EPA-905/4-77-002
ANALYTICAL METHOD, PROCEDURE AND EVALUATION RELATIVE
TO THE REFEREE METHOD SUBMITTED FOR APPROVED USE IN THE
NATIONAL POLLUTION DISCHARGE ELIMINATION SYSTEM
(NPDES)
AS SPECIFIED BY THE OCTOBER 16, 1973 FEDERAL REGISTER
THE DETERMINATION OF ANTIMONY, ARSENIC, BERYLLIUM,CADMIUM,
LEAD, SELENIUM, SILVER AND TELLURIUM IN ENVIRONMENTAL WATER
SAMPLES BY FLAMELESS ATOMIC ABSORPTION
Metals Section
U.S. Environmental Protection Agency
Region V
Central Regional Laboratory
1819 West Pershing Road
Chicago, Illinois 60609
312-353-8370
.,- street
nois ' 6060*
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TECHNICAL REPORT DATA
(Please read laUructions on the reverse before completing)
1. REPORT NO. 2.
EPA-905/4-77-002
4. TITLE AND SUBTITLE
THE DETERMINATION OF ANTIMONY, ARSENIC, BERYLLIUM,
CADMIUM, LEAD, SELENIUM, SILVER, AND TELLURIUM IN
ENVIRONMENTAL WATER SAMPLES BY FLAMELESS ATOMIC ABSORP7
7. AUTHOR(S)
METALS SECTION, CENTRAL REGIONAL LABORATORY, REGION V
U.S. ENVIRONMENTAL PROTECTION AGENCY
9. PERFORMING ORGANIZATION NAME AND ADDRESS
U.S. Environmental Protection Agency, Region V
Central Regional Laboratory
1819 W. Pershing Rd.
Chicago, IL 60609
12. SPONSORING AGENCY NAME AND ADDRESS
3. RECIPIENT'S ACCESSIOWNO.
5. REPORT DATE -
January 5, 1977
6. PERFORMING ORGANIZATION CODE
ION
8. PERFORMING ORGANIZATION REPORT NC
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
NA
13.TYPE OF REPORT AND PERIOD COVERED
Final
14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
16. ABSTRACT
Analytical procedures for measuring concentrations of the title metals in
environmental samples are described. Results obtained using the flameless atomic
absorption procedures are compared to data obtained using the referee method as
defined in the October 16, 1973, Federal Register. It is concluded that the
flameless atomic absorption methods are equivalent or superior to the referee
procedure for these metals.
17. KEY WORDS AND DOCUMENT ANALYSIS
a. DESCRIPTORS
Antimony, Arsenic, Beryllium, Cadmium,
Lead (ner.al), belenluir, Silver, Tellurium
18. DISTRIBUTION STATEMENT
UNLIMITED
b. IDENTIFIERS/OPEN ENDED TERMS
Flameless Atomic
Absorption
Analytical Methods
19. SECURITY CLASS (This Report)
20. SECURITY CLASS (This page)
c. COSATI Field/Group
07B
21. NO. OP PAGES _
16
22. PRICE
EPA Form 2220-1 (9-73)
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1. SCOPE AND APPLICATION
This method is applicable to all surface and drinking waters, domestic
& and industrial wastes at all concentration levels normally found, with
appropriate dilutions, for the elements listed in Table I. Appropriate
linear ranges based on a 50 yl sample volume are also presented in Table I.
2. SUMMARY OF METHOD
41 Sample aliquots are introduced into a graphite furnace of the mini-Massman
design. Separate drying, charring and atomizing program steps are incorporated
in a controller that establishes appropriate resistence heating of the graphite
tube. This unit is used with a double beam Perkin-Elmer* atomic absorption
^ spectrophotometer equipped with a deuterium background corrector. The de-
crease in energy of the hollow cathode or ele'ctrodeless discharge lamp (EDL)
is detected on a strip chart recorder as a transient peak and this peak height
* is proportional to concentration within the ranges given in Table I.
3. SAMPLE HANDLING AND PRESERVATION
Samples are collected in high density polyethylene containers and are
preserved with concentrated nitric acid at a concentration of 0.5%. Reagent
blanks are provided with each set of samples so that net metal concentrations
can be reported.
4. INTERFERENCES
4.1 Broad Band Absorption - This interference occurs when another component
0 of a sample matrix is volatilized simultaneously with the element of interest
and results in an output that masks, or that may be mistaken for, the signal
- from that element. This false response may be caused by molecular absorption
0 and/or light scatter by interfering constituents. High boiling mineral
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acids, i.e. sulfuric, phosphoric, cannot be used with the HGA-2000 Perkin-
Elmer furnace, since these acids have a tendency to recondense in the
cooler regions of the graphite tube during the charring cycle and are
revolitilized into the light beam during the atomization step producing
an interfering signal. In order to eliminate or minimize the non-specific
absorption the need for simultaneous background correction as a function
of sample matrix must be carefully evaluated by visual monitoring of the
signal on the energy meter. In this application, simultaneous background
correction is used for the determination of antimony, arsenic, cadmium,
lead, selenium, and tellurium, and is not required for beryllium and silver.
4.2 Chemical - This interference originates from compound formation by
matrix components with elements of interest at the atomization temperature,
thus reducing the free atom population of the element determined. As a
consequence, sensitivities are generally not invariant as is apparent
from representative standard addition curves in Figures 1 through 6.
Therefore, the following measures are taken in order to reduce this potential
interference.
4.2.1 Acidities in samples and standards must be controlled as to acid
type and concentration.
4.2.2 Sample volumes analyzed must be identical.
4.2.3 The standard additions approach must be used for the determination
of element concentrations.
4.3 Contamination - The inherent absolute sensitivity of the furnace
technique imposes severe restrictions on the cleanliness of laboratory-
ware and the purity of reagents. Great care must be exercised in these
areas to insure valid analytical results.
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5. APPARATUS
5.1 Atomic Absorption Spectrophotometer - Any double beam Perkin-Elmer
instrument, modified with the appropriate optical beam retrofit kit, and
equipped for simultaneous deuterium arc background correction, is satisfactory.
The Perkin-Elmer HGA-2000 or HGA-2100 graphite furnaces are acceptable. Perkin-
Elmer hollow cathodes or EDLs are used as the emission line source.
5.2 Recorder - Any commercial strip chart recorder having a full-scale
response of 0.5 sec. is satisfactory.
5.3 Pipets - Eppendorf type pipets with polypropylene tips are suitable
for sample injection. The absence of metal contaminants in the tips should
be verified experimentally prior to use.
5.4 Glassware - All glassware in this procedure must be cleaned with 8N
nitric acid and rinsed with distilled, deionized water.
5.5 Gases - Prepurified grade nitrogen or argon are satisfactory carrier
gases.
6. REAGENTS
6.1 Water - Distilled, deionized water was found to be acceptable. The
supply should, however, be analyzed for metals of interest prior to use.
6.2 Acid - Ultrex grade (Baker Chem. Co.) or distilled nitric acid have
been found to be suitable for sample and standard preservations. Reagent
grade nitric acid may be used, if the absence of metals of interest is verified
experimentally.
6.3 Standards - Stock commercial 1000 yg/ml metal solution standards in
inert plastic containers are acceptable for preparing working standards by
serial dilutions. All blanks and working standards are preserved with 0.5%
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concentrated nitric acid. All standards at concentrations less than 1 yg/ml
are prepared fresh daily.
7. OPERATION
7.1 Instrumental - The analyst should follow the manufacturer's instructions
on installation, alignment and optimization of the instruments. Suggested instru-
mental settings are presented in Table II. These are, however, not invariant,
and the Perkin-Elmer furnace manual (1) should be consulted for equipment mainten-
ance, analytical line selection, charring and atomization temperatures, and
expected absolute sensitivities. Perkin-Elmer hollow cathode lamps are used for
the determination of beryllium, lead and silver, and the EDLs, due to their
higher energy outputs and thus better signal to noise ratios, are recommended
for the antimony, arsenic, cadmium, selenium and tellurium analyses. Scale
expansion, consistent with the limitations of instrumental background noise,
and the gas interrupt feature of the furnace controller are acceptable means
of signal attenuation, and are used extensively for low level metal determinations,
7.2 Procedure
7.2.1 Prepare a reagent blank and at least 2 working standards for
the concentration range of interest and analyze these under previously
established instrumental conditions. Assess the colinearity of standards
and blank graphically and verify that the calibration curve (peak height
vs. concentration) passes through the origin.
7.2.2 Manually agitate the sample container and with an Eppendorf
pipet inject samples and standards into the furance tube. The data points
provide standard addition curves for the evaluation of element concentrations.
Keep total volume injected constant at less than 100 yl and the acidities
invariant for each analysis.
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7.2.3 Sample concentrations outside the linear range of the previously
determined calibration curve must be diluted or smaller sample volumes taken
for analysis. The determined metal content should be lower than the con-
centration of the highest working standard.
8. COMPUTATION
The method of standard additions is used for the evaluation of element con-
centrations. A sample and at least two sample spikes are analyzed. Peak heights
vs. amount of element added are plotted and the colinear graph is extrapolated
to the intersection with the concentration axis. The numerical value of this
intercept is the determined concentration. Each sample that is suspect or is
shown to have matrix variations must be analyzed individually by standard additions.
The analyses of surface waters free of gross pollution and nearly constant in
composition, i.e. Great Lake water, have shown that working curves remain linear
and invariant in slopes, and thus standard additions on each sample are not re-
quired. However, the performance of the graphite tube and other experimental
variables must be monitored by the redetermination of standard curves on approx-
imately 10% of the samples.
9. COMPARATIVE DATA
Tables III, IV and V summarize comparative data for the graphite furnace and
the appropriate NPDES approved methods on representative effluent samples. Each
set of results represents a separate outfall that had been spiked at a concen-
tration measurable by flame atomic absorption spectrophotometry for beryllium,
cadmium, lead and silver and the hydride generation method for arsenic and selenium.
This range is above the optimum concentration for the flameless atomization method,
and the reported results reflect the use of either smaller sample aliquots or
appropriate dilutions. In addition, the listed furnace data were obtained on
undigested samples, and thus demonstrate that aqueous solutions can be analyzed
with good precision and accuracy in the presence of suspended solids.
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Antimony and tellurium are included in this request, since these metals
are known to be toxic and the approved flame atomic absorption method for
antimony with a sensitivity of 0.5 mg/ml(2) exceeds the recommended level (3)
of 0.2 mg/ml in a marine environment. Tellurium is not included in the NPDES
parameter list; however, its concentration should be of interest in environ-
mental monitoring applications. Table VI documents satisfactory recoveries
for antimony, arsenic, selenium and tellurium in different effluent matrices.
Table VII summarizes experimental precision data for all metals under
study.
10. APPLICABILITY
10.1 Industrial and Municipal Outfalls - The proposed method, due to its
high sensitivity, does provide for a more complete characterization of these
outfalls. This is particularly true for those elements, i.e. Pb, Cd, that
have effluent permit limitations near the detection limit of standard flame
atomic absorption techniques. In addition, the method does allow for an inde-
pendent verification of element concentrations determined by other NPDES
approved methods. This technique is documented in the literature (4,5) for
environmental monitoring of effluents.
10.2 Surface Waters - In view of the low metal concentrations generally
found in surface waters, a sensitive, precise method is needed to determine
baseline contaminant concentrations. The flameless atomization method is
ideally suited for this purpose and will be used extensively for the assessment
of water quality in these environments. Several publications (6,7,8) discuss
this area of applicability.
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REFERENCES
1. Perkin-Elmer Corp., "Analytical Methods Using the HGA Graphite Furnace",
Perkin-Elmer Corp., Norwalk, Conn., 1973.
2. "Methods for Chemical Analysis of Water and Wastes", MDQARL, U.S. EPA,
Cincinnati, Ohio, p. 79, 1974.
3. "Water Quality Criteria 1972", National Academy of Sciences, National
Academy of Engineering, Washington, D.C., p. 242, 1972.
4. J. C. Guillaumin, "Determination of Trace Metals in Power Plant Effluents",
At. Absorption Newsletter, 1_3, 135 (1974).
5. G. C. Kunselman, E. A. Huff, "The Determination of Arsenic, Antimony, Selenium
and Tellurium in Environmental Water Samples by Flameless Atomic Absorption",
submitted to Anal. Chem. (1975).
6. W. M. Barnard, M. J. Fishman, "Evaluation of the Use of the Heated Graphite
Atomizer for the Routine Determination of Trace Metals in Water", At.
Absorption Newsletter, 12, 118 (1972).
7. Raltonelti, "Determination of Soluble Cadmium, Lead, Silver and Indium in
Rainwater and Stream Water with the Use of Flameless Atomic Absorption",
Anal. Chem., 46_, 739 (1974).
8. A. W. Struempler, "Absorption Characteristics of Silver, Lead, Cadmium, Zinc,
and Nickel on Borosilicate Glass, Polyethylene, and Polypropylene Container,
Surfaces", Anal. Chem., 45, 2251 (1973).
* The use of a company name is for identification purposes only and does not
constitute an endorsement by the U.S. EPA.
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TABLE I
Spectrophotometer Settings and Linear Ranges
Element
Ag
As
Be
Cd
Pb
Sb
Se
Te
Wavelength, nm
338.1
193.7
234.9
228.8
283.3
217.6
196.0
214.3
Bandpath, nm
0.7
0,7
0.7
0.7
0.7
0.2
0.7
0.7
Linear Range, yg/1
0.5 - 10.0
1 - 40
1 - 20
0.2 - 3.0
1 - 30
1 - 20
1 - 20
1 - 20
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TABLE II
Furnace Operating Parameters
Element
Ag
As
Be
Cd
Pb
Sb
Se
Te
Gas Flow,
ml/min
50
50
50
50
50
50
50
50
Drying Temp. , °C
(Time, sec.)
125 (60)
125 (60)
125 (60)
125 (60)
125 (60)
125 (60)
125 (60)
125 (60)
Charring Temp. , C
(Time, sec.)
850 (20)
1000 (40)
1200 (30)
400 (20)
700 (30)
1000 (40)
1000 (40)
700 (40)
Atomization Temp
°C (Time, sec.)
2500 (5)
2700 (5)
2700 (5)
2100 (3)
2700 (3)
2200 (5)
2700 (3)
2700 (5)
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TABLE III
Comparative Data for Arsenic and Selenium
Sample
No.
408
428
436
448
452
594
6000
6039
6046
6073
3314
3315
3323
£
J3324
3328
3329
Matrix Type
Metals Industry
Metals Industry
Metals Industry
Metals Industry
Metals Industry
Metals Industry
Power Plant Industry
Power Plant Industry
Power Plant Industry
Power Plant Industry
Indust. & Municipal
Wastes
Indust. & Municipal
Wastes
Indust. & Municipal
Wastes
Indust. & Municipal
Wastes
Indust. & Municipal
Wastes
Indust. & Municipal
Wastes
As, yg/1
Hydride
14
12
28
13
12
20
10
12
12
12
12
14
12
10
12
12
Furnace
16
12
24
16
13
20
14
14
14
14
10
10
11
11
10
10
Se, yg/1
Hydride
14
14
13
14
12
11
11
12
13
13
13
12
13
12
13
13
Furnace
13
14
16
14
13
13
12
11
12
15
13
15
10
11
12
11
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TABLE IV
Comparative Data for Silver and Beryllium
Sample
No.
» 404
432
44°
» 444
464
» 6026
| 6050
6057
» 6064
» 3261
3263
* 3265
3267
* 3333
3334
Matrix Type
Metals Industry
Metals Industry
Metals Industry
Metals Industry
Metals Industry
Power Plant Industry
Power Plant Industry
Power Plant Industry
Power Plant Industry
Indust. & Municipal
Wastes
Indust. & Municipal
Wastes
Indust. & Municipal
Wastes
Indust. & Municipal
Wastes
Indust. & Municipal
Wastes
Indust. & Municipal
Wastes
Ag, yg/1
Flame AA
19
21
21
21
21
21
21
20
21
21
40
29
20
21
Furnace AA
21
17
16
24
19
21
21
26
18
18
45
30
24
20
Be, yg/1
Flame AA
21
19
21
20
20
21
21
21
21
21
20
19
20
21
22
Furnace AA
19
19
20
20
20
19
19
19
18
20
18
19
19
21
20
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TABLE V
Comparative Data for Cadmium and Lead
Sample
No.
404
432
440
444
464
6026
6050
6057
6064
* 3261
3263
* 3265
- 3267
* 3333
^ 3334
"0 . ,, .
Matrix Type
Metals Industry
Metals Industry
Metals Industry
Metals Industry
Metals Industry
Power Plant Industry
Power Plant Industry
Power Plant Industry
Power Plant Industry
Indust. & Municipal
Wastes
Indust. & Municipal
Wastes
Indust. & Municipal
Wastes
Indust. & Municipal
Wastes
Indust. & Municipal
Wastes
Indust. & Municipal
Wastes
Cd, yg/ml
Flame AA
21
21
20
21
20
21
20
20
21
20
25
24
23
24
22
Furnace AA
20
21
19
22
20
22
22
22
21
21
26
26
23
22
25
Pb, yg/ml
Flame AA
100
120
no
120
105
94
94
120
120
130
130
no
130
120
110
Furnace A
105
105
135
130
100
100
100
105
110
135
120
120
120
110
95
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TABLE VII
Precision of the Flameless Atomization Method
»
^
A
Element
Ag
As
Be
Cd
Pb
Sb
Se
Te
Concentration, yg/1
21.0
2.5
10.0
19.1
1.5
27.2
8.9
105
2.5
10.0
3.0
10.0
2.5
10.0
n
10
12
16
10
10
10
10
10
15
15
8
13
15
15
S.D., vg/1
1.0
0.2
0.3
0.6
0.1
1.4
0.4
5
0.1
0.3
0.2
0.5
0.1
0.4
Rel.S.D., %
4.8
8.0
3.0
3.1
6.7
5.1
4.5
4.8
4.0
3.0
6.7
5.0
4.0
4.0
J
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