ASTM D7980 - 15

1.1 This guide applies to ultrapure water that is thought to contain low ppt (parts-per-trillion, weight/weight) levels of anionic contaminants (for example, bromide, chloride, fluoride, nitrate, nitrite, phosphate, and sulfate). To minimize carry-over problems between analyses, it is best to limit the concentration of any one contaminant to approximately 200 ppt (although this limit is only an approximation and may vary, depending on the user’s application).

1.2 This guide is intended to help analysts avoid contamination of ultrapure-water samples, since contamination control is the primary challenge when quantifying ppt-level anions in grab samples.

1.3 This guide does not include recommendations for collecting samples from the water source.

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.