Comparison of exact matching and calibration curve quantification methods for glucose in human serum GC-IDMS analysis and their application for the development of certified reference materials

The establishment of a precise and accurate method for the determination of the analyte is the first step in the development of certified reference materials (CRMs), which play a key role in metrological traceability. To assist the production of a glucose CRM in human serum for clinical chemistry routine tests, we developed a gas chromatography-isotope dilution mass spectrometry method using trimethylsilylation and performed two calibration techniques: exact matching approach and calibration curve. Performance of the method and calibration techniques were evaluated for their suitability for the characterization of a CRM candidate carrying out studies to assign the property value and to assure homogeneity as well as short- and long-term stability. Both calibration approaches were equivalent in terms of accuracy and precision and presented bias lower than 1.0 % with relative standard deviations lower than 3.0 %. Relative measurement uncertainties obtained with the exact matching approach calibration method were between 1.0 % and 2.5 % and were lower than the ones obtained with calibration curve method. This finding justifies the use of the time-consuming exact matching method for the assignment of the property value, while the calibration curve procedure suits the other certification studies.