WATER QUALITY: Analytical Methods: AAS Methods for Trace Metals and Method for Oxygen Demand of Bottom Materials



                                        December 12, 1973

QUALITY OF WATER BRANCH TECHINICAL MEMORANDUM NO. 74.06

Subject: WATER QUALITY: Analytical Methods: AAS Methods for 
         Trace Metals and Method for Oxygen Demand of Bottom 
         Materials

Enclosed is a copy of each of eight revised or new methods 
for water analyses. They include:

1. Cadmium (1135-73), AAS method--direct
2. Cadmium (1136-73), AAS method--chelation/extraction
3. Cobalt (1239-73), AAS method--direct
4. Cobalt (1240-73), AAS method--chelation/extraction
5. Lead (1399-73), AAS--direct
6. Lead (1400-73), AAS-chelation/extraction
7. Nickel (1499-73), AAS--direct
8. Nickel (1500-73), AAS--chelation/extraction

Encloscd also is a new method (5560-73) for determining the 
oxygen demand (COD, dichromate) of bottom materials.

These new or revised methods are being distributed for the 
following reasons:

1. Cadmium (1135-73)--revises the method in TWRI Bk 5 Ch Al 
(p. 62) to the extent of pointing out certain constituents 
that have been shown not to interfere in the determination 
(Para. 3.1) and to point out the interference effect of 
calcium (Para. 3.2).

2. Cadmium (1136-73~--revises the method in TWRI Bk 5 Ch Al 
(p. 63) to point out the interference of iron on the 
determination (Para's 2.2 and 3.1). This interference is 
rarely important when analyzing water samples, but may be a 
factor when analyzing bottom-material samples.

3. Cobalt (1239-73)--this is a new method for the direct AAS 
determination of cobalt without chelation and extraction. It 
must be used to analyze sample which contain iron at 
conccntrations exceeding 25 mg/l, concelltrations which 
seriously interfere in the AAS chelation/extraction method. 
Interferences and non-interferences are describcd in Para.'s 
3.1 and 3.2.

4. Cobalt (1240-73)--this is a revision of the AAS-chelation/ 
extraction method in TWRI Bk 5 Ch Al (p. 80), and points out 
(Para.'s 2.2 and 3.1) that the method cannot be used when 
iron concentrations exceed 25 mg/l.

5. Lead (1399-73)--this is a new direct AAS method, which may 
be used to analyze samples containing iron at concentrations 
greater than 25 mg/l, concentrations that interfere in the 
AAS chelation/extraction method. Substances that do not 
interfere are discussed in Para. 3.1.

6. Lead (1400-73)--this is a revision of the AAS chelation/ 
extraction method in TWRI Bk 5 Ch Al (p. 105), and points out 
(Para.'s 2.2 and 3.1) that the method cannot be used to 
analyze samples which contain iron at concentrations 
exceeding 25 mg/l.

7. Nickel (1499-73)--this is a new direct M S method, which 
must be used to analyze samples containing iron at 
concentrations greater than 25 mg/l, concentrations that 
interfere in the AAS chelation/extraction method. Substances 
that are known not to interfere are discussed in Para. 3.1.

8. Nickel (1500-73)--this is a revision of the AAS-chelation/ 
extraction method.in TWRI Bk 5 Ch Al (p. 115) and points out 
that the method cannot be used to analyze samples containing 
iron at concentrations exceeding 25 mg/l.

9. Oxygen Demand (COD, dichromate), Bottom Materials (5560-
73)--is a new method. The procedure is essentially the same 
as the method (TWRI Bk 5 Ch Al) for determining COD of water 
samples, except that it has been modified (Para's 6.1 and 
6.2) to allow for taking a weighed sample of bottom material 
instead of a volume of water for analysis. The method has not 
been extensively tested for the analysis of bottom material, 
but is widely accepted for water analysis. It is also 
essentially the same as the EPA recommended method for 
determining the COD of bottom sediments ["Chemistry 
Laboratory Manual, Bottom Sediments," compiled (December 
1969) by the Great Lakes Region Committee on Analytical 
Methods, Frederic D. Fuller, Chairman and Editor].

The use of these methods becomes effective upon receipt. They 
supercede previously distributed methods.



                       J. K. Culbertson
                       Acting Chief, Quality of Water Branch

Enclosure

WRD Distribution: A, FO-LS, PO