MIDWEST RESEARCH INSTITUTE
QUALITY ASSURANCE MANUAL
Inductively Coupled Plasma Atomic Emission Spectrosnetry
for
Toxic Trace Metals in Vegetables, Soils, and Sludges
The National Household Garden Survey
by
Lloyd M. Petrie
Senior Chemist
EPA Contract No. 68-01-5915
MRI Project No. 4901-A(42)
May 26, 198;
MIDWEST RESEARCH INSTITUTE 425 VOLKER BOULEVARD, KANSAS CITY, MISSOURI 64110 • 816753-7600
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QUALITY ASSURANCE MANUAL
Inductively Coupled Plasma Atomic Emission Spectrometry
for
Toxic Trace Metals in Vegetables, Soils, and Sludges
in
The National Household Garden Survey
by
Lloyd M. Petrie
Senior Chemist
EPA Contract No. 68-01-5915
MRI Project No. 4901-A(42)
May 26, 1982
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TABLE OF CONTENTS
Page
I. Introduction 1
II. Quality Assurance Objectives 2
III. Personnel Responsibilities 2
IV. Analytical Methods 4
A. Sample Container Cleaning 4
B. Plant Digestion 4
C. Soil and Sludge Leaching 8
D. Inductively Coupled Plasma Atomic Emission
Spectrometry 9
V. Data Analysis, Storage and Retrieval 21
A. General 21
B. Significant Figures 22
C. Sample Concentration Calculations 22
D. Computer Operating Procedures 23
E. Analytical Data Documentation Control 24
F. Other Project Documentation Control 26
VI. Sample Custody and Control 27
A. Field Samples 27
B. Dried and Prepared Samples 27
C. Computerized Sample Status Reporting 27
VII. Safety 28
VIII. References 28
Appendix A - EPA Interim Method 200.7 29
Appendix B - Datatrieve File Structure for the 4901A42 Sample
Status Data Base File 63
11
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I. Introduction
The Field Studies Branch is conducting a nationwide survey of
household gardens fortified with POTW (publicly owned treatment works)
sewage sludge to assess level of pesticides, metals, and parasites in the
soils and vegetables. Approximately 240 garden sites will be sampled
during the 1982 growing season.
Toxic metals are relatively abundant in municipal sewage and tend
to accumulate in high levels in the resulting sewage sludge in parts per
million levels (Page and Chang, 1978; Swanson, 1981). One means of disposal
of the large quantities of sewage sludge is to use it as a fertilizer for
cultivation of edible food crops.
Nationally, a key concern regarding cropland fertilization with
sewage sludge is the rate of uptake of toxic trace metals into the food crops
This potential problem has been and is being studied to determine safe levels
of sewage sludge application (Page and Chang, 1978; Page, 1978; Naylor and
Loehr, 1981; Stoewsand, 1980; Garcia et al., 1981). Page and Chang (1978)
cite Cd, Cu, Mo, Ni, and Zn as the trace metals of greatest concern due to
their abundance in sewage sludge and their mobility in soils. Stoewsand
(1980) cited As, Sb, Pb, Hg, and Pd of greatest human health concern with
Pb and Cd being the most important toxic elements in sewage sludge cropland
disposal due to their abundance and soil mobility. Of these two, Cd is more
readily taken up by plants. The large survey by Garcia et al. was concerned
with soil and plant concentration of Pb, Hg, Cd, and Zn. Again, Cd was sig-
nificantly accumulated in a wide range of edible crops. Therefore, the MRI
trace metal analysis of vegetables, soils, and sludges will include the fol-
lowing key target trace elements Cd, Pb, Cu, Mo, Ni, As, Sb, Hg, and Zn.
Also analyzed will be Sn, Tl, Co, Be, B, Mn, Cr, Ag, Y, Se, and Ba.
Determination of trace metals in this study will be accomplished
by first solubilizing the metals into an acidic medium from the solid samples.
Then, the ICP media will be quantitatively analyzed by inductively coupled
plasma-atomic emission spectrometry (ICP-AES). ICP emission spectrometry
is a rapid technique that is well-suited to multielemental analysis survey
work.
The purpose of this document is to detail the quality assurance
program for ICP-AES to be followed during this study. It is designed to
assure ICP-AES analytical data with acceptable accuracy and precision in a
cost-effective manner. Likewise, the plan is designed to ensure proper
handling and control of samples and all written documentation.
-v
The analytical quality control aspects of this manual conform to
the USEPA Interim Method 200.7, "Inductively Coupled Plasma-Atomic Emission
Spectrometric Method for Trace Analysis of Water and Wastes," EPA-EMSL,
Cincinnati, November 1980. Appendix A contains a copy of this method.
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II. Quality Assurance Objectives
The objective for accuracy is percent recovery values for all
analyte metals in fortified samples between 80% and 120%.
The objective for precision is percent relative standard deviation
values for all analyte metals in duplicated samples between 0% and 10%.
III. Personnel Responsibilities
John Hosenfeld will be the task leader for this program. He will:
* Supervise the collection of all field samples and their transport
to MRI.
* Oversee conformance to the policies and procedures stated in
this Quality Assurance Plan.
* Review and accept each set of analytical data in view of the
quality assurance objectives for ICP-AES metals screen.
* Monitor the technical progress of the program against financial
expenditures.
Lloyd Petrie will be the trace metal analysis leader. He will:
* Direct conformance to the policies and procedures stated in
this Quality Assurance Plan.
* Schedule the preparation and analysis of all field and quality
control samples.
* Provide technical expertise for sample preparation and ICP
emission spectrometric analysis.
* Prepare USEPA AQC standard for validation of instrument
calibration standards.
* Maintain document control of laboratory data, field data, notes,
records, etc.
* Be responsible for sample log-in and chain of custody.
* Enforce instrument calibration and maintenance procedures and
schedule.
* Technically review all analytical data reported to the task
leader.
* Provide technical expertise for operation of the Digital
Equipment Corporation (POP 11/23) computer.
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* Immediately report in memo form any problems which arise during
the course of the program to the task leader.
Gene Ray will be the quality assurance coordinator. He will:
* Prepare blind duplicate samples for sample preparation of both
soils and vegetables.
* Prepare blind analytical quality control standards for all
ICP-AES analyses.
Carolyn Thornton will be the ICP-AES trace metal analyst. She will:
* Perform ICP-AES analysis of all samples according to the pro-
cedures stated in this Quality Assurance Plan.
* Prepare analysis quality control standards and samples according
to the Quality Assurance Plan procedures.
* Prepare instrument calibration standards according to the Quality
Assurance Plan procedures.
* Generate, store and retrieve all analysis documentation according
to the Quality Assurance Plan procedures.
* Handle prepared digests and leachates according to sample custody
procedures stated in the Quality Assurance Plan.
* Be responsible for routine maintenance of the ICP emission spec-
trometer.
Betty Jones will be the sample preparation analyst. She will:
* Retrieve and handle all field samples according to this Quality
Assurance Plan sample custody procedures.
* Clean and label all glassware or plasticware used in sample
preparation according to procedures stated in this Quality
Assurance Plan.
* Prepare all field samples and related quality control samples
according to the appropriate sample preparation procedures.
* Generate, store and retrieve all sample preparation documenta-
tion according to the Quality Assurance Plan procedures.
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IV. Analytical Methods
A. Sample Container Cleaning
1. Objective: To remove all trace metal contamination from the
surface of all plastic or glass containers used for sample handling.
2. Procedures
a. Wash only those glass centrifuge tubes containing organic
residues with freshly prepared soapy deionized water. Do not wash plastic
bottles with soap.
b. Rinse the soap from the containers thoroughly with
deionized water.
c. Soak both glass and plastic containers in 8 N reagent
grade HN03 for 24 hr. Prepare a fresh 8 N reagent grade HN03 bath every
2 weeks.
d. After 24 hr, remove and thoroughly rinse the containers
with deionized water. At least six rinses will be necessary.
e. Dip the Teflon-lined centrifuge tube caps in the 8 N HN03
acid bath, remove immediately, and thoroughly rinse with deionized water.
f. Fill each container with 0.5 N double-distilled HN03 and
tightly cap the containers. Let the container stand at least 12 hr.
g. Empty and rinse the containers six times with laboratory
deionized water.
h. Shake out remaining water, cap, and store the containers
in a clean drawer.
3. Time/material requirements: Approximately 4 hr per batch of
preparation samples should be adequate for sample container cleaning.
Copies of purchase requisitions or supply room orders should be
submitted to the metal analysis leader.
B. Plant Digestion
1. Objective: To fully solubilize the entire plant tissue by a
wet acid digestion.
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2. Procedures
a. Sample preparation sheet: A "SAMPLE PREPARATION SHEET"
(Figure 1) will be completed in duplicate by the trace metal analysis leader.
The following conventions will be used:
Digestion Code: V (vegetable) nn j incremented digestion number
S (soil) nn > (nn) of type preparation
L (sludge) nn ) starting with 01
Sample Names:
Field samples (6-number code)
Example: 01 107 2 = soil
Digestion Sample 5 = sludge
Number Number 7 = vegetable
Sample
Type
Analytical quality control standards AQC1,
(6 alphanumeric code) N476E2
Prepared reagent blank VnnRBm - incremental number (m)
(6 alphanumeric code) '_7—"-.'~*
Digestion
Code
Class Names: RB - prepared reagent blank
(6 alphanumeric code) SAMPLE - prepared field sample
DUP - duplicate
SP1 or SP2 - fortified sample at
level "1" or "2"
SRM1 or SRM2 - standard reference
material "1" or "2"
b. Sample drying
(1) Field vegetable samples should be dried within 1 week
of receipt at MRI.
(2) Place a representative portion of each vegetable
in a clean porcelain dish or glass beaker.
(3) Dry the samples for 4 hr at 90°C.
(4) Remove the dried samples and let them cool to room
temperature.
(5) Place the dried material in clean 30-ml plastic
bottles, each labeled with the field sample number, sample type and date.
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SAMPLE PREPARATION SHEET
Project No.:
Elements:
Analyst:
Date Begun:_
Prep Description:
Sample Volume (ml or mass/g) :_
Digestion Code:
Date Completed:
Fortification Levels (total g) :
Digest Final Volume (ml):
Class
Final Wt.
Class
Final Wt.
1.
2.
3.
4.
5.
6.
7.
26.
27.
28.
29.
30.
31.
32.
8. 33.
9.
10.
11.
12.
13.
34.
35.
36.
37.
38.
U. 39.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
40.
41.
42.
43.
44.
45.
46.
47.
48.
49.
50.
Figure 1
6
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c. Wet digestion
(1) According to the "SAMPLE PREPARATION SHEET," label
the needed number of clean 10-ml centrifuge tubes and 30-ml plastic bottles
with the "Sample" and "Class" names.
(2) Weigh the tubes and bottles and record the tare
weights.
(3) Place approximately 0.1 g dried vegetable in each
preparation tube and weigh the actual amount added.
(4) Add 4.0 ml 8 N Meek Suprapur® HN03 to the tubes.
(5) Wrap the tube threads with Teflon® tape twice and
seal the tube with a clean Teflon®-lined cap.
(6) Place the tube rack in a preheated oven at 90°C.
(7) Check the tubes after 1 hr and gently agitate the
contents of each tube.
(8) Remove tubes after 4 hr at 90°C.
(9) Let the tubes air cool to room temperature.
(10) Dilute the samples in the tubes to 10 g with
deionized water using the platform balance.
(11) Label each tube with the "Sample" name, "Class"
name, "4901A42," and date.
(12) Place a copy of the completed "SAMPLE PREPARATION
SHEET" in the appropriate MRI Technical Record Book and place the original
sheet with the completed samples on a tray.
3. Quality control: Unless stated otherwise on the "SAMPLE
PREPARATION SHEET" to reflect unique conditions, the following percentages
of analytical quality control samples will be prepared with each batch of
field samples:
10% duplicates of field samples
10% fortified field samples
5% reagent blanks
5% quality control check standards or standard reference materials
5% blind field duplicate samples selected by the quality
assurance coordinator
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4. Time/materials requirements: Sample drying should require
2 hr labor time per sample batch.
Wet digestion of a 50-sample set should require 8 hr labor time
and should be fully completed during 1 day to minimize sample handling and
contamination. Approximately 125 ml of Merck Suprapur® concentrated nitric
acid will be the major material usage. The replacement frequency of the
Teflon®-lined centrifuge caps is not known.
C. Soil and Sludge Leaching
1. Objective; To remove all trace metals from soil or sewage
sludge using a rigorous acid leaching without solubilizing all the Al, Fe,
Ca, Mg, Ti, and other nontoxic major elements in the samples.
2. Procedure
a. According to the "SAMPLE PREPARATION SHEET," label the
needed number of clean 10-ml centrifuge tubes and 30-ml plastic bottles
with the "Sample" and "Class" names.
b. Tare each centrifuge tube without the cap and record the
mass.
c. Place approximately 0.1 g soil in the appropriate tubes
and measure the net mass of sample added. Record the masses on the "SAMPLE
PREPARATION SHEET."
d. Add 2 ml 8 N Merck Suprapur® HN03 to the appropriate tubes.
e. Wrap the tube threads with Teflon® tape.
f. Place the tube rack in a preheated oven at 130°C for 8 hr.
g. Set the timer on the oven electrical circuit for a time
8 hr hence.
h. Check the tubes every 2 hr and gently agitate the contents
of each tube.
i. Remove the tubes after 8 hr of heating.
j. Let the tubes air cool to room temperature.
k. Dilute the material in each tube to a final net mass of
10 g with deionized water.
1. Centrifuge each set of four tubes at the maximum setting
of the International Clinical centrifuge in Room 344W for 1 min.
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m. Remove the centrifuged samples and carefully pour the
liquid leachate into the appropriate plastic bottle.
n. Label each plastic bottle with the "Sample" name, "Class"
name, "4901A42" and date.
o. Place a copy of the completed "SAMPLE PREPARATION SHEET"
in the appropriate MRI Technical Record Book and place the original sheet
with the completed samples on a tray.
3. Quality control: Unless stated otherwise, the following per-
centages of analytical quality control samples will be prepared with each
batch of field samples:
10% duplicates of field samples
10% fortified field samples
5% reagent blanks
5% quality control check standards or standard reference materials
5% blind field duplicate samples selected by the quality assurance
coordinator
4. Time/materials requirements: Acid leaching of each 50-sample
set should require 8 hr labor time. Each preparation batch will consume
approximately 75 ml of Merck Suprapur® concentrated nitric acid and Teflon®
tape. The replacement frequency of the Teflon®-lined centrifuge caps is
not known.
D. Inductively Coupled Plasma Atomic Emission Spectrometry
1. Objective; To quantitatively determine the concentration of
toxic trace metals in soil, sludge, and vegetable preparations by inductively
coupled plasma atomic emission spectrometry (ICP-AES).
2. General description of method; ICP emission spectrometry is
a relatively new method for rapid multielemental analysis using a new, stable
excitation source (ICP) with the conventional direct reading or newer scanning
spectrometers.
Compared to other sources, spectral interferences for the ICP are
minimal. It is hot enough to facilitate analyte emission, yet the sustained
argon plasma has fewer of the interferences associated with emission spec-
troscopy. The background in the region with most of the sensitive emission
lines for many elements (190-300 nm) has relatively few interference emissions.
However, there still are spectral interferences that are signifi-
cant when attempting to measure parts-per-billion levels of trace metals in
the presence of parts-per-million levels of Al, Ca, Fe, Ti, and other major
elements in plant and soil material. The two major types of spectral inter-
ferences are (1) direct overlap by an interfering emission peak on the analy-
sis emission peak, and (2) baseline shifts due to stray light, molecular
emission or broad band emission from an intense nearby interfering peaks.
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To account for those cases where other elements may line interfere and are
commonly abundant in high concentrations (Al and Fe, for example), correc-
tion factors are stored in a data file in the computer. As part of the
final concentration calculations, a factor multiplied by the interfering
element intensities is subtracted from the gross analyte intensities.
3. Instrument description; A 30-channel Jarrell-Ash Model 1155A
direct reading ICP emission spectrometer will be used in the study. This
instrument has the following features to enhance sample analysis quality:
* Triple point background correction
* Automatic interelement spectral interference correction
* Spectrum scanning for sample matrix diagnostics
* 200-Sample autosampler
* Peristaltic pump
The emission spectrometer is fully controlled by a sophisticated
set of software performed at the Digital Equipment Corporation PDF 11/23
computer interfaced to the spectrometer.
Based on prior method development studies, Table 1 lists typical
detection limits anticipated for this study for the 30 analytical emission
lines of the Model 1155A spectrometer.
Two Analytical Control Tables will be used for this study:
ACT Name Sample Matrix
VEG Vegetables
SOIL Soils and sludges
4. Daily instrument calibration procedure
a. Instrument calibration is based on Chapter 8 of the
Jarrell-Ash Mark III Atomcomp Interim Operator's Manual. M79, March 1979.
The analytical quality control aspects of calibration conform to USEPA
Interim Method 200.7.
b. Each of the 30 detector channels is calibrated by a
two-point curve method using a reagent blank and a 10-ppm standard, except
100 ppm for K. The elements for the 10-ppm standard are actually grouped
into four mixed standards according to chemical stability and absence of
spectral interferences. Table 2 shows the composition of the ICP-AES cali-
bration standards.
c. It is essential that the matrix of the calibration stan-
dards match the matrix of the samples. In this study the following matrices
for calibration standards will be used.
Vegetables 20% (v/v) Merck Suprapur® HN03
Soils and sludges 10% (v/v) Merck Suprapur® HN03
10
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TABLE 1
AVAILABLE ANALYTICAL CHANNELS
Element
Sn
Tl
As
Hg
Se
Mo
Sb
Zn
P
Pb
Co
Cd
Ni
Be
Al
B
Mn
Fe
Cr
Fe
Mg
Al
Cu
Ag
Ti
Y
Ca
Ba
Na
K
Estimated Detection Limit
o
Wavelength (A)
1899
1908
1936
1942
1960
2020
2068
2138
2149
2203
2286
2288
2316
2348
2373
2496
2576
2599
2677
2714
2795
3082
3247
3280
3349
3710
3968
4934
5890
7665
(Mg/g
Soil
20
70
250
20
1,000
2.0
200
4.0
20
50
1.0
2.0
1.0
0.50
96
1.0
10
350
2.0
20
40
110
2.0
0.5
20
3.0
41
5.4
10
140
sample)
Vegetable
20
10
30
5.0
100
0.23
100
2.0
96
4.0
0.18
0.14
0.49
0.030
8.6
0.75
2.50
6.0
0.23
5.7
340
8.7
0.54
0.5
2.0
0.043
360
0.16
290
690
11
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TABLE 2
ICP-AES CALIBRATION STANDARDS
20% (v/v) HN03 (vegetables) or 10% (v/v) HN03 (soils)
Matrix:
Concentration: 10 ppm except 100 ppmK
Stability: 30 days
Standard ID
STD 1
STD 2
STD 3
STD 4
AG
Elements
Reagent blank
Ba, Ca, Cd, Co, Cu, K, Mg, Mn, Pb, Zn
Al, Be, Fe, Mo, Na, Ni, Sb, Ti, Y
As, B, Cr, P, Se, Sn, Hg, Tl
Ag
12
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d. The shelf life of the calibration standards is 30 days.
e. Each new batch of calibration standards that is prepared
must be verified weekly for accuracy by analyzing a standard reference material
and obtaining measured values within ± 5% of the certified values. See the
section on "Analytical Quality Control."
f. The spectrometer is calibrated according to MRI Interim
Standard Operating Procedure "ICP Emission Spectrometer Calibration."
5. Daily sample analysis procedure: After successful calibration,
a prepared sample set can be analyzed. The Analytical Quality Control aspects
of this procedure conform to USEPA Interim Method 200.7.
a. Fill out an "ICP DATA REPORTING SHEET" (Figure 2) and
place it in the appropriate MRI Technical Record Book. In this study, a
fixed crossflow nebulizer and peristaltic pump will always be used.
b. Aspirate each sample for 1 znin.
c. Analyze one representative sample for one 10-sec inte-
gration without dilution factors to determine if any detection channels are
beyond their linear response range (Table 3). If necessary, dilute the sam-
ples and note that on the "SAMPLE PREPARATION SHEET."
d. Every 10th time, reanalyze STD1 and the ICS, after
thoroughly rinsing the nebulization system.
e. If the analytical results are still within ± 2 x standard
deviation control limits, continue. If the results were out of control,
reanalyze STD1. If the results are still out of control, recalibrate the
instrument.
f. If the measured values for the ICS are still within ± 5%
of the true values, continue. If not, reanalyze the ICS. If the results
are again out of control, recalibrate the instrument.
g. All prepared samples analyzed since the last successful
analysis of STD1 and the ICS must be reanalyzed if the instrument is recali-
brated.
h. Place data, along with a copy of the "ICP DATA REPORTING
SHEET" into the "Sample Analysis" blue multi-ringed binder for computer paper
output.
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ICP DATA REPORTING SHEET
Project No.:
Sample Matrix:_
Elements:
Analyst:^
Date:
Digestion Code:_
Instrument Parameters
Forward Power (kw):_
Reflected Power (w) :
Observation Height (mm):
Nebulizer Type:
(FCF = Fixed crossflow)
(HS = High solids)
Sample Analysis
Coolant Gas Flow (i/min):
Auxiliary Gas Flow (Z/min)
Sample Gas Flow (i/min):
Solution Uptake (ml/min):_
Peristaltic Pump Used?:
ACT Name:
Test Performed:
Spectrum Scan
Integration Time (sec)
Data Files:
Disk Name:
_Quantitation and Log
Command String:
Data File Name:
Disk Name:
Quantitation and Store
Command String:
Data File Name:
Disk Name:
Figure 2
14
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TABLE 3
LINEAR RESPONSE RANGE OF THE ICP-AES CHANNELS
LCN
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
Channel
Ag
Al (3082 A)
Al (2373 A)
As
B
Ba
Be
Ca
Cd
Co
Cr
Cu
Fe (2714 A)
Fe (2599 A)
Hg
K
Mg
Mn
Mo
Na
Ni
P
Pb
Sb
Se
Sn
Ti
Tl
Y
An
Linear Maximum Concentration
(ppra)
100
200
150
500
100
50
50
50
200
100
50
150
500
30
500
500
20
50
50
200
200
200
500
500
200
500
50
200
50
30
15
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6. Analytical quality control
a. Spectral interferences
(1) The occurrence of spectral interferences in ICP
source emission spectrometry is not as frequent as with other emission
sources but is common enough to require correction measures. The "General
description of method" section described the common types of spectral inter-
ferences experienced in ICP-AES: (a) direct overlap by an interfering emis-
sion peak, and (b) baseline shifts due to stray light and molecular emission.
These interferences both result in falsely high analyte emission and, hence,
analyte concentration determinations.
(2) The particular sample matrices to be analyzed in
this study do contain a large number of direct overlap spectral interferences
for ICP source emission spectrometry. This is because plant tissues, soils,
and sewage sludge contain quite high levels of Al, Ca, Fe, K, Na, Mg and
other elements that introduce spectral interferences on As, Hg, Sb, Se, Sn,
Pb, Tl, and other minor elements.
(3) Interferences are identified for a new sample matrix
by aspirating a representative sample and performing 63 2-sec emission inte-
gration counts in a scan 1 angstrom on either side of each analyte emission
peak centerline. Figure 3 is an example of the plotted spectra for four
samples for the Se emission peak. Note the significant Ca interference peak
overlap from the sample named "NEWSD2."
Such plots are prepared for all 30 detector channels.
The plots are interpreted by comparison to a library of spectrum scan plots
performed on known standards. This interpretation information is summarized
on a "SPECTRUM SCAN" sheet (Figure 4).
(4) The above procedure was used to identify 88 spec-
tral interferences requiring correction. On-peak interelement correction
will be used to remove the effects of these interferences by subtracting a
concentration amount from the interfered element detection channel. The
amount to be subtracted equals (concentration of interfering element) x cor-
rection factor. The correction factors are determined by measuring the false
positive reading on the interfered channel when a sample containing 100 ppm
interfering element is measured. The correction factor equals the false
positive concentration per 1 ppm interfering element. Correction factors
are then placed in Group 4 of the appropriate Analytical Control Table (ACT).
Correction factors are specific for a given sample matrix and observation
position in the inductively coupled plasma.
(5) All analysis data used to generate correction fac-
tors and copies of each Group 4 data will be placed in the program "Spectral
Interferences" MRI Technical Record Book.
(6) Correction factors will be redetermined each time
the ICP torch has been cleaned and reassembled.
16
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WAVELENGTH SCANS FOR SE AT 1960 ANGSTROMS
B NEWSD1 @ NEUSD2 X NEUSD3 * NEWSD4
INTENSITY
16000,
12SOO.
9600,
6400.
3200,
Ca Interference Peak
PEAK IS AT POSITION 0 HALF-WIDTH IS 7
Figure 3
17
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SPECTRUM SCAN
Project No: Date:
Integration Time (sec): Analyst:_
LCN Element Wavelength (A) Comments
1 LV 1001
2 Ag 3280
3 Al 3082
4 Al 2373
5 As 1937
6 B 2496
7 Ba 4934
8 Be 2348
9 Ca 3968
10 Cd 2288
11 Co 2286
12 Cr 2677
13 Cu 3247
14 Fe 2599
15 Fe 2714
16 Hg 1942
17 K 7664
18 Mg 2795
19 Mn 2576
20 Mo 2020
21 Na 5890
22 Ni 2316
23 P 2149
24 Pb 2203
25 Sb 2068
26 Se 1960
27 Sn 1899
28 Ti 3349
29 Tl 1908
30 Y 3710
31 Zn 2138
Figure 4
18
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(7) Correction factors will also be redetermined each
time repeated analysis of the Interference Check Standard does not give re-
sults within ± 1.5 o of the true values. Table 4 shows the composition of
the Interference Check Standard.
TABLE 4
INTERFERENCE CHECK STANDARD3
Analyte (mg/2) Interferents (mg/JE)
Al 120
Ca 600
Fe 500
Mg 300
Na 100
Ag
As
B
Ba
Be
Cd
Co
Cr
Cu
Na
Ho
Ni
Pb
Sb
Se
Ti
Tl
V
Zn
K
0.3
1.0
0.5
0.3
0.1
0.3
0.3
0.3
0.3
0.38
0.36
0.3
1.0
1.0
0.5
1.0
1.0
0.3
10
20
Interference QC Sample, EPA-EMSL, Cincinnati,
November 1980.
(8) A representative sample from each sample prepara-
tion batch will be spectrum scanned, plotted, and evaluated to confirm that
all spectral interferences are being compensated by correction factors.
This procedure may be discontinued if repeated interference evaluations re-
veal a constancy of interferences.
b. Accuracy verification of instrument calibration standards
(1) New calibration standards will be prepared every
30 days. See Table 3 for the composition of the mixed calibration standards.
19
-------
(2) Each of the two types of sample matrices will have
a separate set of standards:
Soils and sludges 10% (v/v) HN03 (double-distilled)
Vegetables 20% (v/v) HN03 (double-distilled)
(3) Each volumetric flask holding the calibration standards
will be labeled with the standard name, ACT name, and date.
(4) The accuracy of each new batch of calibration standard
will be verified by analyzing a matrix-matched USEPA analytical quality control
(AQC) standard. This is done by calibrating the ICP spectrometer with the
new standards and analyzing the AQC standard five times: EAANANANANANTDTP.
Accuracy is acceptable if all measured values for the AQC standard are within
± 5% of the certified values. If verification is not successful, recalibrate
the spectrometer and repeat the test. If verification is still not successful,
prepare new standards.
(5) All terminal output for the verification test will
be placed in the program "Instrument Calibration" Technical Record Book.
c. Verification of daily instrument calibration
(1) Two quality control standards are to initially verify
the accuracy of the initial calibration of the ICP emission spectrometer
and to monitor instrument drift. These standards are:
ISC - Instrument Check Standard
Labeled Vnn or Son for the vegetable or soil
matrix, where on starts at 01 and is incre-
mented for each new standare prepared.
STD1 - Calibration reagent blank.
(2) ICSs will be prepared monthly or as needed by the
trace metal analysis leader.
(3) The true or accepted concentration values for a
new ICS will be determined by first successfully calibrating the ICP spectrom-
eter with existing quality control samples and performing 20 replicate analyses
of the new ICS. The mean, standard deviation, and percent relative standard
deviation for the replicate analyses will be determined (TDTP).
(4) The true or accepted values for STD1 will be deter-
mined the same way.
(5) All computer terminal printouts will be placed in
the program "Instrument Calibration" Technical Record Book.
20
-------
(6) As described in Section 5, "Daily Instrument Cali-
bration Procedure," STD1 and the ICS are analyzed at the beginning and every
10th analysis for a sample set to assure continued acceptable instrument
calibration. The control limits are:
STD1 ± 2 standard deviations for mean concentration
values
ICS ± 5% from true or accepted concentration values.
(7) Any samples analyzed after the last successful
verification of the daily instrument calibration will be reanalyzed after
calibration.
d. Verification of purify of double-distilled HN03
(1) Each bottle of Merck Suprepur® HN03 will be checked
for metal contamination before it is used for sample preparation or instru-
mental analysis.
(2) Each bottle will be dated and marked for "4901A42
Use" when opened.
(3) Each bottle will be kept in a plastic bag when not
being used.
(4) The ICP-AES elemental analysis of each bottle will
be kept in the program "Instrument Calibration" Technical Record Book.
7. Time/materials requirements: Complete ICP-AES analysis of a
given 50-sample batch should require 8 hr labor time. This includes docu-
mentation control.
V. Data Analysis, Storage and Retrieval
A. General
1. All data entries will be in accordance with MRI procedure QA-7.
2. All records and data files will be kept in a centralized loca-
tion in Room 346.
3. All entries of original data or information will be made with
waterproof blank ink directly into the appropriate permanent record medium.
4. Entries will be both complete and timely.
5. Calculations and entries of all measured numbers will be accord-
ing to the following significant figure convention.
21
-------
B. Significant Figures
All data for this program will be reported with three significant
figures.
C. Sample Concentration Calculations
1. The final analyte concentrations will be expressed as micro-
grams analyte per gram dried sample.
2. The actual calculations to convert ICP emission intensity into
a microgram per gram (dry) final analyte concentration will be done immediately
upon completion of sample analysis by the computer. The terminal output,
following ICP-AES analysis, will be the final concentrations for all channels.
3. The intensity of emission of each analyte element is measured
by the spectrometer as a series of emission counts. At the end of the emis-
sion intensity measurement period, the count numbers are converted to a digi-
tal count and sent to the computer. These counts are compared to linear
counts versus concentration relationships whose slope (AO) and intercept (Al)
are stored in the Analytical Control Table during instrument calibration:
Concentration = AO x emission counts + Al
4. Then, any interelement spectral interference emission is sub-
tracted out:
n
Corrected Concentration = Uncorrected Concentration - Z K,.C.
i=l U l
where K . = interelement correction factor, ppm analyte/ppm interferent.
C. = interferent element concentration, ppm.
5. Lastly, the corrected analyte concentration in micrograms per
gram digest is converted to microgram per gram (dry) sample by multiplying
the preparation dilution factor:
|Jg analyte x g digest _ M8 analyte
g digest g (dry) sample g (dry) sample)
6. These final concentrations are also stored on disk.
22
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D. Computer Operating Procedures
1. General hardware/software description
a. The computer system used for this program is a Digital
Equipment Corporation PDF 11/23 model with 96K words of dynamic memory and
over 5 megabytes of disk storage space. Two terminals are interfaced to
the computer: (1) an LA 120 180 character/sec printer terminal, and (2) a
VT100 video terminal. The ICP spectrometer is remotely interfaced to the
computer by dual 40-port shielded cables.
The LA 120 terminal located beside the ICP emission spectrom-
eter is the console terminal for the computer and is the terminal for opera-
tion of the spectrometer. The VT100 terminal, located in Room 342W with
the computer, is a remote terminal despite its physical location. One must
"log-on" a remote terminal with a proper User Identification Code (UIC) and
password.
b. The computer operation system is RSX-11M, which is a real-
time multitasking and multiprogramming software system. What this means
for our system is that one person can operate the spectrometer at the LA 120
terminal while another person simultaneously runs other programs at the VT100
terminal.
c. The RSX-11M operating system is both powerful and complex.
Any questions or problems observed while operating the system should be com-
municated to the metals analysis task leader.
d. A good overview of RSX-11M is contained in the following
two Digital Equipment Coproration Manuals:
(1) Introduction RSX-11M, AA-2555C-TC, Vol. 1A
(2) RSX-11M Beginner's Guide, DEC-11-OMBGAA-D, Vol. 1A
2. ICP-AES analytical quality control software:
a. Two programs have been written to permit immediate quality
control evaluation of a sample set analyzed by ICP-AES:
* Generation and storage of accuracy and precision con-
trol limits for standard reference mterials.
* Generation and storage of accuracy and precision con-
trol limits for the sample matrix.
* Calculation and storage of detection limits.
* Testing of all QC samples (SRM, duplicates, and spikes)
for accuracy and precision control. All parameters by samples that are out
of control are flagged.
23
-------
* Printout of data summary tables with the correct
number of significant figures and flagged for < detection limit results.
* Printout of QC accuracy % recovery summary tables.
* Printout of QC precision relative percent standard
deviation summary tables.
b. Table 5 summarizes the analytical quality control statis-
tics and limits used in the two programs.
E. Analytical Data Documentation Control
Below are listed the primary types of data generated during sample
preparation and analysis followed by specific means by which it is to be
stored:
1- Initial sample preparation sheets: These are to be completed
in duplicate by the trace metal analysis leader, who retains one copy. One
copy is forwarded for action to the sample preparation analyst.
2. Completed sample preparation sheets: The original SAMPLE
PREPARATION SHEET, completed by the sample preparation analyst is placed on
the tray with the prepared sample batch. One copy if placed in the current
project "Sample Preparation" Technical Record Book (TRB).
3. Spectrum scan plots and summary sheets: The original SPECTRUM
SCAN SUMMARY sheet is placed in the project "Spectral Interferences" TRB.
A copy of the summary sheet plus the spectrum scan plots are placed in the
blue ringed binder marked "Spectral Interferences."
4. Spectral interelement interferences (Group 4): Signed and
dated, the terminal output and a hard copy of new Group 4 for either VEG or
SOIL ALT is placed in the blue ringed binder marked "SPECTRAL INTERFERENCES."
5. Analyses of the interference check standards: Signed and dated,
the terminal output for successful analysis of the Interference Check Standard
is placed in the project "Spectral Interferences," TRB.
6. Preparation of interference check standards: All information
concerning the preparation and true values of interference check standards
will also be placed in the project "Spectral Interferences" TRB.
7. Analyses of USEPA AQC standards: Terminal output for analyses
of USEPA Analytical Quality Control Standards for accuracy verification of
instrument calibration standards will be placed in the project "Instrument
Calibration" TRB.
8. Preparation of USEPA AQC standards: All information concern-
ing preparation and true values for USEPA AQC standards will also be placed
in the project "Instrument Calibration" TRB.
24
-------
TABLE 5
ANALYTICAL QUALITY CONTROL STATISTICS AND LIMITS
1. PRECISION
• CONTROL STATISTIC - Si - PERCENT RELATIVE STANDARD FOR 1th ELEMENT
OF DUPLICATED SAMPLES •
• CONTROL LIMITS
WARNING LIMIT =1.96 Si (95S CONFIDENCE LEVEL)
CONTROL LIMIT = 2.58 Si (99% CONFIDENCE LEVEL)
2. ACCURACY
. CONTROL STATISTIC » PI - PERCENT RECOVERY OF 1th ELEMENT
100 x (MEASURED SPIKED SAMPLE CONCENTRATION -
SPIKED SAMPLES Pf = MEASURED UNSPIKED SAMPLE CONCENTRATION)
SPIKE CONCENTRATION INCREASE
REFERENCE SAMPLES Pj = 100 x MEASURED SAMPLE CONCENTRATION
KNOWN SAMPLE CONCENTRATION
• CONTROL LIMITS
WARNING LIMITS = MEAN P, * 1.96 dP1 (952 CONFIDENCE LEVEL)
CONTROL LIMITS - MEAN Pj + 2.58 c5Pi (99% CONFIDENCE LEVEL)
WHERE 5Pi = STANDARD DEVIATION OF MEAN PERCENT RECOVERY OF ith ELEMENT
3. DETECTION LIMITS
• CONTROL STATISTIC = 3 x STANDARD DEVIATION OF 10 OR MORE REPLICATE
DETERMINATIONS OF A REPRESENTATIVE SAMPLE
25
-------
9. Analyses of blank (STD1) and instrument check standard (ICS):
The initial analyses terminal output of STD1 aad the ICS will be placed in
the project "Instrument Calibration" TRB. Subsequent analyses will be part
of the analysis sample set data.
10. Preparation of calibration standards and ICS: All information
concerning preparation and true values of calibration standards and ICS,
will also be placed in the project "Instrument Calibration" TRB.
11. Sample set analyses: The original copy of the "ICP Data
Reporting Sheet," will be placed in the project "Sample Analysis" TRB.
A copy of the "ICP Data Reporting Sheet" and all real-time terminal
output will be placed in the blue ringed binder marked "Sample Analysis."
The results are also stored on disk under the file specification:
DL1:[1,54]digestion code.BRN;!.
12. VREPORT summary of sample set analyses: The VREPORT terminal
report of recently completed analyses will be placed with the other terminal
output for that sample set in the ringed binder marked "Sample Analysis."
13. ICP-AES analytical quality control software results and reports:
The summary tables generated during execution of DOR21.TSK;! will be forwarded
with the appropriate "Sample Analysis" TRB and "Sample Analysis" blue ringed
binder for review by the trace metal analysis leader.
Another copy of summary tables plus all terminal output from execu-
tion of DOR20.TSK;! and DOR21.TSK;! will be placed in the "Sample Analysis"
blue ringed binder.
14. Sample analysis data files stored on disk: Each week all new
sample analysis data files stored on the current scratch disk in disk drive
1 will be copied onto the backup disk entitled "DA4901."
15. Data reports to the task leader: The analytical summary tables
of analysis sample sets approved by the trace metal analysis leader will be
forwarded to the task leader with a cover memo.
F. Other Project Documentation Control
1. Purchase requisitions, shipping orders, and memos on stock
room purchases will be kept on file by the trace metal analysis leader.
2. Each week all personnel working on the project will submit to
the trace metal analysis leader a summary of hours worked.
3. Phone contact reports and other correspondence will be kept
on file by the trace metal analysis leader.
26
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VI. Sample Custody and Control
A. Field Samples
1. Samples arriving at MRI from the field will have an MRI "Chain
of Custody Record" sheet (Figure 5) with them.
2. The trace metal analysis leader or designee will receive the
samples by signing the custody sheet.
3. The sheet will be filed by the trace metal analysis leader in
the "Sample Custody" Technical Record Book.
4. Each sample will be logged in the bound "Sample Custody" TRB
by completing the following entries:
• Sample Code
• Arrival Date
• Arrival Time
• Signature of Receiver
5. The status of the samples wll be updated by completing the
following column entries:
• Date
Digest Code
• Analysis Date
• Report Date
Comments
6. Samples will be stored on the designated shelves in custody
refrigerated storage at all time when not being used for sample preparation.
B. Dried and Prepared Samples
1. Dried or digested sample sets will be stored in a metal cabinet
in the Inorganic Analysis Prep Laboratory (Room 344W) until those samples
have been analyzed and the data reported.
2. After data reporting, dried and digested samples will be
archived in the locked refrigerated sample custody storage.
C. Computerized Sample Status Reporting
1. In addition to the bound primary sample status tracking through
the bound MRI "Sample Custody" Technical Record Book, a computerized sample
tracking data base will be maintained.
2. This data base file will be an RMS indexed sequential file
amenable to DEC DATATRIEVE data base management software.
27
-------
3. Each sample record will contain the following information:
• Sample Code • Analysis Date
• Arrival Date • Report Date
• Preparation Dae • Comments Section
• Digest Date
4. A weekly status table printout will be presented to the task
leader.
5. Appendix B contains a copy of the DATATRIEVE file information.
VII. Safety
All samples and extracts will be considered hazardous and will be
handled with utmost care. Rigid sample and extract control will be exercised
to ensure sample integrity and minimize human exposure.
All pertinent regulations of the MRI Safety and Health Manual and
the MRI General Safety Regulations for the Use of Carcinogenic Materials will
be followed. In particular, all equipment and containers will be decontami-
nated as prescribed.
VIII. References
1. Page, A. L., and A. C. Chang, "Trace Elements Impact on Plants
During Cropland Disposal of Sewage Sludge," In: National Confer-
ence on Acceptable Sludge Disposal Technology [Proceedings, 5th],
1978, pp. 91-6.
2. Page, A., "Sludge Treatment and Disposal," Vol. 2, USEPA Transfer
Technology, EPA-625/14-78-012, October 1978.
3. Naylor, L., and R. Loehr, "Increase in Dietary Cadmium as a Result
of Application of Sewage Sludge to Agricultural Land," Environ.
Sci. and Technol.. 15, 881-6 (1981).
4. Stoewsand, G., "Trace Metal Problems with Industrial Waste Materials
Applied to Vegetable Producing Soils," In: The Safety of Foods,
2nd Edition, H. D. Graham (ed.), Avi Publishing, Westport, Connecticut,
1980, pp. 423-43.
5. Garcia, W., et al., "Metal Accumulation and Crop Yield for a Variety
of Edible Crops Grown in Diverse Soil Media Amended with Sewage
Sludge," Environ. Sci. and Technol.. 15, 793-804 (1981).
6. Swanson, S., "Summary of Analytical Methods, Quality Assurance
Procedures, and Analytical Results for Priority Pollutants,"
Draft Final Report, POTW Sludge Analysis—Task 35, EPA Contract
Nos. 68-03-2565 and 68-02-5915, Midwest Research Institute,
Kansas City, Missour, 1981.
28
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APPENDIX A
EPA INTERIM METHOD 200.7
29
-------
U. S. ENVIRONMENTAL PROTECTION AGENCY
Environmental Monitoring and Support Laboratory
Cincinnati, Ohio 45268
30
-------
Foreword
This method has been prepared by the staff of the Environmental
Monitoring and Support Laboratory - Cincinnati, with the cooperation of the
EPA-ICP Users Group. Their cooperation and support is gratefully acknowl-
edged.
This method represents the current state-of-the-art, but as time pro-
gresses, improvements are anticipated. Users are encouraged to identify
problems and assist in updating the method by contacting the Environmental
Monitoring and Support Laboratory, Cincinnati, Ohio, 45268.
11
31
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INDUCTIVELY COUPLED PLASMA-ATOMIC EMISSION SPECTROMETRIC METHOD
FOR TRACE ELEMENT ANALYSIS OF WATER AND WASTES
Scope and Application
1.1 This method may be used for the determination of dissolved, sus-
pended, or total elements in drinking water, surface water,
domestic and industrial wastewaters.
1.2 Dissolved elements are determined in filtered and acidified
samples. Appropriate steps must be taken in all analyses to ensure
that potential interference are taken into account. This is
especially true when dissolved solids exceed 1500 mg/1. (See 4.)
1.3 Total elements are determined after appropriate digestion pro-
cedures are performed. Since digestion techniques increase the
dissolved solids content of the samples, appropriate steps must be
taken to correct for potential interference effects. (See 4.)
1.4 Table 1 lists elements for which this method applies along with
recommended wavelengths and typical estimated instrumental detec-
tion limits using conventional pneumatic nebulization. Actual
working detection limits are sample dependent and as the sample
matrix varies, these concentrations may also vary. In time, other
elements may be added as more information becomes available and as
required.
1.5 Because of the differences between various makes and models of
*
satisfactory instruments, no detailed instrumental operating
instructions can be provided. Instead, the analyst is referred to
the instructions provided by the manufacturer of the particular
instrument.
1
32
-------
Table 1 - Recommended WavelengthsH) and
Estimated Instrumental Detection Limits
Element
Wavelength, nm
Estimated detection
limit, ug/l(2)
Aluminum
Arsenic
Antimony
Barium
Beryllium
Boron
Cadmium
Calcium
Chromium
Cobalt
Copper
Iron
Lead
Magnesium
Manganese
Molybdenum
Nickel
Potassium
Selenium
Silica (S102)
Silver
Sodium
Thallium
Vanadium
Zinc
308.215
193.696
206.333
455.403
313.042
249.773
226.502
317.933
267.716
228.616
324.754
259.940
220.353
279.079
257.610
202.030
231.604
766.491
196.026
288.158
328.068
588.995
190.864
292.402
213.856
45
53
32
2
0.
5
4
10
7
7
6
7
42
30
2
75
58
7
29
40
8
2
(1)
(2)
(3)
The wavelengths listed are recommended because of their sensitivity
and overall acceptance. Other wavelengths may be substituted if
they can provide the needed sensitivity and are treated with the
same corrective techniques for spectral interference. (See 4.1.1).
The estimated instrumental detection limits as shown are taken from
"Inductively Coupled Plasma-Atomic Emission Spectroscopy-Prominent
Lines," EPA-600/4-79-017. They are given as a guide for an instru-
mental limit. The actual method detection limits are sample
dependent and may vary as the sample matrix varies.
Highly dependent on operating conditions and plasma position.
2
33
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2. Summary of Method
2.1 The method describes »«&echf*»quete£cn|
of trace elements in solution. The
basis of the method is the measurement of atomic emission by an
optical spectroscopic technique. Samples are nebulized and the
aerosol that is produced is transported to the plasma torch where
excitation occurs. Characteristic atomic-line emission spectra are
produced by a radio-frequency inductively coupled plasma (ICP).
The spectra are dispersed by a grating spectrometer and the inten-
sities of the lines are monitored by photomultiplier tubes. The
photocurrents from the photomultiplier tubes are processed and
controlled by a computer system. A background correction technique
is required to compensate for variable background contribution to
the determination of trace elements. Background must be measured
adjacent to analyte lines on samples during analysis. The position
selected for the background intensity measurement, on either or
both sides of the analytical line, will be determined by the com-
plexity of the spectrum adjacent to the analyte line. The position
used must be free of spectral interference and reflect the same
change in background intensity as occurs at the analyte wavelength
measured. Background correction is not required in cases of line
broadening where a background correction measurement would actually
degrade the analytical result. The possibility of additional
interferences named in 4.1 (and tests for their presence as
described in 4.2) should also be recognized and appropriate
corrections made.
3
34
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3. Definitions
3.1 Dissolved — Those elements which will pass through a 0.45 urn
membrane filter.
3.2 Suspended — Those elements which are retained by a 0.45 urn
membrane filter.
3.3 Total — The concentration determined on an unfiltered sample
following vigorous digestion (Section 8.3), or the sum of the
dissolved plus suspended concentrations. (Section 8.1 plus 8.2).
3-4 Total recoverable — The concentration determined on an unfiltered
sample following treatment with hot, dilute mineral acid (Section
8.4).
3.5 Instrumental detection limit -- The concentration equivalent to a
signal, due to the analyte, which is equal to three times the
standard deviation of a series of ten replicate measurements of a
reagent blank signal at the same wavelength.
3.6 Sensitivity -- The slope of the analytical curve, i.e. functional
relationship between emission intensity and concentration.
3-7 Instrument check standard — A multielement standard of known
concentrations prepared by the analyst to monitor and verify
instrument performance on a daily basis. (See 6.6.1)
3.8 Interference check sample - A solution containing both interfering
and analyte elements of known concentration that can be used to
verify background and interelement correction factors. (See 6.6.2.)
3-9 Quality control sample — A solution obtained from an outside
source having known, concentration values to be used to verify the
calibration standards. (See 6.6.3)
4
35
-------
3.10 Calibration standards — a series of known standard solutions used
by the analyst for calibration of the instrument (i.e., preparation
of the analytical curve). (See 6.4)
3.11 Linear dynamic range ~ The concentration range over which the
analytical curve remains linear.
3.12 Reagent blank — A volume of deionized, distilled water containing
the same acid matrix as the calibration standards carried through
the entire analytical scheme. (See 6.5.2)
3.13 Calibration blank — A volume of deionized, distilled water acidi-
fied with HN03 and HC1. (See 6.5.1)
3.14 Method of standard addition — The standard addition technique
involves the use of the unknown and the unknown plus a known amount
of standard. (See 9.6.1.)
4. Interferences
4.1 Several types of interference effects may contribute to inac-
curacies in the determination of trace elements. They can be
summarized as follows:
4.1.1 Spectral interferences can be categorized as 1) overlap of a
spectral line from another element; 2) unresolved overlap of
molecular band spectra; 3) background contribution from
continuous or recombination phenomena; and 4) background
contribution from stray light from the line emission of high
concentration elements. The first of these effects can be
compensated by utilizing a computer correction of the raw
data, requiring the monitoring and measurement of the
interfering element. The second effect may require selec-
5
36
-------
tion of an alternate wavelength. The third and fourth
effects can usually be compensated by a background correc-
tion adjacent to the analyte line. In addition, users of
simultaneous multi-element instrumentation must assume the
responsibility of verifying the absence of spectral inter-
ference from an element that could occur in a sample but for
which there is no channel in the instrument array. Listed
in Table 2 are some interference effects for the recommended
wavelengths given in Table 1. The data in Table 2 are
intended for use only as a rudimentary guide for the indica-
tion of potential spectral interferences. For this purpose,
linear relations between concentration and intensity for the
analytes and the interferents can be assumed.
The interference information, which was collected at the
Ames Laboratory , is expressed as analyte concentration
eqivalents (i.e. false analyte concentrations) arising from
100 mg/1 of the interferent element. The suggested use of
this information is as follows: Assume that arsenic (at
193.696 nm) is to be determined in a sample containing
approximately 10 mg/1 of aluminum. According to Table 2,
Ames Laboratory, USDOE, Iowa State University, Ames Iowa 50011
6
37
-------
Table 2. Analyte Concentration Equivalents (mg/1) Arising
From Interferents at the 100 mg/1 Level
OJ
00
Analyte Wavelength,
Aluminum
Antimony
Arsenic
Barium
Beryllium
Boron
Cadmium
Calcium
Chromium
Cobalt
Copper
Iron
Lead
Magnesium
Manganese
Molybdenum
Nickel
Selenium
Silicon
Sodium
Thallium
Vanadium
Zinc
308.215
206.833
193.696
455.403
313.042
249.773
226.502
317.933
267.716
228.616
324.754
259.940
220.353
279.079
257.610
202.030
231.604
196.026
288.158
588.995
190.864
292.402
213.856
nm
Al Ca
• mm *m mm
0.47
1.3
— — _ w
—
0.04
— _ — _
— __
—
~ * • _
__ __
—
0.17
0.02
0.005 —
0.05
_ _ __
0.23
— _ — _
0.30
_- __
—
Cr Cu
„
2.9
0.44
mm •• • _
-_ __
__
mm mm -m mm
0.08
—
0.03
— - __
_-
._
0.11
0.01
mm « •• •_
— — •«
—
0.07
— - -._
-- __
0.05
0.14
Interferent
Fe Mg Mn
0.21
0.08
—
— — _ _ _..
0.32
0.03
0.01 0.01 0.04
0.003 — 0.04
0.005
0.003
0.12
0.13 — 0.25
0.002 0.002
0.03
••— — «• •. mm
0.09
^ i— •• •• ~ m~
— — — — .. _
0.005
__ __ __
N1 T1
.25
0.04
0.02
0.03
_-
0.03 0.15
0.05
0.07
—
mm _ — _
__
—
0.08
0.02
0.29
V
1.4
0.45
1.1
0.05
0.03
0.04
0.02
0.12
--
-m mm
--
0.01
--
__
_ m.
-------
100 mg/1 of aluminum would yield a false signal for arsenic
equivalent to approximately 1.3 mg/1. Therefore, 10 mg/1 of
aluminum would result in a false signal for arsenic equiva-
lent to approximately 0.13 mg/1. The reader is cautioned
that other analytical systems may exhibit somewhat different
levels of interference than those shown in Table 2, and that
the interference effects must be evaluated for each indi-
vidual system.
Only those interferents listed were investigated and the
blank spaces in Table 2 indicate that measurable interfer-
ences were not observed for the interferent concentrations
listed in Table 3. Generally, interferences were discern-
ible if they produced peaks or background shifts corres-
ponding to 2-5% of the peaks generated by the analyte
concentrations also listed in Table 3.
At present, information on the listed silver and potassium
wavelengths are not available but it has been reported that
second order energy from the magnesium 383.231 nm wavelength
interferes with the listed potassium line at 766.491 nm.
4.1.2 Physical interferences are generally considered to be
effects associated with the sample nebulization and
transport processes. Such properties as change in viscosity
and surface tension can cause significant inaccuracies
especially in samples which may contain high dissolved
solids and/or acid concentrations. The use of a peristaltic
pump may lessen these interferences. If these types of
8
39
-------
interferences are operative, they must be reduced by dilu-
tion of the sample and/or utilization of standard addition
techniques. Another problem which can occur from high
dissolved solids is salt buildup at the tip of the nebuli-
zer. This affects aersol flow rate causing instrumental
drift. Wetting the argon prior to nebulization, the use of
a tip washer, or sample dilution have been used to control
this problem. Also, it has been reported that better
control of the argon flow rate improves instrument perform-
ance. This is accomplished with the use of mass flow
controllers.
4.1.3 Chemical Interferences are characterized by molecular
compound formation, iom'zation effects and solute vaporiza-
tion effects. Normally these effects are not pronounced
with the ICP technique, however, if observed they can be
minimized by careful selection of operating conditions (that
is, incident power, observation position, and so forth), by
buffering of the sample, by matrix matching, and by standard
addition procedures. These types of interferences can be
highly dependent on matrix type and the specific analyte
element.
4.2 It is recommended that whenever a new or unusual sample matrix is
encountered, a series of tests be performed prior to reporting
concentration data for analyte elements. These tests, as outlined
in 4.2.1 through 4.2.4, will ensure the analyst that neither
positive nor negative interference effects are operative on any of
9
40
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Table 3. Interferent and Analyte Elemental Concentrations Used
for Interference Measurements in Table 2.
Analytes (rng/1) Interferents (mo/1)
Al 10 Al 1000
As 10 Ca 1000
B 10 Cr 200
Ba 1 Cu 200
Be 1 Fe 1000
Ca 1 Mg 1000
Cd 10 Mn 200
Co 1 Ni 200
Cr 1 Ti 200
Cu 1 V 200
Fe 1
Mg 1
Mn 1
Mo 10
Na 10
Ni 10
Pb 10
Sb 10
Se 10
Si 1
Tl 10
V 1
Zn 10
10
41
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the analyte elements thereby distorting the accuracy of the
reported values.
4.2.1 Serial dilution—If the analyte concentration is sufficiently
high (minimally a factor of 10 above the instrumental
detection limit after dilution), an analysis of a dilution
should agree within 5 percent of the original determination
(or within some acceptable control limit (13.3) that has
been established for that matrix.). If not, a chemical or
physical interference effect should be suspected.
4.2.2 Spike addition—The recovery of a spike addition added at a
minimum level of 10X the instrumental detection limit
(maximum 100X) to the original determination should be
recovered to within 90 to 110 percent or within the estab-
lished control limit for that matrix. If not, a matrix
effect should be suspected. The use of a standard addition
analysis procedure can usually compensate for this effect.
Caution: The standard addition technique does not detect
coincident spectral overlap. If suspected, use of
computerized compensation, an alternate wavelength, or
comparison with an alternate method is recommended (See
4.2.3).
•
4.2.3 Comparison with alternate method of analysis—When investi-
gating a new sample matrix, comparison tests may be
performed with other analytical techniques such as atomic
absorption spectrometry, or other approved methodology.
11
42
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4.2.4 Wavelength scanning of analyte line region—If the appro-
priate equipment is available, wavelength scanning can be
performed to detect potential spectral interferences.
5. Apparatus
5.1 Inductively Coupled Plasma-Atomic Emission Spectrometer.
5.1.1 Computer controlled atomic emission spectrometer with back-
ground correction.
5.1.2 Radiofrequency generator.
5.1.3 Argon gas supply, welding grade or better.
5.2 Operating conditions — Because of the differences between various
makes and models of satisfactory instruments, no detailed operating
instructions can be provided. Instead, the analyst should follow
the instructions provided by the manufacturer of the particular
instrument. Sensitivity, instrumental detection limit, precision,
linear dynamic range, and interference effects must be investigated
and established for each individual analyte line on that particular
instrument. It is the responsibility of the analyst to verify that
the instrument configuration and operating conditions used satisfy
the analytical requirements and to maintain quality control data
confirming instrument performance and analytical results.
6. Reagents and standards
6.1 Acids used in the preparation of standards and for sample proces-
sing must be ultra-high purity grade or equivalent. Redistilled
acids are acceptable.
6.1.1 Acetic acid, cone, (sp gr 1.06).
6.1.2 Hydrochloric acid, cone, (sp gr 1.19).
12
43
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6-1.3 Hydrochloric acid, (1+1): Add 500 ml cone. HC1 (sp gr 1.19)
to 400 ml deionized, distilled water and dilute to 1 liter.
6.1.4 Nitric acid, cone, (sp gr 1.41).
6.1.5 Nitric acid. (1+1): Add 500 ml cone. HN03 (sp. gr 1.41)
to 400 ml deionized, distilled water and dilute to 1 liter.
6.2 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. The purity of this
water must be equivalent to ASTM Type II reagent water of Specifi-
cation D 1193 (13.6).
6.3 Standard stock solutions may be purchased or prepared from ultra
high purity grade chemicals or metals. All salts must be dried for
1 h at 105°C unless otherwise specified.
(CAUTION: Many metal salts are extremely toxic and may be fatal if
swallowed. Wash hands thoroughly after handling.)
Typical stock solution preparation procedures follow:
6.3.1 Aluminum solution, stock. 1 ml = 100 ug Al: Dissolve
0.100 g of aluminum metal in an acid mixture of 4 ml of
(1+1) HC1 and 1 ml of cone. HN03 in a beaker. Warm gently
to effect solution. When solution is complete, transfer
quantitatively to a liter flask add an additional 10 ml of
(1+1) HC1 and dilute to 1,000 ml with deionized, distilled
water.
6.3.2 Antimony solution stock, 1 ml = 100 ug Sb: Dissolve
0.2669 g K(SbO)C4H4Og in deionized distilled water,
13
44
-------
add 10 ml (1+1) HC1 and dilute to 1000 ml with deionized,
distilled water.
6.3.3 Arsenic solution, stock. 1 ml = 100 ug As: Dissolve
0.1320 g of As203 in 100 ml of deionized, distilled
water containing 0.4 g NaOH. Acidify the solution with 2 ml
cone. HN03 and dilute to 1,000 ml with deionized, dis-
tilled water.
6.3.4 Barium solution, stock, 1 ml = 100 ug Ba: Dissolve 0.1516 g
BaCl2 (dried at 250°C for 2 hrs) in 10 ml deionized,
distilled water with 1 ml (1+1) HC1. Add 10.0 ml (1+1) HC1
and dilute to 1,000 ml with deionized, distilled water.
6.3.5 Beryllium solution, stock, 1 ml = 100 ug Be: Do not dry.
Dissolve 1.966 g BeS04 ' 4H20, in deionized, distilled
water, add 10.0 ml cone. HN03 and dilute to 1,000 ml with
deionized, distilled water.
6.3.6 Boron solution, stock, 1 ml = 100 ug B: Do not dry.
Dissolve 0.5716 g anhydrous H3B03 in deionized, dis-
tilled water and dilute to 1,000 ml. Use a reagent meeting
ACS specifications, keep the bottle tightly stoppered and
store in a desiccator to prevent the entrance of atmospheric
moisture.
6.3.7 Cadmium solution, stock, 1 ml = 100 ug Cd: Dissolve
0.1142 g CdO in a minimum amount of (1+1) HN03. Heat to
increase rate of dissolution. Add 10.0 ml cone. HN03 and
dilute to 1,000 ml with deionized, distilled water.
6.3.8 Calcium solution, stock, 1 ml = 100 ug Ca: Suspend 0.2498 g
45
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CaC03 dried at 180°C for 1 h before weighing in deion-
ized, distilled water and dissolve cautiously with a minimum
amount of (1+1) HNOj. Add 10.0 ml cone. HN03 and dilute
to 1,000 ml with deionized, distilled water.
6.3.9 Chromium solution, stock. 1 ml = 100 ug Cr: Dissolve
0.1923 g of Cr03 in deionized, distilled water. When
solution is complete, acidify with 10 ml cone. HNO, and
dilute to 1,000 ml with deionized, distilled water.
5-3.10 Cobalt solution, stock, 1 ml = 100 ug Co: Dissolve 0.1000 g
of cobalt metal in a minimum amount of (1+1) HNO,. Add
0
10.0 ml (1+1) HC1 and dilute to 1,000 ml with deionized,
distilled water.
6.3.11 Copper solution, stock, 1 ml = 100 ug Cu: Dissolve 0.1252 g
CuO in a minimum amount of (1+1) HN03. Add 10.0 ml cone.
HN03 and dilute to 1,000 ml with deionized, distilled
water.
6.3.12 Iron solution, stock, 1 ml = 100 ug Fe: Dissolve 0.1430 g
Fe203 in 10 ml deionized, distilled water with 1 ml
(1+1) HC1. Add 10.0 ml cone. HN03 and dilute to 1,000 ml
with deionized, distilled water.
6.3.13 Lead solution, stock, 1 ml = 100 ug Pb: Dissolve 0.1599 g
Pb(N03)2 in a minimum amount of (1+1) HN03- Add 10.0
ml cone. HN03 and dilute to 1,000 ml with deionized, dis-
tilled water.
6.3.14 Magnesium solution, stock, 1 ml = 100 ug Mg: Dissolve
0.1658 g MgO in a minimum amount of (1+1) HNO-,. Add 10.0
15
46
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ml cone. HN03 and dilute to 1,000 ml with deionized,
distilled water.
6.3.15 Manganese solution, stock. 1 ml = 100 ug Mn: Dissolve
0.1000 g of manganese metal in the acid mixture 10 ml cone.
HC1 and 1 ml cone. HNOj, and dilute to 1,000 ml with
deionized, distilled water.
6.3.16 Molybdenum solution, stock. 1 ml = 100 ug Mo: Dissolve
0.2043 g (NH4)2Mo04 in deionized, distilled water and
dilute to 1,000 ml.
6.3.17 Nickel solution, stock. 1 ml = 100 ug Ni: Dissolve 0.1000 g
of nickel metal in 10 ml hot cone. HN03> cool and dilute
to 1,000 ml with deionized, distilled water.
6.3.18 Potassium solution, stock. 1 ml = 100 ug K: Dissolve 0.1907
g KC1, dried at 110°C, in deionized, distilled water
dilute to 1,000 ml.
6.3.19 Selenium solution, stock. 1 ml = 100 ug Se: Do not dry.
Dissolve 0.1727 g H2Se03 (actual assay 94.6X) in deion-
ized, distilled water and dilute to 1,000 ml.
6.3.20 Silica solution, stock. 1 ml = 100 ug SiO.: Do not dry.
Dissolve 0.4730 g Na2Si03 .9H20 in deionized, dis-
tilled water. Add 10.0 ml cone. HN03 and dilute- to 1,000
ml with deionized, distilled water.
6.3.21 Silver solution, stock. 1 ml = 100 ug Ag: Dissolve 0.1575 g
AgN03 in 100 ml of deionized, distilled water and 10 ml
cone. HN03. Dilute to 1,000 ml with deionized, distilled
water.
16
47
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6.3.22 Sodium solution, stock. 1 ml = 100 ug Na: Dissolve 0.2542 g
Nad in deionized, distilled water. Add 10.0 ml cone.
HN03 and dilute to 1,000 ml with deionized, distilled
water.
6.3.23 Thallium solution, stock. 1 ml = 100 ug Tl: Dissolve
0.1303 g T1N03 in deionized, distilled water. Add 10.0 ml
cone. HN03 and dilute to 1,000 ml with deionized, dis-
tilled water.
6-3.24 Vanadium solution, stock. 1 ml = 100 ug V: Dissolve 0.2297
NH4V03 in a minimum amount of cone. HN03. Heat to
increase rate of dissolution. Add 10.0 ml cone. HN03 and
dilute to 1,000 ml with deionized, distilled water.
6.3.25 Zinc solution, stock. 1 ml = 100 ug Zn: Dissolve 0.1245 g
ZnO in a minimum amount of dilute HN03. Add 10.0 ml cone.
HN03 and dilute to 1,000 ml with deionized, distilled
water.
6.4 Mixed calibration standard solutions—Prepare mixed calibration
standard solutions by combining appropriate volumes of the stock
solutions in volumetric flasks. (See 6.4.1 thru 6.4.5) Add 2 ml
of (1+1) HN03 and 10 ml of (1+1) HC1 and dilute to 100 ml with
deionized, distilled water. (See Notes 1 and 6.) Prior to pre-
paring the mixed standards, each stock solution should be analyzed
separately to determine possible spectral interference or the
presence of impurities. Care should be taken when preparing the
mixed standards that the elements are compatible and stable.
Transfer the mixed standard solutions to a FEP fluorocarbon or
17
48
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unused polyethylene bottle for storage. Fresh mixed standards
should be prepared as needed with the realization that concentra-
tion can change on aging. Calibration standards must be initially
verified using a quality control sample and monitored weekly for
stability (See 6.6.3). Although not specifically required, some
typical calibration standard combinations follow when using those
specific wavelengths listed in Table 1.
6-4-1 Mixed standard solution I—Manganese, beryllium, cadmium,
lead, and zinc.
6'4*2 M1xed standard solution II—Barium, copper, iron, vanadium,
and cobalt.
6.4.3 Mixed standard solution III-Molvbdenum. silica, arsenic,
and selenium.
6.4.4 Mixed standard solution IV—Calcium, sodium, postassium,
aluminum, chromium and nickel.
6-4-5 Mixed standard solution V—Antimony, boron, magnesium,
silver, and thallium.
NOTE 1: If the addition of silver to the recommended
acid combination results in an initial precipitation, add
15 ml of deionlzed distilled water and warm the flask
until the solution clears. Cool and dilute to 100 ml
with deionlzed, distilled water. For this acid combina-
tion the silver concentration should be limited to 2
mg/1. Silver under these conditions is stable in a tap
water matrix for 30 days. Higher concentrations of
silver require additional HC1.
18
49
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6.5 Two types of blanks are required for the analysis. The calibration
blank (3.13) is used in establishing the analytical curve while the
reagent blank (3.12) is used to correct for possible contamination
resulting from varying amounts of the acids used in the sample
processing.
6.5.1 The calibration blank is prepared by diluting 2 ml of (1+1)
HN03 and 10 ml of (1+1) HC1 to 100 ml with deionized,
distilled water. (See Note 6.) Prepare a sufficient
quantity to be used to flush the system between standards
and samples.
6.5.2 The reagent blank must contain all the reagents and in the
same volumes as used in the processing of the samples. The
reagent blank must be carried through the complete procedure
and contain the same acid concentration in the final solu-
tion as the sample solution used for analysis.
6.6 In addition to the calibration standards, an instrument check
standard (3.7), an interference check sample (3.8) and a quality
control sample (3.9) are also required for the analyses.
6.6.1 The instrument check standard is prepared by the analyst by
combining compatible elements at a concentration equivalent
to the midpoint of their respective calibration curves.
(See 11.1.1.)
6.6.2 The interference check sample is prepared by the analyst in
the following manner. Select a representative sample which
contains minimal concentrations of the analytes of interest
but known concentration of interfering elements that will
19
50
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provide an adequate test of the correction factors. Spike
the sample with the elements of interest at the approximate
concentration of either 100 ug/1 or 5 times the estimated
detection limits given in Table 1. (For effluent samples of
expected high concentrations, spike at an appropriate level.)
If the type of samples analyzed are varied, a synthetically
prepared sample may be used if the above criteria and intent
are met. A limited supply of a synthetic interference check
sample will be available from the Quality Assurance Branch
of EMSL-Cincinnati. (See 11.1.2).
6.6.3 The quality control sample should be prepared in the same
acid matrix as the calibration standards at a concentration
near 1 mg/1 and in accordance with the instructions provided
by the supplier. The Quality Assurance Branch of EMSL-
Cincinnati will either supply a quality control sample or
information where one of equal quality can be procured.
(See 11.1.3.)
7. Sample handling and preservation
7.1 For the determination of trace elements, contamination and loss are
of prime concern. Oust in the laboratory environment, impurities
in reagents and impurities on laboratory apparatus which the sample
contacts are all sources of potential contamination. Sample
containers can introduce either positive or negative errors in the
measurement of trace elements by (a) contributing contaminants
through leaching or surface desorption and (b) by depleting concen-
20
51
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trations through adsorption. Thus the collection and treatment of
the sample prior to analysis requires particular attention.
Laboratory glassware including the sample bottle (whether poly-
ethylene, polyproplyene or FEP-fluorocarbon) should be thoroughly
washed with detergent and tap water; rinsed with (1+1) nitric acid,
tap water, (1+1) hydrochloric acid, tap and finally deionized,
distilled water in that order (See Notes 2 and 3).
NOTE 2: Chromic acid may be useful to remove organic deposits from
glassware; however, the analyst should be cautioned that the glass-
ware must be thoroughly rinsed with water to remove the last traces
of chromium. This is especially important if chromium is to be
included in the analytical scheme. A commercial product, NOCHROMIX,
available from Godax Laboratories, 6 Varick St., New York, NY
10013, may be used in place of chromic acid. Chromic acid should
not be used with plastic bottles.
NOTE 3: If it can be documented through an active analytical
quality control program using spiked samples and reagent blanks,
that certain steps in the cleaning procedure are not required for
routine samples, those steps may be eliminated from the procedure.
7.2 Before collection of the sample a decision must be made as to the
type of data desired, that is dissolved, suspended or total, so
that the appropriate preservation and pretreatment steps may be
accomplished. Filtration, acid preservation, etc., are to be
performed at the time the sample is collected or as soon as
possible thereafter.
21
52
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7.2.1 For the determination of dissolved elements the sample must
be filtered through a 0.45-um membrane filter as soon as
practical after collection. (Glass or plastic filtering
apparatus are recommended to avoid possible contamination.)
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) HNOj to a pH of 2 or less.
Normally, 3 ml of (1+1) acid per liter should be sufficient
to preserve the sample.
7.2.2 For the determination of suspended elements a measured
volume of unpreserved sample must be filtered through a
0.45-um membrane filter as soon as practical after collec-
tion. The filter plus suspended material should be trans-
ferred to a suitable container for storage and/or shipment.
No preservative is required.
7.2.3 For the determination of total or total recoverable elements,
the sample is acidified with (1+1) HN03 to pH 2 or less as
soon as possible, preferably at the time of collection. The
sample is not filtered before processing.
3. Sample Preparation
8.1 For the determinations of dissolved elements, the filtered, pre-
served sample may often be analyzed as received. The acid matrix
and concentration of the samples and calibration standards must be
the same. (See Note 6.) If a precipitate formed upon acidifica-
tion of the sample or during transit or storage, it must be re-
dissolved before the analysis by adding additional acid and/or by
22
53
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heat as described in 8.3.
8.2 For the determination of suspended elements, transfer the membrane
filter containing the insoluble material to a 150-ml Griffin beaker
and add 4 ml cone. HN03. 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 and digest the material.
When the acid has nearly evaporated, cool the beaker and watch
glass and add another 3 ml of cone. HNO-j. Cover and continue
heating until the digestion is complete, generally indicated by a
light colored digestate. Evaporate to near dryness (2 ml), cool,
add 10 ml HC1 (1+1) and 15 ml deionized, distilled water per 100 ml
dilution and warm the beaker gently for 15 min. to dissolve any
precipitated or residue material. Allow to cool, wash down the
watch glass and beaker walls with deionized distilled water and
filter the sample to remove insoluble material that could clog the
nebulizer. (See Note 4.) Adjust the volume based on the expected
concentrations of elements present. This volume will vary depend-
ing on the elements to be determined (See Note 6). The sample is
now ready for analysis. Concentrations so determined shall be
reported as "suspended."
NOTE 4: In place of filtering, the sample after diluting and mix-
ing may be ceritrifuged or allowed to settle by gravity overnight to
remove insoluble material.
8.3 For the determination of total elements, choose a measured, volume
of the well mixed acid preserved sample appropriate for the
expected level of elements and transfer to a Griffin beaker. (See
23
54
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Note 5.) Add 3 ml of cone. HNOj. Place the beaker on a hot
plate and evaporate to near dryness cautiously, making certain that
the sample does not boil and that no area of the bottom of the
beaker is allowed to go dry. Cool the beaker and add another 5 ml
portion of cone. HNOj. Cover the beaker with a watch glass and
return to the hot plate. Increase the temperature of the hot plate
so that a gentle reflux action occurs. Continue heating, adding
additional acid as necessary, until the digestion is complete
(generally indicated when the digestate is light in color or does
not change in appearance with continued refluxing.) Again, evapo-
rate to near dryness and cool the beaker. Add 10 ml of 1+1 HC1 and
15 ml of deionized, distilled water per 100 ml of final solution
and warm the beaker gently for 15 min. to dissolve any precipitate
or residue resulting from evaporation. Allow to cool, wash down
the beaker walls and watch glass with deionized distilled water and
filter the sample to remove insoluble material that could clog the
nebulizer. (See Note 4.) Adjust the sample to a predetermined
volume based on the expected concentrations of elements present.
The sample is now ready for analysis (See Note 6). Concentrations
so determined shall be reported as "total."
NOTE 5: If low determinations of boron are critical, quartz glass-
ware should be used.
NOTE 6: If the sample analysis solution has a different acid con-
centration from that given in 8.4, but does not introduce a
physical interference or affect the analytical result, the same
calibration standards may be used.
24
55
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8.4 For the determination of total recoverable elements, choose a
measured volume of a well mixed, acid preserved sample appropriate
for the expected level of elements and transfer to a Griffin
beaker. (See Note 5.) Add 2 ml of (1+1) HN03 and 10 ml of (1+1)
HC1 to the sample and heat on a steam bath or hot plate until the
volume has been reduced to near 25 ml making certain the sample
does not boil. After this treatment, cool the sample and filter to
remove insoluble material that could clog the nebulizer. (See
Note 4.) Adjust the volume to 100 ml and mix. The sample is now
ready for analysis. Concentrations so determined shall be reported
as "total."
9. Procedure
9.1 Set up instrument with proper operating parameters established in
Section 5.2. The instrument must be allowed to become thermally
stable before beginning. This usually requires at least 30 min. of
operation prior to calibration.
9.2 Initiate appropriate operating configuration of computer.
9.3 Profile and calibrate instrument according to instrument manufac-
turer's recommended procedures, using the typical mixed calibration
standard solutions described in Section 6.4. Flush the system with
the calibration blank (6.5.1) between each standard. (See Note
7.) (The use of the average intensity of multiple exposures for
both standardization and sample analysis has been found to reduce
random error.)
NOTE 7: For boron concentrations greater than 500 ug/1 extended
flush times of 1 to 2 minutes may be required.
25
56
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9.4 Before beginning the sample run, reanalyze the highest mixed cali-
bration standard as if it were a sample. Concentration values
obtained should not deviate from the actual values by more than ± 5
percent (or the established control limits whichever is lower). If
they do, follow the recommendations of the instrument manufacturer
to correct for this condition.
9.5 Begin the sample run flushing the system with the calibration blank
solution (6.5.1) between each sample. (See Note 7.) Analyze the
instrument check standard (6.6.1) and the calibration blank (6.5.1)
each 10 samples.
9.6 If it has been found that methods of standard addition are required,
the following procedure is recommended.
9.6.1 The standard addition technique (13.2) involves preparing
new standards in the sample matrix by adding known amounts
of standard to one or more aliquots of the processed sample
solution. This technique compensates for a sample constitu-
ent that enhances or depresses the analyte signal thus
producing a different slope from that of the calibration
standards. It will not correct for additive interference
which causes a baseline shift. The simplest version of this
technique is the single-addition method. The procedure is
as follows. Two identical aliquots of the sample solution,
each of volume V , are taken. To the first (labeled A) is
A
added a small volume Vg of a standard analyte solution of
concentration GS. To the second (labeled B) is added the
same volume V of the solvent. The analytical signals of
25
57
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A and B are measured and corrected for nonanalyte signals
signals. The unknown sample concentration c is calcu-
A
lated:
SBVscs
l*A * V Vx
where Sft and Sg are the analytical signals (corrected
for the blank) of solutions A and B, respectively. V and
GS should be chosen so that SA is roughly twice S« on
the average. It is best if Vs is made much less than
V , and thus c is much greater than c , to avoid
* 5 X
excess dilution of the sample matrix. If a separation or
concentration step is used, the additions are best made
first and carried through the entire procedure.
For the results from this technique to be valid, the follow-
ing limitations must be taken into consideration:
1. The analytical curve must be linear.
2. The chemical form of the analyte added must respond the
same as the analyte in the sample.
3. The interference effect must be constant over the working
range of concern.
4. The signal must be corrected for any additive interfer-
ence.
10. Calculation
10.1 Reagent blanks (6.5.2) should be subtracted from all samples. This
is particularly important for digested samples requiring large
quantities of acids to complete the digestion.
27
58
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10.2 If dilutions were performed, the appropriate factor must be applied
to sample values.
10.3 Data should be rounded to £he thousandth place and all results
should be reported in mg/1 up to three significant figures.
11. Quality Control (Instrumental)
11.1 Check the instrument standardization by analyzing appropriate
quality control check standards as follow:
11.1.1 Analyze an appropriate instrument check standard (5.6.1)
containing the elements of interest at a frequency of 10%.
This check standard is used to determine instrument drift.
If agreement is not within * 5% of the expected values or
within the established control limits, whichever is lower,
the analysis is out of control. The analysis should be
terminated, the problem corrected, and the instrument
recalibrated.
Analyze the calibration blank (6.5.1) at a frequency of
10%. The result should be within the established control
limits of 2 standard deviations of the mean value. If not,
repeat the analysis two more times and average the three
results. If the average is not within the control limit,
terminate the analysis, correct the problem and recalibrate
the instrument.
11.1.2 To verify interelement and background correction factors
analyze the interference check sample (6.6.2) at the begin-
ning, end, and at periodic intervals throughout the sample
run. Results should fall within the established control
28
59
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limits of 1.5 times the standard deviation of the mean
value. If not, terminate the analysis, correct the problem
and recalibrate the instrument.
11.1.3 A quality control sample (6.6.3) obtained from an outside
source must first be used for the initial verification of
the calibration standards. A fresh dilution of this sample
shall be analyzed every week thereafter to monitor their
stability, if the results are not within + 5% of the true
value listed for the control sample, prepare a new calibra-
tion standard and recalibrate the instrument. If this does
not correct the problem, prepare a new stock standard and a
new calibration standard and repeat the calibration.
12. Precision and Accuracy
12.1 In an EPA round robin phase 1 study, seven laboratories applied the
ICP technique to acid-distilled water matrices that had been dosed
with various metal concentrates. Table 4 lists the true value, the
mean reported value and the mean % relative standard deviation.
13. References
13.1 Winge, R.K., V.J. Peterson, and V.A. Fassel, "Inductively Coupled
Plasma-Atomic Emission Spectroscopy: Prominent Lines, EPA-600/4-
79-017.
13.2 Winefordner, J.D., "Trace Analysis: Spectroscopic Methods for
Elements," Chemical Analysis. Vol. 46, pp. 41-42.
13.3 Handbook for Analytical Quality Control in Water and Wastewater
Laboratories, EPA-600/4-79-019.
29
60
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Table 4. ICP Precision and Accuracy Data
Sample
Sample 12
Sample 03
CJ
o
Element
Be
Mn
V
As
Cr
Cu
Fe
Al
Cd
Co
N1
Pb
Zn
Se
True
Value
ng/i
750
350
750
200
150
250
600
700
50
500
250
250
200
40
Mean
Reported
Value
ng/l
733
345
749
208
149
235
594
696
48
512
245
236
201
32
Mean
Percent
RSD
6.2
2.7
1.8
7.5
3.8
5.1
3.0
5.6
12
10
5.8
16
5.6
21.9
True
Value
M9/1
20
15
70
22
10
11
20
60
2.5
20
30
24
16
6
Mean
Reported
Value
ug/1
20
15
69
19
10
11
19
62
2.9
20
28
30
19
8.5
Mean
Percent
RSD
9.8
6.7
2.9
23
18
40
15
33
16
4.1
11
32
45
42
True
Value
ug/1
180
100
170
60
50
70
180
160
14
120
60
80
80
10
Mean
Reported
Value
ug/1
176
99
169
63
50
67
178
161
13
108
55
80
82
8.5
Mean
Percent
RSO
5.2
3.3
1.1
17
3.3
7.9
6.0
13
16
21
14
14
9.4
8.3
Not all elements were analyzed by all laboratories.
-------
13.4 Garbarino, J.R. and Taylor, H.E., "An Inductively-Coupled Plasma
Atomic Emission Spectrometric Method for Routine Water Quality
Testing," Applied Spectroscopy 33, No. 3(1979).
13.5 "Methods for Chemical Analysis of Water and Wastes,"
EPA-600/4-79-020.
13.6 Annual Book of ASTM Standards, Part 31.
31
62
-------
APPENDIX B
DATATRIEVE FILE STRUCTURE FOR THE 4901A42
SAMPLE STATUS DATA BASE FILE
63
-------
: REPORT 12
STATUS REPORT OF MRI PROJECT 4901A-42 METALS ANALYSES
13-MAY-B2
PAGE 1
ARRIVAL PREP
SAMPLE DATE DATE
1012
1022
1032
1042
1052
1025
1017
1027
1062
1072
1032
1067
1077
1087
1037
1047
05-03-82
05-03-82
05-03-82
05-03-32
05-03-82
05-03-82
05-03-32
05-03-82
05-03-82
05-03-32
05-03-82
05-03-82
05-03-82
05-03-82
05-03-32
05-03-82
DIGEST ANALYSIS REPORT
CODE DATE DATE
COMMENTS
DTK
-------
DTK SHOW TASK425
DOMAIN TASK42
USING
FASK42-FILE ON DL1ICl»543TASK42.IDX51»
DTP:
DTK. SHOW TASM2-FILE5
RECORD TA3K42-FILE
USING
01 TAS!\42.
03 SAMPLE PIC X<6) .
03 ARRIVAL-DATE PIC X(S).
03 PREP-DATE PIC X(S) .
03 DIGEST-CODE PIC X<4) .
03 ANALYSIS-DATE PIC X(8),
03 REPORT-DATE PIC X,
03 COMMENTS PIC X(30).
A
7
DTF:
BT: SHOW REPORT--?2 ?
PROCEDURE REPORT42
REPORT TASN42 SORTED BY DESC ARRIVAL-DATE
SET F:EPORT-NAME='STATUS REPORT OF MRI PROJECT 4901A-42 METALS ANALYSES-
SET CQLUMNS-PAGE=80
P'^INT SAMPLE*ARRIVAL-DATEiPREP-DATEFDIGEST-CODE*ANALYSl3-DATEiREPORT-DATEiCOMMEN
T3-
REPORT EMD;
END-PROCEDURE
DTR
65
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