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Standard Interpretation

Standard: 2009 TNI
Section: V2M2, Section 6.3


Looking for a clarification.

Section 6.3 says: The Primary AB shall allow the laboratory to analyze the same PT sample using different technologies and/or multiple test methods for any FoPT. If a laboratory reports more than one test method per technology per FoPT, an unacceptable score for either test method shall result in an unacceptable score for both test methods for that FoPT.

If a lab uses 2 different extraction procedures for the same analytical method (e.g. Semi-Volatile GCMS in NPW matrix using Liquid/liquid Extraction sometimes and Solid Phase extraction at other times with many of the same analytes). Would it be acceptable to run a PT sample for each technology/extraction combination as long as they stick with the "fail one/fail both" concept that is in the referenced section? It get a little muddy since the TNI standard does not really recognize preparation methods and only looks at the technology but in reality it is like 2 different test methods.
Clarification would be welcome. Thank you


(Laboratory Accreditation Body Expert Committee and NELAP AC, 10-4-14)

The interpretation of the standard is that if PTs are analyzed using multiple preparation methods while being analyzed by a single analytical technology per an FoPT, then if one PT fails, all of the groups under that technology fail, regardless of the preparation method. The PT assessment is made by analytical technology per FoPT.