Objectives: Commutability of reference materials is essential for ensuring the traceability of patient measurement results and the technical basis for the use of reference materials. Commutability is only relevant for matrixed reference material; it is a prerequisite for the accuracy and authenticity of calibration methods. In this study, we evaluated the commutability of reference materials for homocysteine.
Methods: Five conventional measurement methods were applied to simultaneously measure 30 serum samples and seven homocysteine reference materials from the National Institute of Standards and Technology and the National Institute of Metrology. Liquid chromatography tandem-mass spectrometry was used as a reference method. Two methods were used to evaluate the commutability of the seven reference materials according to the Clinical and Laboratory Standards Institute EP30-A and the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) commutability assessment document.
Results: Among 35 combinations of the five conventional methods and seven reference materials, after evaluation in accordance with the EP30-A, the seven reference materials passed the commutability assessment, and 34 combinations were commutable. According to the IFCC, the commutability evaluation of 28 combinations was conclusive (commutable or non-commutable), while results for the remaining seven combinations could not be determined.
Conclusions: The homocysteine reference materials showed good commutability. The sensitivity of the measurement procedure, measurement deviation and uncertainty, and differences in the "measurand" selected by different methods may affect the evaluation results. Additionally, different judgment standards for different methods may explain the observed variations in evaluation results.
Keywords: EP30-A; International Federation of Clinical Chemistry and Laboratory Medicine; commutability; homocysteine; measurand.
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