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Standard Interpretation

Standard: 2003 NELAC
Section: (d)
Link to relevant standard


My question concerns the definition of a second source standard. What input variables (analyte lot, solvent lot, balance, operator, etc) must change in order for a second lot of standard to be considered to be prepared independently? Thanks for your help.


(Quality Systems Expert Committee/NELAP Board, 2-19-09) d states that a standard obtained from a second lot may be used if the lot can be demonstrated from the manufacturer as prepared independently from other lots. In our mind, this is analogous to a preparation batch being prepared with the same process, personnel and reagents during a set timeframe. Assuming the manufacturer prepares a specific quantity of standard and declares that quantity a “lot”, another lot prepared at another time would be independent of the first. The laboratory would be expected to contact the manufacturer to verify that one lot is not the same as another.