Where should one refer to for federally approved sample holding times and preservation techniques?

The reference to federally approved sample holding times and preservation techniques is found in the Code of Federal Regulations, specifically in 40 CFR (Code of Federal Regulations) Part 136, 141, and 143. These sections provide the necessary guidelines and standards set by the Environmental Protection Agency (EPA) for water quality testing, including requirements for sample handling and storage to ensure accurate analysis results.

40 CFR 136 outlines the guidelines for the methods for the detection and measurement of pollutants. Meanwhile, Parts 141 and 143 specifically cover the regulations regarding drinking water standards and the control of contaminants, including specifications for sampling, preservation, and holding times necessary for compliance with the Safe Drinking Water Act. This information is crucial for laboratory analysts to ensure that water quality samples remain viable and provide accurate data for monitoring drinking water safety.

Other resources, such as EPA Guidelines or state regulations, may provide additional instructions, but the most authoritative and comprehensive source for nationally recognized requirements is found within the relevant sections of the Code of Federal Regulations.