Description
PRIMARY CERTIFIED REFERENCE MATERIALS (CRMs)
Data is established by a method specific inter-laboratory study in full compliance with ISO Guide 34 in accordance with accreditation under UKAS. These materials are intended to be used at least once a year for instrument and/or method verification in accordance with ASTM D92 and ASTM D93, Procedure A.
SECONDARY WORKING STANDARDS (SWSs)
These are standards that have been manufactured and certified according to ISO 17025 and ISO Guide 34. These standards have been characterised in accordance with ASTM D92 or ASTM D93 and are designed to be used on a frequent basis in order to verify test equipment functionality as specified in ASTM D92 or ASTM D93, Procedure A. This is in addition to the use of primary CRM for the annual verification of an instrument.
