Standard: 2003 NELAC
Section: 18.104.22.168.2.1 (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?
TNI FINAL RESPONSE:
(Quality Systems Expert Committee / NELAP Board, 10-11-09)
Surrogates are intended to provide a measure of recovery for every sample matrix (D.22.214.171.124 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.