Achieving metrological traceability in chemical and bioanalytical measurement

Having confidence in the comparability of measurement results is central to international trade, accurate diagnosis and effective treatment of medical conditions, and successful delivery of multinational technical projects. The concept of metrological traceability underpins comparability of measurement results and is a key component of two important laboratory quality standards, ISO/IEC 17025 and ISO 15189. These are widely used accreditation standards against which the competence of testing and clinical laboratories, respectively, are assessed. This tutorial article describes the role and importance of metrological traceability in achieving comparable measurement results, compares the traceability requirements of ISO/IEC 17025 and ISO 15189, and gives practising analysts a scheme for identifying and addressing the important factors in their measurement procedures which influence traceability in order to meet these requirements. It introduces the reader to some important metrological concepts, using the International Vocabulary of Metrology (VIM) as a reference, and describes the international measurement infrastructure. The article focuses on chemical and biological measurements, but the basic concepts are relevant to all analytical measurements.