What is traceability?

We use two definitions when attempting to define traceability. The first is the NIST definition, which says that traceability is described as an uninterrupted record of documentation (“documentation traceability”) or an uninterrupted chain of measurements and associated uncertainties (“metrological traceability”). When applied here, the word “traceability” always refers to “metrological traceability.” The ISO 17025 definition of traceability is “a property of a measurement result whereby the result can be related to a reference through a documented unbroken chain of calibrations, each contributing to the measurement uncertainty.” The specialty gas specification at PurityPlus® can be traced back to NIST’s Standard Reference Materials where similar gas standards exist. If certain SRM’s are nonexistent, equally comparable standards are used, directly sourced from a national government agency outside of the United States, or by having a gas standard reviewed and certified by NIST or another designated entity.