4.1 The test for cadmium is necessary because it is a toxicant and because there is a limit specified for cadmium in potable water in the National Interim Primary Drinking Water Regulations. This test serves to determine whether the cadmium content of potable water is above or below the acceptable limit.

1.1 These test methods cover the determination of dissolved and total recoverable cadmium in water and wastewater by atomic-absorption spectrophotometry and differential pulse anodic stripping voltammetry.² Four test methods are included as follows:

Concentration
Range

Sections

Test Method A—Atomic Absorption,
Direct

0.05 to 2.0 mg/L

 7 to 15

Test Method B—Atomic Absorption,
Chelation-Extraction

5 to 200 μg/L

16 to 24

Test Method C—Differential Pulse
Anodic Stripping Voltammetry

1 to 100 μg/L

25 to 34

Test Method D—Atomic Absorption,
Graphite Furnace

2 to 10 μg/L

35 to 43

1.2 Test Method B can be used to determine cadmium in brines. It is the user's responsibility to ensure the validity of these test methods for waters of untested matrices.

1.3 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system are mathematical conversions and may not be exact equivalents; therefore, each system shall be used independently of the other.

1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.