The analysis of many types of water for metals using flame atomic absorption spectrophotometry, inductively coupled plasma emission spectrophotometry, direct current plasma emission spectrophotometry, or graphite furnace atomic absorption spectrophotometry necessitates the use of a digestion practice in order to ensure the proper statistical recovery of the metals from the sample matrix. The use of closed vessel microwave techniques will speed the complete recovery of metals from the water matrices and eliminate sample contamination from external sources.

1.1 This practice covers the general considerations for quantitative sample digestion for total metals in water using closed vessel microwave heating technique. This practice is applicable to surface, saline, domestic, and industrial wastewater.

1.2 Because of the differences among various makes and models of satisfactory instruments, no detailed operating instructions can be provided. Instead, the analyst should follow the instructions provided by the manufacturer of the particular instrument.

1.3 This practice can be used with the following ASTM standards, providing the user determines precision and bias based on this digestion practice: Test Methods D 857, Test Methods D 858, Test Methods D 1068, Specification D 1192, Test Methods D 1687, Test Methods D 1688, Test Methods D 1691, Test Methods D 1886, Practices D 3370, Test Methods D 3557, Test Methods D 3559, Practice D 3919, Test Methods D 4190, Practice D 4453, and Practice D 4691.

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 Section 9.