Significance and Use
4.1 Copper is found in naturally occurring minerals principally as a sulfide, oxide, or carbonate. It makes up approximately 0.01 % of the earth's crust and is obtained commercially from such ores as chalcopyrite (CuFeS2). Copper is also found in biological complexes such as hemocyanin.
4.2 Copper enters water supplies through the natural process of dissolution of minerals, through industrial effluents, through its use, as copper sulfate, to control biological growth in some reservoirs and distribution systems, and through corrosion of copper alloy water pipes. Industries whose wastewaters may contain significant concentrations of copper include mining, ammunition production, and most metal plating and finishing operations. It may occur in simple ionic form or in one of many complexes with such groups as cyanide, chloride, ammonia, or organic ligands.
4.3 Although its salts, particularly copper sulfate, inhibit biological growth such as some algae and bacteria, copper is considered essential to human nutrition and is not considered a toxic chemical at concentrations normally found in water supplies.
4.4 ICP-MS or ICP-AES may also be appropriate but at a higher instrument cost. See Test Methods D5673 and D1976.
Scope
1.1 These test methods cover the determination of copper in water by atomic absorption spectrophotometry. Section 34 on Quality Control pertains to these test methods. Three test methods are included as follows:
| Test Method | Concentration |  Sections |
| A—Atomic Absorption, | 0.05 to 5 mg/L |  7 – 15 |
| B—Atomic Absorption, | 50 to 500 μg/L | 16 – 24 |
| C—Atomic Absorption, | 5 to 100 μg/L | 25 – 33 |
1.2 Either dissolved or total recoverable copper may be determined. Determination of dissolved copper requires filtration through a 0.45-μm (11.10) membrane filter at the time of collection. In-line membrane filtration is preferable.
1.3 The 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.
1.4 Three former photometric test methods were discontinued. Refer to Appendix X1 for historical information.
1.5 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. For specific hazard statements, see 11.3, 11.9.1, 20.10, and 22.11.
1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
