Reference materials are essential tools for ensuring the accuracy and comparability of measurement results. A certified reference material (CRM) is accompanied by a certificate that provides the property value, its associated uncertainty, and a statement of metrological traceability.

CRMs are produced by national metrology institutes such as NIST, the European Commission’s Joint Research Centre (IRMM), and accredited reference material producers. The production process involves material preparation, homogeneity testing, stability assessment, characterization by one or more reference methods, and value assignment with uncertainty estimation.

Homogeneity testing ensures that the property value is consistent within and between units of the CRM. Between-unit homogeneity is assessed by analyzing a representative sample of units using a method with sufficient precision. Within-unit homogeneity considers potential segregation or stratification. Stability testing includes short-term stability under transport conditions and long-term stability under storage conditions, using isochronous or classical study designs.

Reference materials are used for calibration of analytical instruments, validation of analytical methods, quality control of routine measurements, and assignment of values to secondary reference materials. Calibration standards establish the relationship between instrument response and analyte concentration. Internal standards correct for variations in sample preparation and instrument performance.

Matrix-matched reference materials closely resemble the composition of test samples and account for matrix effects in complex matrices such as food, soil, blood, or pharmaceuticals. Pure substance reference materials are high-purity compounds used for primary calibration. Gas standards are certified mixtures for atmospheric monitoring and emissions testing.

Proper use of reference materials requires following the certificate instructions, using within the expiration period, and applying the uncertainty stated on the certificate. The measurement uncertainty of the CRM propagates through the uncertainty budget of the laboratory’s measurements.