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Standard Interpretation

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


The section in question states:
d) All initial instrument calibrations must be verified with a standard obtained from a second manufacturer or lot if the lot can be demonstrated from the manufacturer as prepared independently from other lots. Traceability shall be to a national standard, when commercially available. Our question is, does the requirement for second source standard include calibration curves for surrogate compounds?


(Quality Systems Expert Committee / NELAP Board, 10-11-09)

Surrogates are intended to provide a measure of recovery for every sample matrix (D. a). A second source check is designed to assure that the analytes of concern are being correctly identified and quantified. Since surrogates are not analytes of concern, and may be held at a constant level in a calibration curve, they are not required to be verified by a second source.