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Combined Interpretations of the 2003, 2009, and 2016 Standards that apply to Volume 1 of the 2016 TNI Standard


MODULE 2: QUALITY SYSTEM GENERAL REQUIREMENTS
Section: 5.4.6

Question:  Please explain what types of procedures for estimating uncertainty of measurements. I am not sure which area you mean.

TNI Response:  Section 5.4.6 has created some confusion. Please note that as a laboratory it is impossible for you to calculate "Total Uncertainty" unless you are given all of the additional pieces from external sources to the lab itself. This section requires a laboratory to have a procedure in place, so that if requested by a client it could be determined. The key language is "Quality control measurement data may be used to determine analytical uncertainty."  For example, a comparison of CCV data and LCS data could lead to an estimate of the uncertainty caused by the preparation process. A similar comparison between LCS data and MS data could lead to an estimate of the uncertainty introduced by the sample matrix. Organizations such as A2LA and the Department of the Navy have developed tools to aid a laboratory in accomplishing this task. This section was rewritten in the 2009 (and 2016) standards to state "Quality control measurement data may be used to determine analytical uncertainty."  This definition was also added: "Analytical Uncertainty: A subset of Measurement Uncertainty that includes all laboratory activities performed as part of the analysis." The Committee doesn't intend to reply with a how-to document. Note that radiological requirements are well defined and are addressed in Module 6, and may also be addressed by WET methods