Why do some Standard Reference Materials have no expiration date?
This statement in quotes below states the NIST Policy on those SRM Certificates of Analysis that do not have a stated date of expiration. “The certificates for NIST Standard Reference Materials (SRMs) traditionally have been in conformance with guidance criteria issued by the ISO Advisory Committee on Reference Materials. The criteria for the contents of certified reference material (CRM) certificates are contained in ISO Guide 31. Until recently, Guide 31 omitted the rationale and procedures for stating a certificates period of validity and placed such responsibility on the CRM producer. However, in response to ISO 9001 and 9002 requirements, ISO Guide 31 has now been revised to indicate that a period of validity should be stated in every CRM certificate. As a matter of policy, NIST is complying with these revised guidelines by assigning specific Expiration of Certification periods to new and renewal SRMs, but because of the number of SRMs affected, it will be some years before all ce
