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



Katrice Lippa, David L. Duewer, Michael Nelson, Stephen Davies, Lindsey Mackay


Metrological traceability for organic measurements is a documented unbroken chain of calibrations with stated uncertainties that link the chemical result for a sample and a measurement procedure 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 mass fraction. We explore the evolution of chemical purity capabilities across metrology institutes and the OAWG comparisons conducted to demonstrate these capabilities. The OAWG work program has led to the evolution of capabilities typically involving rigorous assessment of impurities within high purity calibrators as part of "mass balance" purity determinations. The use of quantitative nuclear magnetic resonance spectroscopy has evolved and is now regularly employed as a direct ratio method. A combination of mass balance and qNMR has been shown to provide a best practice approach. The 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.
Accreditation and Quality Assurance


metrological traceability, calibration, SI, chemical purity, qNMR, mass balance, impurities


Lippa, K. , Duewer, D. , Nelson, M. , Davies, S. and Mackay, L. (2019), The role of the CCQM OAWG in providing SI traceable calibrators for organic chemical measurements, Accreditation and Quality Assurance, [online], (Accessed March 1, 2024)
Created October 7, 2019, Updated July 25, 2023