The role of the CCQM OAWG in providing SI traceable calibrators for organic chemical measurements.

ABSTRACT

Metrological traceability for organic chemical measurements is a documented unbroken chain of calibrations with stated uncertainties that ideally link the measurement result for a sample to a primary calibrator in appropriate SI units (e.g., mass fraction). A comprehensive chemical purity determination of the organic calibrator is required to ensure a true assessment of this result. We explore the evolution of chemical purity capabilities across metrology institute members of the Consultative Committee for Amount of Substance Metrology in Chemistry and Biology's Organic Analysis Working Group (OAWG). The OAWG work program has promoted the development of robust measurement capabilities, using indirect "mass balance" determinations via rigorous assessment of impurities and direct determination using quantitative nuclear magnetic resonance spectroscopy methods. A combination of mass balance and qNMR has been shown to provide a best practice approach. Awareness of the importance of the traceability of organic calibrators continues to grow across stakeholder groups, particularly in key areas such as clinical chemistry where activities related to the Joint Committee for Traceability in Laboratory Medicine have raised the profile of traceable calibrators.