Standard: 2003 NELAC
Section: Appendix C.3.1 (b)
Link to relevant standard
It is felt that the LOD validation procedure in the 2003 NELAC Standard is ambiguous and can result in two different interpretations. By using the relevant standards (C.3.1.b, D.1.2.1.a) as well as definitions in the glossary especially for terms such as a quality system matrix, you can construe two different procedures.
One interpretation is that the LOD must be determined only in the matrix of the sample. In other words, if a lab is analyzing wastewater effluent samples, the LOD must be validated only in a wastewater effluent matrix. Not only is this not practical but not possible for many analytes.
This is a challenge to the practical and second interpretation which allows for the LOD to be validated in a reagent water matrix.
As someone who is engaged in quality assurance work, whenever an alternative interpretation is brought to me, I must evaluate objectively all viewpoints and I feel there is merit to the alternative argument. With respect to the two choices, we like to hear from you as to which choice is right and as stated we like to alert you that they may be an ambiguity issue with the LOD procedure.
TNI FINAL RESPONSE:
(Quality Systems Committee / NELAP Board, 12-19-08)
Reagent water (however named) is accepted as the quality systems matrix used for the determination of LOD for wastewater analyses.