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

Section: 4.2

Question:  Section 2.5 of the 2003 NELAC standard states "When analyzing a PT sample, a laboratory shall employ the same calibration, laboratory quality control and acceptance criteria, sequence of analytical steps, number of replicates and other procedures as uses when analyzing routine samples."  Questions 3 through 11 of the NELAC checklist contain additional details for this section of the NELAC standard.  Are these statements an official interpretation?  A laboratory analyzes the PT provider companion quality control sample with the unknown PT sample.  The laboratory includes all routine QC, such as blanks, LCS, etc, in the batch.  In addition to using the routine QC criteria, the companion QC sample is used to determine the acceptability of the batch containing the PT.  This is not a routine practice of the laboratory.  Is this considered a finding versus Section 2.5 of the NELAC standard?

TNI Response:  It is the consensus of the PT Committee that Questions 3-11 are appropriate interpretation of the requirements specified in Section 2.5 of the 2003 NELAC Standard. 2) It is the consensus of the PT Committee that the scenario described in the problem is a finding against Section 2.5 of the NELAC Standard.  The 2009 standard (V2) contains explicit language concerning the routine analysis of PT samples.  The 2016 standard (V2) removed most of the language in the 2009 standard, but Section 4.2.2 of V1M1states "PT samples shall be analyzed in accordance with the laboratory’s established standard operating procedures (SOPs) using the same quality control (QC), acceptance criteria and staff as used for the analysis of routine environmental samples."