ASTM D6568-00(2018)

4.1 This guide establishes basic requirements which should be met by water and environmental laboratories that generate and report test chemical analyses which the laboratory client desires to be traceable to SI units (Note 1) or certified reference materials traceable to SI units. Traceability of chemical analyses is important because it provides a uniform basis for the comparison of results from different measurement systems and because it relates those results to our current knowledge of physical laws (Note 2).

4.2 Many waters-related laboratories comply with ISO Guide 17025 and participate in Proficiency Testing Programs. Laboratories that are connected to the same accreditation bodies and Proficiency Test providers can be expected to report statistically similar results on the same sample. However, some test methods and some certified reference materials are not supported with data traceable to SI units. Therefore, fully compliant laboratories that are not connected to the same providers may report statistically different chemical analysis results if they used the same nontraceable test method on the same sample. This problem could be minimized if they used test methods, measurement devices, and certified reference materials that are traceable to SI units, where available.

4.3 Although some standard test methods and certified reference materials provide evidence of traceability to SI units, many others do not. Therefore, not all laboratories can be expected to universally meet all requests for traceable analyses until the traceability of more test methods and certified reference materials is recognized through appropriate documentation.

4.4 The primary significance of this guide is that it establishes a consensus that, in order for a laboratory to generate traceable measurements, it must (4.5 It is expected that this guide will be used by Committee D19 in setting policies for the technical content of its standards that are designated to be usable to generate traceable chemical analyses.

1.1 This guide sets a protocol for generating and reporting chemical analyses that are traceable to SI units or to certified reference materials in laboratories that serve the water and environmental industry.

1.2 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.3 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.