ASTM D5172-91(2015)

5.1 The exact analytical test methods and procedures used in any laboratory may be unique and affect the usability of their analytical results. A general reference to a book of standard analytical test methods, guides, and practices published by a reputable organization such as ASTM is not sufficient to guarantee acceptable results. As a point of clarification, a procedure may be part of a test method or it may be any other routine process the laboratory personnel must follow, for example, glassware cleaning, quality control, routine maintenance, or data reporting procedures.

5.2 A significant part of the variability of results generated by different laboratories analyzing the same samples and citing the same general reference is due to differences in the way the analytical test methods and procedures are actually performed in each laboratory. These differences are often caused by the slight changes or adjustments allowed by the general reference, but that can affect the final results.

5.3 The manual of SOPs is an important component of any laboratory's quality assurance program. As with all quality assurance activities, the importance of this manual lies in its impact on maintaining uniformity of test method performance and the utility of data generated by the laboratory.

5.4 Each laboratory should develop and maintain a loose-leaf manual containing an exact step-by-step description of how every test method and procedure is performed in the laboratory to help guarantee uniform performance among different analysts using them.

5.5 With adequate documentation of a laboratory's complete and exact analytical test methods and procedures, a laboratory will have improved confidence in its ability to reproduce analytical conditions exactly and thereby general reproducible results. This manual of SOPs is the cornerstone of a laboratory's creditability.

1.1 This guide addresses the need for each laboratory engaged in the analysis of water and wastewater to develop and maintain an up-to-date written manual that clearly and completely delineates the exact steps followed in performing every test method and procedure used in the laboratory, that is, a manual of their standard operating procedures (SOPs).

1.2 This guide details the practices necessary to provide clear in-house SOPs and a mechanism whereby the normal development and evolution of an analytical test method or procedure can be controlled and properly evaluated for incorporation into the SOP used in that laboratory.

1.3 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. Specific precautionary statements are given in the note.