1.1These test methods 2^, 3^, 4 cover the atomic absorption determination of nickel in water and wastewaters. Three test methods are given as follows:

	Concentration Range	Sections
Test Method A-Atomic Absorption, Direct	0.1 to 10 mg/L	7 - 16
Test Method B-Atomic Absorption, Chelation-Extraction	10 to 1000 μg/L	17 - 26
Test Method C-Atomic Absorption, Graphite Furnace	5 to 100 μg/L	27 - 36

1.2Test Methods A, B, and C have been used successfully with reagent grade water and natural waters. Evaluation of Test Method C was also made in condensate from a medium Btu coal gasification process. It is the user's responsibility to ensure the validity of these test methods for other matrices.

1.3The values stated in SI units are to be regarded as standard. The values given in parentheses are mathematical conversion to inch-pound units that are provided for information only and are not considered standard.

1.4This 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. For specific hazards statements, see Note 5, 11.8.1, 21.11, 23.7, and 23.10.

1.5Two former colorimetric test methods were discontinued. Refer to Appendix X1 for historical information.