere may cause a gross, positive error.
4.1.1 Extreme care should be exercised to avoid inclusion
of organic materials in the distilled water used
for reagent preparation or sample dilution.
4.1.2 Glassware used in the test should be conditioned by
running blank procedures to eliminate traces of
organic material.
4.2 Volatile materials may be lost when the sample temperature
rises during the sulfuric acid addition step.
4.3 Chlorides are quantitatively oxidized by dichromate and
represent a positive interference. Mercuric sulfate is
added to the digestion flask to complex the chlorides,
thereby effectively eliminating the interference on all but
brine samples.
5. Apparatus
5.1 Reflux apparatus - Glassware should consist of a 500 ml
Erlenmeyer flask or a 300 ml round bottom flask made of
heat-resistant glass connected to a 12 inch Allihn condenser
by means of a ground glass joint. Any equivalent reflux
apparatus may be substituted provided that a ground-glass
connection is used between the flask and the condenser.
20
-------
(Chemical Oxygen Demand)
(Low Level)
6. Reagents
6.1 Distilled water. Special precautions should be taken to
insure that distilled water used in this test be low in
organic matter.
6.2 Standard potassium dichromate solution (0.025 N) - Dissolve
12.259 g ICCr-O-, primary standard grade, previously dried
at 103°C for two hours, in distilled water and dilute to
1000 ml. Mix this solution thoroughly then dilute 100 ml
to one liter with distilled water.
6.3 Sulfuric acid reagent - Cone. H-SC" containing 23.5 g silver
sulfate, Ag_SO., per 9 Ib. bottle (one to two days required
for dissolution).
6.4 Standard ferrous ammonium sulfate (0.025 N) - Dissolve 98 g
of Fe(NH4)2(S04)2.6H20 in distilled water. Add 20 ml of cone.
H2SO., cool and dilute to 1000 ml. Dilute 100 ml of this
solution to one liter with distilled water. This solution
must be standardized daily against JCCr^CL solution.
6.4.1 Standardization - To 15 ml of distilled water add
10 ml of 0.025 N Kr2Cr20 solution. Add 20 ml of
H_SO. and cool. Titrate with ferrous ammonium sulfate
using 1 drop of ferroin indicator. The color change is
sharp, going from blue-green to reddish-brown.
Normality = (ml KCr0 ) (0.025)
ml Fe (NH4)2(S04)2
21
-------
(Chemical Oxygen Demand)
(Low Level)
6.5 Mercuric sulfate - Powdered HgSCL.
6.6 Phenanthroline ferrous sulfate (ferroin) indicator solution -
Dissolve 1.48 g of 1-10-(ortho)-phenanthroline monohydrate,
together with 0.70 g of FeSCK.TH-O in 100 ml of water. This
indicator may be purchased already prepared.
6.7 Silver sulfate - Powdered Ag^SO..
6.8 Sulfuric acid (sp. gr. 1.84) - Concentrated H2S04.
7. Procedure
7.1 Place several boiling stones in the reflux flask, followed by
1 g of HgSO.. Add 5.0 ml cone. H SO (6.8); swirl until mercuric
sulfate has dissolved. Place reflux flask in an ice bath and
slowly add, with swirling, 25.0 ml of 0.025 N K Cr 0 . Now
add 70.0 ml of sulfuric acid-silver sulfate solution (6.3) to
the cooled reflux flask, again using slow addition with swirling
motion.
7.2 With the reflux flask still in the ice bath, place 50.0 ml of
sample or a sample aliquot diluted to 50.0 ml into the reflux
flask. Caution: Care must be taken to assure that the contents
of the flask are well mixed. If not, superheating may result,
and the mixture may be blown out of the open end of the con-
denser. Attach the flask to the condenser and start the cooling
water.
7.3 Apply heat to the flask and reflux for 2 hours. For some waste
waters, the 2-hour reflux period is not necessary. The time
required to give the maximum oxidation for a waste water of
constant or known composition may be determined and a shorter
period of refluxing may be permissible.
22
-------
(Chemical Oxygen Demand)
(Low Level)
7.4 Allow the flask to cool and wash down the condenser with
about 25 ml of water. If a round bottom flask has been used,
transfer the mixture to a 500-ml Erlenmeyer flask, washing
out the reflux flask 3 or 4 times with water. Dilute the
acid solution to about 300 ml with water and allow the
solution to cool to about room temperature. Add 8 to 10
drops of phenanthroline ferrous sulfate solution to the
solution and titrate the excess dichromate with 0.025 N
ferrous ammonium sulfate solution to the end point. The
color change will be sharp, changing from a blue-green to a
reddish hue.
7.5 Blank - Simultaneously run a blank determination following
the details given in 7.1 and 7.2, but using low COD water
in place of the sample.
8. Calculation
8.1 Calculate the COD in the sample in mg/1 as follows:
COD, mg/liter = (A - B) N x 8000
S
where:
A = milliliters of Fe (NH^^CSO^)~ solution required
for titration of the blank,
.!
B = milliliters of Fe (^4)2(804)2 solution required
for titration of the sample,
N = normality of the Fe (NI^) 2 (SO^)-solution, and
S = milliliters of sample used for the test.
23
-------
(Chemical Oxygen Demand)
(Low Level)
9. Precision
9.1 The precision of the low level test described in the
foregoing material has not been determined by collaborative
testing.
24
-------
CHEMICAL OXYGEN DEMAND
(High Level for Saline Waters)
1. Scope and Application
1.1 When the chloride level exceeds 1000 mg/1 the minimum
accepted value for the COD will be 250 mg/1. COD levels
which fall below this value are highly questionable because
of the high chloride correction which must be made.
2. Summary of Method
2.1 Organic and oxidizable inorganic substances in an aqueous
sample are oxidized by potassium dichromate solution in 50
percent (by volume) sulfuric acid solution. The excess di-
chromate is titrated with standard ferrous ammonium sulfate
using orthophenanthroline ferrous complex (ferroin) as an
indicator.
3. Sample Handling and Preservation
3.1 Collect the samples in glass bottles, if possible. Use of
plastic containers is permissible if it is known that no
organic contaminants are present in the containers.
3.2 Biologically active samples should be tested as soon as pos
sible. Samples containing settleable material should be
well mixed, preferably homogenized, to permit removal of
representative aliquots.
3.3 Samples are preserved by the addition of 2 ml of cone. ^SO
per liter of sample.
25
-------
(COD - High Level for
Saline Waters)
4. Interferences
4.1 Traces of organic material either from the glassware or atmos-
phere may cause a gross, positive error.
4.1.1 Extreme care should be exercised to avoid inclusion of
organic materials in the distilled water used for
reagent preparation or sample dilution.
4.1.2 Glassware used in the test should be conditioned by
running blank procedures to eliminate traces of organic
material.
4.2 Volatile materials may be lost when the sample temperature
rises during the sulfuric acid addition step.
4.3 Chlorides are quantitatively oxidized by dichromate and re-
present a positive interference. Mercuric sulfate is added
to the digestion flask to complex the chlorides, thereby
effectively eliminating the interference on all but brine
samples.
5. Apparatus
5.1 Reflux apparatus - Glassware should consist of a 500 ml Erlen-
meyer flask or a 300 ml round bottom flask made of heat-
resistant glass connected to a 12 inch Allihn condenser by means
of a ground glass joint. Any equivalent reflux apparatus may
be substituted provided that a ground-glass connection is used
between the flask and the condenser.
26
-------
(COD - High Level for
Saline Waters)
6. Reagents
6.1 Standard potassium dichromate solution, (0.25 N): Dissolve
12.2588 g of K2Cr207, primary standard grade, previously dried
for 2 hours at 1Q3°C in water and dilute to 1.0 liter.
6.2 Sulfuric acid reagent: Cone. H2S04 containing 23.5 g silver
sulfate, Ag2SC>4, per 9 Ib. bottle (1 to 2 days required for
dissolution).
6.3 Standard ferrous ammonium sulfate, 0.250 N: Dissolve 98 g of
Fe(NH4)2(S04)2.6H20 in distilled water. Add 20 ml of cone.
H2S04, cool and dilute to 1000 ml. This solution must be
standardized against the standard potassium dichromate solution
daily.
6.3.1 Standardization: Dilute 25.0 ml of standard dichromate
solution to about 250 ml with distilled water. Add 75
ml cone, sulfuric acid. Cool, then titrate with ferrous
ammonium sulfate titrant, using 10 drops of ferroin
indicator.
Normality = (ml K2Cr20?) (0.25)
ml Fe(NH4)2(S04)2
6.4 Mercuric sulfate - Powdered HgSCh.
6.5 Phenanthroline ferrous sulfate (ferroin) indicator solution -
Dissolve 1.48 g of 1-10-(ortho)-phenanthroline monohydrate,
together with 0.70 g of FeS04.7H20 in 100 ml of water. This
indicator may be purchased already prepared.
27
-------
(COD - High Level for
Saline Waters)
6.6 Silver sulfate - Powdered Ag-SCK.
6.7 Sulfuric acid (sp. gr. 1.84) - Concentrated H-SO..
7. Procedure
7.1 Pipet a 50 ml aliquot of sample not to exceed 800 mg/1 of COD
into a 500 ml, flat bottom, Erlenmeyer flask. Add 25 ml of
0.25 N K^C^Oy, then 5.0 ml of cone. t^SO, (containing.no
silver sulfate). Add HgSO, in the ratio of 10 mg to 1 mg
chloride, based upon the mg of chloride in the sample aliquot.
Swirl until all the mercuric sulfate has dissolved. Care-
fully add 70 ml of sulfuric acid-silver sulfate solution and
gently swirl until the solution is thoroughly mixed. Glass
beads should be added to the reflux mixture to prevent bumping,
which can be severe and dangerous. (CAUTION: The reflux
mixture must be thoroughly mixed before heat is applied. If
this is not done, local heating occurs in the bottom of the
flask, and the mixture may be blown out of the condenser).
7.1.1 If volatile organics are present in the sample, use
an Allihn condenser and add the sulfuric acid-silver
sulfate solution through the condenser, while cooling
the flask, to reduce loss by volatilization.
7.2 Attach the flask to the condenser and reflux the mixture for
two hours.
7.3 Cool, and wash down the interior of the condenser with 25 ml
of distilled water. Disconnect the condenser and wash the flask
28
-------
(COD - High Level for
Saline Waters)
and condenser joint with 25 ml of distilled water. Remove the
condenser and carefully add to the flask 175 ml of distilled
water so that the total volume is 350 ml. Cool to room tem-
perature .
7.4 Titrate with standard ferrous ammonium sulfate using 10 drops
of ferroin indicator. (This amount must not vary from blank,
sample and standardization). The color change is sharp, going
from blue-green to reddish-brown and should be taken as the
end point although the blue-green color may reappear within
minutes.
7.5 Run a blank, using 50 ml of distilled water in place of the
sample together with all reagents and subsequent treatment.
7.6 For COD values greater than 800 ml, a smaller aliquot of sample
should be taken; however, the volume should be readjusted to
50 ml with distilled water having a chloride concentration
equal to the sample.
7.7 Chloride correction* - Prepare a standard curve of COD versus
mg/1 of chloride, using sodium chloride solutions of varying
concentrations following exactly the procedure outlined. The
chloride interval, as a minimum should be 4000 mg/1 up to 20,000
mg/1 chloride. Lesser intervals of greater concentrations
must be run as per the requirements of the data, but in no case
must extrapolation be used.
*Burns, E. R., Craig, N., Journal WPCF, Vol. 37, pp 1716-1721, 1967.
29
-------
(COD - High Level for
Saline Waters)
8. Calculation
8.1 mg/1 COD = (A - B) C x 8000 - D x 1.20
ml sample
where:
COD = chemical oxygen demand from dichromate
A = ml Fe(NH4)2(S04)2 for blank;
B = ml Fe(NH.)2(S04)2 for sample;
C = normality of Fe(NH4)2(S04)2;
D = chloride correction from curve (step 7.7).
1.20 = compensation factor to account for the extent of
chloride oxidation which is dissimilar in systems
containing organic and nonorganic material.
9. Precision and Accuracy
9.1 Precision and accuracy data are not available at this time.
30
-------
CHLORIDE
(Automated Ferricyanide Method)
1. Scope and Application
1.1 This automated method is applicable on surface water, domestic
and industrial wastes, and saline waters. The applicable
range is 1 to 250 mg Cl/1. Approximately 15 samples per hour
can be analyzed.
2. Summary of Method
2.1 Thiocyanate ion (SCN) is liberated from mercuric thiocyanate,
through sequestration of mercury by chloride ion to form
un-ionized mercuric chloride. In the presence of ferric ion,
the liberated SCN forms highly colored ferric thiocyanate, in
concentration proportional to the original chloride concen-
tration.
3. Sample Handling and Preservation
3.1 No special requirements.
4. Interferences
4.1 No significant interferences.
5. Apparatus
5.1 Technicon AutoAnalyzer consisting of:
5.1.1 Sampler I.
5.1.2 Continuous filter.
5.1.3 Manifold.
5.1.4 Proportioning pump.
31
-------
(Chloride)
5.1.5 Colorimeter equipped with 15 mm tubular flow cell
and 480 my filters.
5.1.6 Recorder
6. Reagents
6.1 Ferric Ammonium Sulfate: Dissolve 60 g of FeNH (SO ) .12 HO
in approximately 500 ml distilled water. Add 355 ml of cone
HNO- and dilute to 1 liter with distilled water. Filter.
6.2 Saturated Mercuric Thiocyanate: Dissolve 5 g of Hg(SCN)2 in
1 liter of distilled water. Decant and filter a portion of the
saturated supernatant liquid to use as the reagent and refill
the bottle with distilled water.
6.3 Stock Solution (0.141 N NaCl): Dissolve 0.8241 g of
pre-dried NaCl in distilled water. Dilute to 1 liter.
1 ml = 0.5 mg Cl".
6.3.1 Prepare a series of standards by diluting suitable volumes
of stock solution to 100.0 ml with distilled water. The
following dilutions are suggested:
ml of Stock Solution Cone., mg/1
0.2 1.0
1.0 5.0
2.0 10
4.0 20.
8.0 40
15.0 75
20.0 100
30.0 150
40.0 200
50.0 250
32
-------
(Chloride)
7. Procedure
7.1 No advance sample preparation is required. Set up manifold as
shown in Figure 1. For water samples known to be consistently
low in chloride content, it is advisable to use only one distilled
water intake line.
7.2 Allow both colorimeter and recorder to warm up for 30 minutes.
Run a baseline with all reagents, feeding distilled water through
the sample line. Adjust dark current and operative opening on
colorimeter to obtain stable baseline.
7.3 Place distilled water wash tubes in alternate openings in
sampler and set sample timing at 2.0 minutes.
7.4 Place working standards in sampler in order of decreasing concen-
trations. Complete filling of sampler tray with unknown samples.
7.5 Switch sample line from distilled water to sampler and begin
analysis.
8. Calculation
8.1 Prepare standard curve by plotting peak heights of processed
standards against known concentrations. Compute concentration
of samples by comparing sample peak heights with standard curve.
9. Precision and Accuracy
9.1 In a single laboratory, using surface water samples at concentra-
tions of 1, 100, and 250 mg Cl~/l, the standard deviation was
-0.3 (AQC Laboratory).
i
33
-------
(Chloride)
9.2 In a single laboratory (AQC), using surface water samples at
concentrations of 10 and 100 mg Cl/1. recoveries were 97% and
104%, respectively.
Reference
1. J. E. O'Brien, "Automatic Analysis of Chlorides in Sewage,"
Wastes Engr., 33, 670-672 (Dec. 1962).
34
-------
CONTINUOUS FILTER
co
01
Fe NH4(S04J2
(SCNJ2
PROPORTIONING
PUMP
COLORIMETER
15mm TUBULAR f/c
480mjJ FILTERS
SAMPLING TIME: 2.0 MINUTES
WASH TUBES: ONE
FIGURE 1. CHLORIDE MANIFOLD
-------
COLOR
1. Scope and Application
1.1 The Platinum-Cobalt method is useful for measuring color of
water derived from naturally occurring materials, i.e.,
vegetable residues such as leaves, barks, roots, humus and
peat materials. The method is not applicable to color
measurement on waters containing highly colored industrial
wastes.
Note - The Spectrophotometric and Tristimulus methods are
useful for detecting specific color problems. The use of
these methods, however, is laborious and unless determination
of the hue, purity, and luminance is desired, they are of
limited value.
2. Summary of Method
2.1 Color is measured by visual comparison of the sample with
platinum-cobalt standards. One unit of color is that pro-
duced by 1 mg/1 platinum in the form of the chloroplatinate
ion.
3. Interference
3.1 Since very slight amounts of turbidity interfere with the
determination, samples showing visible turbidity should be
clarified by centrifugation.
37
-------
(Color)
4. Sample Handling and Preservation
4.1 Representative samples shall be taken in scrupulously
clean glassware.
4.2 Since biological activity may change the color characteristics
of a sample, the determination should be made as soon as
possible. Refrigeration at 4°C is recommended.
5. Apparatus
5.1 Nessler tubes - Matched, tall form, 50 ml capacity.
6. Reagents
6.1 Standard chloroplatinate solution. Dissolve 1.246 g potassium
chloroplatinate, K PtCl,, (equivalent to 0.500 g metallic Pt)
and 1 g crystalline cobaltous chloride, CoCl-^tLO, in distilled
water containing 100 ml of cone. HC1. Dilute to 1 liter with
distilled water. This standard solution is equivalent to 500
color units.
7. Preparation of Standards
7.1 Prepare standards in increments from 5 to 70 units.
The following series is suggested:
ml of Standard Solution
Diluted to 50.0 ml Color in
with Distilled Water Chloroplatinate Units
0.0 0
0.5 5
1.0 10
1.5 15
2.0 20
2.5 25
3.0 30
3.5 35
4.0 40
4.5 45
5.0 50
6.0 60
7.0 70
38
-------
CColor)
7.2 Protect these standards against evaporation and
contamination by use of clean, inert stoppers.
Note - The standards also must be protected against the
absorption of ammonia since an increase in color will result.
8. Procedure
8.1 Apparent color - Observe the color of the sample by filling
a matched Nessler tube to the 50 ml mark with the water and
compare with standards. This comparison is made by looking
vertically downward through the tubes toward a white or
specular surface placed at such an angle that light is re-
flected upward through the columns of liquid. If turbidity
has not been removed by the procedure given in 8.2, report
the color as "apparent color." If the color exceeds 70
units, dilute the sample with distilled water in known
proportions until the color is within the range of the standards.
8.2 True color - Remove turbidity by centrifuging the sample until
the supernatant is clear. Compare the centrifuged sample with
distilled water to insure that turbidity has been removed. If
the sample is clear, then compare with standards as given in 8.1,
9. Calculation
9.1 Calculate the color units by means of the following equation:
A x 50
Color units =
V
39
-------
(Color)
Where: A = estimated color of diluted sample.
V = ml sample taken for dilution.
9.2 Report the results in whole numbers as follows:
Color Units Record to Nearest
1-50 1
51-100 5
101-250 10
251-500 20
10. Precision and Accuracy
10.1 Precision and accuracy data are not available at this
time.
Reference - Standard Methods for the Examination of Water
and Wastewater, 12th Edition, 127-129, 1965.
APHA Inc., N.Y.
40
-------
CYANIDE
1. Scope and Application
1.1 This method is applicable to the determination of cyanide
in surface waters, domestic and industrial wastes, and
saline waters.
1.2 The titration procedure using silver nitrate with p-
dimethylamino-benzalrhodanine indicator is used for
measuring concentrations of cyanide exceeding 1 mg/1
(0.2 mg/200 ml of absorbing liquid).
1.3 The colorimetric procedure is used for concentrations
below 1 mg/1 of cyanide and is sensitive to about 5 yg/1.
2. Summary of Method
2.1 The cyanide as hydrocyanic acid (HCN) is released from
metallic cyanide complex ions by means of a reflux-distilla-
tion operation and absorbed in a scrubber containing sodium
hydroxide solution. The cyanide ion in the absorbing
solution is then determined by volumetric titration or
colorimetrically.
2.2 The colorimetric measurement employs the pyridine-pyrazolone
reaction in which the cyanide is coupled with free chlorine
to form cyanogen chloride and then with pyridine to a
glutaconic aldehyde. The aldehyde then reacts with 1-phenyl-
3-methyl-5-pyrazolone to form a highly colored blue dye.
41
-------
(Cyanide)
2.3 The titrimetric measurement uses a standard solution
of silver nitrate to titrate cyanide in the presence
of a silver sensitive indicator.
3. Definitions
3.1 Cyanide is defined as cyanide ion and complex cyanides
converted to hydrocyanic acid (HCN) by reaction in a
reflux system of a mineral acid in the presence of
. magnesium and mercuric ions.
4. Sample Handling and Preservation
4.1 The sample should be collected in plastic bottles of 1
liter or larger size. All bottles must be thoroughly
cleansed and thoroughly rinsed to remove soluble material
from containers.
4.2 Samples must be preserved with 20 ml of a 1 N sodium
hydroxide per liter of sample at the time of collection.
4.3 Samples should be analyzed as rapidly as possible after
collection. If storage is required, the samples should
be stored in a refrigerator or in an ice chest filled with
water and ice to maintain temperatures at 4°C.
5. Interferences
5.1 Interferences are eliminated or reduced by using the distillate
obtained with the preliminary screening procedure.
5.2 Sulfides are an interference that should be removed prior to
distillation. Remove sulfides with pH adjustment to >11,
42
-------
( Cyanide)
addition of lead carbonate and mixing. Filter sample to
remove lead sulfide. Repeat until no more lead sulfide
is formed as evidenced by whiteness of the lead carbonate.
5.3 Oxidizing substances interfere and should be treated with
ascorbic acid.
6. Apparatus
6.1 Reflux distillation apparatus such as shown in Figure 1 or
Figure 2. The boiling flask should be of 1 liter size with
inlet tube and provision for condenser.
6.2 Microburet, 5.0 ml (for titration).
6.3 Spectrophotometer suitable for measurements at 620 my with
a 1.0 cm cell or larger.
7. Reagents
7.1 Sodium hydroxide solution, 1 N. Dissolve 40 g of NaOH in
distilled water, and dilute to a liter with distilled water.
7.2 Lead carbonate.
7.3 Ascorbic acid.
7.4 Mercuric chloride solution. Dissolve 34 g HgCl? in 500 ml
distilled water.
7.5 Magnesium chloride solution. Dissolve 51 g MgCl~.6H70 in
100 ml distilled water.
7.6 Sulfuric acid, concentrated.
7.7 Sodium dihydrogenphosphate, 1 M. Dissolve 138 g of
NaH-PO-.H 0 in a liter of distilled water. Refrigerate this
solution.
43
-------
ALLIHN CONDENSER—*
AIR INLET
CONNECTING TUBING
ONE LITER
BOILING FLASK
SUCTION
GAS ABSORBER
FIGURE 1
CYANIDE DISTILLATION APPARATUS
45
-------
COOLING WATER
INLET TUBE'
SCREW CLAMP
I
HEATER
TO LOW VACUUM
SOURCE
- ABSORBER
^ DISTILLING FLASK
O
FIGURE 2
CYANIDE DISTILLATION APPARATUS
47
-------
(Cyanide)
7.8 Stock cyanide solution. Dissolve 2.51 'g of KCN and 2 g
KOH in a liter of distilled water. Standardize with
0.0192 N AgNO,. Dilute to appropriate concentration
so that 1 ml = 1 mg CN~.
7.9 Standard cyanide solution, intermediate. Dilute 10 ml
of stock (1 ml = 1 mg CN) to a liter of distilled water
(1 ml = 10 yg).
7.10 Standard cyanide solution. Prepare fresh daily by
diluting 100 ml of intermediate cyanide solution to a
liter of distilled water and store in a glass stoppered
bottle. One ml = 1.0 yg CN (1.0 ppm).
7.11 Standard silver nitrate solution, 0.0192 N. Prepare by
crushing approximately 5 g AgNO, crystals and drying to
constant weight at 40°C. Weigh out 3.2647 g of dried AgNO ,
dissolve in water, and dilute to liter (1 ml = 1 mg CN).
7.12 Rhodanine indicator. Dissolve 20 mg of p-dimethylamino-
benzalrhodanine in 100 ml of acetone.
7.13 Chloramine T solution. Dissolve 1.0 g of white water
soluble Chloramine T in 100 ml of distilled water and
refrigerate until ready to use. Prepare fresh weekly.
7.14 Pyridine-pyrazolone solution.
7.14.1 One-phenyl-3-methyl-5-pyrazolone reagent. Weigh
0.25 g of 3-methyl-l-phenyl-2-pyrazolone-5-one and
49
-------
(Cyanide)
dissolve in 50 ml of distilled water by heating
to 60°C. Cool after reagent is in solution.
7.14.2 Three,3'-Dimethyl-1,1'-diphenyl-4,4'-bi-2
pyrazolone - 5,5' dione (bispyrazolone). Dissolve
0.01 g of bispyrazolone in 10 ml of pyridine.
7.14..3 Pour solution 7.14.1 through nonacid-washed
filter paper. Collect the filtrate. Through the
same filter paper pour solution 7.14.2 collecting
the filtrate in the same container as filtrate
from 7.14.1. Mix until the filtrates are homoge-
neous. The mixed reagent develops a pink color but
this does not affect the color production with
cyanide if used within 24 hours of preparation.
8. Procedure
8.1 Place 500 ml of sample, or an aliquot diluted to 500 ml in
the 1-liter boiling flask. Add 50 ml of 1 N sodium
hydroxide (7.1) to the absorbing tube and dilute if
necessary with distilled water to obtain an adequate depth
of liquid in the absorber. Connect the boiling flask,
condenser, absorber and trap in the train.
8.2 Start a slow stream of air entering the boiling flask by
adjusting the vacuum source. Adjust the vacuum so that
approximately 1 bubble of air per second enters the boiling
50
-------
(Cyanide)
flask through the air inlet tube. (Caution: The
bubble rate will not remain constant after the reagents
have been added and while heat is being applied to the
flask. It will be necessary to readjust the air rate
occasionally to prevent the solution in the boiling flask
from backing up into the air inlet tube.)
8.3 Add 10 ml of mercuric chloride solution (7.4) and 40 ml
of magnesium chloride solution (7.5) through the air inlet
tube. Rinse the air inlet tube with a few ml of distilled
water and allow the air flow to mix the contents of the
flask for at least 3 minutes.
8.4 Slowly add 25 ml of concentrated sulfuric acid (7.6)
through the air inlet tube and rinse with distilled water.
8.5 Heat the solution to boiling, taking care to prevent the
solution from backing up into and overflowing from the air
inlet tube. Reflux for one hour. Turn off heat and
continue the airflow for at least 15 minutes. After cooling
of the boiling flask disconnect absorber and close off the
vacuum source.
8.6 Drain the solution from the absorber into a 250 ml volumetric
flask and bring up to volume with distilled water washings
from the absorber tube. Cool the volumetric flask in an ice
bath until the temperature of the solution is 5°C.
51
-------
(Cyanide)
8.7 Withdraw 50 ml of the solution from the volumetric flask
and transfer to a 100-ml volumetric flask. Add 10 ml of
sodium phosphate solution (7.7) and 0.2 ml of Chloramine
T solution (7.13) and mix. Add an additional 5 ml of the
sodium phosphate (7.7), followed by 5 ml of mixed pyridine-
pyrazolone solution, (7.14.3), bring to mark with distilled
water and mix. Allow 40 minutes for color development.
8.8 Read absorbance at 620 my using at least a 1.0 cm cell.
8.9 Prepare a series of standards by diluting suitable volumes
of standard solution to 500.0 ml with distilled water as
follows:
ml of Standard Solution Cone., When Diluted to
(1.0 ml = 1 yg CN) 500 ml, mg/1 CN
0 (Blank) 0
5.0 0.01
10.0 0.02
20.0 0.04
50.0 0.10
100.0 0.20
150.0 0.30
200.0 0.40
8.9.1 Standards must be treated in the same manner as the
samples, as outlined in 8.1 through 8.8 above.
8.9.2 Prepare a standard curve by plotting absorbance of
standards vs. cyanide concentrations.
8.9.3 Subsequently, at least two standards (a high and a
low) should be treated as in 8.9.1 to verify standard
curve. If results are not comparable (±20%), a com-
plete new standard curve must be prepared.
52
-------
(Cyanide)
8.9.4 To check the efficiency of the sample distillation,
add an increment of cyanide from either the inter-
mediate standard (7.9) or the working standard (7.10)
to insure a level of 10 yg/1 or a significant increase
in absorbance value. Proceed with the analysis as in
Procedure (8.) using the same flask and system from
which the previous sample was just distilled.
8.10 Alternatively, if the sample contains more than 1 mg of
CN~ transfer the distillate, or a suitable aliquot diluted
to 250 ml, to a 500-ml Erlenmeyer flask. Add 10-12 drops
of the benzalrhodanine indicator.
8.11 Titrate with standard silver nitrate to the first change
in color from yellow to brownish-pink. Titrate a distilled
water blank using the same amount of sodium hydroxide and
indicator as the sample.
8.12 The analyst should familiarize himself with the end point
of the titration and the amount of indicator to be used
before actually titrating the samples. A 5 or 10 ml micro-
buret may be conveniently used to obtain a more precise
titration.
9. Calculation
9.1 Using the colorimetric procedure, calculate concentration of
CN, mg/1, directly from prepared standard curve.
9.2 Using the titrimetric procedure, calculate concentration of
CN as follows:
53
-------
CN, mg/1 =
(Cyanide)
(A-B) x 1000 250
Vol. of original sample Vol. of aliquot titrated
where:
A = volume of AgNOg for titration of sample.
B = volume of AgNOj for titration of blank.
10. Precision and Accuracy
10.1 A synthetic sample prepared by the Analytical Reference Ser-
vice (PHS) at a known concentration of 0.02 mg/1 CN was analyzed
by 47 analysts; the data showed a standard deviation of 0.035
mg/1 for the titrimetric procedure and 0.020 mg/1 for the colori-
metric procedure. Similarly, at a concentration of 1.10 mg/1
of CN, the data showed a standard deviation of 0.333 mg/1 for
the titrimetric procedure and 0.306 mg/1 for the colorimetric
procedure.
References
1. Bark, L. S., and Higson, H. G. Investigation of reagents for the
colorimetric determination of small amounts of cyanide. Talanta,
2:471-479 (1964).
2. Ely, C. T. Recovery of cyanides by modified Serfass distillation.
Journal Water Pollution Control Federation, 40:848-856 (1968).
54
-------
DISSOLVED OXYGEN
(Modified Winkler With Full-Bottle Technique)
1. Scope and Application
1.1 This method is applicable for use with most wastewaters and
streams that contain nitrite nitrogen and not more than 1
mg/1 of ferrous iron. Other reducing or oxidizing materials
should be absent. If 1 ml fluoride solution is added before
acidifying the sample and there is no delay in titration, the
method is also applicable in the presence of 100-200 mg/1
ferric iron.
1.2 The azide modification is not applicable under the following
conditions: (a) samples containing sulfite, thiosulfate,
polythibnate, appreciable quantities of free chlorine or
hypochlorite; (b) samples high in suspended solids; (c)
samples containing organic substances which are readily
oxidized in a highly alkaline solution, or which are oxi-
dized by free iodine in an acid solution; (d) domestic sewage;
(3) biological floes; and (f) where sample color interferes
with endpoint detection. In instances where the azide modi-
fication is not applicable, a DO probe should be used.
2. Summary of Method
2.1 The sample is treated with manganous sulfate, potassium
hydroxide, and potassium iodide (the latter two reagents
combined in one solution) and finally sulfuric acid. The
55
-------
(Dissolved Oxygen)
initial precipitate of manganous hydroxide, Mn(OH)2, combines
with the dissolved oxygen in the sample to form a brown pre-
cipitate, manganic hydroxide, Mn 0(OH)2- Upon acidification,
the manganic hydroxide forms manganic sulfate which acts as
an oxidizing agent to release free iodine from the potassium
iodide. The iodine, which is stoichiometrically equivalent
to the dissolved oxygen in the sample is then titrated with
sodium thiosulfate.
3. Interferences
3.1 There are a number of interferences to the dissolved oxygen
test, including oxidizing and reducing agents, nitrite ion,
ferrous iron, and organic matter.
3.2 Various modifications of the original Winkler procedure for
dissolved oxygen have been developed to compensate or elimi-
nate interferences. The Alsterberg modification is commonly
used to successfully eliminate the nitrite interference, the
Rideal-Stewart modification is designed to eliminate ferrous
iron interference, and the Theriault procedure is used to
compensate for high concentration of organic materials.
3.3 Most of the common interferences in the Winkler procedure
may be overcome by use of the dissolved oxygen probe.
4. Sample Handling and Preservation
4.1 Where possible, collect the sample in a 300 ml BOD incu-
bation bottle. Special precautions are required to avoid
56
-------
(Dissolved Oxygen)
entrainment or solution of atmospheric oxygen or dissolution
of dissolved oxygen.
4.2 Where samples are collected from shallow depths (less than 5
feet), use of an APHA-type sampler is recommended. Use of a
Kemmerer type sampler is recommended for samples collected
from depths of greater than 5 feet.
4.3 When a Kemmerer sampler is used, the BOD sample bottle should
be filled to overflowing. (Overflow for approximately 10
seconds.) Outlet tube of Kemmerer should be inserted to
bottom of BOD bottle. Care must be taken to prevent turbu-
lence and the formation of bubbles when filling bottle.
4.4 The sample temperature should be recorded at time of sampling
as precisely as required.
4.5 Do not delay the determination of dissolved oxygen in samples
having an appreciable iodine demand or containing ferrous
iron. If samples must be preserved either method 4.5.1 or
4.5.2, below, may be employed.
4.5.1 Add 2 ml of manganous sulfate reagent and then 2 ml
of alkali azide reagent to the sample contained in
the BOD bottle. Both reagents must be added well
below the surface of the liquid. Stopper the bottle
immediately and mix the contents thoroughly. The
sample should be stored at the temperature of the
collection water, or water sealed and kept at a tem-
perature of 10 to 20°C, in the dark.
57
-------
(Dissolved Oxygen)
entrairunent or solution of atmospheric oxygen or dissolution
of dissolved oxygen.
4.2 Where samples are collected from shallow depths (less than
five feet) use of an APHA-type sampler is recommended. Use
of a Kemmerer type sampler is recommended for samples collected
from depths of greater than 5 feet.
4.3 When a Kemmerer sampler is used, the BOD sample bottle should
be filled to overflowing. (Overflow for approximately 10
seconds). Outlet tube of Kemmerer should be inserted to
bottom of BOD bottle. Care must be taken to prevent turbu-
lence and the formation of bubbles when filling bottle.
4.4 The sample temperature should be recorded at time of sampling
as precisely as required.
4.5 Do not delay the determination of dissolved oxygen in samples
having an appreciable iodine demand or containing ferrous
iron. If samples must be preserved either 4.5.1 or 4.5.2
below may be employed.
4.5.1 Add 2 ml of manganous sulfate reagent and then 2 ml
of alkali azide reagent to the sample contained in
the BOD bottle. Both reagents must be added well
below the surface of the liquid. Stopper the bottle
immediately and mix the contents thoroughly. The
sample should be stored at the temperature of the
collection water; or water sealed and kept at a tem-
perature of 10 to 20°C, in the dark.
58
-------
(Dissolved Oxygen)
4.5.2 Add 0.7 ml of concentrated ^864 and 1 ml sodium
azide solution (2 g NaN, in 100 ml distilled water)
to the sample in the DO bottle. Store sample as in
4.5.1. Complete the procedure using 2 ml of
manganous sulfate solution, 3 ml alkali iodide solu-
tion, and 2 ml of concentrated 1^504.
4.6 If either preservation technique is employed, complete the
analysis within 4-8 hours after sampling.
5. Apparatus
5.1 Sample bottles - 300 ml ±3 ml capacity BOD incubation bottles
with tapered ground glass pointed stoppers and flared mouths.
5.2 Pipets - with elongated tips capable of delivering 2.0 ml
±0.1 ml of reagent.
6. Reagents
6.1 Manganous sulfate solution: Dissolve 480 g of manganous
sulfate (MnSO .4H 0) in distilled water and dilute to 1 liter.
6.1.1 Alternately, use 400 g of MnSO .2H 0 or 364 g of MnSO .HO
4- £, T- £
per liter. When uncertainty exists regarding the water
of crystallization, a solution of equivalent strength
may be obtained by adjusting the specific gravity of
the solution to 1.270 at 20°C.
6.2 Alkaline iodide solution: Dissolve 500 g of sodium hydroxide
(NaOH) or 700 g of potassium hydroxide (KOH) and 135 g of
sodium iodide (Nal) or 150 g of potassium iodide (KI) in
59
-------
(Dissolved Oxygen)
distilled water and dilute to 1 liter. To this solution add
10 g of sodium azide (NaN ) dissolved in 40 ml of distilled
water.
6.3 Sulfuric acid, concentrated.
6.4 Starch solution: Prepare an emulsion of 10 g soluble starch
in a mortar or beaker with a small quantity of distilled
water. Pour this emulsion into 1 liter of boiling water,
allow to boil a few minutes, and let settle overnight. Use
the clear supernate. This solution may be preserved by the
addition of 5 ml per liter of chloroform and storage in a
10°G refrigerator.
6.4.1 Dry, powdered starch indicators such as "thyodene"
may be used in place of starch solution.
6.5 Potassium fluoride solution: Dissolve 40 g KF.2H20 in dis-
tilled water and dilute to 100 ml.
6.6 Sodium thiosulfate. stock solution. 0.75 N: Dissnlvfi 186.15 a
^28203. SF^O in boiled and cooled distilled water and dilute
to liter. Preserve by adding 5 ml chloroform.
6.7 Sodium thiosulfate standard titrant, 0.0375 N: Prepare by
diluting 50.0 ml of stock solution to 1 liter. Preserve by
adding 5 ml of chloroform. Standard sodium thiosulfate,
exactly 0.0375 N is equivalent to 0.300 mg of DO per 1.00
ml. Standardize with 0.0375 N potassium biniodate.
6.8 Potassium biniodate standard, 0.375 N: Dissolve 4.873 g
potassium biniodate, previously dried 2 hours at 103°C, in
1.0 liter of distilled water. Dilute 250 ml to 1.0 liter for
0.0375 N biniodate solution.
60
-------
(Dissolved Oxygen)
6.9 Standardization of 0.0375 N sodium thiosulfate: Dissolve
2 g ±1.0 g KI in 100 to 150 ml distilled water; add 10 ml
of 10% H-SO. followed by 20 ml standard potassium biniodate.
Place in dark for 5 minutes, dilute to 300 ml, and titrate
with the standard sodium thiosulfate titrant to a pale straw
color. Add 1-2 ml starch solution and continue the titration
drop by drop until the blue color disappears. Run in duplicate.
Duplicate determinations should agree within ±0.05 ml.
7. Procedure
7.1 To the sample collected in the BOD incubation bottle, add 2
ml of the manganous sulfate solution followed by 2 ml of the
alkali-iodide-azide reagent, well below the surface of the
liquid; stopper with care to exclude air bubbles, and mix well
by inverting the bottle several times. When the precipitate
settles, leaving a clear supernatant above the manganese
hydroxide floe, shake again. With estuarine-type waters, a
minimum 2-minute period of contact with the precipitate
rather than settling is sufficient. When settling has produced
at least 100 ml of clear supernate, carefully remove the
stopper and immediately add 2.0 ml of cone. H-SO. (sulfamic
acid packets, 3 g may be substituted for FUSO.) *• ' by allowing
(l)Kroner, R. C., Longbottom, J. E., Gorman, R., A Comparison of Various
Reagents Proposed for Use in the Winkler Procedure for Dissolved
Oxygen, PHS Water Pollution Surveillance System Applications and
Development Report #12, Water Quality Section, Basic Data Branch,
July 1964.
61
-------
(Dissolved Oxygen)
the acid to run down the neck of the bottle, re-stopper, and
mix by gentle inversion until the iodine is uniformly dis-
tributed throughout the bottle. Complete the analysis within
45 minutes.
7.2 Transfer the entire bottle contents by inversion into a 500-ml
wide mouth Erlenmeyer flask and titrate with 0.0375 N thio-
sulfate solution (where problems of stability arise, 0.0375 N
PAO may be substituted as titrant) to a pale straw color.
Add 1-2 ml of starch solution or 0.1 g of powdered indicator
and continue to titrate to the first disappearance of the
blue color.
7.3 If ferric iron is present (100 to 200 ppm), add 1.0 ml of
KF solution before acidification.
7.4 Occasionally, a dark brown or black precipitate persists in
the bottle after acidification. This precipitate will dis-
solve if the solution is kept for a few minutes longer than
usual or, if particularly persistent, a few more drops of
H2S04 will effect dissolution.
8. Calculation
8.1 Each ml of 0.0375 sodium thiosulfate titrant is equivalent
to 1 mg/1 DO when the entire bottle contents are titrated.
8.2 If the results are desired in milliliters of oxygen gas per
liter at 0°C and 760 mm pressure, multiply mg/1 DO by 0.698.
62
-------
(Dissolved Oxygen)
8.3 To express the results as percent saturation at 760 mm
atmospheric pressure, the solubility data in Table 25
(Whipple & Whipple Table, p. 409, Standard Methods, 12th
Edition) may be used. Equations for correcting the solu-
bilities to barometric pressures other than mean sea level
are given below the table.
8.4 The solubility of DO in distilled water at any barometric
pressure, P (mm Hg), temperature, T°C, and saturated vapor
pressure, y (mm Hg), for the given T, may be calculated
between the temperature of 0° and 30°C by:
ml/1 DO = (P - U) x 0.678
35 + T
and between 30° and 50°C by:
ml/1 DO = (P - U) x 0.827
49 + T
9. Precision and Accuracy
9.1 Exact data are unavailable on the precision and accuracy of
this technique; however, reproducibility is approximately
0.2 ppm of DO at the 7.5 ppm level due to equipment toler-
ances and uncompensated displacement errors.
63
-------
DISSOLVED OXYGEN
(Probe Method)
1. Scope and Application
1.1 The probe method for dissolved oxygen is recommended for those
samples containing materials which interfere with the modified
Winkler procedure such as sulfite, thiosulfate, polythionate,
mercaptans, free chlorine or hypochlorite, organic substances
readily hydrolyzed in alkaline solutions, free iodine, in-
tense color or turbidity, biological floes, etc.
1.2 The probe method is recommended as a substitute for the modified
Winkler procedure in monitoring of streams, lakes, outfalls,
etc., where it is desired to obtain a continuous record of the
dissolved oxygen content of the water under observation.
1.3 The probe method may be used as a substitute for the modified
Winkler procedure in BOD determinations where it is desired to
perform non-destructive DO measurements on a sample.
1.4 The probe method may be used under any circumstances as a sub-
stitute for the modified Winkler procedure provided that the
probe itself is standardized against the Winkler method on
samples free of interfering materials.
1.5 The electronic readout meter for the output from dissolved
oxygen probes is normally calibrated in convenient scales
(0 to 10, 0 to 15, 0 to 20 ing/liter, for example) with a
sensitivity of approximately 0.05 mg/liter.
65
-------
(DO - Probe Method)
2. Summary of Method
2.1 The most common instrumental probes for determination of dis-
solved oxygen in water are dependent upon electrochemical
reactions. Under steady-state conditions, the current or
potential can be correlated with DO concentrations. Inter-
facial dynamics at the probe-sample interface are a factor in
probe response and a significant degree of interfacial turbu-
lence is necessary. For precision performance, turbulence
should be constant.
3. Sample Handling and Preservation
3.1 See 4.1, 4.2, 4.3, 4.4 under Modified Winkler Method.
4. Interferences
4.1 Dissolved organic materials are not known to interfere in the
output from dissolved oxygen probes.
4.2 Dissolved inorganic salts are a factor in the performance of
dissolved oxygen probe.
4.2.1 Probes with membranes respond to partial pressure of
oxygen which in turn is a function of dissolved inorganic
salts. Conversion factors for seawater and brackish waters
may be calculated from dissolved oxygen saturation
versus salinity data. Conversion factors for specific
inorganic salts may be developed experimentally. Broad
variations in the kinds and concentrations of salts in
samples can make the use of a membrane probe difficult.
66
-------
(DO - Probe Method)
/
4.2.2 The thallium probe requires the presence of salts in
concentrations which provide a minimum conductivity of
approximately 200 micromhos.
4.3 Reactive compounds can interfere with the output or the per-
formance of dissolved oxygen probes.
4.3.1 Reactive gases which pass through the membrane of
membrane probes may interfere. For example, chlorine
will depolarize the cathode and cause a high probe-
output. Long-term exposures to chlorine will coat the
anode with the chloride of the anode metal and eventu-
ally desensitize the probe. Alkaline samples in which
free chlorine does not exist will not interfere. Hydrogen
sulfide will interfere with membrane probes if the
applied potential is greater than the half-wave potential
of the sulfide ion. If the applied potential is less
than the half-wave potential, an interfering reaction
will not occur, but coating of the-anode with the sulfide
of the anode metal can take place.
4.3.2 Sulfur compounds (hydrogen sulfide, sulfur dioxide and
mercaptans, for example) cause interfering outputs from
the thallium probe. Halogens do not interfere with the
thallium probe.
4.4 At low dissolved oxygen concentrations, pH variation below
pH 5 and above pH 9 interfere with the performance of the
67
-------
(DO - Probe Method)
thallium probe (approximately ±0.05 mg/1 DO per pH unit).
The performance of membrane probes is not affected by pH
changes.
4.5 Dissolved oxygen probes are temperature sensitive, and tem-
perature compensation is normally provided by the manufac-
turer. The thallium probe has a temperature coefficient of
1.9 m/°C. Membrane probes have a temperature coefficient
of 4 to 6 percent/°C dependent upon the membrane employed.
5. Apparatus
5.1 No specific probe or accessory is especially recommended as
superior. However, probes which have been evaluated or are
in use and found to be reliable are the Weston § Stack DO
Analyzer Model 30, the Yellow Springs Instrument (YSI) Model
54, and the Delta Scientific, Model 85.
6. Calibration
Follow manufacturer instructions.
7. Procedure
Follow manufacturer instructions.
8. Calculation
Follow manufacturer instructions.
9. Precision and Accuracy
Manufacturer's specification claim 0.1 mg/1 repeatability with ±1% accuracy.
68
-------
FLUORIDE
(Automated Coraplexone Method)
1. Scope and Application
1.1 This method is applicable to surface waters, domestic and
industrial wastes, and saline waters. The applicable range
of the method is 0.05 to 1.5 mg F/l. Twelve samples per
hour can be analyzed.
2. Summary of Method
2.1 Fluoride ion reacts with the red cerous chelate of alizarin
complexone. It is unlike other fluoride procedures in that
a positive color is developed as contrasted to a bleaching
action in previous methods.
3. Sample Handling and Preservation
3.1 No special requirements.
4. Interferences
4.1 Method is free from most anionic and cationic interferences,
except aluminum, which forms an extremely stable fluoro com-
-2
pound, AIFg . This is overcome by treatment with 8-hydroxy
quinoline to complex the aluminum and by subsequent extraction
with chloroform.
69
-------
(Fluoride)
5. Apparatus
5.1 Technicon AutoAnalyzer Unit consisting of:
5.1.1 Sampler I.
5.1.2 Manifold.
5.1.3 Proportioning pump.
5.1.4 Continuous filter.
5.1.5 Colorimeter equipped with 15 mm tabular
flow cell and 650 my filters.
5.1.6 Recorder equipped with range expander.
6. Reagents
6.1 Sodium acetate solution: Dissolve 272 g (2 moles) of sodium
acetate in distilled water and dilute to 1 liter.
6.2 Acetic acid-8-hydroxyquinoline solution: Dissolve 6 g of 8-
hydroxyquinoline in 34 ml of cone, acetic acid, and dilute
to 1 liter.
6.3 Chloroform: Analytical reagent grade.
6.4 Ammonium acetate solution (6.7%): Dissolve 67 g of ammonium
acetate in distilled water and dilute to 1 liter.
6.5 Hydrochloric acid (2 N): Dilute 172 ml of cone. HC1 to 1 liter.
6.6 Lanthanum-alizarin fluoride blue solution: Dissolve 0.18 g of
alizarin fluoride blue in a solution containing 0.5 ml of cone.
ammonium hydroxide and 15 ml of 6.7% ammonium acetate. Add a
solution that contains 41 g of anhydrous sodium carbonate and 70
ml of glacial acetic acid in 300 ml of distilled water. Add 250
ml of acetone. Dissolve 0.2 g of lanthanum oxide in 12.5 of 2 N
hydrochloric acid and mix with above solution. Dilute to 1 liter.
70
-------
(Fluoride)
6.7 Stock Solution: Dissolve 2.210 g of sodium fluoride in 100
ml of distilled water and dilute to 1 liter. 1 ml = 1.0 mg F.
6.8 Standard Solution: Dilute 10.0 ml of stock solution to 1
liter. 1 ml = 0.01 mg F.
6.8.1 Using standard solution, prepare the following stan-
dards in 100-ml volumetric flasks:
mg F/l ml Standard Solution/100 ml
0.05 0.5
0.10 1.0
0.20 2.0
0.40 4.0
0.60 6.0
0.80 8.0
1.00 10.0
1.20 12.0
1.50 15.0
7. Procedure
7.1 Set up manifold as shown in Figure 1.
7.2 Allow both colorimeter and recorder to warm up for 30 minutes.
Run a baseline with all reagents, feeding distilled water
through the sample line. Adjust dark current and operative
opening on colorimeter to obtain stable baseline.
7.3 Place distilled water wash tubes in alternate openings in
Sampler and set sample timing at 2.5 minutes.
7.4 Arrange fluoride standards in Sampler in order of decreasing
concentration. Complete loading of Sampler tray with unknown
samples.
7.5 Switch sample line from distilled water to Sampler and begin
analysis.
71
-------
(Fluoride)
8. Calculation
8.1 Prepare standard curve by plotting peak heights of processed
fluoride standards against concentration values. Compute
concentration of samples by comparing sample peak heights with
standard curve.
9. Precision and Accuracy
9.1 In a single laboratory, using surface water samples at con-
centrations of 0.06, 0.15, 0.55, and 1.08 mg F/l, the stan-
dard deviation was ±0.018 (AQC Laboratory).
9.2 In a single laboratory, using surface water samples at concen-
trations of 0.14 and 1.25 mg F/l recoveries were 89% and 102%,
respectively (AQC Laboratory).
References
1. R. Greenhaigh and J. P. Riley, "The Determination of Fluorides in
Natural Waters, with Particular Reference to Sea Water." Anal.
Chim. Acta, 25_, 179 (1961).
2. K. M. Chan and J. P. Riley, "The Automatic Determination of
Fluoride in Sea Water and Other Natural Waters." Anal. Chim. Acta,
35, 365 (1966).
72
-------
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FIGURE 1. FLUORIDE MANIFOLD
-------
FLUORIDE
(Specific Ion Electrode Method)
1. Scope and Application
1.1 This method is applicable to the measurement of fluoride in
finished waters, natural waters, brines, and industrial waste
waters and the need for distillation of the sample is elimi-
nated.
1.2 Concentrations of fluoride from 0.1 up to 1000 mg/liter may
be measured.
2. Summary of Method
2.1 The fluoride is determined potentiometrically using a specific
ion fluoride electrode in conjunction with a standard single
junction sleeve-type reference electrode and a pH meter having
an expanded millivolt scale or a specific ion meter having a
direct concentration scale for fluoride.
2.2 The fluoride electrode consists of a lazer-type doped lanthanum
fluoride crystal across which a potential is developed by
fluoride ions. The cell may be represented by Ag/Ag Cl, Cl
(0.3), F" (0.001) LaF / test solution/SCE/.
o
3. Interferences
3.1 Extremes of pH interfere; sample pH should be between 5 and 9.
Polyvalent cations of Si , Fe and Al interfere by forming
complexes with fluoride. The degree of interference depends
75
-------
(Fluoride)
upon the concentration of the complexing cations, the con-
centration of fluoride and the pH of the sample. The
addition of a pH 5.0 buffer (described below) containing a
strong, chelating agent preferentially complexes aluminum
(the most common interference), silicon, and iron, and
eliminates the pH problem.
4. Sample Handling and Preservation
4.1 No special requirements.
5. Apparatus
5.1 Electrometer, (pH meter) with expanded mv scale or a specific
ion meter such as the Orion 400 Series.
5.2 Fluoride Ion Activity Electrode, such as Orion No. 94-09.
5.3 Reference electrode, single junction, sleeve-type, such as
Orion No. 90-01, Beckman No. 40454, or Corning No. 476010.
5.4 Magnetic Mixer, Teflon-coated stirring bar.
6. Reagents
6.1 Buffer solution, pH 5.0-5.5. To approximately 500 ml of
distilled water in a one-liter beaker add 57 ml of glacial
acetic acid, 58 g of sodium chloride and 2 g of CDTA •
^ 'CDTA is the abbreviated designation of 1,2-cyclohexylene dinitrilo
tetraacetic acid, produced by Mathieson, Coleman § Bell, Cat. No.
P8661.
76
-------
(Fluoride)
Stir to dissolve and cool to room temperature. Adjust pH of
solution to between 5.0 and 5.5 with 5 N sodium hydroxide
(about 150 ml will be required). Transfer solution to a
1-liter volumetric flask and dilute to the mark with dis-
tilled water. For work with brines, additional Nad should
be added to raise the chloride level to twice the highest
expected level of chloride in the sample.
Note - CDTA replaces citric acid used in the original buffer
formula. It is a strong chelating agent and more effectively
ties up aluminum than the original citric acid.
6.2 Sodium fluoride, stock solution (1.0 ml = 0.01 mg F),
7. Calibration
7.1 Prepare a series of standards using the fluoride stock solu-
tion (1 ml = 0.01 mg F) in the range of 0 to 2.00 mg/liter
by diluting appropriate volumes to 50 ml. The following
series may be used:
Milliliters of Stock Concentration when Diluted
(1.0 ml = 0.01 mg/F) to 50 ml, mg F/liter
0.00 0.00
1.00 0.20
2.00 0.40
3.00 0.60
4.00 0.80
5.00 1.00
6.00 1.20
8.00 1.60
10.00 2.00
77
-------
(Fluoride)
7.2 Calibration of Electrometer: Immerse the electrodes in each
stock solution starting with the lowest concentration and
measure the developed potential while mixing. The electrodes
must remain in the solution for at least three minutes or
until the reading has stabilized. Using semilogarithmic
graph paper, plot the concentration of fluoride in mg/liter
on the log axis vs. the electrode potential developed in the
standard on the linear axis, starting with the lowest concen-
tration at the bottom of the scale.
7.3 Calibration of a specific ion meter: Follow the directions
of the manufacturer for the operation of the instrument.
8. Procedure
8.1 Place 50.0 ml of sample and 50.0 ml of buffer in a 150-ml
beaker. Place on a magnetic stirrer and mix at medium speed.
Immerse the electrodes in the solution and observe the meter
reading while mixing. The electrodes must remain in the
solution for at least three minutes or until the reading has
stabilized. At concentrations under 0.5 ml/liter F, it may
require as long as five minutes to reach a stable meter reading;
higher concentrations stabilize more quickly. If a pH meter
is used, record the potential measurement for each unknown
sample and convert the potential reading to the fluoride ion
concentration of the unknown using the standard curve. If a
specific ion meter is used, read the fluoride level in the
unknown sample directly in mg/1 on the fluoride scale.
78
-------
(Fluoride)
\
9. Precision and Accuracy
9.1 A synthetic sample prepared by the Analytical Reference Ser-
vice, PHS, containing 0.85 mg/1 fluoride and no interferences
was analyzed by 111 different analysts; a mean of 0.84 mg/1
with a standard deviation of ±0.030 was obtained.
9.2 On the same study, a synthetic sample containing 0.75 mg/1
fluoride, 2.5 mg/1 polyphosphate and 300 mg/1 alkalinity, was
analyzed by the same 111 analysts; a mean of 0.75 mg/1
fluoride with a standard deviation of ±0.036 was obtained.
79
-------
HARDNESS, TOTAL
(Automated Eriochrome BT Method)
1. Scope and Application
1.1 This automated method is applicable to surface and saline
waters. The applicable range is 10 to 400 mg/1 as CaCO .
o
Approximately 12 samples per hour can be analyzed.
2. Summary of Method
2.1 The disodium magnesium EDTA exchanges magnesium on an equi-
valent basis for any calcium and/or other cations to form a
more stable EDTA chelate than magnesium. The free magnesium
reacts with Eriochrome Black T at a pH of 10 to give a red-
violet complex. Thus, by measuring only magnesium concen-
tration in the final reaction stream, an accurate measurement
of total hardness is possible.
3. Sample Handling and Preservation
3.1 No special requirements.
4. Interferences
4.1 No significant interferences.
5. Apparatus
5.1 Technicon AutoAnalyzer consisting of:
5.1.1 Sampler I.
5.1.2 Continuous Filter.
81
-------
(Hardness, Total)
5.1.3 Manifold.
5.1.4 Proportioning Pump.
5.1.5 Colorimeter equipped with 15 mm tubular flow cell
and 520 my filters.
5.1.6 Recorder equipped with range expander.
6. Reagents
6.1 Buffer: Dissolve 67.6 g NH4C1 in 572 ml of NhLOH and dilute
to 1 liter.
6.2 Eriochrome Black T (or Calmagite): Dissolve 0.25 g in 500 ml
of distilled water by stirring approximately 30 minutes on a
magnetic stirrer. Filter.
6.3 Magnesium EDTA: Dissolve 0.2 g of MgEDTA in 1 liter of dis-
tilled water.
6.4 Stock Solution: Weigh 1.0 g of calcium carbonate (pre-dried
at 105°C) into 500 ml Erlenmeyer flask; add 1:1 HC1 until all
CaCOj has dissolved. Add 200 ml of distilled water and boil
for a few minutes. Cool, add a few drops of methyl red indi-
cator, and adjust to the orange color with 3N NH.OH and dilute
to 1 liter. 1.0 ml = 1.0 mg CaC03.
6.4.1 Dilute each of the following volumes of stock solutions
to 250 ml for appropriate standards:
Stock Solution, ml CaC03, mg/1
2.5 10.0
5.0 20.0
10.0 40.0
15.0 60.0
25.0 100
35.0 140
50.0 200
75.0 300
100.0 400
82
-------
(Hardness, Total)
7. Procedure
7.1 Set up manifold as shown in Figure 1.
7.2 Allow both colorimeter and recorder to warm up for 30 minutes.
Run a baseline with all reagents, feeding distilled water
through the sample line. Adjust dark current and operative
opening on colorimeter to obtain stable baseline.
7.3 Place distilled water wash tubes in alternate openings in
Sampler and set sample timing at 2.5 minutes.
7.4 Arrange working standards in Sampler in order of decreasing
concentration. Complete loading of Sampler tray with unknown
samples.
7.5 Switch sample line from distilled water to Sampler and begin
analysis.
8. Calculation
8.1 Prepare standard curve by plotting peak heights of processed
standards against concentration values. Compute concentration
of samples by comparing sample peak heights with standard curve.
o
9. Precision and Accuracy
9.1 In a single laboratory (AQC), using surface water samples at
concentrations of 19, 120, 385, and 366 mg/1 as CaCO.,, the
standard deviations were ±1.5, ±1.5, ±4.5, and ±5.0, respec-
tively
9.2 In a single laboratory (AQC), using surface water samples at
concentrations, of 39 and 296 mg/1 as CaCOj, recoveries were
89% and 93%, respectively.
83
-------
(Hardness, Total)
References
1. Technicon AutoAnalyzer Methodology, Bulletin No. 2, Technicon
Controls, Inc., Chauncey, New York (July 1960).
2. Standard Methods, 12th Edition, p 147, American Public Health
Association, New York, N.Y. (1965).
84
-------
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-------
.METALS
(Atomic Absorption Methods)
1. Scope and Application
1.1 Metals in solution may be readily determined by atomic
absorption spectroscopy. The method is simple, rapid, and
applicable to a large number of metals in surface waters,
domestic and industrial wastes, and saline waters.
1.2 Detection limits, sensitivity and optimum ranges of the
metals will vary with the various makes and models of
satisfactory atomic absorption spectrophotometers. The
data shown in Table 1, however, will provide the reader
with some indication of the concentration ranges deter-
minable. In the majority of instances the concentration
range shown in the table may be extended much lower with
scale expansion and conversely extended upwards by using
a less sensitive wavelength. Sensitivity may also be ex-
tended through concentration of the sample, or through
solvent extraction techniques. Following are detection
limits, sensitivities, and the optimum concentration
ranges achieved directly on the sample using the
Instrumentation Laboratories, Model IL-153 without scale
expansion (Pos 2.5).
87
-------
(Metals)
Optimum
Concentration
Metal
Aluminum
Arsenic
Cadmium
Calcium
Chromium
Copper
Iron
Lead
Magnesium
Manganese
Potassium
Silver
Sodium
Zinc
Detection Limit
mg/1
0.1
0.25
0.001
0.003
0.01
0.005
0.004
0.01
0.0005
0.005
0.005
0.01
0.001
0.005
Sensitivity
mg/1
0.4
0.5
0.004
0.07
0.02
0.04
0.006
0.06
0.005
0.04
0.01
0.05
0.003
0.02
Range
mg/1
10
10
0.1
1
1
0.1
0.1
1
0.01 -
0.1
0.01 -
0.1
1
0.1
1000
100
2
200
200
10
20
10
2
20
2
20
200
2
2. Summary of Method
2.1 Atomic absorption spectroscopy is similar to flame emission
photometry in that a sample is aspirated into a flame and
atomized. Flame photometry, however, measures the amount of
light emitted, whereas, in atomic absorption spectrophotometry
a light beam is directed through the flame into a monochromator,
and onto a detector that measures the amount of light absorbed.
In many instances absorption is more sensitive because it de-
pends upon the presence of free unexcited atoms and generally
the ratio of unexcited to excited atoms at a given moment is
very high. Since the wavelength of the light beam is character-
istic 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.
88
-------
Metals
2.2 Although methods have been reported for the analysis of solids
by atomic absorption spectroscopy the technique generally is
limited to metals in solution or solubilized through some form
of sample processing. Thus it is a relatively simple matter to
determine metals in the soluble fraction by aspirating a
filtered portion of the water sample.
2.21 In those instances where complete characterization of a sample
is desired, the suspended material must also be analyzed. This
may be accomplished by filtration and acid digestion of the sus-
pended material. Metalic constituents in this acid digest are
subsequently determined and the sum of the dissolved plus sus-
pended concentrations will then provide the total concentrations
present
2.22 The sample may also be treated with acid before filtration to
measure what may be termed "extractable" concentrations.
3. Definition Of Terms
3.1 Sensitivity: is the concentration in milligrams of metal per
liter that produces an absorption of 1%.
3.2 Detection Limit: is defined as the concentration that produces
absorption equivalent to twice the magnitude of the fluctuation
in the background (zero absorption). •
3.3 Dissolved: those constituents which will pass through a 0.45 y
membrane filter.
3.4 Suspended: those constituents which are retained by a 0.45 y
membrane filter.
89
-------
(Metals)
3.5 Total: concentration is the sum of the concentrations in
the dissolved and suspended fraction.
3.6 Extractable: the extractable fraction is the dissolved
concentrations plus that quantity adsorbed on the surface of
the silt particles that is soluble in hot dilute mineral
acids.
4. Sample Handling and Preservation
4.1 For the determination of trace metals, contamination and
loss are of prime concern. Dust in the laboratory environ-
ment, impurities in reagents and impurities on laboratory
apparatus which the sample contacts are all sources of
potential contamination. For liquid samples, containers
can introduce either positive or negative errors in the
measurement of traee metals by (a) contributing contaminants
through leaching or surface desorption and (b) by depleting
concentrations through adsorption. Thus the collection and
treatment of the sample prior to analysis requires particular
attention. The sample bottle should be thoroughly washed
with detergent and tap water; rinsed with chromic acid, tap
water, nitric acid, tap water and finally distilled water in
that order. After collection of the sample the analyst must
decide on the type of desired data, ie., dissolved, suspended,
total or extractable, before proceeding with the sample
handling.
90
-------
(Metals)
4.11 For the determination of soluble constituents the sample
should be filtered through a 0.45 y membrane filter as soon
as practicable after collection. Use the first 50-100 ml to
rinse the filter flask. Discard this portion and collect the
required volume of filtrate. Acidify the filtrate with 1:1
redistilled nitric acid (3 ml per liter). Normally this amount
of acid will lower the pH to 2 or 3 and should be sufficient to
preserve the sample indefinitely. Analyses performed on a sam-
ple so treated shall be reported as "dissolved" concentrations.
4.12 For the determination of suspended metals a representative
volume of sample should be filtered through a 0.45 y
membrane filter. When considerable sediment is present, as
little as 100 ml of a well shaken sample is filtered.
Record the volume filtered and transfer the membrane filter
containing the sediment to a 250 ml Griffin beaker and add
3 ml distilled HNO,. Cover the beaker with a watch glass and
heat gently. The warm acid will soon dissolve the membrane.
Increase the temperature of the hot-plate ar.d digest the
material. When the acid has evaporated, cool the beaker
and watch glass and add another 3 ml of distilled HNO,.
Cover and continue heating until the digestion is complete,
generally indicated by a light colored residue. Add dis-
tilled 1:1 HC1 (2 ml) to the dry residue and again warm the
91
-------
(Metals)
beaker gently to dissolve the material. Wash down the
watch glass and beaker walls with distilled water and
filter the sample to remove silicates and other insoluble
material that would clog the atomizer. Adjust the volume
to some predetermined value based on the expected concen-
trations of trace metals present. This volume will vary
depending on the metal to be determined. The sample is
now ready for analysis. Concentrations so determined
shall be reported as "suspended". STORET parameter num-
bers for reporting this type of data are currently not
available.
4.13 To determine metals soluble in diluted hot HC1 - HNO,,
o
acidify the entire sample at the time of collection with
redistilled HNO,, 5 ml/1. At the time of analysis the
o
sample is mixed and a 100-ml aliquot transferred to a beaker
or flask. Five ml of redistilled hydrochloric acid is added
and the sample heated for 15 minutes on a steam bath or hot
plate. After this digestion period the sample is filtered
and the volume adjusted to 100 ml. The sample is then ready
for analysis.
The data so obtained are significant in terms of "total"
metals in the sample, with the reservation that something
less than "total" is actually measured. Concentrations of
metal found, especially in heavily silted samples, will be
92
-------
(Metals)
substantially higher than data obtained on only the soluble
fraction. STORE! parameter numbers for the storage of this
type data are not available.
5. Interferences
5.1 The most troublesome type of interference in atomic absorption
spectrophotometry is usually termed "chemical" and results
from lack of absorption of atoms bound in molecular combina-
tion in the flame. This phenomenon can occur when the flame
is not sufficiently 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 inter-
ference in the magnesium determination. Similarly, silica
interference in the determination of manganese can be elimi-
nated by the addition of calcium.
5.11 Chemical interferences may also be eliminated by separating
the metal from the interfering material. While complexing
agents are usually employed to increase the sensitivity of
the analysis they may also be used to eliminate or reduce
interferences.
6. Apparatus
6.1 Atomic absorption spectrophotometer: Instrumentation Laboratory,
Model IL-153 or equivalent. A satisfactory instrument will have
93
-------
(Metals)
an energy source, an atomizer burner system, a monochrometer,
and a detector.
6.2 Burner: A Boling burner is recommended for most aqueous
solutions. A premix burner is used for organic solvents.
For certain elements the nitrous oxide burner is preferred.
6.3 Volumetric flasks; 200 ml, for extraction with organic
solvents.
6.4 Glassware: All glassware, including sample bottles, should
be washed with detergent, rinsed with tap water, chromic
acid, tap water, 1:1 nitric acid, tap water and distilled
water in that order.
6.5 Borosilicate glass distillation apparatus.
7. Reagents
7.1 Deionized distilled water: Prepare by passing distilled
water through a mixed bed of cation and anion exchange
resins. Use deionized distilled water for the preparation
of all reagents, calibration standards, and as dilution
water.
7.2 Nitric acid (cone): Distill reagent grade nitric acid in a
borosilicate glass distillation apparatus. Prepared a 1:1
dilution with deionized distilled water.
7.3 Hydrochloric acid (1:1): Prepare a 1:1 solution of reagent
grade hydrochloric acid and distilled water. Distill this
mixture from a borosilicate glass distillation apparatus.
94
-------
(Metals)
7.4 Stock metal solutions: Prepare as directed in 8.1 and
under the individual metal procedures.
7.5 Standard metal solutions: Prepare a series of standards
of the metal by dilution of the appropriate stock metal
solution to cover the concentration range desired.
7.6 Fuel and oxidant: Commercial grade acetylene is generally
acceptable. Air may be supplied from a compressed air line,
a laboratory compressor, or from a cylinder of compressed
air. Reagent grade nitrous oxide is also required for
certain determinations.
7.7 Special reagents for the extraction procedure
a. Ammonium pyrrolidine dithiocarbamate solution (APDC):
Dissolve Ig APDC in 100 ml of deionized distilled water.
Prepare fresh before use.
b. Bromphenol blue indicator solution:
Dissolve 0.Ig bromphenol blue in 100 ml 50% ethanol.
c. Hydrochloric acid, 0.5N:
Mix 25 ml cone. HC1 with deionized distilled water and
dilute to 1 liter.
d. Methyl isobutyl ketone (MIBK):
Ammonium pyrrolidine dithiocarbamate (APDC) may be obtained commercially
from Fisher Scientific Company (Cat. No. A-182), K and K Labs Inc. or
Eastman Kodak.
95
-------
(Metals)
e. Sodium hydroxide, 2.5N:
Dissolve 10 g NaOH in deionized distilled water and
dilute to 100 ml.
8. Preparation of Standards and Calibration
8.1 Stock solutions are prepared from high purity metals,
oxides or nonhygroscopic reagent grade salts using redis-
tilled nitric or hydrochloric acids. Sulfuric or phosphoric
acids should be avoided as they produce an adverse effect on
many elements. The stock solutions are prepared at concen-
trations of 1000 mg/1.
8.2 Standard solutions are prepared by diluting the stock metal
solutions at the time of analysis. For best results, cali-
bration standards should be prepared fresh each time an
analysis is to be made and discarded after use. Prepare a
blank and calibration standards in graduated amounts in the
appropriate range. As the filtered samples are preserved
with redistilled nitric acid (3 ml (1:1) per liter) the acid
strength of the calibration standards should be similarly
adjusted. Beginning with the blank and working toward the
highest standard, aspirate the solutions and record the
readings. Repeat the operation with both the calibration
standards and the samples a sufficient number of times to
secure a reliable average reading for each solution.
8.3 For those instruments which do not read out directly in
concentration a calibration curve is prepared to cover the
96
-------
(Metals)
j
appropriate concentration range. Usually, this means the
preparation of standards which produce an absorption of 0
to 80 percent. The correct method for plotting data derived
from an atomic absorption instrument equipped with a linear
readout system is to convert percent absorption to absorbance
and plot the absorbance against concentration. The following
relationship is used to convert absorption values to absorbance:
absorbance = log (100/% T) = 2 - log % T
where % T = 100 - % absorption
As the curves are frequently nonlinear, especially at high
absorption values, the number of standards should be increased
in that portion of the curve.
9. General Procedure for Analysis by Atomic Absorption
9.1 Differences between the models of satisfactory atomic absorp-
tion spectrophotometers prevent the formulation of detailed
instructions applicable to every instrument. The analyst
should follow the manufacturer's operating instructions for
. his particular instrument. In general, after choosing the
correct hollow cathode lamp for the analysis, the lamp should
be allowedto warm up for a minimum of 15 minutes. During
this period, align the instrument, position the monochromator
at the correct wavelength, select the proper monochromator
slit width, adjust the hollow cathode current according to
the manufacturer's recommendation, light the flame and regulate
97
-------
('Metals)
the flow of fuel and oxidant, adjust the burner for maximum
percent absorption and stability and balance the photometer.
Run a series of standards of the element under analysis and
construct working curves by plotting the concentrations of
the standards against the absorbance. For those instruments
which read directly in concentration set the curve corrector
to read out the proper concentration. Aspirate the samples
and determine the concentrations either directly or from the
calibration curve. For best results run standards each time
a sample or series of samples are run.
9.2 Special Extraction Procedure: When the concentration of the
metal is not sufficiently high to determine directly, or when
considerable dissolved solids are present in the sample, cer-
tain of the metals may be chelated and extracted with organic
solvents. Ammonium pyrrolidine dithiocarbamate (APDC) is
widely used for this purpose and is particularly useful for
zinc, cadmium, iron, manganese, copper, silver, lead and
chromium . The most frequently used organic solvent for
APDC is methyl isobutyl ketone (MIBK). Apart from the fact
that the solvent should extract the chelate, it should burn
and provide a stable flame. In addition, the physical prop-
erties of the solvent such as viscosity, surface tension,
boiling point, and mutual solubility in an aqueous medium
must be taken into account. It should not produce toxic
products during combustion or give a high background in the
flame.
98
-------
(Metals)
9.21 Extraction Procedure with APDC
a. Pipet a volume of sample (100 ml max.) into a 200 ml
volumetric flask and adjust the volume to 100 ml with
deionized distilled water.
b. Prepare a blank and sufficient standards in the same
manner and adjust the volume of each to approximately
100 ml with deionized distilled water.
c. Add 2 drops of bromphenol blue indicator solution.
d. Adjust the pH of the sample by dropwise addition of
2.5N NaOH until a blue color persists. Add 0.3N HC1
dropwise until the blue color just disappears in both
standards and samples. Then add 2.0 ml of 0.3N HC1 in
excess.
e. Add 2.5 ml fresh APDC solution and mix.
f. Add 10.0 ml MIBK and shake vigorously for 1 minute.
g. Allow the layers to separate and add deionized distilled
water until the ketone layer is completely in the neck
of the flask.
h. Aspirate the ketone layer and record the scale readings
for each standard and sample against the prepared blank.
Repeat and average the duplicate results. Plot a cali-
bration curve in pg metal vs. absorbance.
Note:
When aspirating organic solvents the fuel-to-air ratio should
be reduced as the burning of the organic solvent contributes
to the fuel supply. When adjusting the fuel-to-air ratio of
99
-------
(Metals)
the gas mixture at the burner, begin with the settings
recommended by the manufacturer. Gradually reduce the fuel
flow while the organic solvent is being aspirated until the
flame is as blue as possible. Care should be taken that the
flame does not lift off the burner producing an undesirable
luminescent flame.
10. Calculation
10.1 Direct determination: Read the metal value in mg/1 from the
calibration curve or directly from the readout system of the
instrument.
mg/1 metal in sample = (mg/1 of metal in the aliquot) x D
where D = ml of aliquot + ml of deionized distilled water
ml of aliquot
10.2 Extracted samples: Read the metal value in Ug from the extracted
calibration curve or from the readout system of the instrument.
mg/1 metal in sample = yg metal in aliquot
ml of aliquot
11. Precision and Accuracy
11.1 Three synthetic unknown samples containing varying concen-
trations of cadmium, chromium, copper, iron, lead, magnesium,
manganese, silver, and zinc were analyzed in 59 laboratories
with the results indicated in Table 2. (Analytical Reference
Service PHS)
100
-------
(Metals)
Table 2
Precision and Accuracy Data for Atomic Absorption Methods
Metal
Metal
Concentration,
Hg/1
Relative
Error,
percent
Relative
Standard
Deviation,
percent
Direct determination
Cadmium
Chromium
Copper
Iron
Magnesium
Manganese
Silver
Zinc
Extracted samples
Cadmium
Lead
50
50
1000
300
200
50
50
500
10
50
8.15
2.29
3.42
0.64
6.30
6.00
10.57
0.41
3.03
19.00
21.62
26.44
11.23
16.53
10.49
13.50
17.47
8.15
72'. 77
23.46
101
-------
(Metals)
Aluminum - Standard Conditions
Optimum Concentration Range 10-1000 mg/1 using the 3092 A line
Sensitivity 0.4 mg/1
Detection Limit 0.1 mg/1
Preparation of Standard Solution
1. Stock Solution: Carefully weigh 1.000 gram of aluminum
metal (analytical reagent grade). Add 15 ml of concen-
trated HC1 to the metal in a covered beaker and warm
gently. When solution is complete, transfer quantitatively
to a 1 liter volumetric flask and make up to volume with
distilled water. One ml equals 1 mg Al.
2. Prepare dilutions of the stock solution to be used as
calibration standards at the time of analysis. Maintain
an acid strength of 0.15% nitric acid in all calibration
standards.
Instrumental Parameters (General)
1. Aluminum hollow cathode lamp
2. Wavelength: 3092 A
3. Type of burner: Nitrous oxide
4. Fuel: Acetylene
5. Oxidant: Nitrous oxide
6. Type of flame: Fuel rich
7. Photomultiplier tube: IP-28
102
-------
(Metals)
Notes
1. The following lines may also be used
3082 A Relative Sensitivity 1
3962 A Relative Sensitivity 2
3944 A Relative Sensitivity 2.5
103
-------
(Metals)
Arsenic - Standard Conditions
Optimum Concentration Range 10-100 mg/1 using the 1937 A line
Sensitivity 0.5 mg/1
Detection Limit 0.25 mg/1
Preparation of Standard Solution
1. Stock Solution: Dissolve 1.320 grams of arsenic trioxide
(AsJD,, analytical reagent grade) in a small quantity of
distilled water in which a pellet of NaOH has previously
been dissolved. When solution is complete acidify with
HC1 and make up to 1 liter with distilled water. One ml
equals 1 mg As (1000 mg/1.
2. Prepare dilutions of the stock solution to be used as
calibration standards at the time of analysis. Do not
acidify with nitric acid.
Instrumental Parameters (General)
1. Arsenic hollow cathode lamp
2. Wavelength: 1937 A
3. Type of burner: Doling
4. Fuel: Hydrogen
5. Oxidant: Argon
6. Type of flame: Fuel rich
7. Photomultiplier tube: R-106
104
-------
(Metals)
Notes
1. The R-106 photomultiplier tube is more sensitive to UV
light and therefore is suggested in place of the IP-28
phototube.
2. The presence of nitric acid causes interference in the
argon-hydrogen system, therefore a separate sample pre-
served with HC1 should be analyzed.
3. Samples high in total salt content (above 1%) will
produce an apparent absorption at the 1937 A arsenic
line even when the element is absent. It is necessary,
therefore, to correct absorption readings at low ab-
sorptions by subtracting the signal obtained at a
neighboring, nonabsorbing line.
4. The high-solids burner is reported to give lower
detection limits.
105
-------
(Metals)
Cadmium - Standard Conditions
Optimum Concentration Range 0.1-1 mg/1 using the 2288 A line
Sensitivity 0.004 mg/1
Detection Limit 0.001 mg/1
Preparation of Standard Solution
1. Stock Solution: Carefully weigh 1.142 gram of cadmium
oxide (CdO, analytical reagent grade) and dissolve in
5 ml redistilled HNO . Dilute to 1 liter with distilled
water. One ml equals 1 mg Cd.
2. Prepare dilutions of the stock solution to be used as
calibration standards at the time of analysis. Maintain
an acid strength of 0.15% nitric acid in all calibration
standards.
Instrumental Parameters (General)
1. Cadmium hollow cathode lamp
2. Wavelength: 2288 A
3. Type of burner: Boling
4. Fuel: Acetylene
5. Oxidant: Air
6. Type of flame: Oxidizing
7. Photomultiplier tube: IP-28
106
-------
(Metals)
Calcium - Standard Conditions
Optimum Concentration Range 1.0-200 mg/1 using the 4227 A line
Sensitivity 0.07 mg/1
Detection Limit 0.003 mg/1
Preparation of Standard Solution
1. Stock Solution: Suspend 1.250 grams of CaCO, (analytical
reagent grade), dried at 180 C for 1 hour before weighing,
in distilled water and dissolve cautiously with a minimum
of dilute HC1. Dilute to 1000 ml with distilled water.
One ml equals 0.5 mg of Ca (500 mg/1).
2. Lanthaum chloride solution: Dissolve 29 g of La?0 , slowly
^ -J
and in small portions, in 250 ml concentrated HC1. (Caution!
Reaction is violent) and dilute to 500 ml with distilled water.
3. Prepare dilutions of the stock calcium solution to be used as
calibration standards at the time of analysis. To each cali-
bration standard solution, add 1.0 ml of Lad, solution for
each 10 ml of volume of working standard, ie., 20 ml working
standard + 2 ml Lad- = 22 ml.
Instrumental Parameters (General)
1. Calcium hollow cathode lamp
2. Wavelength: 4227 A
3. Type of burner: Boling
4. Fuel: Acetylene
5. Oxidant: Air
6. Type of flame: Reducing
7. Photomultiplier tube: IP-28
107
-------
(Metals)
Notes
1. Phosphate, sulfate and aluminum interfere but are masked
by the addition of lanthanum. Since low calcium values
result if the pH of the sample is above 7, both standards
and samples are prepared in dilute hydrochloric acid
solution. Concentrations of magnesium greater than 1000
mg/1 also cause low calcium values. Concentrations of up
to 500 mg/1 each of sodium, potassium and nitrate cause no
interference.
2. Anionic chemical interferences can be expected if lanthanum
is not used in samples and standards.
3. The nitrous oxide-acetylene flame will provide two to five
times greater sensitivity and freedom from chemical inter-
ferences, lonization interferences should be controlled
by adding a large amount of alkali to the samples and
standards. The analysis appears to be free from chemical
supressions in the nitrous oxide - acetylene flame.
4. The 2399 A line may also be used. This line has a sensitivity
of 20 mg/1.
108
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(Metals)
Chromium - Standard Conditions
Optimum Concentration Range 1.0-200 mg/1 using the 3579 A line
Sensitivity 0.02 mg/1
Detection Limit 0.01 mg/1
Preparation of Standard Solution
1. Stock Solution: Dissolve 1.923 gram of chromium trioxide
(CrO_, reagent grade) in distilled water. When solution
is complete acidify with redistilled HNO, and dilute to 1
liter with distilled water. One ml equals 1 mg chromium.
2. Prepare dilutions of the stock solution to be used as
calibration standards at the time of analysis. Maintain
an acid strength of 0.15% nitric acid in all calibration
standards.
Instrumental Parameters (General)
1. Chromium hollow cathode lamp
2. Wavelength: 3579 A
3. Type of burner: Doling
4. Fuel: Acetylene
5. Oxidant: Air
6. Type of flame: Slightly fuel rich
7. Photomultiplier tube: IP-28
109
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(Metals)
Notes
1. The following wavelengths may also be used
3605 A Relative Sensitivity 1.2
3593 A Relative Sensitivity 1.4
4254 A Relative Sensitivity 2
4274 A Relative Sensitivity 3
4289 A Relative Sensitivity 4
2. The determination of chromium requires a rich acetylene
flame. The absorption is very sensitive to the fuel-to-
air ratio.
3. The absorption of chromium is suppressed by iron and nickel.
If the analysis is performed in a lean flame the inter-
ference can be lessened but the sensitivity will also be
reduced. The interference does not exist in a nitrous oxide -
acetylene flame.
110
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(Metals)
Copper - Standard Conditions
Optimum Concentration Range 0.1-10 mg/1 using the 3247 A line
Sensitivity 0.04 mg/1
Detection Limit 0.005 mg/1
Preparation of Standard Solution
1. Stock Solution: Carefully weigh 1.00 gram of electrolytic
copper (analytical reagent grade). Dissolve in 5 ml re-
distilled HNO, and make up to 1 liter with distilled water.
Final concentration is 1 mg Cu per ml (1000 mg/1).
2. Prepare dilutions of the stock solution to be used as
calibration standards at the time of analysis. Maintain
an acid strength of 0.15% nitric acid in all calibration
standards.
Instrumental Parameters (General)
1. Copper hollow cathode lamp
2. Wavelength: 3247 A
3. Type of burner: Boling
4. Fuel: Acetylene
5. Oxidant: Air
6. Type of flame: Oxidizing
7. Photomultiplier tube: IP-28
111
-------
(Metals)
Notes
1. For copper concentrations below 0.05 mg/1, the extraction
procedure is suggested.
2. Copper atoms are distributed over a wider area in laminar
flow-flames than that normally found. Consequently, the
burner parameters are not as critical as for most other
elemental determinations.
3. Because of the spectral intensity of the 3247 A line, the
P.M. tube may become saturated. If this situation occurs
the current should be decreased.
4. Numerous absorption lines are available for the deter-
mination of copper. By selecting a suitable absorption
wavelength, copper samples may be analyzed over a very
wide range of concentration. The following lines may be
used.
3264 A Relative Sensitivity 2
2178 A Relative Sensitivity 4
2165 A Relative Sensitivity 7
2181 A Relative Sensitivity 9
2225 A Relative Sensitivity 20
2024 A Relative Sensitivity 20
2492 A Relative Sensitivity 90
112
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(Metals)
Iron - Standard Conditions
Optimum Concentration Range 0.1-20 mg/1 using the 2483 A line
Sensitivity 0.006 mg/1
Detection Limit 0.004 mg/1
Preparation of Standard Solution
1. Stock Solution: Carefully weigh 1.000 gram of pure iron
wire (analytical reagent grade) and dissolve in 5 ml re-
distilled HNO,, warming if necessary. When solution is
complete make up to 1 liter with distilled water. One ml
equals 1 mg Fe.
2. Prepare dilutions of the stock solution to be used as
calibration standards at the time of analysis. Maintain
an acid strength of 0.15% nitric acid in all calibration
standards.
Instrumental Parameters (General)
1. Iron hollow cathode lamp
2. Wavelength: 2483 A
3. Type of burner: Boling
4. Fuel: Acetylene
5. Oxidant: Air
6. Type of flame: Oxidizing
7. Photomultiplier tube: IP-28
113
-------
(Metals)
Notes
1. The following lines may also be used
2488 A Relative Sensitivity 2
2522 A Relative Sensitivity 2
2719 A Relative Sensitivity 4
3021 A Relative Sensitivity 5
2527 A Relative Sensitivity 6
2721 A Relative Sensitivity 9
3720 A Relative Sensitivity 10
2967 A Relative Sensitivity 12
3860 A Relative Sensitivity 20
3441 A Relative Sensitivity 30
2. Absorption is strongly dependent upon the lamp current.
3. Better signal-to-noise can be obtained from a neon-filled
hollow cathode lamp than from an argon-filled lamp.
114
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(Metals)
Lead - Standard Conditions
Optimum Concentration Range 1-10 mg/1 using the 2170 A line
Sensitivity 0.06 mg/1
Detection Limit 0.01 mg/1
Preparation of Standard Solution
1. Stock Solution: Carefully weigh 1.599 gram of analytical
reagent grade lead nitrate (Pb(NO,)_,) and dissolve in re-
distilled water. When solution is complete acidify with
10 ml redistilled HN03 and dilute to 1 liter with distilled
water. One ml equals 1 mg Pb (1000 mg/1).
2. Prepare dilutions of the stock solution to be used as
calibration standards at the time of analysis. Maintain
an acid strength of 0.15% nitric acid in all calibration
standards.
Instrumental Parameters (General)
1. Lead hollow cathode lamp
2. Wavelength: 2170
3. Type of burner: Boling
4. Fuel: Acetylene
5. Oxidaht.c. Air
6. Type of flame: Slightly oxidizing
7. Photomultiplier tube: IP-28
115
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(Metals)
Notes
1. The analysis of this metal is exceptionally sensitive to
turbulence and absorption bands in the flame. Therefore,
some care should be taken to position the light beam in
the most stable, center portion of the flame. To do this,
first adjust the burner to maximize the absorbance reading
with a lead standard. Then, aspirate a water blank and
make minute adjustments in the burner alignment to
minimize the signal.
2. Better analytical results with the 2170 A line may be
obtained by using a R-106 photomultiplier tube which is
more sensitive to UV light.
3. For lead concentrations below 0.2 mg/1, the extraction
procedure is suggested.
4. The following lines may also be used
2833 A Relative Sensitivity 2
2614 A Relative Sensitivity 500
3683 A Relative Sensitivity 900
116
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(Metals)
Magnesium - Standard Conditions
Optimum Concentration Range 0.01-2 mg/1 using the 2852 A line
Sensitivity 0.005 mg/1
Detection Limit 0.0005 mg/1
Preparation of Standard Solution
1. Stock Solution: Dissolve 0.829 g of magnesium oxide, MgO
(analytical reagent grade) in 10 ml of redistilled HNO
O
and dilute to 1 liter with distilled water. One ml equals
0.50 Mg.
2. Lanthanum chloride solution: Dissolve 29 g of La_0 ,
^ •_)
slowly and in small portions in 250 ml concentrated HC1.
(Caution! Reaction is violent) and dilute to 500 ml with
distilled water.
3. Prepare dilutions of the stock magnesium solution to be
used as calibration standards at the time of analysis.
To each calibration standard solution, add 1.0 ml of
LaCl_ solution for each 10 ml of volume of working stan-
O
dard, ie., 20 ml working standard + 2 ml LaCl_ = 22 ml.
Instrumental Parameters (General)
1. Magnesium hollow cathode lamp
2. Wavelength: 2852 A
3. Type of burner: Boling
4. Fuel: Acetylene
5. Oxidant: Air
6. Type of flame: Reducing
7. Photomultiplier tube: IP-28
117
-------
(Metals)
Notes
1. Analytical sensitivity decreases with increased lamp
current.
2. The interference caused by aluminum at concentrations
greater than 2 mg/1 is masked by addition of lanthanum.
Since low magnesium values result if the pH of the sam-
ples is above 7, both standards and samples are prepared
in dilute hydrochloric acid. Sodium, potassium and
calcium cause no interference at concentrations less
than 400 mg/1.
3. Because of the spectral intensity of the 2852 line,
the P.M. tube may become saturated. If this situation
occurs, the current should be decreased.
4. The following lines may also be used
2025 A Relative Sensitivity 250
7025 A Relative Sensitivity 250
2796 A Relative Sensitivity 1000
5. To cover the range of magnesium values normally observed
in surface waters (0.1-20 mg/1), it is suggested that
the burner be rotated 55°.
118
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(Metals)
Manganese - Standard Conditions
Optimum Concentration Range 0.1-20 mg/1 using the 2795 A line
Sensitivity 0.04 mg/1
Detection Limit 0.005 mg/1
Preparation of Standard Solution
1. Stock Solution: Carefully weigh 1.583 gram of analytical
reagent grade manganese dioxide, MnC" and dissolve in 10 ml
of HC1. When solution is complete dilute to 1 liter with
distilled water. One ml equals 1 mg Mn.
2. Prepare dilutions of the stock solution to be used as cali-
bration standards at the time of analysis. Maintain an
acid strength of 0.15% nitric acid in all calibration
standards.
Instrumental Parameters (General)
1. Manganese hollow cathode lamp
2. Wavelength: 2795 A
3. Type of burner: Boling
4. Fuel: Acetylene
5. Oxidant: Air
6. Type of flame: Oxidizing
7. Photomultiplier tube: IP-28
Notes
1. For manganese concentrations below 0.01 mg/1, the extraction
procedure is suggested. The extraction is carried out at pH
4.5-5.
2. Analytical sensitivity is somewhat dependent on lamp current.
119
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(Metals)
Potassium - Standard Conditions
Optimum Concentration Range 0.01-2 mg/1 using the 7665 A line
Sensitivity 0.01 mg/1
Detection Limit 0.005 mg/1
Preparation of Standard Solutions
1. Stock Solution: Dissolve 0.1907 grains of KC1 (analytical
reagent grade), dried at 110 C, in distilled water and
make up to 1 liter. One ml equals 0.10 mg of potassium
(100 mg/1).
2. Prepare dilutions of the stock solution to be used as
calibration standards at the time of analysis.
Instrumental Parameters (General)
1. Potassium hollow cathode lamp
2. Wavelength: 7665 A
3. Type of burner: Boling
4. Fuel: Acetylene
5. Oxidant: Air
6. Type of flame: Slightly oxidizing
7. Photomultiplier tube: IP-21
120
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(Metals)
Notes
1. If an IP-21 photodetector tube is not available, the IP-28
may be used. This will result in some loss of sensitivity.
2. The Osram potassium vapor-discharge lamp may also be used
in the Perkin-Elmer 303. In this case the lamp current
should be 350 ma or the optimum operating current.
3. Sodium may interfere if present at much higher levels than
the potassium. This effect can be avoided by approximately
matching the sodium content of the potassium standards with
that of the sample.
4. Potassium absorption is enhanced in the presence of Na, Li
and Cs, especially in a high-temperature flame. This en-
hancement effect of sodium can be eliminated by changing
the burner height and the type of flame used. The burner
assembly is set approximately 0.05 cm below the optical
light path so that the optical light path is sliced at the
bottom by the burner head. A fuel-rich flame is used (303-
burner, airflow 7.5, acetylene flow 9.0).
5. The 4044 A line may also be used. This line has a sensitivity
of 5 mg/1 for 1% absorption.
6. To cover the range of potassium values normally observed in
surface waters (0.1-20 mg/1), it is suggested that the burner
be rotated 75 .
121
-------
(Metals)
Silver - Standard Conditions
Optimum Concentration Range 0.1-20 mg/1 using the 3281 A line
Sensitivity 0.05 mg/1
Detection Limit 0.01 mg/1
Preparation of Standard Solution
1. Stock Solution: Dissolve 1.575 g of AgNO, (analytical
reagent grade) in distilled water, add 10 ml HNO, and
make up to 1 liter. One ml equals 1 mg of silver.
2. Prepare dilutions of the stock solution to be used as
calibration standards at the time of analysis. Maintain
an acid strength of 0.15% HNO_ in all calibration
standards.
Instrumental Parameter (General)
1. Silver hollow cathode lamp
2. Wavelength: 3281 A
3. Type of burner: Boling
4. Fuel: Acetylene
5. Oxidant: Air
6. Type of flame: Oxidizing
7. Photomultiplier tube: IP-28
122
-------
(Metals)
Notes
1. The 3382 A line may also be used. This line has a
relative sensitivity of 3.
2. Silver nitrate standards are light sensitive.
Dilutions of the stock solution should be discarded
after use as concentrations below 10 mg/1 are not
stable over long periods of storage.
123
-------
(Metals)
Sodium - Standard Conditions
Optimum Concentration Range 1.0-200 mg/1 using the 3302 A line
Sensitivity 0.003 mg/1
Detection Limit 0.001 mg/1
Preparation of Standard Solutions
1. Stock Solution: Dissolve 2.542 g of NaCl (analytical reagent
grade), dried at 140°C, in distilled water and make up to 1
liter. One ml equals 1 mg of sodium.
2. Prepare dilutions of the stock solution to be used as
calibration standards at the time of analysis.
Instrumental Parameters (General)
1. Sodium hollow cathode lamp
2. Wavelength: 3302 A
3. Type of burner: Doling
4. Fuel: Acetylene
5. Oxidant: Air
6. Type of flame: Oxidizing
7. Photomultiplier tube: IP-28
124
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(Metals)
Notes
1. For the Perkin-Elmer instrument the "290" burner is
used to increase the concentration range of sodium
using the most sensitive line 5890. The burner is
installed perpendicular (rotated 90 ) to the light
path. The upper concentration limit is 60 mg/1.
without sample dilution.
2. The 3302 A resonance line of sodium yields a sensitivity
of about 5 mg/1 sodium for 1% absorption and provides a
convenient way to avoid the need to dilute more concen-
trated solutions of sodium.
3. Low-temperature flames increase sensitivity by reducing
the extent of ionization of this easily ionized metal.
4. For more sensitivity the IP-21 photomultiplier tube and
the 5890 A line may be used to extend the range to 0.005-
0.2 mg/1.
125
-------
Zinc - Standard Conditions
Optimum Concentration Range 0.1-2 mg/1 using the 2139 A line
Sensitivity 0.02 mg/1
Detection Limit 0.005 mg/1
Preparation of Standard Solution
1. Stock Solution: Carefully weigh 1.00 gram of analytical
reagent grade zinc metal and dissolve cautiously in 10 ml
MHO,. When solution is complete make up to 1 liter with
distilled water. One ml equals 1 mg Zn.
2. Prepare dilutions of the stock solution to be used as
calibration standards at the time of analysis. Maintain
an acid strength of 0.15% HNO in all calibration standards,
Instrumental Parameters (General)
1. Zinc hollow cathode lamp
2. Wavelength: 2139 A
3. Type of burner: Doling
4. Fuel: Acetylene
5. Oxidant: Air
6. Type of flame: Oxidizing
7. Photomultiplier tube: IP-28
Notes
1. High levels of silicon may interfere.
2. The air-acetylene flame absorbs about 25% of the energy at
the 2139 A line.
3. The sensitivity may be increased by the use of low-
temperature flames.
126
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NITROGEN-AMMONIA
(Distillation Procedure)
1. Scope and Application
1.1 This distillation method covers the determination of
ammonia-nitrogen, exclusive of total Kjeldahl nitrogen, in
surface waters, domestic and industrial wastes, and saline
waters. It is the method of choice where economics and
sample-load do not warrant the use of automated equipment.
1.2 The method covers the range from about 0.05 to 1.0 mg/1
NH /N per liter for the colorimetric procedures and from
o
1.0 to 25 mg/1 for the titrimetric procedure.
1.3 This method is described for macro glassware; however,
micro distillation equipment may also be used.
2. Summary of Method
2.1 The sample is buffered at a pH of 9.5 with a borate buffer
in order to decrease hydrolysis of cyanates and organic
nitrogen compounds, and is then distilled into a solution
of boric acid. The ammonia in the distillate can be
determined either colorimetrically by nesslerization or
titrimetrically with standard sulfuric acid with the use
of a mixed indicator, the choice between these two
procedures depending on the concentration of the ammonia.
127
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(Nitrogen-Ammonia)
3. Sample Handling and Preservation
3.1 Until more conclusive data is obtained samples may be
preserved by addition of 40 mg HgCl- and stored at 4CC.
If only ammonia is to be determined on the sample it may
be preserved with 1.0 ml of concentrated H2SO. per liter
and stored at 4°C.
4. Interferences
4.1 A number of aromatic and aliphatic amines, as well as
other compounds, both organic and inorganic, will cause
turbidity upon the addition of Nessler reagent, so direct
nesslerization (i.e., without distillation), has been
discarded as an official method.
4.2 Cyanate, which may be encountered in certain industrial
effluents, will hydrolyze to some extent even at the pH
of 9.5 at which distillation is carried out. Volatile
alkaline compounds such as hydrazine will influence the
titrimetric results. Some volatile compounds, such as
certain ketones, aldehydes, and alcohols, may cause an
off-color upon nesslerization in the distillation method.
Some of these, such as formaldehyde, may be eliminated by
boiling off at a low pH prior to distillation and
nesslerization.
4.3 Residual chlorine must also be removed by pre-treatment
of the sample with sodium thiosulfate before distillation.
128
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(Nitrogen-Ammonia)
4.4 If the sample has been preserved with a mercury salt, the
mercury ion must be complexed with sodium thiosulfate
prior to distillation.
5. Apparatus
5.1 An all-glass distilling apparatus with an 800-1000 ml
flask.
5.2 Spectrophotometer or filter photometer for use at 425 mp
and providing a light path of 1 cm or more.
5.3 Nessler tubes: Matched Nessler tubes (APHA Standard)
about 300 mm long, 17 mm inside diameter, and marked at
225 mm ± 1.5 mm inside measurement from bottom.
5.4 Erlenmeyer flasks: The distillate is collected in 500 ml
glass-stoppered flasks. These flasks should be marked at
the 350 and the 500 ml volumes. With such marking, it is
not necessary to transfer the distillate to volumetric
flasks.
6. Reagents
6.1 Distilled water should be free of ammonia. Such water is
best prepared by passage through an ion exchange column
containing a strongly acidic cation exchange resin mixed
with a strongly basic anion exchange resin. Regeneration
of the column should be carried out according to the
manufacturer's instructions.
129
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(Nitrogen-Ammonia)
6.2 Ammonium chloride, stock solution, (1.0 ml = 1.00 mg NH,-N)
O
Dissolve 3.819 g NH.C1 in water and bring to volume in a
1 liter volumetric flask for use as a stock solution.
6.3 Ammonium chloride, standard solution, (1.0 ml = 0.01 mg).
Dilute 10 ml of this stock solution to 1 liter in a
volumetric flask for use as the standard ammonium chloride
solution.
6.4 Boric acid solution (20 g/1). - Dissolve 20 g H B0_ in
water and dilute to 1 liter.
6.5 Mixed indicator. - Mix 2 volumes of 0.2 percent methyl red
in 95 percent ethyl alcohol with 1 volume of 0.2 percent
methylene blue in 95 percent ethyl alcohol. This solution
should be prepared fresh every 30 days.
Note 1 - Specially denatured ethyl alcohol conforming to
Formula 3A or 30 of the U.S. Bureau of Internal Revenue
may be substituted for 95 percent ethanol.
6.6 Nessler reagent. - Dissolve 100 g of mercuric iodide and.
70 g of potassium iodide in a small amount of water. Add
this mixture slowly, with stirring, to a cooled solution
of 160 g of NaOH in 500 ml of water. Dilute the mixture
to 1 liter. If this reagent is stored in a Pyrex bottle
out of direct sunlight, it will remain stable for a period
of up to 1 year.
Note 2 - This reagent should give the characteristic color
130
-------
(Nitrogen-Ammonia)
with ammonia within 10 minutes after addition, and
should not produce a precipitate with small amounts of
ammonia (0.04 mg in a 50 ml volume).
6.7 Borate buffer. - Add 88 ml of 0.1 N NaOH solution to
500 ml of 0.025 M sodium tetraborate solution (5.0 g
Na-B.O- per liter) and dilute to 1 liter.
6.8 Sulfuric acid, standard1 solution, (0.02 N, 1 ml = 0.28 mg
NH,-N). Prepare a stock solution of approximately 0.1 N
acid by diluting 3 ml of concentrated H SO. (sp. gr. 1.84)
to 1 liter with (XL-free distilled water. Dilute 200 ml of
this solution to 1 liter with CO--free distilled water.
Standardize the approximately 0.02 N acid so prepared
against 0.0200 N Na-CO solution. This last solution is
prepared by dissolving 1.060 g anhydrous Na_CO_, oven-dried
at 140°C, and diluting to 1 liter with C02-free distilled
water.
Note 3 - An alternate and perhaps preferable method is to
standardize the approximately 0.1 N H^SO. solution against
a 0.100 N Na-CO solution. By proper dilution the 0.0200
N acid can then be prepared.
6.9 Sodium hydroxide, 1 N. Dissolve 40 g NaOH in ammonia-free
water and dilute to 1 liter.
6.10 Dechlorinating reagents. A number of dechlorinating
reagents may be used to remove residual chlorine prior to
131
-------
(Nitrogen-Ammonia)
distillation. These include:
(a) Sodium thiosulfate (1/70 N) : Dissolve 3.5 g
Na.S-O, in ammonia-free water and dilute to 1
liter. One ml of this solution will remove 1
mg/1 of residual chlorine in 500 ml of sample.
(b) Sodium arsenite (1/70 N): Dissolve 1.0 g NaAsO_
in ammonia-free water and dilute to 1 liter.
7. Procedure
7.1 Preparation of equipment. - Add 500 ml of ammonia-free
water to an 800 ml Kjeldahl flask. The addition of
boiling chips which have been previously treated with
dilute NaOH will prevent bumping. Steam out the
distillation apparatus until the distillate shows no
trace of ammonia with Nessler reagent.
7.2 Sample preparation. - To 400 ml of sample add 1 N NaOH
until the pH is 9.5, checking the pH during addition with
a pH meter or by use of a short range pH paper.
7.3 Distillation. - Transfer the sample, the pH of which has
been adjusted to 9.5, to an 800 ml Kjeldahl flask and add
25 ml of the borate buffer. Distill 300 ml at the rate of
6-10 ml/min. into 50 ml of 2% boric acid contained in a
500 ml glass stoppered Erlenmeyer flask. Dilute the
distillate to 500 ml in the flask and nesslerize an aliquot
to obtain an approximate value of the ammonia-nitrogen
132
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(Nitrogen-Ammonia)
concentration. For concentrations above 1.0 mg/1 the
ammonia should be determined titrimetrically. For concen-
trations below this value it is determined colorimetrically,
7.4 Determination of ammonia in distillate. - Determine the
ammonia content of the distillate either titrimetrically
or colorimetrically as described below. (See 7.4.1 and
7.4.2).
7.4.1 Titrimetric determination. Add 3 drops of the
mixed indicator to the distillate and titrate the
ammonia with the 0.02 N H^SO., matching the end
point against a blank containing the same volume
of ammonia-free water and H,BO, solution.
7.4.2 Colorimetric determination. Prepare a series of
Nessler tube standards as follows:
ml of Standard Cone., When Diluted to
1.0 ml = 0.01 mg NH3/N 50.0 ml, mg NH3/N/liter
0.0 (Blank) 0.0
0.2 0.04
0.5 0.10
1.0 0.20
1.5 0.30
2.0 0.40
3.0 0.60
4.0 0.80
Dilute each tube to 50 ml with ammonia-free water,
add 1.0 ml of Nessler reagent and mix. After 20
minutes read the optical densities at 425 my
133
-------
(Nitrogen-Ammonia)
against the blank. From the values obtained
plot optical density (absorbance) vs concentration
for the standard curve.
7.4.3 It is not imperative that all standards be distilled
in the same manner as the samples. It is recommended
that at least 2 standards Ca high and low) be dis-
tilled and compared to similar values on the curve
to insure that the distillation technique is
reliable. If distilled standards do not agree with
undistilled standards the operator should find the
cause of the apparent error before proceeding.
7.5 Determine the ammonia in the distillate by nesslerizing
50 ml or an aliquot diluted to 50 ml and reading the
optical density at 425 my as described above for the
standards. Ammonia-nitrogen content is read from the
standard curve.
8. Calculations
8.1 Titrimetric
mg/1 NH--N = A x 0.28 x 1000
6 S
in which:
A = ml 0.02 N H SO used
S = ml sample
134
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(Nitrogen-Ammonia)
8.2 Spectrophotometric
mg/1 NH -N = A x 1000
0.8 S
in which:
A = mg NH -N read from standard curve
S = volume of distillate nesslerized
9. Precision and Accuracy
9.1 Precision and accuracy data are not available at this time,
135
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NITROGEN, AMMONIA
(Automated Method)
1. Scope and Application
1.1 This method pertains to the determination of ammonia present
in surface and saline waters. Depending upon the selection of
the size of flow cell, and extent of dilution, concentrations
in the range between .01 and 20 mg/liter N present as NH, may
be determined.
2. Summary of Method
2.1 The intensity of the indophenol blue color , formed by the
reaction of ammonia with alkaline phenol hypochlorite, is meas-
ured. Sodium nitroprusside is used to intensify the blue color.
3. Sample Handling and Preservation
3.1 Preservation by addition of 40 mg HgC^ per liter and re-
frigeration at 4°C.
4. Interferences
4.1 In sea water, calcium and magnesium ions are present in concen-
trations sufficient to cause precipitation problems during the
analysis. This problem is eliminated by using 5% EDTA.
4.2 Any marked variation in acidity or alkalinity among samples
should be eliminated, since the intensity of the color used
to quantify the concentration is pH dependent. Likewise, the
137
-------
(Nitrogen, Ammonia)
pH of the wash water and the standard ammonia solutions should
approximate that of the samples. For example, if the samples
have been preserved with 1 ml concentrated H-SO./liter, the
wash water and standards should also contain 1 ml cone. F^SO./
5. Apparatus
5.1 Technicon AutoAnalyzer Unit consisting of:
5.1.1 Sampler.
5.1.2 Manifold.
5.1.3 Proportioning pump.
5.1.4 Heating bath with double delay coil.
5.1.5 Colorimeter equipped with 15 mm tubular flow cell and
630 or 650 my filters.
5.1.6 Recorder.
6. Reagents
6.1 Distilled Water: Special precaution must be taken to insure
that distilled water is free of ammonia. Such water is pre-
pared by passage of distilled water through an ion exchange
column comprised of a mixture of both strongly acidic cation
and strongly" basic anion exchange resins. Since organic con-
tamination may interfere with this analysis, use of the resin
Dowex XE-75 or equivalent which also tends to remove organic
impurities is advised. The regeneration of the ion exchange
column should be carried out according to the instruction of
the manufacturer.
138
-------
(Nitrogen, Ammonia)
6.2 Segmenting Fluid: Air scrubbed with 5N H~SO.. Ammonia free
concentrated sulfuric acid and ammonia free distilled water
used in the acid preparation.
6.3 Sodium Phenolate: Using a 1 liter Erlenmeyer flask, dissolve
83 g phenol in 500 ml distilled water. In small increments,
cautiously add with agitation, 32 g of NaOH. Periodically,
cool flask under water faucet. When cool, dilute to 1 liter.
6.4 Sodium Hypochlorite Solution ("Chlorox"): Dilute 100 ml of
5% "Chlorox" to 500 ml with distilled water. Available chlorine
level should approximate 1%. Since "Chlorox" is a proprietary
product and its formulation is subject to change, the analyst
must remain alert to detecting any variation in this product
significant to its use in this procedure.
6.5 EDTA (5%): Dissolve 50 g of EDTA (disodiumsalt) and approxi-
mately six pellets of NaOH in 1 liter of ammonia-free water.
6.6 Sodium Nitroprusside (0.005%): Dissolve 0.05 g of sodium
nitroprusside in 1 liter of ammonia-free water.
6.7 Stock Solution: Dissolve 3.819 g of anhydrous ammonium
chloride, NhLCl, dried at 105°C, in ammonia-free water, and
dilute to 1 liter. 1 ml = 1.0 mg NHj-N.
6.8 Standard Solution A: Dilute 10.0 ml of stock solution to 1
liter with ammonia-free water. 1 ml - .01 mg NH,-N.
6.9 Standard Solution B: Dilute 10.0 ml of standard solution A
to 100 ml with ammonia-free water. 1 ml = .001 mg NH--N.
139
-------
(Nitrogen, Ammonia)
6.10 Using standard solutions A and B, prepare the following stan-
dards in 100 ml volumetric flasks (prepare fresh each week):
NH3-N, mg/1 ml Standard Solution/100 ml
Solution B
0.01 1.0
0.02 2.0
0.05 5.0
0.10 10.0
Solution A
0.20 2.0
0.50 5.0
0.80 8.0
1.00 10.0
1.50 15.0
2.00 20.0
Note: When saline water samples are analyzed, Substitute
Ocean Water (SOW) should be used for preparing the above
standards used for the calibration curve; otherwise, distilled
water is used. If SOW is used, determine its blank background.
Substitute Ocean Water (SOW)
NaCl 24.53 NaHC03 0.20
MgCl2 5.20 KBr 0.10
Na2S04 4.09 H3B03 0.03
CaCl2 1.16 SrCl2 .03
KC1 0.70 NaF .003
140
-------
(Nitrogen, Ammonia)
7. Procedure
7.1 For a working range of 0.01 to 2.00 NH3-N mg/1, set up the
manifold as shown in Figure 1. Higher concentrations may
be accommodated by decreasing sample size and/or through
dilution of sample.
7.2 Allow both colorimeter (with 650 my filters and 15 mm flow
cell) and recorder to warm up for 30 minutes. Run a baseline
with all reagents, feeding ammonia-free water through sample
line. Adjust dark current and operative opening on colori-
meter to obtain stable baseline.
7.3 Place a distilled water wash tube in alternate openings in
sampler and set sample timing at 2.0 minutes. All tubes must
be rinsed with ammonia-free water before use.
7.4 Arrange ammonia standards in sampler in order of decreasing
concentration of nitrogen. Complete loading of sampler tray
with unknown samples.
7.5 Switch sample line from distilled water to sampler and begin
analysis.
8. Calculations
8.1 Prepare appropriate standard curve derived from processing
ammonia standards through manifold. Compute concentration
of samples by comparing sample peak heights with standard
curve.
141
-------
(Nitrogen, Ammonia)
9. Precision and Accuracy
9.1 In a single laboratory (AQC), using surface water samples
at concentrations of 1.41, 0.77, 0.59, and 0.43 mg NHj-N/l",
the standard deviation was ±0.005.
9.2 In a single laboratory (AQC), using surface water samples
at concentrations of 0.16 and 1.44 mg NH -N/l, recoveries were
O
107% and 99%, respectively.
References
1. D. Van Slyke and A. Miller, "Determination of Ammonia in Blood,"
J. Biol. Chem. 102, 499 (1933).
2. B. O'Connor, R. Dobbs, B. Villiers, and R. Dean, "Laboratory Dis-
tillation of Municipal Waste Effluents," JWPCP _39_, R 25 (1967).
3. J. E. O'Brien and J. Fiore, "Ammonia Determination by Automatic
Analysis," Wastes Engineering 33, 352 (1962).
4. A wetting agent recommended and supplied by the Technicon Corporation
for use in Autoanalyzers.
5. ASTM "Manual on Industrial Water and Industrial Waste Water,"
2nd Ed., 1966 printing, 418.
142
-------
FWPCA Methods for Chemical Analysis of Water and Wastes (November.1969)
Suggested Changes and.Errata ,
Page
6
Section
Table 1
Line
Solids,
filterabl
13
14
17
21
Table 1
Threshold odor
8 Table 2 Nitrogen,
ammonia
Table 2 Nitrogen,
nitrate-nitrite
Table 2 Oil & Grease
Table 2 Phosphorus
6.4
Dilution
Table
6.4.1
Change
Change 00515 to 70300
For TO at 60°C; add STORET #00086 , .
Write in TO at 40°C and STORET #00087
Add footnote 1 - "HgCl2 will complex
with NH~; this complex may not be
broken in dist'n. step"
Add footnote 2 - "HgCl™ will destroy
reduction column in cadmium reduction
method"
Change preservative to: "5 ml cone.
HC1 per liter - 4°C"
Add footnote 3 - "Must have minimum
of 50 mg Cl/liter in sample to prevent
precipitation when HgCl« is used"
Change to read; "Dissolve 1.060 gm of
anhydrous sodium carbonate (oven dried
at 140 C for 1 hour) in distilled water
and dilute to 1.0 liter. 1.0 ml =
1.00 mg CaC03
Change mg/1 to mg/1 as CaCO~
Remove page 17 and replace with
accompanying new page 17
Formula should be:
(ml K2Cr20 ) x (0.025)
Normality =
[ml Fe(NH4)2(S04)2]
29
7.6
Change 800 ml to 800 mg/1
29
Footnote
Reference should read: "Burns, E.R.,
Marshall, C., Journal WPCF, 37,
pp 1716-1721 (1965).
-------
Page Section Line
30 8.1
54 Ref 2.
85 Figure 1
Change
139
143
149
6.6
Figure 1
7.2
Note 2
Formula should be
mg/1 COD = [(A-B)C x 8000 - -50 D] x 1.20
ml sample
Change Ely to Elly
Change sample rate from 3.90 to 0. 8
and distilled water rate from 0.8 to 3.90
(color code P-W and R-R is correct but
rates were reversed)
Change (0.005%) to (0.057,) and 0.05 gm
to 0. 5 gm
Change
to 5N
Sentence should read "Alternately digest
the sample with 1 Kel-Pac (Olin-Matheson)
opened or unopened and 20 ml of cone.
157 8.1.3
173-4 6.7
174
175
207
240
251
6.10
6.11
8.2
7.8
7.4
Change 360°C to 390°C and 330°C to 360°C
At end of paragraph 6.7 on page 174 insert
paragraph 6.7.1 to read: "Dilute 90 ml of
6.7 to 4 liters with distilled water to
obtain working solution"
Change potassium nitrite to sodium nitrite
Change potassium nitrite to sodium nitrite
Insert sentence "If sample has been
preserved with HC1 and pH is below 3,
omit acid addition at this step"
Change "Add 40 ml of sulfuric acid
solution to 1 liter" --- to "Add 40 ml
of strong acid solution (reagent 7.6)
to 1 liter"
Insert (reagent 7.1) after "sulfuric
acid solution"
-------
BIOCHEMICAL OXYGEN DEMAND
1. Scope and Application
1.1 The biochemical oxygen demand test (BOD) is used for
determining the relative oxygen requirements of municipal
and industrial wastewaters. Application of the test to
organic waste discharges allows calculation of the effect
of the discharges on the oxygen resources of the receiving
water. Data from BOD tests are used for the development
of engineering criteria for the design of wastewater
treatment plants.
1.2 The BOD test is an empirical bioassay-type procedure which
measures the dissolved oxygen consumed by microbial life
while assimilating and oxidizing the organic matter present.
The standard test conditions include dark incubation at 20°C
for a specified time period (often 5 days). The actual
environmental conditions of temperature, biological population,
water movement, sunlight, and oxygen concentration cannot be
accurately reproduced in the laboratory. Results obtained
must take into account the above factors when relating BOD
results to stream oxygen demands.
1.3 Ancillary information relating to oxygen demanding charac-
teristics and carbon content of wastewaters can be gained
by applying the Total Organic Carbon (TOC) and Chemical
Oxygen Demand (COD) Tests.
17
-------
(.BOD)
1,4 Because of the effect of local conditions, types of
samples to be tested and variabilities in this type of
procedure, FWPCA has not selected a specific standard
test for the determination of Biochemical Oxygen Demand.
2. Procedure
2.1 Directions for conducting the BOD test are found in:
Standard Methods for the Examination of Water and
Wastewater, 12 Edition (1965), pp. 415-421.
ASTM Standards (1968) Part 23, Water; Atmospheric
Analyses, pp. 727-732.
2.2 Determinations of dissolved oxygen in the BOD test may be
made by use of either the Modified Winkler with Full-Bottle
Technique (p. 55) or the Probe Method (p. 65) in this
manual.
3. Precision and Accuracy
3.1 In 34 laboratories, the standard deviation of the BOD test,
| using a glucose-glutamic acid mixture, was ±31 mg/1 at a
mean BOD concentration of 184 mg/1. In a single laboratory,
the precision was ±11 mg/1 at a BOD of 218 mg/1 (Analytical
Reference Service, PHS).
3.2 There is no method available to determine the accuracy of
the BOD test.
18
-------
CO
1
SMALL MIXING COIL (Sm]
LARGE MIXING COIL (Lm) '
00000000
L-
Lm
00000000
0000
Sm
'
t
0000
r t
(m°cjj) HEATING BATH
1 0000
Sm
<
COLORIMETER
15mm TUBULAR f/c
M
•
1 4CTP «
flo 1 c
1 J
ib
|t
PR
*
P
R
G
B
R
G
G G
W
W
E_
W
W
R
P P
OPORTIONING
•
T
IX
1 '
ml/min
,2.90 SAMPLE
,
^0.80 5% EDTA ^lS-
42.00 FILTERED SAMPLE f3 ^
,2.00 AIR* CONTINUOUS FILTER
40.60 Na PHENOLATE
0.60 NaOCI
0.80 NITROPRUSSIDE
.2.50 WASTE
PUMP
RECORDER
650 mji FILTERS
SAMPLING TIME:2.0 MINUTES
WASH TUBES: ONE
'SCRUBBED THROUGH 5NH2 $04
FIGURE 1. AMMONIA MANIFOLD
-------
NITROGEN KJELDAHL, TOTAL
1. Scope and Application
1.1 This method covers the determination of total Kjeldahl nitrogen
in surface waters, domestic and industrial wastes, and saline
waters. The procedure converts nitrogen of components of bio-
logical origin such as amino acids, proteins and peptides to
ammonia, but may not convert the nitrogenous compounds of some
industrial wastes such as amines, nitro'compounds, hydrazones,
oximes, semi-carbazones and some refractory tertiary amines.
1.2 Two alternatives are listed for the determination of ammonia
after distillation; the titrimetric method which is applicable
to concentrations above 1 mg N/liter and the Nesslerization
method which is applicable to concentrations below 1 mg N/liter.
1.3 This method is described for a macro system of glassware; .
however, micro glassware which does not change the chemistry of
the procedure is equally applicable.
2. Definitions
2.1 Total Kjeldahl is defined as the sum of free ammonia and
organic nitrogen compounds which are converted to ammonium
sulfate (NH.)?SO., under the conditions of digestion
described below.
2.2 Organic Kjeldahl Nitrogen is defined as the difference
obtained by subtracting the free ammonia value (cf Nitrogen,
Ammonia, this Manual) from the total Kjeldahl nitrogen value.
145
-------
(Nitrogen Kjeldahl, Total)
This may be determined directly by removal of ammonia before
digestion.
3. Summary of Method
3.1 The sample is heated in the presence of concentrated sulfuric
acid, K?SO. and HgSO. and evaporated until SO, fumes are ob-
tained and the solution becomes colorless or pale yellow. The
residue is cooled, diluted, and is treated and made alkaline
with a hydroxide-thiosulfate solution. The ammonia is distilled
and determined after distillation either by nesslerization or
titrimetrically.
4. Sample Handling and Preservation
4.1 Samples may be preserved by addition of 40 mg HgCl_ and stored
at 4°C. Even when so preserved, conversion of organic nitrogen
to ammonia may occur. Preserved samples should be analyzed as
soon as possible.
5. Apparatus
5.1 Digestion apparatus. A Kjeldahl digestion apparatus with 800 ml
flasks and suction takeoff to remove S0_ fumes and water is re-
quired. Use of micro-Kjeldahl equipment is also permissible.
5.2 Distillation apparatus. The Kjeldahl flask is connected to a
condenser and an adaptor so that the distillate can be collected
for nesslerization or in indicating H,BO_ solution for titration.
146
-------
(Nitrogen Kjeldahl, Total)
7.2 Place a. measured sample or the residue from the distillation in
the ammonia determination (for Organic Kjeldahl only) into an
800-ml Kjeldahl flask. The sample size can be determined from
the following table:
Kjeldahl Nitrogen Sample Size
in Sample, mg/1 ml
0-5 500
5-10 250
10 - 20 100
20-50 50.0
50 - 100 25.0
Dilute the sample, if required, to 500 ml, and add 100 ml
sulfuric-acid - mercuric sulfate - potassium sulfate solution
(Note 2), and evaporate the mixture in the Kjeldahl apparatus
until SO, fumes are given off and the solution turns colorless
or pale yellow. Cool the residue and add 300 ml water.
Note 2 - Alternately digest the sample with 1 Kel-Pac
(Olin-Matheson) and 20 ml H SO .
7.3 Make the digestate alkaline by careful addition of the sodium
hydroxide-thiosulfate solution without mixing.
(Note - Slow addition of the heavy caustic solution down the
tilted neck of the digestion flask will cause the heavier so-
lution to underlay the aqueous sulfuric acid solution without
loss of free ammonia. Do not mix until the digestion flask has
been connected to the distillation apparatus.)
7.4 Connect the Kjeldahl flask to the condenser with the tip of
condenser (or an extension of the condenser tip) below the
level of the boric acid solution in the receiving flask.
149
-------
(Nitrogen Kjeldahl, Total)
7.5 Distill 300 ml at the rate of 6-10 ml/min., into 50 ml of 2%
boric acid contained in a 500-ml glass stoppered Erlenmeyer
flask.
7.5.1 If it is anticipated that the ammonia measurement will
be by nesslerization, 50 ml of boric acid is preferred.
If, however, sufficient ammonia is present to permit
titration of a larger volume of boric acid, either 100
or 200 ml, may be used.
7.6 Dilute the distillate to 500 ml in the flask and nesslerize
an aliquot, to obtain an approximate value of the ammonia-
nitrogen concentration. For concentrations above 1.0 mg/1
the ammonia should be determined titrimetrically. For con-
centrations below this value it is determined colorimetrically.
7.7 Determination of ammonia in distillate. - Determine the
ammonia content of the distillate either titrimetrically or
colorimetrically as described below.
7.7.1 Titrimetric determination. Add 3 drops of the mixed
indicator to the distillate and titrate the ammonia
with the 0.02 N H-SO., matching the endpoint against
a blank containing the same volume of ammonia-free
water and H BO solution.
o o
. 150
-------
(Nitrogen Kjeldahl, Total)
5.3 Spectrophotometer for use at 400 to 425 my with a light path of
1 cm or longer.
5.4 Nessler tubes, tall form, 50 ml.
6. Reagents
6.1 Distilled waters should be free of ammonia. Such water is best
prepared by the passage of distilled water through an ion ex-
change column containing a strongly acidic cation exchange resin
mixed with a strongly basic anion exchange resin. Regeneration
of the column should be carried out according to the manufacturer's
instructions.
6.2 Mercuric sulfate solution. Dissolve 8 g red, mercuric oxide (HgO)
in 50 ml of 1:5 sulfuric acid and dilute to 100 ml with distilled
water.
6.3 Sulfuric acid-mercuric sulfate-potassium sulfate solution.
Dissolve 267 g K?SO. in 1300 ml water and add 400 ml concentrated
H?SO.. Add 50 ml mercuric sulfate solution and dilute to 2 liters.
6.4 Sodium hydroxide-sodium thiosulfate solution. Dissolve 500 g
NaOH and 25 g Na-S^O 5H 0 in water and dilute to 1 liter.
6.5 Phenolphthalein indicator solution. Dissolve 5 g phenolphthalein
in 500 ml 95% ethyl alcohol or isopropanol and add 500 ml water.
Add 0.02 NaOH dropwise until a faint, pink color appears.
6.6 Mixed indicator. Mix 2 volumes of 0.2% methyl red in 95% ethanol
with 1 volume of 0.2% methylene blue in ethanol. Prepare fresh
every 30 days.
147
-------
(Nitrogen Kjeldahl, Total)
6.7 Boric acid solution. Dissolve 20 g boric acid, H BO in water
and dilute to 1 liter with water.
6.8 Sulfuric acid titrant, 0.020 N. (1-00 ml = 0.28 mg N.)
6.9 Ammonium chloride, stock solution, (1.0 ml = 1.0 mg NH /N).
Dissolve 3.819 g NH4C1 in water and make up to 1.0 liter with
ammonia free water.
6.10 Ammonium chloride, standard solution, (1.0 ml = 0.01 mg NH,/N).
o
Dilute 10.0 ml of the stock solution to 1.0 liter.
6.11 Nessler reagent. - Dissolve 100 g of mercuric iodide and 70 g
of potassium iodide in a small volume of water. Add this mixture
slowly, with stirring, to a cooled solution of 160 g of NaOH in
500 ml of water. Dilute the mixture to 1 liter. The solution
is stable for at least one year if stored in a pyrex bottle out
of direct sunlight.
Note - Reagents 6.9, 6.10, and 6.11 are identical to reagents
6.2, 6.3 and 6.6 described under Nitrogen, Ammonia.
7. Procedure
7.1 The distillation apparatus should be pre-steamed before use by
distilling a 1:1 mixture of ammonia-free water and sodium
hydroxide-sodium thiosulfate solution until the distillate is
ammonia free. This operation should be repeated each time the
apparatus is out of service long enough to accumulate ammonia
(usually 4 hours or more).
148
-------
(Nitrogen Kjeldahl, Total)
7.7.2 Colorimetric determination. Prepare a series of Nessler
tube standards as follows:
ml of Standard Cone., When Diluted to
1.0 ml = 0.01 mg NH'/N 50.0 ml, mg NH /N/liter
0.0 (Blank) 0.0
0.2 0.04
0.5 0.10
1.0 0.20
1.5 0.30
2.0 0.40
3.0 0.60
4.0 0.80
Dilute each tube to 50 ml with ammonia-free water, add
1.0 ml of Nessler reagent and mix. After 20 minutes read
the optical densities at 425 my against the blank. From
the values obtained plot optical density (absorbance) vs
concentration for the standard curve.
7.7.3 It is not imperative that all standards be distilled in
the same manner as the samples. It is recommended that
at least 2 standards (a high and low) be distilled and
compared to similar values on the curve to insure that
the distillation technique is reliable. If distilled
standards do not agree with undistilled standards the
operator should find the cause of the apparent error
before proceeding.
7.8 Determine the ammonia in the distillate by nesslerizing 50 ml
or an aliquot diluted to 50 ml and reading the optical density
at 425 my as described above for the Standards. Ammonia-
nitrogen is read from the standard curve.
151
-------
(Nitrogen Kjeldahl, Total)
8. Calculation
8.1 If the titrimetric procedure is used calculate Total Kjeldahl
Nitrogen, in mg/1, in the original sample as follows:
T * i »-• ij ui •* /i (A-B)x N x F x 1000
Total Kjeldahl nitrogen, mg/1 = ^
O
where:
A = milliliters of standard 0.020 N H_SO. solution used
in titrating sample.
B = milliliters of standard 0.020 N H?SO solution used
in titrating blank.
N = normality of sulfuric acid solution.
F = millequivalent weight of nitrogen (14 mg).
S = milliliters of sample digested.
If the sulfuric acid is exactly 0.02 N the formula is shortened
to:
TKN, mg/1 . (A-B) X 28°
O
8.2 If the Nessler procedure is used, calculate the Total Kjeldahl
Nitrogen, in mg/1, in the original sample as follows:
TKN, mg/1 = A X 100°
* 0.8 x S
where:
A = mg NH_/N read from curve.
O
S = volume of distillate nesslerized.
8.3 Calculate Organic Kjeldahl Nitrogen in mg/1, as follows:
Organic Kjeldahl Nitrogen = TKN - NH /N
9. Precision
9.1 Precision and accuracy data are not available at this time.
152
-------
NITROGEN, KJELDAHL, TOTAL
(Automated Phenolate Method)
1. Scope and Application
1.1 This automated method may be used to determine Kjeldahl
nitrogen in surface waters, domestic and industrial wastes,
and saline waters. The applicable range is 0.05 to 2.0 mg
N/l. Approximately 20 samples per hour can be analyzed.
2. Summary of Method
2.1 The sample is automatically digested with a sulfuric acid
solution containing potassium sulfate and mercuric sulfate
as a catalyst to convert organic nitrogen to ammonium sulfate.
The solution is then automatically neutralized with sodium
hydroxide solution and treated with alkaline phenol reagent
and sodium hypochlorite reagent. This treatment forms a blue
color designated as indophenol. Sodium nitropruss"ide, which
increases the intensity of the color, is added to obtain
necessary sensitivity for measurement of low level nitrogen. '
3. Definitions
3.1 Total Kjeldahl nitrogen is defined as the sum of free ammonia
and of organic compounds which are converted to (NH^^SO, under
the conditions of digestion which are specified below.
153
-------
(Nitrogen, Kjeldahl, Total)
3.2 Organic Kjeldahl nitrogen is defined as the difference obtained
by subtracting the free ammonia value from the total Kjeldahl
nitrogen value. Also, organic Kjeldahl nitrogen may be deter-
mined directly by removal of ammonia before digestion.
4. Sample Handling and Preservation
4.1 Preservation by addition of 40 mg HgCl? per liter and refri-
geration at 4°C is necessary.
5. Interferences
5.1 Iron and chromium ions tend to catalyze while copper ions
tend to inhibit the indophenol color reaction.
6. Apparatus
6.1 Technicon AutoAnalyzer consisting of:
6.1.1 Sampler II, equipped with continuous mixer.
6.1.2 Two proportioning pumps.
6.1.3 Manifold I
6.1.4 Manifold II
6.1.5 Continuous Digester
6.1.6 Peristaltic pump
6.1.7 Five-galIon Carboy fume-trap
6.1.8 80°C Heating bath
6.1.9 Colorimeter equipped with 50 mm tubular flow cell and
630 my filters.
6.1.10 Recorder equipped with range expander.
154
-------
(Nitrogen, Kjeldahl, Total)
7. Reagents
7.1 Distilled Water: Special precaution must be taken to insure
that distilled water is free of ammonia. Such water is
prepared by passage of distilled water through an ion exchange
column comprised of a mixture of both strongly acidic cation
and strongly basic anion exchange resins. Furthermore, since
organic contamination may interfere with this analysis, use
of the resin Dowex XE-75 or equivalent which also tends to
remove organic impurities is advised. The regeneration of
the ion exchange column should be carried out according to
the instruction of the manufacturer.
7.2 Sulfuric acid: As it readily absorbs ammonia, special pre-
caution must also be taken with respect to its use. Do not
store bottles reserved for this determination in areas of
potential ammonia contamination.
7.3 EDTA (2% solution): Dissolve 20 g disodium ethylenediamine
tetraacetate in 1 liter of distilled water. Adjust pH to
10.5-11.
7.4 Sodium hydroxide (30% solution): Dissolve 30 g NaOH in
1 liter of distilled water. (May have to be adjusted to
give neutralization in the water-jacketed mixing coil).
7.5 Sodium nitroprusside, Stock (1% solution): Dissolve 10 g
Na2Fe(CN)5N0.2H20 in 1 liter distilled H20.
7.6 Sodium nitroprusside, working solution: Dilute 50 ml stock
solution to 1 liter with distilled water.
155
-------
(Nitrogen, Kjeldahl, Total)
7.7 Alkaline phenol reagent: Pour 550 mis liquid phenol (88-90%)
slowly with mixing and cooling into 1 liter of 40% NaOH.
Make up to 2 liters with distilled water.
7.8 Sodium hypochlorite (1% solution): Dilute commercial
"Clorox" - 200 ml to 1 liter with distilled water.
7.9 Digestion mixture: Place 2 g HgO in a 2-liter container.
Slowly add, with stirring, 300 ml of acid water (100 ml H2SO -
200 ml HJ3) and stir until cool. Add 100 ml 10% K2SO.. Dilute
to a volume of 2 liters with cone, sulfuric acid (approximately
500 ml at a time, allowing time for cooling).
7.10 Stock Solution: Dissolve 4.7619 g of pre-dried ammonium
sulfate in distilled water and dilute to 1.0 liter. Dissolve
2.1276 g of urea in distilled water and dilute to 1.0 liter.
Dissolve 30.5263 g of glutamic acid in distilled water and
dilute to 1.0 liter. 1 ml = 1.0 mg N.
7.11 Standard Solution: Dilute 10.0 ml of respective stock solution
to 1.0 liter. 1 ml = 0.01 mg N.
7.11.1 Using the respective standard solutions, prepare the
following standards in 100.0-ml volumetric flasks:
Cone., mg N/l ml Standard Sdlutibn/100 ml
0.00 0.0
0.05 0.5
0.10 1.0
0.20 2.0
0.40 4.0
0.60 6.0
0.80 8.0
1.00 10.0
1.50 15.0
2.00 20.0
156
-------
(Nitrogen, Kjeldahl, Total)
8. Procedure
8.1 Set up manifolds as shown in Figures 1, 2, and 3.
8.1.1 In the operation of Manifold No. 1, the contro.l
of three key factors is required to enable Manifold
No. 2 to receive the mandatory representative feed.
First, the digestate flowing into the pulse chamber
(PC-1) must be bubble free, otherwise, air will
accumulate in A-7, thus altering the ratio of sample
to digestate in digester. Second, in maintaining even
flow from the helix, the peristaltic pump must be
adjusted to cope with differences in density of the
digestate and the wash water. Third, the sample pick-up
rate from the helix must be precisely adjusted to insure
that the entire sample is aspirated into the mixing
chamber. And finally, the contents of the "Mixing Chamber'
must be kept homogeneous by the proper adjustment of
the air bubbling rate.
8.1.2 In the operation of Manifold No. 2, it is important
in the neutralization of the digested sample to adjust
the concentration of the NaOH so that the waste from
the C-3 debubbler is slightly acid to Hydrion B paper.
8.1.3 The digester temperature is 360°C for the first stage
and 330°C for the second and third stages.
8.2 Allow both colorimeter and recorder to warm up for 30 minutes.
Run a baseline with all reagents, feeding distilled water
157
-------
(Nitrogen, Kjeldahl, Total)
through the sample line. Adjust dark current and operative
opening on colorimeter to obtain stable baseline.
8.3 Set sampling rate of Sample II at 20 samples per hour, using
a wash to sample ratio of 2 to 1.
8.4 Arrange various standards in Sampler cups in order of
increasing concentration. Complete loading of sampler tray
with unknown samples.
8.5 Switch sample line from distilled water to sampler and begin
analysis.
8.5.1 If equipment is operating properly, 100% nitrogen
recovery should be obtained for glutamic acid and
urea when compared to ammonium sulfate standards.
9. Calculation
9.1 Prepare standard curve by plotting peak heights of processed
standards against concentration values. Compute concentration
of samples by comparing sample peak heights with standard curve.
9.2 Any sample that has a computed concentration that is less than
10% of the sample run immediately prior to it must be rerun.
10. Precision and Accuracy
10.1 Precision and accuracy data are not available at this time.
158
-------
(Nitrogen, Kjeldahl, Total)
References
1. Kammerer, P.A.; Rodel, M.G.; Hughes, R.A.; and Lee, G.F.;
"Low Level Kjeldahl Nitrogen Determination on the Technicon
AutoAnalyzer." Environmental Science and Technology. 1:4:340
(April 1967).
2. McDaniel, William H.; Hemphill, R.N.; Donaldson, W.T.; "Automatic
Determination of Total Kjeldahl Nitrogen in Estuarine Waters."
Presented at Technicon Symposium on Automation in Analytical
Chemistry, New York, October 3, 1967.
3. B. O'Connor, Dobbs, Villiers, and Dean, "Laboratory Distillation of
Municipal Waste Effluents". JWPCP 39^, R 25, 1967.
159
-------
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NITROGEN, NITRATE
1. Scope and Application
1.1 This method is applicable to the analysis of surface waters,
domestic and industrial wastes, and saline waters. Modifi-
cation can be made to remove or correct for turbidity, color,
salinity, or dissolved organic compounds in the sample.
1.2 The applicable range of concentrations is 0.1 to 2 mg NO^-N/
liter.
2. Summary of Method
2.1 This method is based upon the reaction of the nitrate ion with
brucine sulfate in a 13 N H-SO. solution at a temperature of
100°C. The color of the resulting complex is measured at 410 my.
Temperature control of the color reaction is extremely critical.
3. Sample Handling and Preservation
3.1 Until more conclusive data is obtained, samples may be pre-
served by addition of 40 mg HgCl2 per liter and storage at 4°C.
4. Interferences
4.1 Dissolved organic matter will cause an off color in 13 N
t^SO^ and must be compensated for by additions of all reagents.
except the brucine-sulfanilic acid reagent. This also applies
to natural color present not due to dissolved organics.
165
-------
(Nitrogen, Nitrate)
4.2 The effect of salinity is eliminated by addition of sodium
chloride to the blanks, standards and samples.
4.3 All strong oxidizing or reducing agents interfere. The
presence of oxidizing agents may be determined by the
addition of orthotolidine reagent.
4.4 Residual chlorine interference is eliminated by the
addition of sodium arsenite.
4.5 Ferrous and ferric iron and quadrivalent manganese give
slight positive interference, but in concentrations less.
than 1 mg/1 these are negligible.
4.6 Uneven heating of the samples and standards during the
reaction time will result in erratic values. The necessity
for absolute control of temperature during the critical
color development period cannot be too strongly emphasized.
5. Apparatus
5.1 Spectrophotometer or filter photometer suitable for measuring
optical densities at 410 my and capable of accommodating 25 mm
diameter cells.
5.2 Sufficient number of 25 mm diameter matched tubes for reagent
blanks, standards, and samples.
5.3 Neoprene coated wire racks to hold 25 mm diameter tubes.
5.4 Water bath suitable for use at 100°C. This bath should
contain a stirring mechanism so that all tubes are at same
temperature and should be of sufficient capacity to accept
166
-------
(Nitrogen, Nitrate)
the required number of tubes without significant drop in
temperature when the tubes are immersed.
5.5 Water bath suitable for use at 10-15°C.
6. Reagents
6.1 Distilled water free of nitrite and nitrate is to be used
in preparation of all reagents and standards.
6.2 Sodium chloride solution (300 g/1). Dissolve 300 g NaCl
in distilled water and dilute to 1000 ml.
6.3 Sulfuric acid solution. Carefully add 500 ml H SO (sp.
gr. 1.84) to 125 ml distilled water. Cool and keep
tightly stoppered to prevent absorption of atmospheric
moisture.
6.4 Brucine-sulfanilic acid reagent. Dissolve 1 g brucine
sulfate [(C23H26N204)2.H2S04.7H20] and 0.1 g sulfanilic
acid (NH2C6H4S03H.H20) in 70 ml hot distilled water. Add
3 ml concentrated HC1, cool, mix and dilute to 100 ml.
Store in a dark bottle at 5°C. This solution is stable
for several months; the pink color that develops slowly does
not effect its usefulness. Mark bottle with warning:
CAUTION: Brucine Sulfate is toxic; take care to avoid
ingestion.
6.5 Potassium nitrate stock solution (1 ml = 0.1 mg NO,-N).
O
Dissolve 0.7218 g anhydrous potassium nitrate (KNO_) in
distilled water and dilute to 1 liter.
167
-------
(Nitrogen, Nitrate)
6.6 Potassium nitrate standard solution (1 ml = 0.01 mg NO,-N).
Dilute 100 ml of the stock solution to 1 liter. This
standard solution should be prepared fresh weekly.
6.7 Acetic acid (1 + 3). Dilute 1 vol. glacial acetic acid
(CH COOH) with 3 volumes of distilled water.
7. Procedure
7.1 Adjust the pH of the samples to approximately pH 7 with
1:3 acetic acid and, if necessary, filter through a 0.45 u
pore size filter.
7.2 Set up the required number of matched tubes in the rack to
handle reagent blank, standards and samples. It is
suggested that tubes be spaced evenly throughout the rack
to allow for even flow of bath water between the tubes.
Even spacing of tubes should assist in achieving uniform
heating of all tubes.
7.3 If it is necessary to correct for color or dissolved organic
matter which will cause color on heating, a set of duplicate
tubes must be used to which all reagents except the brucine-
sulfanilic acid has been added.
7.4 Pipette 10 ml or an aliquot of the samples diluted to 10 ml
into the sample tubes.
7.5 If the samples are saline, add 2.0 ml of the 30 percent
sodium chloride solution to the reagent blank, standards and
samples. For fresh water samples, sodium chloride solution
168
-------
(Nitrogen-Nitrate)
may be omitted. Mix contents of tubes of swirling and
place rack in cold water bath (0-10°C).
7.6 Pipette 10 ml of sulfuric acid solution into each tube
and mix by swirling. Allow tubes to come to thermal
equilibrium in the cold bath. Be sure that temperatures
have equilibrated in all tubes before continuing.
7.7 Add 0.5 ml brucine-sulfanilic acid reagent to each tube
(except the interference control tubes) and carefully mix
by swirling, then place the rack of tubes in the boiling
water bath for exactly 25 minutes. CAUTION: Immersion
of the tube rack into the bath should not decrease the
temperature of the bath. Flow of bath water between the
tubes should not be restricted by crowding too many tubes
into the rack. If color development in the standards reveals
discrepancies in theprocedure the operator should repeat the
procedure after reviewing the temperature control steps.
7.8 Remove rack of tubes from the hot water bath and immerse in
the cold water bath and allow to reach thermal equilibrium
(20-25°€).
7.9 Dry tubes and read optical density against the reagent blank
at 410 my.
169
-------
(Nitrogen, Nitrate)
8. Calculation
8.1 Obtain a standard curve by plotting the optical densities
of standards run by the above procedure against mg NCL-N.
(The color reaction does not always follow Beer's law.)
8.2 Subtract the absorbance of the sample without the brucine-
sulfanilic reagent from the absorbance of the sample
containing brucine-sulfanilic acid and read the optical
density in mg NCL-N. Multiply by factor for converting mg
•J
per aliquot of sample to mg per liter.
NCL-N mg/1 = mg NCL-N from curve x
1000
ml sample
9. Precision and Accuracy
9.1 Precision and accuracy data are not available at this time.
170
-------
NITROGEN, NITRATE AND NITRITE
(Automated Hydrazine Reduction Method)
1. Scope and Application
1.1 This method is applicable to surface waters, and domestic
and industrial wastes which contain less than 500 mg/1
calcium. The applicable range of this method is 0.05-10
mg/1 nitrite or nitrate nitrogen. Approximately 20
samples per hour can be analyzed.
2. Summary of Method
2.1 This method, using the Technicon AutoAnalyzer, determines
NCL-N by the conventional diazotization-coupling reaction.
The NCL-N is reduced with hydrazine sulfate in another
portion of the sample and the nitrite thus formed is
determined in the usual manner.
2.2 Subtraction of the NCL-N originally present in the sample
from the total NCL-N found will give the original NCL-N
^ J
concentration in terms of NCL-N.
3. Sample Handling and Preservation
3.1 Preservation by addition of 40 mg HgCl2 per liter and
refrigeration at 4°C.
4. Interferences
4.1 The following table lists the concentration of ions that
cause no interference in the determination of nitrite and
nitrate nitrogen. The same interfering ion concentration
171
-------
(Nitrogen, Nitrate and Nitrite)
applies to either nitrite or nitrate:
Ion mg/1 Ion Not Causing Interference
Cl~ 30,000
P04'3 50
S"2 Note
NH -N 80
o
Mg+2 75
Ca+2 240
Fe+3 30
ABS 60
Note 1. -- The apparent NO, and NO- concentrations varied ±
10 percent with concentrations of sulfide ion up to 10 mg/1.
4.2 The pH of the samples should be between 6 and 9.
5. Apparatus
5.1 Technicon AutoAnalyzer consisting of:
5.1.1 Two proportional pumps.
5.1.2 Two colorimeters each with an 8 mm flow-through cell
and 520 my filters.
5.1.3 One continuous filter.
5.1.4 One Sampler I.
5.1.5 Two recorders.
5.1.6 One 38°C temperature bath.
5.1.7 Two time delay coils.
172
-------
(Nitrogen, Nitrate and Nitrite)
6. Reagents
6.1 Color developing reagent: To approximately 3 liters of
distilled water add 400 ml concentrated phosphoric acid
(sp. gr. 1.834), 60 g sulfanilamide (H N-C H SO NH )
^ OH* ^ £
followed by 3.0 g N (l-Naphthyl)ethylene-diamine dihydro-
chloride. Dilute the solution to 4 liters with distilled
water and store in a dark bottle in the refrigerator.
This solution is stable for approximately 1 month.
Note 2 -- It may be necessary to apply heat in order to
dissolve the sulfanilamide.
6.2 Copper sulfate; stock solution: Dissolve 2.5 g of copper
sulfate (CuSO,.5H 0) in distilled water and dilute to 1
liter.
6.3 Copper sulfate; dilute solution: Dilute 20 ml of stock
solution to 2 liters with distilled water.
6.4 Sodium hydroxide; stock solution, (10 N): Dissolve 400 g
NaOH in 750 ml distilled water, cool and dilute to 1 liter.
6.5 Sodium hydroxide(1.ON): Dilute 100 ml of stock NaOH
solution to 1 liter.
6.6 Sodium hydroxide(0.3N): Dilute 60 ml of stock NaOH to 2
liters.
6.7 Hydrazine sulfate solution: Dissolve 54.92 g of hydrazine
sulfate (N_H .H SO ) in 1800 ml of distilled water and dilute
173
-------
(Nitrogen, Nitrate and Nitrite)
to 2000 ml. This solution is stable for approximately
6 months .
CAUTION: Toxic if ingested. Mark container with warning.
6.8 Potassium nitrate; stock solution (1000 mg/1 . NO,-N) :
Dissolve 7.2180 g of KN03, oven dried at 100-105°C for
2 hours, in distilled water and dilute to 1000 ml. Add
1 ml chloroform as a preservative. Stable for 6 months.
6.9 Potassium nitrate; standard solution (100 mg/1 NCL-N) :
o
Dilute 50 ml of stock KNO solution to 500 ml in a
o
volumetric flask. From this dilute solution prepare the
following standards in 500 ml volumetric flasks:
mg/1 NO--N ml Standard Solution
0.4 2.0
1.0 5.0
1.6 8.0
3.0 15.0
5.0 25.0
7.0 35.0
10.0 50.0
6.10 Potassium nitrite; stock solution (1000 mg/1 NO_-N) : Dissolve
4.9260 g NaNO , oven dried at 100-105°C for two hours, in
distilled water and dilute to 1000 ml. Add 1 ml chloroform as
preservative. Store in the refrigerator. Stable for 1 month.
174
-------
(Nitrogen, Nitrate and Nitrite)
6.11 Potassium nitrite; standard solution (100 mg/1): Dilute
»
50 ml of stock NaNCL solution to 500 ml in a volumetric
flask. From this dilute solution prepare the same
volumetric standards as in 6.9. Prepare fresh each week.
7. Procedure
7.1 Set up the manifold as shown in Figures 1 and 2. Allow
both colorimeter (with the proper filters) and recorder to
warm up for 30 minutes, then run a baseline with all reagents,
feeding distilled water through the sample line. Adjust dark
current and operative opening on each colorimeter. Adjust
baseline to 0.01 optical density. Place a distilled water
wash tube in alternate openings on sampler and set sample
timing at 1.5 minutes.
7.2 Run a 2.0 mg/1 NO -N and a 2.0 mg/1 NO--N standard through
the system to check for 100% reduction of nitrate to nitrite.
The two peaks should be of equal height. If the NO, peak is
lower than that of the N02 peak, the temperature of the
reduction bath should be increased until they are equal. If
the NO, peak is higher than the nitrate, the temperature should
be reduced. When the correct temperature of the bath has been
determined, no further adjustment should be necessary.
7.3 Arrange standards in sampler in N0~-N0, order with increasing
concentration of nitrogen. Place unknown samples in sampler
175
-------
(Nitrogen, Nitrate and Nitrite)
tubes and place in alternate openings of sampler. A NO-
and NO, standard of equal nitrogen concentration should
be placed after every 10 samples as a further check on
the system and to more easily identify peaks.
8. Calculation
8.1 Prepare standard curve by plotting peak heights of pro-
cessed standards against known concentrations. Compute
concentrations of samples by comparing sample peak heights
with standard curve.
8.2 Subtract the NC>2 concentration in the sample from the total
NC>2 found (nitrite plus nitrate) on the reduction side to
calculate the NO^ concentration in the sample.
9. Precision and Accuracy
9.1 In a single laboratory (AQC), using surface water samples
at concentrations of 0.1, 0.2, 0.8, and 2.1 mg-N/-^, the
standard deviations were 0.0, ±0.04, ±0.05, and ±0.05,
respectively.
9.2 In a single laboratory (AQC), using surface water samples
at concentrations of 0.2 and 2.2 mg-N/^, recoveries were
100% and 96%, respectively.
References
1. D. Jenkins and L. Medsker, "Brucine Method for Determination of
Nitrate in Ocean, Estuarine, and Fresh Waters." Anal. Chem.,
36^ 610 (1964).
2. L. Kamphake, S. Hannah, and J. Cohen, "Automated Analysis for
Nitrate by Hydrazine Reduction." Water Research, 1, 205 (1967).
176
-------
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-------
NITROGEN, NITRATE-NITRITE
(Automated Cadmium Reduction Method)
1. Scope and Application
1.1 This method pertains to the determination of nitrates and
nitrites, singly or combined, present in surface and saline
waters. The prescribed specifications permit analyses of
samples in the range of 0.05 to 10 mg/liter, N present as
NO .
O
2. Summary of Method^
(2)
2.1 The initial step J is to reduce the nitrates to nitrites
by using a cadmium-copper catalyst. The nitrites (those
originally present plus reduced nitrates) are then reacted
with sulfanilamide to form the diazo compound which is then
coupled in an acid solution (pH 2.0 - 2.5) with N-l naphthyl-
ethylenediamine hydrochloride to form the azo dye. The azo
dye intensity, which is proportional to the nitrate concen-
tration, is then measured. Separate rather than combined
nitrate-nitrite values are readily obtainable by carrying
out the procedure—first with, and then without, the initial Cd-Cu
reduction step.
3. Sample Handling and Preservation
3.1 Preservation by addition of 40 mg HgCl2 per liter and refrig-
eration at 4°C is necessary.
181
-------
(Nitrogen, Nitrate-Nitrite)
4. Interferences
4.1 Ammonia and primary amines which are frequently present in
natural waters may react to some extent with nitrites- to
form nitrogen. Thus,, since, as in nature, the sample is
not stable, the analyses should be performed as soon as
possible.
4.2 In surface waters normally encountered in surveillance
studies, the concentration of oxidizing or reducing agents
and potentially interfering metal ions are well below the
limits causing interferences. When present in sufficient
concentration, metal ions may produce a positive error,
i.e., Hg (II) and Cu (II); may form colored complex ions
having absorption bands in the region of color measurement.
5. Apparatus
5.1 Technicon AutoAnalyzer consisting of the following components:
5.1.1 Sampler II.
5.1.2 Manifold (including Cu-Cd column).
5.1.3 Colorimeter equipped with 50 mm tubular flow cell
and 540 my filters.
5.1.4 Range expander.
5.1.5 Recorder.
5.2 Cadmium-copper reduction column .
5.2.1- Preparation: Shake the 30 - 60 mesh av. diam. 0.5 mm
cadmium turnings (Note 1) with a solution of 2% (wt/vol)
182
-------
(Nitrogen, Nitrate-Nitrite)
copper sulfate pentahydrate solution. A weight of
solution equal to 10 times the weight of the cadmium
is used. The copper sulfate-treated cadmium catalyst
is then placed in a 8 mm x 50 mm pyrex tubing and is
followed by av. diam. 0.6 mm length 3.0 mm copper
rods made from hydrogen treated copper wire (Note 2).
The volume ratio of the cadmium bed to that of the
copper should be about 3 - 1 to 4 - 1. (See Figure 1).
Pyrex wool, inserted at the lower end of the reactor,
is used to prevent the catalyst from dropping out of
the reactor. The ends of the reactor are (fabricated
to accommodate the reactor into the system. The sample
enters the column at the copper granule-packed end.
To minimize back pressure due to a vertical position
or channelling due to a horizontal position, the
reductant tube is placed in an up-flow 20° incline.
Note 1 - Supplied by Technicon Corp., Ardsley, N.Y.
Note 2 - Supplied by F§M Scientific Corp., Avondale, Pa.
5.2.2 Regeneration: HC1, diluted 1 to 4, is pumped through
the NH.C1 line for one minute, followed by water for
two minutes and then 2% copper sulfate solution for five
minutes. For complete cleaning and coating, remove the
column from the manifold. Using a small funnel and a
short plastic connecting tube, the acid water and copper
183
-------
(Nitrogen, Nitrate-Nitrite)
sulfate solution are successively poured into the
column and allowed to flow through by gravity. The
cadmium should ultimately acquire a moss-black
appearance and the copper, a bright orange.
6. Reagents
6.1 Distilled water: Because of possible contamination, this
should be prepared by passage through an ion exchange column
comprised of amixture of both strongly acidic-cation and
strongly basic-anion exchange resins. The regeneration of
the ion exchange column should be carried out according to
the instruction of the manufacturer.
6.2 Color reagent: To approximately 800 ml of distilled water,
add, while stirring, 100 ml concentrated phosphoric acid,
40 g sulfanilamide, and 2 g N-l naphthylethylenediamine
dihydrochloride. Stir until dissolved and dilute to one
liter. Store in brown bottle and keep in the dark when not
in use. This solution is stable for several months.
6.3 Wash solution: Use distilled water for unpreserved samples;
samples preserved with hLSO., use 1 ml H-SO. per liter of
wash water.
6.4 Ammonium Chloride Solution (8.5% NH.C1): Dissolve 85 g of
NH.C1 reagent grade Ammonium Chloride in distilled water and
dilute to one liter with distilled water. Add 1/2 ml Brij-
184
-------
(Nitrogen, Nitrate-Nitrite)
6.5 Stock nitrate solution: Dissolve 7.218 g KNO and dilute
to 1000 ml with distilled water. Preserve with 2 ml of
chloroform per liter. Solution is stable for 6 months.
1 ml = 1.0 mg NO -N.
o
6.6 Stock nitrite solution: Dissolve 6.072 g KNO? and dilute
to 1000 ml with distilled water. Solution is unstable;
prepare as required. 1 ml = 1.0 mg NCL-N.
6.7 Standard nitrate solution: Dilute 10.0 ml of stock nitrate
solution to 1 liter. 1 ml = 0.01 mg NO_-N. Preserve with
2 ml of chloroform per liter. Solution is stable for 6
months.
6.8 Standard nitrite solution: Dilute 10.0 ml of stock nitrite
solution to 1 liter. 1 ml = 0.01 mg NCL-N. Solution is
unstable; prepare as required.
6.9 Using either standard nitrate solution or standard nitrite
solution, prepare the following standards in 100.0-ml
volumetric flasks:
Cone., mg NCL-N or NO -N/l Standard Solution/100 ml
0.0 0
0.05 0.5
0.10 1.0
0.20 2.0
0.50 5.0
1.00 10.0
2.00 20.0
4.00 40.0
6.00 60.0
185
-------
(Nitrogen, Nitrate-Nitrite)
Note: When the samples to be analyzed are saline waters,
substitute Ocean Water (SOW) (5) should be used for
preparing the standards; otherwise, distilled water
is used. A tabulation of SOW composition follows:
NaCl - 24.53 g/1 MgCl2 - 5.20 g/1 Na2S04 - 4.09 g/1
CaCl2 - 1.16 g/1 KC1 - 0.70 g/1 NaHC03 - 0.20 g/1
KBr - 0.10 g/1 H3B03 ' °-03 g/1 SrC12 " 0>03
NaF - 0.003 g/1
7. Procedure
7.1 Set up the manifold as shown in Figure 2. Note that reductant
column should be in 20° incline position with Cu at lower end.
7.2 Allow both colorimeter and recorder to warm up for 30 minutes.
Run a baseline with all reagents, feeding distilled water
through the sample line. Adjust dark current and operative
opening on colorimeter to obtain stable baseline.
7.3 Place appropriate nitrate and/or nitrite standards in sampler
in order of decreasing concentration of nitrogen. Complete
loading of sampler tray with unknown samples.
7.4 Switch sample line to sampler and start analysis.
8. Calculations
8.1 Prepare appropriate standard curve or curves derived from
processing NO, and/or N07 standard through manifold. Compute
«J ^
concentration of samples by comparing sample peak heights with
standard curve. Any sample whose computed concentration is
less than 10% of its immediate predecessor must be rerun.
186
-------
(Nitrogen, Nitrate-Nitrite)
9. Precision and Accuracy
9.1 Precision and accuracy data are not available at this time.
References
1. J.E. O'Brien and J. Fiore, "Automation in Sanitary Chemistry -
parts 1 § 2 Determination of Nitrates and Nitrites." Wastes
Engineering, 33, 128 $ 238 (1962).
2. J.D. Strickland, C.R. Stearns, and F.A. Armstrong, "The Measure-
ment of Upwelling and Subsequent Biological Processes by Means
of the Technicon AutoAnalyzer and Associated Equipment." Deep
Sea Research 14, 381-389 (1967).
3. "ASTM Manual on Industrial Water and Industrial Waste Water,"
Method D 1254, page 465 (1966).
4. Chemical Analyses for Water Quality Manual, Department of the
Interior, FWPCA, R.A. Taft Sanitary Engineering Center Training
Program, Cincinnati, Ohio 45226 (January 1966).
5. "ASTM Manual on Industrial Water and Industrial Waste Water,"
Substitute Ocean Water, Table 1, page 418, 1966 edition.
187
-------
INDENTATIONS FOR
SUPPORTING CATALYST
GLASS WOOL
Cd-TURNINGS
Cu-FILINGS (FINE MESH)
TILT COLUMN TO 20° POSTION
FIGURE 1. CADMIUM-COPPER REDUCTION COLUMN
(1 1/2 ACTUAL SIZE)
189
-------
TO SAMPLE WASH
SAMPLER 2
t
WASTE
C
VS-3
0000 .
-3*
HO
MIXER
k
/ _WASTE
00000000
DOUBLE MIX
WASTE
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COLORIMETER
50mm TUBULAR f/c
540mji FILTERS
ER
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I 1
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1-
Cu
HO COLUMN
1
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T
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R R
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0 0
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BLUE BLUE
Y Y
Y Y
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0.42
1.60 NaHCOa
0.80 AIR (
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0.42 COLOR REAGENT
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1.20 AIR
PROPORTIONING PUMP
RECORDER
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** SEE FIGURE 1. FOR DETAIL. COLUMN
SHOULD BE IN 20° INCLINE POSITION
WITH Cu AT LOWER END.
FIGURE 2. NITRATE-NITRITE MANIFOLD
-------
NITROGEN, NITRITE
1. Scope and Application
1.1 This method is applicable to the determination of nitrite in
surface waters, domestic and industrial wastes, and saline
waters.
1.2 The method is applicable in the range from 0.05 to 1.0 mg/1
N02/N.
2. Summary of Method
2.1 The diazonium compound formed by diazotation of sulfanilamide
by nitrite in water under acid conditions is coupled with
N-(l-naphthyl)-ethenediamine to produce a reddish-purple color
which is read in a spectrophotometer at 540 my.
3. Sample Handling and Preservation
3.1 Until more conclusive data is obtained, samples may be pre-
served by addition of 40 mg HgCl2 per liter and stored at
4°C.
4. Interferences
4.1 There are very few known interferences at concentrations less
than 1,000 times that of the nitrite; however, recent addition
of strong oxidants or reductants to the samples will readily
affect the nitrite concentrations. High alkalinity (>600 mg/1)
will give low results due to a shift in pH of the color reaction.
193
-------
(.'Nitrogen, Nitrite)
5. Apparatus
5.1 Spectrophotometer equipped with 1.0 and 5.0 cm cuvettes
for use at 540 mp.
5.2 Nessler tubes, 50 ml or volumetric flasks, 50 ml.
6. Reagents
6.1 Distilled water free of nitrite and nitrate is to be used
in preparation of all reagents and standards.
6.2 Buffer-color reagent. To 250-ml of distilled water, add
105-ml concentrated hydrochloric acid, 5.0 g sulfanilamide
and 0.5 g N-1-Naphthylethylenediamine dihydrochloride.
Stir until dissolved. Add 136 g of sodium acetate and
again stir until dissolved. Dilute to 500 ml with dis-
tilled water. This solution is stable for several weeks
if stored in the dark.
6.3 Nitrite-nitrogen stock solution, 1.0 ml = 0.10 mg N02-N.
Dissolve 0.4926 g of dried anhydrous sodium nitrite, in
distilled water and dilute to 1000 ml. Preserve with 2-ml
chloroform per liter.
6.4 Nitrite-nitrogen standard solution, 1.0 ml = 0.001 mg NO--N.
Dilute 10 ml of the stock solution to 1.0 liter.
7. Procedure
7.1 If the sample has a pH greater than 10 or a total alkalinity
in excess of 600 mg/1 adjust to approximately pH 6 with
1:3 HC1.
194
-------
(Nitrogen, Nitrite)
7.2 Filter the sample through a 0.45 y pore size filter using
the first portion of filtrate to rinse the filter flask.
7.3 Place 50 ml of sample, or an aliquot diluted to 50 ml in
a 50-ml Nessler tube; hold until preparation of standards
is completed.
7.4 At the same time prepare a series of standards in 50-ml
Nessler tubes as follows:
ml of Standard Solution Cone., When Diluted to
1.0 ml = 0.001 mg NO -N 50 ml, mg/1 of NO -N
0.0 (Blank) 0.0
0.5 0.01
1.0 0.02
1.5 0.03
2.0 0.04
3.0 0.06
4.0 0.08
5.0 0.10
10.0 0.20
7.5 Add 2.0 ml of buffer-colored reagent to each standard and
sample, mix and allow color to develop for at least 15
minutes. The color reaction medium should be between
pH 1.5 and 2.0.
7.6 Read the color in the spectrophotometer at 540 my against
the blank and plot concentration of NO,,-N against optical
density.
8. Calculation
8.1 Read the concentration of N02-N directly from the curve.
195
-------
(Nitrogen, Nitrite)
8.2 Calculate the concentration of NO -N in the sample in
milligrams per liter as follows:
ND N /I - absorbance of sample x mg/1 standard x 50
2~ ' ^ ~ absorbance of standard x ml sample
9. Precision and Accuracy
9.1 Precision and accuracy data are not available at this time.
196
-------
NITROGEN, ORGANIC + AMMONIA
(Automated Phenolate Method)
1. Scope and Application
1.1 This automated method is applicable to surface and saline
waters. The applicable range is 1.0 to 10.0 mg N/l.
Approximately 15 samples per hour can be analyzed.
2. Summary of Method
2.1 Organic nitrogen is determined by manually digesting the
sample with potassium persulfate and sulfuric acid to con-
vert the organic nitrogen, and any ammonia present, to ammonium
sulfate. Subsequently, the automated phenol-hypochlorite pro-
cedure is used to measure the ammonia nitrogen. Nitrate-
nitrite nitrogen is not measured by this procedure.
3. Sample Handling and Preservation
3.1 Preservation by addition of 40 mg HgCl2 per liter and refrig-
eration at 4°C is necessary.
4. Interferences
4.1 No significant interferences.
5. Apparatus
5.1 Technicon AutoAnalyzer consisting of:
197
-------
(Nitrogen, Organic
+ Ammonia)
5.1.1 Sampler I.
5.1.2 Continuous Filter.
5.1.3 Manifold.
5.1.4 Proportioning Pump.
5.1.5 Colorimeter equipped with 15 mm tubular flow cell
and 650 mp filters.
5.1.6 Recorder equipped with range expander.
5.2 Hot plate.
6. Reagents
6.1 Distilled Water: Special precaution must be taken to insure
that distilled water is free of ammonia. Such water is pre-
pared by passage of distilled water through an ion exchange
column comprised of a mixture of both strongly acidic cation
and strongly basic anion exchange resins. Since organic
contaminants may interfere with this analysis, use of the
resin Dowex XE-75 or equivalent which also tends to remove
organic impurities is advised. The regeneration of the ion
exchange column should be carried out according to the in-
structions of the manufacturer.
Note: All glassware must be pre-rinsed with this ammonia-
free water to prevent contamination.
198
-------
(Nitrogen, Organic
+ Ammonia)
6.2 Sulfuric Acid: As it readily absorbs ammonia, special pre-
caution must also be taken with respect to its use. Do not
store bottles reserved for this determination in areas of
potential ammonia contamination.
6.3 Potassium persulfate, low N (0.001%): Certain lots of this
reagent do not meet this specification for nitrogen content.
In order to insure this purity, dissolve 50 g of the reagent
in 500 ml of distilled water at 60° to 70°C. Make alkaline
with 10 ml of sodium hydroxide solution, 2.2M. Bubble air
that has been passed through a 10% sulfuric acid solution
through a tube which has been drawn into a capillary into the
solution while withdrawing air from the solution, which is
contained in a suction flask, under reduced pressure. Control
the air flow so that a rather vigorous bubbling through the
solution is maintained. After 30 minutes of vigorous bubbling,
cool the solution overnight in a refrigerator at about 4°C.
Filter the crop of crystals through a No. 40 Whatman filter
paper previously washed with ammonia-free water. Wash the
crystals with ice-cold ammonia-free water. Dry the crystals
at 60 to 70°C and store in a tightly closed reagent bottle.
6.3 Sulfuric acid solution: Add slowly and with stirring 310
ml of reagent grade, concentrated sulfuric acid to 600 ml of
ammonia-free water. Cool and dilute to 1,000 ml.
6.4 Phenol solution: Dissolve 83 g of phenol in 500 ml of ammonia-
free water by stirring with a Teflon coated magnet for 10
minutes. Add 32 g NaOH and dilute to 1 liter.
199
-------
(Nitrogen, Organic
+ Ammonia)
6.5 Sodium hypochlorite solution: Dilute 250 ml of bleach solution
containing 5.25% NaOCl to 500 ml with ammonia-free water.
6.6 Neutralizing solution: Dissolve 6 g EDTA disodium salt and
65 g of NaOH in 500 ml of distilled water. Dilute to 1,000
ml.
6.7 Stock solution: Dissolve 4.7168 g of ammonium sulfate analy-
tical reagent in ammonia-free water and dilute to 1,000 ml.
1.0 ml = 1.00 mg N.
6.8 Standard solution: Dilute 10.0 ml of stock solution to 100.0
ml. 1 ml = 0.10 mg N.
6.8.1 Using standard solution, prepare the following standards
in 100-ml volumetric flasks:
mg N/l ml Standard Solution/100 ml
0.0 0
1.0 1.0
2.0 2.0
3.0 3.0
4.0 4.0
5.0 5.0
6.0 6.0
8.0 8.0
10.0 10.0
7. Procedure
7.1 Transfer a 25-ml sample of water to a 125-ml Erlenmeyer flask.
7.2 Add 3 ml of sulfuric acid solution and evaporate on a hot
plate to light fumes of SO,. This step may require approximately
one hour. Close attention is not required of the sample; how-
ever, it should not be allowed to go to dryness. Cool the
sample.
200
-------
(Nitrogen, Organic
+ Ammonia)
7.3 Add 1 ml of ammonia-free water and 1 g of potassium persul-
fate, low N, and swirl the flask.
7.4 Digest the sample on the hot plate for 15 minutes. Fumes
of S0_ should begin coming off after 7 minutes. The samples
should become clear and transparent after this step, except
in the presence of large amounts of silica. Cool the sample;
dilute to 25 ml with ammonium free water. The sample is now
ready for automatic analysis.
7.5 Set up manifold as shown in Figure 1.
7.6 Allow both colorimeter and recorder to warm up for 30 minutes.
Run a baseline with all reagents, feeding distilled water
through the sample line. Adjust dark current and operative
opening on colorimeter to obtain stable baseline.
7.7 Place distilled water wash tubes in alternate openings in
Sampler and set sample timing at 2.0 minutes.
7.8 Arrange standards in Sampler in order of decreasing concen-
tration. Complete loading of Sampler tray with unknown
samples from 7.4
7.9 Switch sample line from distilled water to Sampler and begin
analysis.
8. Calculation
8.1 Prepare standard curve by plotting peak heights of processed
standards against concentration values. Compute concentration
of samples by comparing sample peak heights with standard curve.
201
-------
(Nitrogen, Organic
+ Ammonia)
9. Precision and Accuracy
9.1 Precision and accuracy data are not available at this time.
References
1. E. C. Julian and R. C. Kroner, "Determination of Organic Nitrogen
in Water by Semi-Automatic Analysis," Automation in Analytical
Chemistry, Technicon Symposia, 1966, Vol. 1, Mediad Inc., White
Plains, N.Y. (1967), p 542.
2. D. D. Van Slyke and A. J. Hiller, Biol. Chem., 102, 499 (1933).
202
-------
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. WASTE
HP
SAMPLING TIME • 2 MIN.
WASH TUBES - ONE
r
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TER
COLORIMETER RECORDER
15mm TUBULAR f/c
650 mji FILTERS
FIGURE 1 • ORGANIC NITROGEN & AMMONIA MANIFOLD
-------
OIL AND GREASE
1. Scope and Application
1.1 This method includes the measurement of hexane extractable
matter from waters, industrial wastes, and sewages. It is
applicable to the determination of relatively non-volatile
hydrocarbons, animal fats and waxes, grease and other types
of greasy-oily matters.
1.2 The method is not applicable to measurement of light
hydrocarbons that volatilize at temperatures below 80 C.
•1.3 The method covers the range from 5 to 1000 mg/1 of
extractable material.
2. Summary of Method
2.1 The sample is acidified to a low pH (<3) and extracted
with hexane using a Soxhlet extraction. The solvent is
evaporated from the separated extract and the residue
weighed.
3. Definitions
3.1 The definition of grease and oil is based on the
procedure used. The source of the oil and/or grease,
the solvent used, and presence of extractable non-oily
matter will influence the material measured and
interpretation of results.
205
-------
(Oil and Grease)
4. Purity of Reagents
4.1 Reagent grade hexane shall be used.
5. Sampling and Storage
5.1 A representative sample should be collected in a wide-
mouth bottle marked at the 1 liter volume. The initial
step of acidification shall be carried out in the
sample bottle. The entire sample is used for the test.
5.2 Because losses of grease will occur on sampling equip-
ment, collection of a composite sample is impractical,
and the examination of individual portions collected
at prescribed time intervals must be used to obtain
the average concentration over an extended period.
6. Apparatus
6.1 Extraction apparatus consisting of:
6.1.1 Soxhlet Extractor, medium size (Corning No. 3740 or
equivalent).
6.1.2 Soxhlet thimbles, to fit in Soxhlet Extractor, 6.1.1.
6.1.3 Blask, 125 ml (Corning No. 4100 or equivalent).
6.1.4 Condenser, Allihn (bulb) type, to fit extractor.
6.2 Vacuum pump, or other source of vacuum.
6.3 Buchner funnel, 12 cm.
206
-------
(Oil and Grease)
7. Reagents
7.1 Hydrochloric acid - Cone. (sp. g 1.18).
7.2 N-Hexane, b.p. 69° C.
7.3 Filter paper, Whatman No. 40, 11 cm.
7.4 Muslin cloth discs, 11 cm.
7.5 Diatomaceous - silica filter aid suspension,
10 g/1 distilled water.
Note 1 - Hyflo Super-Gel (Johns-Manvilie Corp.)
or equivalent is used in the preparation of the
filter aid suspension.
8. Procedure
8.1 In the following procedure, all steps must be rigidly
adhered to if consistent results are to be obtained.
8.2 Acidify the 1 liter sample to pH <3, which generally
requires 5 ml of cone. HC1. Use of a pH sensitive
paper is recommended when checking the pH of the sample.
8.3 Prepare a filter consisting of a muslin cloth disc
overlaid with filter paper. Place the assembled filter
in the Buchner funnel and wet the filter, pressing down
the edges to secure a seal. Using a vacuum, add 100 ml
of the filter aid suspension through the filter and then
wash with 3-100 ml volumes of distilled water. Continue
the vacuum until no more water passes through the filter.
8.4 Filter the acidified sample under vacuum and again con-
tinue the vacuum until no more water passes through the
filter.
207
-------
(Oil and Grease)
8.5 Remove the filter paper to a watch glass by means of
forceps. Add the material adhering to the edges of
the muslin cloth disc. Wipe the sides and bottom of the
collecting vessel, the stirring rod, and the Buchner
funnel with pieces of filter paper soaked in hexane.
Care must be taken to remove all films due to .grease
and to collect all solid material. Add all pieces of
filter paper to-the paper on the watch glass. Roll
the filter paper and the pieces of filter paper and
fit into a paper extraction thimble. Wipe the watch
glass with a piece of filter paper soaked in hexane
and place in the extraction thimble.
8.6 Dry the extraction thimble containing the filter paper
in an oven at 103° C for exactly 30 minutes. Fill the
thimble with small glass beads or glass wool.
8.7 Weigh the extraction flask, add the hexane, and connect
to the Soxhlet apparatus in which the extraction thimble
has been placed. Extract at the rate of 20 cycles per
hour for four hours. The four hours is timed from the
first cycle.
8.8 Distill the solvent from the extraction flask in a
water bath at 85° C. Dry by placing the flask on a
steam bath and draw air through the flask by means
of an applied vacuum for 15 minutes.
8.9 Cool in a desiccator for 30 minutes and weigh.
208
-------
(Oil and Grease)
9. Calculation
9.1 mg/1 .total grease = mg increase in weight of flask x 1,000
ml sample
10. Precision and Accuracy
10.1 Precision and accuracy data are not available.
209
-------
ORGANIC CARBON, TOTAL AND DISSOLVED
1. Scope and Application
1.1 This method includes the measurement of organic carbon in
surface waters, domestic and industrial wastes, and saline
waters. Exclusions are noted under Definitions and
Interferences.
1.2 The method is applicable to measurement in the range of 1
to 150 mg/liter.
2. Summary of Method
2.1 A micro sample of the wastewater to be analyzed is injected
into a catalytic combustion tube which is enclosed by an
electric furnace thermostated at 950°C. The water is
vaporized and the carbonaceous material is oxidized to
carbon dioxide (C02) and steam in a carrier stream of pure
oxygen. The oxygen flow carries the steam and C07 out of
the furnace where the steam is condensed and the condensate
removed. The C02, oxygen, and remaining water vapor enter
an infrared analyzer sensitized to provide a measure of CO^.
The amount of CO- present is directly proportional to the
concentration of carbonaceous material in the injected
sample.
3. Definitions
3.1 The carbonaceous analyzer measures all of the carbon in a
sample after injection into the combustion tube. Because
211
-------
(Organic Carbon)
of various properties of carbon-containing compounds in
liquid samples, preliminary treatment of the sample prior
to injection dictates the definition of the carbon as it
is measured.
Forms of carbon that are measured by the combustion-
infrared method are:
A) soluble, nonvolatile organic carbon; for
instance, natural sugars
B) soluble, volatile organic carbon; for instance,
mercaptans
C) insoluble, partially volatile carbon; for
instance, oils
D) insoluble, particulate carbonaceous materials;
for instance, cellulose fibers
E) soluble or insoluble carbonaceous materials
adsorbed or entrapped on insoluble inorganic
suspended matter; for instance, oily matter
adsorbed on silt particles
3.2 The final usefulness of the carbon measurement is in
assessing the potential oxygen-demanding load of organic
material on a receiving stream. This statement applies
whether the carbon measurement is made on a sewage plant
effluent, industrial waste, or on water taken directly from
the stream. In this light, carbonate and bicarbonate carbon
are not a part of the oxygen demand in the stream and therefore
212
-------
(Organic Carbon)
should be discounted in the final calculation or removed
prior to analysis. The manner of preliminary treatment
therefore defines the types of carbon which are measured.
4. Sample Handling and Preservation
4.1 Sampling and storage of samples in glass bottles is
preferable. Sampling and storage in plastic bottles such
as conventional polyethylene and cubitainers is permissible
if it is established that the containers do not contribute
contaminating organics to the samples (Note 1).
Note 1 - A brief study performed in the AQC 'Laboratory
indicated that distilled water stored in new, one quart
cubitainers did not show any increase in organic carbon
after two weeks exposure.
4.2 Because of the possibility of oxidation or bacterial
decomposition of some components of aqueous samples, the
lapse of time between collection of samples and start of
analysis should be kept to a minimum. Also, samples should
be kept cool (4°C) and protected from sunlight and atmospheric
oxygen.
4.3 In instances where analysis cannot be performed within two
hours (2 hours) from time of sampling, it is recommended
that the sample be acidified (pH = 2) with HC1.
5. Interferences
5.1 Carbonate and bicarbonate carbon represent an interference
under the terms of this test and must be removed or accounted
213
-------
(Organic Carbon)
for in the final calculation.
5.2 This procedure is applicable only to homogeneous samples
which can be injected into the apparatus reproducibly
by means of a microliter type syringe. The needle
openings of the syringe limit the maximum size of particles
which may be included in the sample. (Cf 6.3)
6. Apparatus
6.1 Apparatus for blending or homogenizing samples:
Generally, a Waring-type blender is satisfactory.
6.2 Apparatus for total and dissolved organic carbon:
6.2.1 Dow-Beckman Carbonaceous Analyzer, (single
channel) or
6.2.2' Dow Beckman Carbonaceous Analyzer Model No. 915
(dual channel).
6.3 Hypodermic syringe, 0-50 yl, needle opening of
approximately 150 microns; Hamilton No. 705 N or equivalent
is satisfactory.
6.3.1 Hamilton No. 750 N, 0-500 yl has a needle opening
of approximately 400 microns and may be used for
samples containing large particulates.
7. Reagents and Materials
7.1 Distilled water used in preparation of standards and for
dilution of samples should be ultra pure to reduce the
size of the blank. Carbon dioxide-free, double distilled
214
-------
(Organic Carbon)
water is recommended. Ion exchanged waters are not recom-
mended because of the possibility of contamination with
organic materials from the resins.
7.2 Potassium Hydrogen Phthalate, stock solution, 1000 mg carbon/
liter: Dissolve 0.2128 gof potassium hydrogen phthalate
(Primary Standard Grade) in double distilled water and dilute
to 100.0 ml.
Note: Sodium oxalate and acetic acid are not recommended as
stock solutions.
7.3 Potassium Hydrogen Phthalate, standard solutions: Prepare
standard solutions from the stock solution with double dis-
tilled water as follows:
ml of Stock Solution Standard
Diluted to 100 ml mg C/liter
1.0 10
2.0 20
3.0 30
4.0 40
5.0 50
6.0 60
8.0 80
10.0 100
7.4 Carbonate-bicarbonate, stock solution, 1000 mg carbon/liter:
Weigh 0.3500 g of sodium bicarbonate and 0.4418 g of sodium
carbonate and transfer both to the same 100 ml volumetric
flask. Dissolve with double distilled water.
7.5 Carbonate-bicarbonate, standard solution: Prepare a series
of standards similar to 7.3.
7.6 Blank solution: Use the same distilled water (or similar
quality water) used for the preparation of the standard
solutions.
215
-------
(Organic Carbon)
7.7 Packing for total carbon tube. Dissolve 20 g of
Co(N0_)-.6H-0 (cobalt nitrate hexahydrate) in 50 ml of
distilled water. Add this solution to 15 grams of long-
fiber asbestos in a porcelain evaporating dish. Mix and
evaporate to dryness on a steam bath. Place the dish in
a cold muffle furnace and bring to a temperature of 950°C.
After one to two hours at this temperature, remove the
dish and allow to cool. Break up any large lumps and mix
adequately but not excessively.
With the combustion tube held in a vertical position,
taper joint up, put about 1/2" of untreated asbestos in
the tube first, then transfer, in small amounts, approx-
imately one gram of catalyst into the tube with forceps or
tweezers. As it is added, tap or push the material gently
with a 1/4" glass rod. Do not force the packing. The
weight of the rod itself is sufficient to compress the
material. When completed, the length of the packing should
be about five or six centimeters.
Test the packed tube by measuring the flow rate of gas
through it at room temperature, and then at 950°C. The
rate should not drop more than 20%.
7.8 Packing for carbonate tube, (dual channel instrument).
Place a small wad of quartz wool or asbestos near the exit
end of the carbonate evolution tube. From the entrance
216
-------
(Organic Carbon)
end add 6-12 mesh quartz chips, allowing these to
collect against the wad to a length of 10 cm. Pour an
excess of 85 percent phosphoric acid into the tube while
holding it vertically, and allow the excess to drain out.
8. Instrument Adjustment
8.1 Turn on the infrared analyzer, recorder, and tube furnaces,
setting the total carbon furnace at 950°C and the carbonate
furnace at 175°C. Allow a warm-up time of at least 2 hr.
for attainment of stable operation; in daily use the
analyzer can be left on continuously. Adjust the oxygen
flow rate to 80 to 100 ml/min through the total carbon
tube. With the recorder set at the 5-mv range, adjust the
amplifier gain so that a 20-yl sample of the 100 mg/liter
carbon standard gives a peak height of approximately half
the recorder scale (see 7.3). At this setting the noise
level should be less than 0.5 percent of full scale. If the
noise level is higher, the analyzer or the recorder may re-
quire servicing.
8.2 Immediately prior to carrying out calibrations or analyses,
inject several portions of the appropriate 100 mg/liter
standard (see 7.2) into the tube to be used, until constant
readings are obtained.
217
-------
(Organic Carbon)
9. Calibration - Dual Channel Instrument
9.1 Successively introduce 20 yl of each phthalate standard
into the total carbon tube and read the height of the
corresponding peak. Between injections allow the recorder
pen to return to its base line. The actual injection
technique is as follows: Rinse the syringe several times
with the solution to be analyzed, fill, and adjust to 20 yl.
Wipe off the excess with soft paper tissue, taking care that
no lint adheres to the needle. Remove the plug from the
syringe holder, insert the sample syringe, and inject the
sample into the combustion tube with a single, rapid move-
ment of the index finger. Leave the syringe in the holder
until the flow rate returns to normal, then replace it with
the plug. Run duplicate determinations on each solution and
on a water blank.
9.2 Correct standards for blank correction as follows: Standard
peak height minus blank peak height = correct peak height
in mm. Prepare a standard curve of total carbon versus peak
height.
9.3 In the same way, prepare a series of diluted carbonate
standards containing 20, 40, 60, 80, and 100 mg of inorganic
carbon per liter. Turn the four-way valve of the apparatus
to direct the gas flow through the low temperature tube and
218
-------
(Organic Carbon)
to the analyzer. Adjust the flow rate to 80 to 100 ml/min
and allow the baseline to become stabilized. Successively
introduce 20 yl of each standard and a water blank in
duplicate into the low temperature tube and read the peak
heights as previously described.
9.4 Prepare a standard curve of inorganic carbon versus peak
height applying the correction as noted in 9.2.
10. Procedure - Dual Channel Instrument
10.1 Mix or blend each sample thoroughly and carry out any
appropriate dilution to bring the carbon content within the
range of the standard curve.
10.2 Following the technique described in 9.1 and 9.3, inject
20-yl samples successively (in duplicate) into each tube
and read the peak heights corresponding to total carbon
and inorganic (carbonate) carbon. From the appropriate
calibration curve and each peak height observed, read the
corresponding carbon concentration in mg/liter.
10.3 Subtract the inorganic carbon value from the total carbon
value. The difference thus obtained is operationally
defined as Total Organic Carbon.
10.4 Filter a 100 ml aliquot through a pre-rinsed 0.45 y pore
size filter. Repeat sample injection as in 10.2.
219
-------
(Organic Carbon)
10.5 Subtract the dissolved inorganic carbon value from the
dissolved carbon value. The difference thus obtained
is operationally defined as Dissolved Organic Carbon.
11. Calibration - Single Channel Instrument
11.1 Standardize the instrument according to directions given
in 9.1 and 9.2.
12. Procedure - Single Channel Instrument
12.1 Transfer a representative aliquot of about 10 - 15 ml to
a 30 ml beaker, add 2 or more drops of concentrated HC1
until the pH is reduced to = 2 and purge with C0_-free
nitrogen gas for about 5-10 minutes. (Do not use
plastic tubing). Place the beaker on a magnetic stirrer
and while stirring withdraw a 20 yl sample. Inject the
sample as in 9.1.
12.2 Obtain concentration directly from standard curve. The
carbon thus measured is operationally defined as Total
Organic Carbon.
12.3 Filter a 100-ml aliquot through a pre-rinsed 0.45 p pore
size filter and proceed as in 12.1.
12.4 Obtain concentration directly from standard curve. The
carbon thus measured is operationally defined as Dissolved
Organic Carbon.
220
-------
(Organic Carbon)
13. Precision and Accuracy
13.1 The precision of this method as determined by ASTM is
expressed as follows:
S = 0.032 x + 0.03 where
Li
ST = single laboratory precision and
Lt
x = concentration of carbon in mg/1
221
-------
PHOSPHORUS, ALL FORMS
(Single Reagent Method)
1. Scope and Application
1.1 These methods cover the determination of specified forms
of phosphorus in surface waters, domestic and industrial
wastes, and saline waters. They may be applicable to
sediment-type samples, sludges, algal blooms, etc., but
sufficient data is not available at this time to warrant
such usage when measurements for phosphorus content are
required.
1.2 The methods are based on reactions that are specific for
the orthophosphate ion. Thus, depending on the prescribed
pre-treatment of the sample, the various forms of phos-
phorus given in Figure 1 may be determined. These forms are,
in turn, defined in Table 1.
1.2.1 Except for in-depth and detailed studies, the most
commonly measured forms are phosphorus and dissolved
phosphorus, and orthophosphate and dissolved ortho-
phosphate. Hydrolyzable phosphorus is normally
found only in sewage-type samples and insoluble
forms of phosphorus, as noted, are determined by
calculation.
1.3 The methods are usable in the 0.01 to 0.5 mg/1 P range.
223
-------
to
Residue
SAMPLE
Total Sample (No Filtration)
V
Direct
Colorimetry
V
Hydrolysis
Orthophosphate
Hydrolyzable §
Orthophosphate
Filter (through 0.45 u membrane filter)
N/
Filtrate
\
Direct
Colorimetry
/
Dissolved
Orthophosphate
\
/
H2S04
Hydrolysis fT
Colorimetry
Diss . Hydrolyzable
§ Orthophosphate
Persulfate
Digestion §
.Colorimetry
Dissolved
Phosphorus
\
Persulfate
Digestion
Co lorimptry
Phosphorus
Figure 1. Analytical Scheme for Differentiation of Phosphorus Forms.
-------
(Phosphorus)
2. Summary of Method
2.1 Ammonium molybdate and potassium antimonyl tartrate react
in an acid medium with dilute solutions of phosphorus to
form an antimony-phosphate-molybdate complex. This com-
plex is reduced to an intensely blue-colored complex by
ascorbic acid. The color is proportional to the phosphorus
concentration.
2.2 Only orthophosphate forms a blue color in this test.
Polyphosphates (and some organic phosphorus compounds)
may be converted to the orthophosphate form by sulfuric-
acid-hydrolysis. Organic phosphorus compounds may be
converted to the orthophosphate form by persulfate di-
gestion.
3. Definitions
3.1 The various forms of phosphorus are defined in Table 1.
4. Sample Handling and Preservation
4.1 If benthic deposits are present in the area being sampled,
great care should be taken not to include these deposits.
4.2 Sample containers may be of plastic material, such as
cubitainers, or of Pyrex glass.
4.3 If the analysis cannot be performed the same day of
collection, the sample should be preserved by the ad-
dition of 40 mg HgCl- per liter and refrigeration at
4° C.
225
-------
(Phosphorus)
TABLE 1
PHOSPHORUS TERMINOLOGY
1. Phosphorus (P) - all of the phosphorus present in the sample,
regardless of form, as measured by the persulfate digestion
procedure.
a. Orthophosphate (P, ortho) - inorganic phosphorus
[(PO.) ] in the sample as measured by the direct color-
imetric analysis procedure.
b. Hydrolyzable Phosphorus (P, hydro) - phosphorus in the
sample as measured by the sulfuric acid hydrolysis pro-
cedure, and minus pre-determined orthophosphates.
This hydrolyzable phosphorus includes polyphosphates
-4 -5
[(P-O-) , (P_0 _) , etc.] + some organic phosphorus.
c. Organic Phosphorus (P, org) - phosphorus (inorganic +
oxidizable organic) in the sample as measured by the
persulfate digestion procedure, and minus hydrolyzable
phosphorus and orthophosphate.
2. Dissolved Phosphorus (P-D) - all of the phosphorus present
in the filtrate of a sample filtered through a phosphorus-free
filter of 0.45 micron pore size and measured by the persulfate
digestion procedure.
a. Dissolved Orthophosphate (P-D, ortho) - as measured by
the direct colorimetric analysis procedure.
b. Dissolved Hydrolyzable Phosphorus (P-D, hydro) - as
measured by the sulfuric acid hydrolysis procedure and
minus pre-determined dissolved orthophosphates.
226
-------
(Phosphorus)
TABLE 1 (Continued)
c. Dissolved Organic Phosphorus (P-D, org) - as measured
by the persulfate digestion procedure, and minus dis-
solved hydrolyzable phosphorus and orthophosphate.
3. The following forms, when sufficient amounts of phosphorus are
present in the sample to warrant such consideration, may be
calculated:
a. Insoluble Phosphorus (P-I) = (P) - (P-D).
(1) Insoluble orthophosphate (P-I, ortho) = (P, ortho) -
(P-D, ortho).
(2) Insoluble Hydrolyzable Phosphorus (P-I, hydro) =
(P, hydro) - (P-D, hydro).
(3) Insoluble Organic Phosphorus (P-I, org) = (P, org) -
(P-D, org).
4. All phosphorus forms shall be reported as P, mg/1.
5. Interferences
5.1 It is reported that no interference is caused by copper,
iron, or silicate at concentrations many times greater than .
their greatest reported concentration in sea water. However,
high iron concentrations can cause precipitation of phosphorus
through the formation of clumps in the bottom of the sample.
5.2 The salt error for samples ranging from 5 to 20 percent salt
content was found to be less than 1 percent .
5.3 Arsenate, in concentrations greater than found in sea water,
does not interfere
227
-------
(Phosphorus)
6. Apparatus
6.1 Photometer - A spectrophotometer or filter photometer suitable
for measurements at 880 my, and providing a light path of 1
inch (2.54 cm) or longer, should be used.
6.2 Acid-washed glassware: All glassware used in the determination
should be washed with hot 1:1 HC1 and rinsed with distilled
water. The acid-washed glassware should be filled with dis-
tilled water and treated with all the reagents to remove the
last traces of phosphorus that might be adsorbed on the glass-
ware. Preferably, this glassware should be used only for the
determination of phosphorus and after use it should be rinsed
with distilled water and kept covered until needed again. If
this is done, the treatment with 1:1 HC1 and reagents is only
required occasionally. Commercial detergents should never be
used.
7. Reagents
7.1 Sulfuric acid solution, 5N: Dilute 70 ml of cone. H SO with
distilled water to 500 ml.
7.2 Potassium antimonyl tartrate solution: Weigh 1.3715 g
K(SbO)C4H 0 .1/2 HO, dissolve in 400 ml distilled water
in 500 ml volumetric flask, dilute to volume. Store in
glass-stoppered bottle.
4
7.3 Ammonium molybdate solution: Dissolve 20 g (NH.)6Mo_02.. H_0
in 500 ml distilled water. Store in a plastic bottle at 4° C.
228
-------
(Phosphorus)
7.4 Ascorbic acid, 0.1M: Dissolve 1.76 g of ascorbic acid in
100 ml of distilled water. The solution is stable for
about a week if stored at 4° C.
7.5 Combined reagent: Mix the above reagents in the following
proportions for 100 ml of the mixed reagent: 50 ml of
5N H-SQ., 5 ml of potassium antimonyl tartrate solution, 15
ml of ammonium molybdate solution, and 30 ml of ascorbic
acid solution. Mix after addition of each reagent. All
reagents must reach room temperature before they are mixed
and must be mixed in the order given. If turbidity forms
in the combined reagent, shake and let it stand for a few
minutes until the turbidity disappears before preceding.
The reagent is stable for one week if stored at 4° C.
7.6 Strong-acid solution: Slowly add 310 ml cone. H SO. to
600 ml distilled water. When cool, dilute to 1 liter.
7.7 Ammonium persulfate.
7.8 Stock Solution: Dissolve in distilled water 0.2197 g of
potassium dihydrogen phosphate, KH^PO., which has been dried
in an oven at 105° C. Dilute the solution to 1,000 ml;
1.00 ml equals 0.05 mg P.
7.9 Standard Solution: Dilute 10.0 ml of stock phosphorus
solution to 1,000 ml with distilled water; 1.00 ml equals
0.5 yg P.
7.9.1 Using standard solution, prepare the following
229
-------
(Phosphorus)
standards in 50.0-ml volumetric flasks:
ml of Standard Solution Cone., mg/1
0
1.0
3.0
5.0
10.0
20.0
30.0
40.0
50.0
0.00
0.01
0.03
0.05
0.10
0.20
0.30
0.40
0.50
8. Procedure
8.1 Phosphorus
8.1.1 Add 1 ml of strong-acid solution to a 50 ml
)
sample in a 125-ml Erlenmeyer flask.
8.1.2 Add 0.4 gram of ammonium persulfate.
8.1.3 Boil gently on a pre-heated hot plate for
approximately 30-40 minutes or until a final
volume of about 10 ml is reached. Do not al-
low sample to go to dryness. Alternatively,
heat for 30 minutes in an autoclave at 121° C
(15-20 psi).
8.L.4 Add phenolphthalein and adjust sample to pink
with IN NaOH. Bring back to colorless with one
drop strong-acid solution. Cool and dilute the
sample to 50 ml.
8.1.5 Determine phosphorus as outlined in 8.3.2 Ortho-
phosphate .
8.2 Hydrolyzable Phosphorus
8.2.1 Add 1 ml of strong-acid solution to a 50-ml
230
-------
(Phosphorus)
sample in a 125-ml Erlenmeyer Flask.
8.2.2 Boil gently on a pre-heated hot plate for 30-40
minutes or until a final volume of about 10 ml is
reached. Do not allow sample to go to dryness.
Alternatively, heat for 30 minutes in an auto-
clave at 121° C (15-20 psi).
8.2.3 Add phenolphthalein and adjust sample to pink
with 1 N NaOH. Bring back to colorless with one
drop strong-acid solutions. Cool and dilute the
sample to 50 ml.
8.2.4 The sample is now ready for determination of
phosphorus as outlined in 8-3.2 Orthophosphate.
8.3 Orthophosphate
8.3.1 Add 1 drop of phenolphthalein indicator to the
50.0 ml sample. If a red color develops, add
strong-acid solution drop-wise to just discharge
the color.
8.3.2 Add 8.0 ml of combined reagent to sample and mix
thoroughly. After a minimum of ten minutes, but
no longer than thirty minutes, measure the color
absorbance of each sample at 880 my with a spectro-
photometer, using the reagent blank as the reference
solution.
9. Calculation
9.1 Prepare standard curve by plotting absorbance values of
standards as ordinates and the corresponding phosphorus
concentrations as abscissas.
231
-------
(Phosphorus)
9.1.1 Process standards and blank exactly as the samples.
Run at least a blank and two standards with each
series of samples. If the standards do not agree
within * 2% of the true value, prepare a new cali-
bration curve.
9.2 Obtain concentration value of sample directly from prepared
standard curve. Report results as P, mg/1.
10. Precision and Accuracy
10.1 In eight laboratories involving 13 analysts, using a
variety of natural water samples, both salt and fresh,
the standard deviation at a concentration of 0.23mg P/l
was ± 0.004 (AQC Laboratory).
10.2 Under the same conditions, recovery was 101% (AQC Laboratory)
References
1. J. Murphy and J. Riley, "A Modified Single Solution Method
for the Determination of Phosphate in Natural Waters."
Anal. Chim. Acta., 27, 31 (1962).
2. M. Gales, Jr., E. Julian, and R. Kroner, "Method for
Quantitative Determination of Total Phosphorus in Water."
Jour AWWA, 58, No. 10, 1363 (1966).
232
-------
PHOSPHORUS, ALL FORMS
(Automated Single Reagent Method)
1. Scope and Application
1.1 These methods cover the determination of specified forms
of phosphorus in surface waters, domestic and industrial
wastes, and saline waters. They may be applicable to
sediment-type samples, sludges, algal blooms, etc., but
sufficient data is not available at this time to warrant
such usage when measurements for phosphorus content are
required.
1.2 The methods are based on reactions that are specific for
the orthophosphate ion. Thus, depending on the prescribed
pre-treatment of the sample, the various forms of phos-
phorus given in Figure 1 may be determined. These forms are,
in turn, defined in Table 1.
1.2.1 Except for in-depth and detailed studies, the most
commonly measured forms are phosphorus and dissolved
phosphorus, and orthophosphate and dissolved ortho-
phosphate. Hydrolyzable phosphorus is normally
found only in sewage-type samples and insoluble
forms of phosphorus, as noted, are determined by
calculation.
1.3 The methods are usable in the 0.01 to 1.0 mg P/l range.
Approximately 20 samples per hour can be analyzed.
233
-------
to
co
Total Sample (No Filtration)
\/
\/
Direct
Colorimetry
Hydrolysis
N/ Colorimetrv
Orthophosphate
Hydrolyzable §
Orthophosphate
Filter (through 0.45 u membrane filter)
Direct
Colorimetry
\/
Hydrolysis
Colorimetry
Dissolved
Orthophosphate
Persulfate
Digestion §
\/ Colorimetry
Diss. Hydrolyzable
§ Orthophosphate
Dissolved
Phosphorus
Persulfate
Digestion
\1/ Colorimetrv
Phosphorus
Figure 1. Analytical Scheme for Differentiation of Phosphorus Forms.
-------
(Phosphorus)
2. Summary of Method
2.1 Ammonium molybdate and potassium antimonyl tartrate react
in an acid medium with dilute solutions of phosphorus to
form an antimony-phosphate-molybdate complex. This com-
plex is reduced to an intensely blue-colored complex by
ascorbic acid. The color is proportional to the phosphorus
concentration.
2.2 Only orthophosphate forms a blue color in this test.
Polyphosphates (and some organic phosphorus compounds) may
be converted to the orthophosphate form by manual sulfuric-
acid-hydrolysis. Organic phosphorus compounds may be con-
verted to the orthophosphate form by manual persulfate
(2)
digestion . The developed color is measured automatically
on the AutoAnalyzer.
3. Definitions
3.1. The various forms of phosphorus are defined in Table 1.
4. Sample Handling and Preservation
4.1 If benthic deposits are present in the area being sampled,
great care should be taken not to include these deposits.
4.2 Sample containers may be of plastic material, such as
cubitainers, or of Pyrex glass.
4.3 If the analysis cannot be performed the same day of collection,
the sample should be preserved by the addition of 40 mg HgCl2
per liter and refrigeration at 4°C.
235
-------
(Phosphorus)
TABLE 1
PHOSPHORUS TERMINOLOGY
1. Phosphorus (P) - all of the phosphorus present in the sample
regardless of form, as measured by the persulfate digestion
procedure.
a. Orthophosphate (P, ortho) - inorganic phosphorus
[(PO.) ] in the sample as measured by the direct color-
imetric analysis procedure.
b. Hydrolyzable Phosphorus (P, hydro) - phosphorus in the
sample as measured by the sulfuric acid hydrolysis pro-
cedure, and minus pre-determined orthophosphates. This
hydrolyzable phosphorus includes polyphosphates
[(P 0_)~ , (PjO n)~ , etc.] + some organic phosphorus.
c. Organic Phosphorus (P, org) - phosphorus (inorganic +
oxidizable organic) in the sample as measured by the
persulfate digestion procedure, and minus hydrolyzable
phosphorus and orthophosphate.
2. Dissolved Phosphorus (P-D) - all of the phosphorus present
in the filtrate of a sample filtered through a phosphorus-free
filter of 0.45 micron pore size and measured by the persulfate
digestion procedure.
a. Dissolved Orthophosphate (P-D, ortho) - as measured by the
direct colorimetric analysis procedure.
236
-------
(Phosphorus)
b. Dissolved Hydrolyzable Phosphorus (P-D, hydro) - as
measured by the sulfuric acid hydrolysis procedure and
minus pre-determined dissolved orthophosphates.
c. Dissolved Organic Phosphorus (P-D, org) - as measured
by the persulfate digestion procedure, and minus dissolved
hydrolyzable phosphorus and orthophosphate.
3. The following forms, when sufficient amounts of phosphorus are
present in the sample to warrant such consideration, may be
calculated:
a. Insoluble Phosphorus (P-I) = (P) - (P-D).
(1) Insoluble orthophosphate (P-I, ortho) = (P, ortho) -
(P-D, ortho).
(2) Insoluble Hydrolyzable Phosphorus (P-I, hydro) =
(P, hydro) - (P-D, hydro).
(3) Insoluble Organic Phosphorus (P-I, org) = (P, org) -
(P-D, org).
4. All phosphorus forms shall be reported as P, mg/1.
5. Interferences
5.1 It is reported that no interference is caused by copper,
iron, or silicate at concentrations many times greater than
their greatest reported concentration in sea water. However,
high iron concentrations can cause precipitation of phosphorus
through the formation of clumps in the bottom of the sample.
5.2 The salt error for samples ranging from 5 to 20 percent salt
content was found to be less than 1 percent .
237
-------
(Phosphorus)
5.3 Arsenate, in concentrations greater than found in sea water,
does not interfere .
6. Apparatus
6.1 Technicon AutoAnalyzer consisting of:
6.1.1 Sampler I
6.1.2 Manifold
6.1.3 Proportioning Pump
6.1.4 Heating Bath, 50°C
6.1.5 Colorimeter equipped with 50 mm tubular flow cell and
650 my filters
6.1.6 Recorder
6.2 Hot Plate or Autoclave
6.3 Acid-washed glassware: All glassware used in the determination
should be washed with hot 1:1 HC1 and rinsed with distilled
water. The acid-washed glassware should be filled with distilled
water and treated with all the reagents to remove the last traces
of phosphorus that might be adsorbed on the glassware. Preferably,
this glassware should be used only for the determination of phos-
phorus and after use it should be rinsed with distilled water and
kept covered until needed again. If this is done, the treatment
with 1:1 HC1 and reagents is only required occasionally. Commercial
detergents should never be used.
7. Reagents
7.1 Sulfuric acid solution, 5N: Dilute 70 ml of cone. H SO with
distilled water to 500 ml.
238
-------
(Phosphorus)
7.2 Potassium antimonyl tartrate solution: Weigh 0.3 g
K(SbO)C4H.O 1/2 HO, dissolve in 50 ml distilled water
in 100 ml volumetric flask, dilute to volume. Store in
glass-stoppered bottle.
4
7.3 Ammonium molybdate solution: Dissolve 4 g (NH.) ..Mo-O^.. H..O
in 100 ml distilled water. Store in a plastic bottle at 4°C.
7.4 Ascorbic acid, 0.1M: Dissolve 1.8 g of ascorbic acid in
100 ml of distilled water. The solution is stable for about
a week if stored at 4°C.
7.5 Combined reagent: Mix the above reagents in the following
proportions for 100 ml of the mixed reagent: 50 ml of
5N H?S04, 5 ml of potassium antimonyl tartrate solution,
15 ml of ammonium molybdate solution, and 30 ml of ascorbic
acid solution. Mix after addition of each reagent. All
reagents must reach room temperature before they are mixed
and must be mixed in the order given. If turbidity forms
in the combined reagent, shake and let it stand for a few
minutes until the turbidity disappears before proceeding.
This volume is sufficient for 4 hours operation. Since the
stability of this solution is limited, it must be freshly
prepared for each run.
7.6 Strong-acid solution: Slowly add 310 ml cone. H-SO. to
600 ml distilled water. When cool, dilute to 1 liter.
7.7 Ammonium persulfate.
239
-------
(Phosphorus)
7. 8 Wash water: Add 40 ml of sulfuric acid solution to 1 liter
of distilled water and dilute to 2 liters. (Not to be used
when only orthophosphate is being determined.)
7. 9 Stock Solution: Dissolve 0.4393 g of pre-dried KH PQ in
distilled water and dilute to 1 liter. 1 ml = 0.1 mg P.
7.10 Standard Solution A: Dilute 100 ml of stock solution to 1
liter. 1 ml = 0.01 mg P.
7.11 Standard Solution B: Dilute 100 ml of standard solution A
to 1 liter. 1 ml = 0.001 mg P.
7.12 Prepare a series of standards by diluting suitable volumes
of standard solutions A and B to 100.0 ml with distilled
water. The following dilutions are suggested:
ml
ml
of Standard Solution B
0.0
2.0
5.0
10.0
of Standard Solution A
2.0
5.0
8.0
10.0
Cone . ,
mg P/l
0.00
0.02
0.05
0.10
0.20
0.50
0.80
1.00
Note: When the samples to be analyzed are saline waters,
Substitue Ocean Water (SOW) should be used for preparing
the standards; otherwise, distilled water is used. A
tabulation of SOW composition follows:
NaCl - 24.53g/l MgCl2 - 5.20g/l Na2S04 - 4.09g/l
CaCl2 - 1.16g/l KC1 - 0.70g/l NaHC03 - 0.20g/l
KBr - 0.10g/l H3B03 - 0.03g/l SrCl2 - 0.03g/l
NaF - 0.003g/l
240
-------
(Phosphorus)
8. Procedure
8.1 Phosphorus
8.1.1 Add 1 ml of strong-acid solution to a 50 ml sample in
a 125-ml Erlenmeyer flask.
8.1.2 Add 0.4 gram of ammonium persulfate.
8.1.3 Boil gently on a pre-heated hot plate for approximately
30-40 minutes or until a final volume of about 10 ml is
reached. Do not allow sample to go to dryness. Alter-
natively, heat for 30 minutes in an autoclave at 121°C
(15-20 psi). •
8.1.4 Cool and dilute the sample to 50 ml.
8.1.5 Determine phosphorus as outlined in 8.3 Orthophosphate.
8.2 Hydrolyzable Phosphorus
8.2.1 Add 1 ml of strong-acid solution to a 50-ml sample in a
125-ml Erlenmeyer Flask.
8.2.2 Boil gently on a pre-heated hot plate for 30-40 minutes
or until a final volume of about 10 ml is reached. Do
not allow sample to go to dryness. Alternatively, heat
for 30 minutes in an autoclave at 121°C (15-20 psi).
8.2.3 Cool and dilute the sample to 50.0 ml.
8.2.4 The sample is now ready for determination of phosphorus
as outlined in 8.3 Orthophosphate.
8.3 Orthophosphate
8.3.1 Set up manifold as shown in Figure 1.
241
-------
(Phosphorus)
8.3.2 Allow both colorimeter and recorder to warm up for
30 minutes. Run a baseline with all reagents, feeding
distilled water through the sample line. Adjust dark
current and operative opening on colorimeter to obtain
stable baseline.
8.3.3 Place wash water tubes (see 7.8) in Sampler, in sets
of 2, leaving every third position vacant. Set sample
timing at 1.0 minutes.
8.3.4 Place standards in Sampler in order of decreasing
concentration. Complete filling of sampler tray with
unknown samples.
8.3.5 Switch sample line from distilled water to Sampler and
begin analysis.
9. Calculation
9.1 Prepare standard curve by plotting peak heights of processed
standards against known concentrations. Compute concentrations
of samples by comparing sample peak heights with standard curve.
Any sample whose computed value is less than 5% of its immediate
predecessor must be rerun.
10. Precision ajid Accuracy
10.1 In a single laboratory, using surface water samples at
concentrations of .04, 0.19, 0.35, and 0.84 mg P/l, standard
deviations were ±0.005, ±0.000, ±0.003, and ±0.000, respectively
(AQC Laboratory).
242
-------
(Phosphorus)
10.2 In a single laboratory, using surface water samples at
concentrations of 0.07 and 0.76 mg P/l, recoveries were
99% and 100%, respectively (AQC Laboratory).
References
1. J. Murphy and J. Riley, "A Modified Single Solution Method for the
Determination of Phosphate in Natural Waters." Anal. Chim. Acta.,
27_, 31 (1962).
2. M. Gales, Jr., E. Julian, and R. Kroner, "Method for Quantitative
Determination of Total Phosphorus in Water." Jour AWWA, 58, No. 10,
1363 (1966).
243
-------
to
^
50
^
LARGE MIXING COIL (LM)
00000000
°CJ)) HEATING BATH
SM
0000
SM
01 _ 0000
I
G;
COLORIMETER
Rflmm TIIRIII AR f If
|~~
3 I-1"
^ r
VASTE
r
I
V
IX
P
P B
R R
Y Y
0 0
G G
ROPORTIONING PUM
» nm i LLH
ml/min. fe ct
(o ^^
2.90 ^SAMPLE ^^
0.80 , AIR
1.20 ^DISTILLED WATER
0.42 ^MIXED REAGENT
2.00, WASTE
P
RECORDER SAMPLING TIME: 1.0 M
650 mjl FILTERS
FIGURE 1. PHOSPHORUS SINGLE REAGENT MANIFOLD
-------
PHOSPHORUS, ALL FORMS
(Automated Stannous Chloride Method)
1. Scope and Application
1.1 These methods cover the determination of specified forms
of phosphorus in surface waters, domestic and industrial
wastes. They may be applicable to sediment-type samples,
sludges, algal blooms, etc., but sufficient data is not
available at this time to warrant such usage when measure-
ments for phosphorus content are required.
1.2 The methods are based on reactions that are specific for
the orthophosphate ion. Thus, depending on the prescribed
pre-treatment of the sample, the various forms of phos-
phorus given in Figure 1 may be determined. These forms are,
in turn, defined in Table 1.
1.2.1 Except for in-depth and detailed studies, the most
commonly measured forms are phosphorus and dissolved
phosphorus, and orthophosphate and dissolved ortho-
phosphate. Hydrolyzable phosphorus is normally
found only in sewage-type samples and insoluble
forms of phosphorus, as noted, are determined by
calculation.
1.3 The methods are usable in the 0.01 to 1.0 mg P/l range.
Approximately 15 samples per hour can be analyzed.
247
-------
SAMI
\
Total Sample (No Filtration)
' N/
Direct H-SO.
Colorimetry Hydro ly
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Hydrolyzab
Orthophosphate Orthophos]
Filter (through 0.45y membrane filter)
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Persulfate
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ihate Phosphorus
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Diss. Hydrolyzable
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, Colorimetry
Dissolved
Phosphorus
Figure 1. Analytical Scheme for Differentiation of Phosphorus Forms
-------
(Phosphorus)
2. Summary of Method
2.1 Phosphorus is determined by manually digesting the samples
with ammonium persulfate and sulfuric acid to convert the
various forms of phosphorus to the orthophosphate form and
measurement of this orthophosphate on the AutoAnalyzer.
2.2 In this colorimetric method, ammonium molybdate reacts with
the orthophosphate in an acid medium to form a heteropoly acid,
molybdophosphoric acid. This acid is reduced by stannous
chloride to form the intensely colored complex, molybdenum blue,
which is directly proportional to the amount of phosphorus.
3. Definitions
3.1 The various forms of phosphorus are defined in Table 1.
4. Sample Handling and Preservation
4.1 If benthic deposits are present in the area being sampled,
great care should be taken not to include these deposits.
4.2 Sample containers may be of plastic material, such as
cubitainers, or of Pyrex glass.
4.3 If the analysis cannot'be performed the same day of
collection, the sample should be preserved by the ad-
dition of 40 mg HgCl~ per liter and refrigeration at
4° C.
5. Interferences
5.1 Method does not work on saline waters.
249
-------
(Phosphorus)
6. Apparatus
6.1 Acid-washed glassware: To prevent contamination, all glass-
ware used in the preparation of standards and actual deter-
minations should be washed with hot 1:1 HC1 and rinsed with'
distilled water. The acid-washed glassware should be filled
with distilled water and treated with all the reagents to
remove the last traces of phosphorus that might be adsorbed
on the glassware. Preferably, this glassware should be used
only for the determination of phosphorus and after use it
should be rinsed with distilled water and kept covered until
needed again. If this is done, the treatment with 1:1 HC1
and reagents is only required occasionally. Commercial
detergents should never be used.
6.2 Technicon AutoAnalyzer consisting of:
6.2.1 Sampler I
6.2.2 Continuous Filter
6.2.3 Manifold
6.2.4 Proportioning Pump
6.2.5 Colorimeter equipped with 15 mm tubular flow cell and
650 my filters.
6.2.6 Recorder
6.3 Hot Plate or Autoclave
250
-------
(Phosphorus)
7. Reagents
7.1 Sulfuric acid solution: Cautiously add 310 ml of concentrated
sulfuric acid slowly and with stirring to about 600 ml of dis-
tilled water. Cool and dilute to 1 liter.
7.2 Ammonium molybdate solution: Dissolve 12.5 g of (NH.)^Mo-O,,. . 4H_0
in 175 ml of distilled water. Cautiously add 77.5 ml of con-
centrated sulfuric acid slowly and with stirring to 400 ml of
distilled water. Cool. Add the molybdate solution to the acid
solution and dilute to 1 liter.
7.3 Stannous chloride solution: Dissolve 2.5 g of fresh SnCl_.2H 0
in 20 ml of hydrochloric acid. Warming on a hot plate will aid
in dissolving this material. Dilute to 400 ml. Stable for 1
week at room temperature; one month at 4°C.
7.4 Wash water: Add 40 ml of sulfuric acid solution to 1 liter of
distilled water and dilute to 2 liters.
7.5 Stock Solution: Dissolve 0.4393 g of pre-dried KH PO in
distilled water and dilute to 1 liter. 1 ml = 0.1 mg P.
7.6 Standard Solution A: Dilute 100 ml of stock solution to 1 liter.
1 ml = 0.01 mg P.
7.7 Standard Solution B: Dilute 100 ml of standard solution A to
1 liter. 1 ml = 0.001 mg P.
251
-------
(Phosphorus)
7. 8 Prepare a series of standards by diluting suitable volumes
of standard solutions A and B to 100.0 ml with distilled
water. The following dilutions are suggested:
Cone.,
ml of Standard Solution B mg P/l
1.0 0.01
2.0 0.02
5.0 0.05
10.0 0.10
ml of Standard Solution A
2.0 0.20
5.0 0.50
8.0 0.80
10.0 1.00
7. 9 Ammonium persulfate, reagent grade.
7.10 NaOH-EDTA solution: Dissolve 65 g NaOH and 6 g EDTA in
distilled water and dilute to 1 liter.
8. Procedure
8. 1 Phosphorus
8.1.1 Add 1 ml of sulfuric acid solution to a 50-ml sample
in a 125-ml Erlenmeyer flask.
8.1.2 Add 0.4 g ammonium persulfate.
8.1.3 Boil gently on a pre-heated hot plate for approximately
30-40 minutes or until a final volume of about 10 ml is
reached. Do not allow sample'to go to dryness.
Alternatively, heat for 30 minutes in an autoclave at
121°C (15-20 psi).
8.1.4 Cool and dilute the sample to 50 ml.
252
-------
(Phosphorus)
8.1.5 The sample is now ready for automatic analysis as
outlined in 8.3 Orthophosphate.
8.2 Hydrolyzable Phosphorus
8.2.1 Add 1 ml of sulfuric acid solution to a 50-ml sample
in a 125-ml Erlenmeyer flask.
8.2.2 Boil gently on a pre-heated hot plate for approximately
30-40 minutes or until a final volume of about 10 ml
is reached. Do not allow sample to go to dryness.
Alternatively, heat for 30 minutes in an autoclave at
121°C (15-20 psi).
8.2.3 Cool and dilute the sample to 50 ml.
8.2.4 The sample is now ready for automatic analysis as
outlined in 8.3 Orthophosphate.
8.3 Orthophosphate
8.3.1 Set up manifold as shown in Figure 1.
8.3.2 Allow both colorimeter and recorder to warm up for
30 minutes. Run a baseline with all reagents, feeding
distilled water through the sample line. Adjust dark
current and operative opening on colorimeter to obtain
stable baseline.
8.3.3 Place wash water tubes (see 7.4) in alternate openings
in Sampler and set sample timing at 2.0 minutes. Use
distilled water, instead of acid-wash water when only
Orthophosphate is being determined.
253
-------
(Phosphorus)
8.3.4 Place standards in Sampler in order of decreasing
concentration. Complete filling of sampler tray with
unknown samples.
8.3.5 Switch sample line from distilled water to Sampler and
begin analysis.
8.3.6 At end of run, clean out manifold system with NaOH-EDTA
solution.
9. Calculation
9.1 Prepare standard curve by plotting peak heights of processed
standards against known concentrations. Compute concentration
of samples by comparing sample peak heights with standard curve,
10. Precision and Accuracy
10.1 In a single laboratory, using surface water samples at
concentrations of 0.06, 0.11, 0.48, and 0.62 mg P/l, the
standard deviation was ±0.004 (AQC Laboratory).
10.2 In a single laboratory, using surface water samples at
concentrations of 0.11 and 0.74 mg P/l, recoveries were
90% and 95%, respectively (AQC Laboratory).
References
1. Standard Methods for the Examination of Water and Wastewater, 12th
Edition, p. 234, Amer. Pub. Health Asso., Inc., New York, N.Y. (1965),
2. M. Gales, Jr., E. Julian, and R. Kroner, "Method for Quantitative
Determination of Total Phosphorus in Water." Jour. AWWA, 58, No. 10,
1363 (1966).
254
-------
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FIGURE 1 • PHOSPHORUS MANIFOLD
-------
SOLIDS, TOTAL
1. Scope and Application
1.1 This method is applicable to surface waters, domestic and
industrial wastes, and saline waters.
1.2 The practical range of the determination is from 10 mg/1
to 30,000 mg/1.
2. Summary of Method
2.1 A well mixed aliquot of the test sample is quantitatively
transferred to a pre-weighed evaporating dish and evaporated
to dryness at 103-105°C.
3. Definitions
3.1 Total Solids are defined as the sum of the homogenous sus-
pended and dissolved materials in a sample.
4. Sample Handling and Preservation
4.1 No special precautions are required.
5. Interferences
5.1 Large, floating particles or submerged agglomerates (non-
homogenous materials) should be excluded from the test sample.
5.2 Floating oil and grease, if present, should be included in
the sample and dispersed by a blender device before aliquoting.
257
-------
(Solids, Total)
6. Apparatus
6.1 Evaporating Dishes, Porcelain, 90 mm, 100-ml capacity.
(Vycor or platinum dishes may be substituted and smaller
size dishes may be used if required.)
7. Procedure
7.1 Heat the clean evaporating dish to 550±50°C for 1 hour in
a muffle furnace. Cool, dessicate, weigh and store in
dessicator until ready for use.
7.2 Transfer a measured aliquot of sample to the pre-weighed
dish and evaporate to dryness on a steam bath or in a drying
oven.
7.2.1 Choose an aliquot of sample sufficient to contain a
residue of at least 25 mg. To obtain a weighable
residue, successive aliquots of sample may be added
to the same dish.
7.2.2 If the evaporation is performed in a drying oven,
the temperature should be lowered to approximately
98°C to prevent boiling and splattering of the sample.
7.3 Dry the evaporated sample for at least 1 hour at 103-105°C.
Cool in a dessicator and weigh. Repeat the cycle of drying
at 103-105°C, cooling, dessicating and weighing until a
constant weight is obtained or until loss of weight is less
than 4% of the previous weight, or 0.5 mg, whichever is less.
258
-------
(Solids, Total)
8. Calculation
8.1 Calculate total solids as follows:
Total Solids, mg/1 = (Wt. of sample + dish - wt. of dish) 1000
Vol. of Sample
9. Precision and Accuracy
9.1 Precision and accuracy data are not available at this time.
259
-------
SOLIDS, FILTERABLE
1. Scope and Application
1.1 This method is applicable to surface waters, domestic and
industrial wastes, and saline waters.
1.2 The practical range of the determination is 10 mg/1 to 20,000
mg/1.
2. Summary of Method
2.1 A well-mixed sample is filtered through a standard glass
fiber filter. The filtrate is evaporated and dried to con-
stant weight at 180°C.
3. Definitions
3.1 Filterable solids are defined as those solids capable of
passing through a standard glass fiber filter and dried to
constant weight at 180°C.
4. Sample Handling and Preservation
4.1 No special precautions are required.
5. Interferences
5.1 Highly mineralized waters containing significant concentrations
of calcium, magnesium, chloride and/or sulfate may be hygro-
scopic and will require prolonged drying and dessication and
quick weighing.
261
-------
(Solids, Filterable)
5.2 Samples containing high concentrations of bicarbonate will
require careful and possibly prolonged drying at 180°C to
insure that all the bicarbonate is converted to carbonate.
5.3 Too much residue in the evaporating dish will crust over and
entrap water that will not be driven off during drying.
Total residue should be limited to about 200 mg.
6. Apparatus
6.1 Glass fiber filter discs, 4.7 cm or 2.2 cm, without organic
binder, Reeve Angel type 984 H, Gelman type A, or equivalent.
6.2 Filter holder, membrane filter funnel or Gooch crucible adapter.
6.3 Suction flask, 500 ml.
6.4 Gooch crucibles, 25 ml (if 2.2 cm filter is used).
6.5 Evaporating dishes, porcelain, 100 mlj volume. (Vycor or
platinum dishes may be substituted).
6.6 Steam bath.
6.7 Drying oven, 180°C±2°C.
6.8 Dessicator.
6.9 Analytical balance, 200 g capacity, capable of weighing to
0.1 mg.
7. Procedure
7.1 Preparation of glass fiber filter disc: Place the disc on
the membrane filter apparatus or insert into bottom of a
suitable Gooch crucible. While vacuum is applied, wash the
262
-------
(Solids, Filterable)
disc with three successive 20 ml volumes of distilled water.
Remove all traces of water by continuing to apply vacuum
after water has passed through. Remove filter from membrane
filter apparatus or both crucible and filter if Gooch crucible
is used, and dry in an oven at 103-105°C for one hour. Remove
to dessicator and store until needed.
7.2 Preparation of evaporating dishes: Heat the clean dish to
550°C for one hour in a muffle furnace. Cool in dessicator
and store until needed. Weigh immediately before use.
7.3 Assemble the filtering apparatus and begin suction. Shake
the sample vigorously and rapidly transfer 100 ml to the
funnel by means of a 100 ml volumetric cylinder. If sus-
pended matter is low, a larger volume may be filtered.
7.4 Filter the sample through the glass fiber filter and continue
to apply vacuum for about 3 minutes after filtration is com-
plete to remove as much water as possible.
7.5 Transfer 100 ml (or a larger volume) of the filtrate to a
weighed evaporating dish and evaporate to dryness on a steam
bath.
7.6 Dry the evaporated sample for at least one hour at 180±2°C.
Cool in a dessicator and weigh. Repeat the drying cycle
until a constant weight is obtained or until weight loss is
less than 0.5 mg.
7.7 Note: The filtrate from the test for SOLIDS, NON-FILTERABLE,
may be used for this determination.
263
-------
(Solids, Filterable)
8. Calculation
8.1 Calculate filterable solids as follows:
Filt. solids, mg/1 = (Wt. of dried residue + dish - wt. of dish) x 1000
Volume of filtrate used
9. Precision and Accuracy
9.1 Precision data are not available at this time.
9.2 Accuracy data on actual sample cannot be obtained.
264
-------
SOLIDS, NON-FILTERABLE
1. Scope and Application
1.1 This method is applicable to surface waters, domestic and
industrial wastes, and saline waters.
1.2 The practical range of the determination is 20 mg/1 to 20,000
mg/1.
2. Summary of Method
2.1 A well-mixed sample is filtered through a standard glass fiber
filter, and the residue retained on the filter is dried to
constant weight at 103-105°C.
3. Definitions
3.1 Non-filterable solids are defined as those solids which are
retained by a standard glass fiber filter and dried to con-
stant weight at 103-105°C.
4. Sample Handling and Preservation
4.1 Non-homogenous particulates such as leaves, sticks, fish, and
lumps of fecal matter should be excluded from the sample.
4.2 Preservation of the sample is not practical.
5. Interferences
5.1 Too much residue on the filter will entrap water and may re-
quire prolonged drying.
265
-------
(Solids, Non-Filterable)
6. Apparatus
6.1 Glass fiber filter discs, 4.7 cm or 2.2 cm, without organic
binder, Reeve Angel type 984 H, Gelman type A, or equivalent.
6.2 Filter holder, membrane filter funnel or Gooch crucible adapter.
6.3 Suction flask, 500 ml.
6.4 Gooch crucibles, 25 ml (if 2.2 cm filter is used).
6.5 Drying oven, 103-105°C.
6.6 Dessicator.
6.7 Analytical balance, 200 g capacity, capable of weighing to
0.1 mg.
7. Procedure
7.1 Preparation of glass fiber filter disc: Place the disc on the
membrane filter apparatus or insert into bottom of a suitable
Gooch crucible. While vacuum is applied, wash the disc with
three successive 20 ml volumes of distilled water. Remove
all traces of water by continuing to apply vacuum after water
has passed through. Remove filter from membrane filter
apparatus or both crucible and filter if Gooch crucible is
used, and dry in an oven at 103-105°C for one hour. Remove
to dessicator and store until needed. Weigh immediately
before use.
7.2 Assemble the filtering apparatus and begin suction. Shake
the sample vigorously and rapidly transfer 100 ml to the
funnel by means of a 100 ml volumetric cylinder. If sus-
pended matter is low, a larger volume may be filtered.
266
-------
(Solids, Non-Filterable)
7.3 Carefully remove the filter from the membrane filter funnel
assembly. Alternatively, remove crucible and filter from
crucible adapter. Place in drying oven and dry at 103-105°C
to constant weight.
8. Calculations
8.1 Calculate non-filterable solids as follows:
Non-filterable solids, mg/1 = (Wt. of filter + residue - wt. of filter) x 1000
ml of sample filtered
9. Precision and Accuracy
9.1 Precision data are not available at this time.
9.2 Accuracy data on actual samples cannot be obtained.
267
-------
SULFATE
(Automated Chloranilate Method)
1. Scope and Application
1.1 This automated method is applicable to surface waters, dom-
estic and industrial wastes, and saline waters, in the range
of 10 to 400 mg SO /I. Approximately 15 samples per hour can
be analyzed.
2. Summary of Method
2.1 When solid barium chloranilate is added to a solution con-
taining sulfate, barium sulfate is precipitated, releasing the
highly colored acid chloranilate ion. The color intensity in
the resulting chloranilic acid is proportional to the amount
of sulfate present.
3. Sample Handling and Preservation
3.1 No special requirements.
4. Interferences
4.1 Cations, such as calcium, aluminum, and iron, interfere by
precipitating the chloranilate. These ions are removed auto-
matically by passage through an ion exchange column.
269
-------
(Sulfate)
5. Apparatus
5.1 Technicon AutoAnalyzer consisting of:
5.1.1 Sampler I.
5.1.2 Continuous filter.
5.1.3 Manifold
5.1.4 Proportioning pump.
5.1.5 Colorimeter equipped with 15 mm tubular flow cell and
520 my filters'.
5.1.6 Recorder.
5.1.7 Heating bath, 45°C.
5.2 Magnetic stirrer.
6. Reagents
6.1 Barium chloranilate: Add 9 g of barium chloranilate (BaC.-Cl-O.)
to 333 ml of ethyl alcohol and dilute to 1 liter with distilled
water.
6.2 Acetate buffer, pH 4.63: Dissolve 13.6 g of sodium acetate in
distilled water. Add 6.4 ml of acetic acid and dilute to 1
liter with distilled water. Make fresh weekly.
6.3 NaOH-EDTA Solution: Dissolve 65 g of NaOH and 6 g of EDTA in
distilled water and dilute to 1 liter.
Note: This solution is also used to clean out manifold system
at end of sampling run.
6.4 Ion Exchange Resin: Dowex-50 W-X8, ionic form -H+.
270
-------
(Sulfate)
Note: Column is prepared by sucking a solution of the
resin into 12 inches of 3/16-inch OD sleeving. This
may be conveniently done by using a pipette and.a
loose-fitting glass wool plug in the sleeve. The column,
upon exhaustion, turns red.
6.5 Stock solution: Dissolve 1.4790 g of pre-dried Na-SO. in
distilled water and dilute to 1 liter. 1 ml = 1 mg.
6.5.1 Prepare a series of standards by diluting suitable
volumes of stock solution to 100.0 ml with distilled
water. The following dilutions are suggested:
ml of Stock Solution Cone., mg/1
1.0 10
2.0 20
4.0 40
6.0 60
8.0 80
10.0 100
15.0 150
20.0 200
30.0 300
40.0 400
7. Procedure
7.1 Set up manifold as shown in Figure 1. (Note that any pre-
cipated BaSC^ and the unused barium chloranilate are removed
by filtration. If any BaSC>4 should come through the filter,
it is complexed by the NaOH-EDTA reagent).
7.2 Allow both chlorimeter and recorder to warm up for 30 minutes,
Run a baseline with all reagents, feeding distilled water
through the sample line. Adjust dark current and operative
opening on colorimeter to obtain suitable baseline.
271
-------
(Sulfate)
7.3 Place distilled water wash tubes in alternate openings in
sampler and set sample timing at 2.0 minutes.
7.4 Place working standards in sampler in order of decreasing
concentration. Complete filling of sampler tray with unknown
samples.
7.5 Switch sample line from distilled water to sampler and begin
analysis.
8. Calculation
8.1 Prepare standard curve by plotting peak heights of processed
standards against known concentrations. Compute concentration
of samples by comparing sample peak heights with standard curve.
9. Precision and Accuracy
9.1 In a single laboratory (AQC), using surface water samples at
concentrations of 39, 111, 188, and 294 mg SO /I, the standard
deviations were ±0.6, ±1.0, ±2.2, and ±0.8, respectively.
9.2 In a single laboratory (AQC) using surface water samples at
concentrations of 82 and 295 mg SO /I, recoveries were 99%
and 102%, respectively.
Reference
1. R. J. Bertolocini and J. E. Barney, Anal. Chem., 29, 283 (1957).
272
-------
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FIGURE 1 - SULFATE MANIFOLD
-------
TURBIDITY
1. Scope and Application
1.1 This method is applicable to surface and saline waters in
the range of turbidity from 0 to 40 Jackson units.
2. Summary of Method
2.1 The method is based upon a comparison of the intensity of
light scattered by the sample under defined conditions
with the intensity of light scattered by a standard refer-
ence suspension. The higher the intensity of scattered
light, the higher the turbidity. Readings, in Jackson
units, are made in a nephelometer designed according to
specifications outlined in Apparatus, 5. A standard
suspension of Formazin, also prepared under closely
defined conditions, is used to calibrate the instrument.
2.1.1 Formazin polymer is used as the turbidity reference
suspension for water because it is more reproducible
than other types of standards previously used for
turbidity standards.
3. Sample Handling and Preservation
3.1 Samples taken for turbidity measurements should be analyzed
as soon as possible. Preservation of samples is not recom-
mended.
275
-------
(Turbidity)
4. Interferences
4.1 The presence of floating debris and coarse sediments which
settle out rapidly will give false high readings. Finely
divided air bubbles will also affect the results in a positive
manner.
4.2 The presence of true color, that is the color of water which
is due to dissolved substances which absorb light will cause
turbidities to be low, although this effect is generally not
significant with finished waters.
5. Apparatus
5.1 The turbidimeter shall consist of a nephelometer with light
source for illuminating the sample and one or more photo-
electric detector with a readout device to indicate the in-
tensity of light scattered at right angles to the path of the
incident light. The turbidimeter should be so designed that
little stray light reaches the detector in the absence of
turbidity and should be free from significant! drift after a
short warm-up period.
5.2 The sensitivity of the instrument should permit detection of
turbidity differences of 0.02 unit or less in waters having
turbidities less than 1 unit. The instrument should measure
from 0 to 40 units turbidity. Several ranges will be neces-
sary to obtain both adequate coverage and sufficient sensitivity
for low turbidities.
276
-------
(Turbidity)
5.3 The sample tubes to be used with the available instrument
must be of clear, colorless glass. They should be kept
scrupulously clean, both inside and out, and discarded when
they become scratched or etched. They must not be handled
at all where the light strikes them, but should be provided
with sufficient extra length, or with a protective case, so
that they may be handled.
5.4 Differences in physical design of turbidimeters will cause
differences in measured values for turbidity even though the
same suspension is used for calibration. To minimize such
differences, the following design criteria should be observed:
5.4.1 Light source: Tungsten lamp operated at not less than
85% of rated voltage or more than rated voltage.
5.4.2 Distance traversed by incident light and scattered
light within the sample tube: Total not to exceed 10 cm.
5.4.3 Angle of light acceptance of the detector: Centered
at 90° to the incident light path and not to exceed
±30° from 90°.
5.4.4 Maximum turbidity to be measured: 40 units.
5.5 At the time of this writing, the only instrument commercially
available with these specifications is the Hach Turbidimeter,
Model 3100. This instrument is recommended.
277
-------
(Turbidity)
6. Reagents
6.1 Turbidity-free water - Pass distilled water through a 0.45 y
pore size membrane filter if such filter and water shows a
lower turbidity than the distilled water.
6.2 Stock turbidity suspension:
Solution 1: Dissolve l.OOg hydrazine sulfate, (HN-^.H SO.,
in distilled water and dilute to 100 ml in a volumetric flask.
Solution 2: Dissolve lO.OOg hexamethylenetetramine in
distilled water and dilute to 100 ml in a volumetric flask.
In a 100-ml volumetric flask, mix 5.0 ml Solution 1 with
5.0 ml Solution 2. Allow to stand 24 hours at 25 ± 3°C, then
dilute to the mark and mix.
6.3 Standard turbidity suspension: Dilute 10.00 ml stock turbidity
suspension to 100 ml with turbidity-free water. The turbidity
of this suspension is defined as 40 units. Dilute portions of
the standard turbidity suspension with turbidity-free water as
required.
6.3.1 A new stock turbidity suspension should be prepared each
month. The standard turbidity suspension and dilute
turbidity standards should be prepared weekly by dilution
of the stock turbidity suspension.
7. Procedure
7.1 Turbidimeter calibration: The manufacturer's operating instruc-
tions should be followed. Measure standards on the turbidimeter
covering the range of interest. If the instrument is already
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calibrated in standard turbidity units, this procedure will
check the accuracy of the calibration scales. At least one
standard should be run in each instrument range to be used.
Some instruments permit adjustment of sensitivity so that
scale values will correspond to turbidities.
Reliance on a manufacturer's solid scattering standard
for setting overall instrument sensitivity for all ranges is
not an acceptable practice unless the turbidimeter has been
shown to be free of drift on all ranges. If a pre-calibrated
scale is not supplied, then calibration curves should be
prepared for each range of the instrument.
7.2 Turbidities less than 40 units: Shake the sample to
thoroughly disperse the solids. Wait until air bubbles
disappear then pour the sample into the turbidimeter tube.
Read the turbidity directly from the instrument scale or
from the appropriate calibration curve.
7.3 Turbidities exceeding 40 units: Dilute the sample with one
or more volumes of turbidity-free water until the turbidity
falls below 40 units. The turbidity of the original sample
is then computed from the turbidity of the diluted sample
and the dilution factor. For example, if 5 volumes of tur-
bidity-free water were added to 1 volume of sample, and the
diluted sample showed a turbidity of 30 units, then the
turbidity of the original sample was 180 units.
7.3.1 The Hach Turbidimeter, Model 2100, is equipped with
5 separate scales: 0-.02, 0-1.0, 0-10.0, 0-100, and
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0-1000 JTU. It is strongly recommended, however,
that the upper scales be used as indications of
required dilution volumes to reduce readings to
less than 40 JTU. (NOTE: Comparative work per-
formed in the AQC Laboratory indicates a progressive
error on sample turbidities in excess of 40 units.)
Calculation
8.1 Multiply sample reading by appropriate dilution to obtain
final reading.
8.2 Report results as follows:
Jackson Turbidity Record
Units to nearest:
0.0-1.0 0.05
1-10 0.1
10-40 1
40-100 5
100-400 10
400-1000 50
>1000 100
Precision and Accuracy
9.1 Precision and accuracy data are not available at this time.
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