ISO 33405:2024— Reference Materials
A reference material is a material or substance whose property values are sufficiently homogenous, stable, and well established to be used for calibration of an apparatus, the assessment of a measurement method, or for assigning values to materials. From calibration of measurement systems to validation of methods, reference materials assure accuracy in analysis and testing. ISO 33405:2024— Reference Materials – Approaches For Characterization And Assessment Of Homogeneity And Stability applies to reference materials.
What Are Reference Materials in a Lab?
A reference material is a substance with a specific defined characteristic that serves as a comparative value for analyses. As such, most reference materials are prepared as batches of “units” (e.g., bottles, vials test items, or test pieces). Specifically, the material must be sufficiently homogeneous and stable with respect to one or more specified properties, which has been established to be fit for its intended use in a measurement process.
An example of how a reference material is used would be in mycotoxin analysis—a way to detect and identify mycotoxins in food, feed, and other materials. A reference material could be contaminated corn, flour, animal feed, barley, millet, rice, or wheat sample with a clearly defined mycotoxin concentration. These samples would be contaminated with one or more mycotoxins at difference concentrations. The known comparative value enables the analysis result to be better evaluated.
Hence, one of the major uses of reference materials in laboratories is for the quality assurance of analytical measurements. As such, it is essential to assure the quality of reference materials for accurate and comparability of analysis results. ISO 33405:2024 sets specifications to assure the utmost quality of reference materials.
What Is ISO 33405?
ISO 33405:2024 explains concepts and provides approaches to the following aspects of the production of reference materials (RMs):
- The assessment of homogeneity
- The assessment of stability and the management of the risks associated with possible stability issues related to the properties of interest
- The characterization and value assignment of properties of an RM
- The evaluation of uncertainty for certified values
- The establishment of the metrological traceability of certified values.
The guidance given supports the implementation of ISO 17034. Other approaches can also be used as long as the requirements of ISO 17034 are fulfilled. You can learn more about this International Standard for the Competence of Reference Material Producers in the blog post, What Is ISO 17034?.
Certified Reference Material
When reference materials are certified, it ensures that they are sufficiently homogenous and traceability. Certified reference material (CRM) is a reference material characterized by a metrologically valid procedure for one or more specified properties. CRMs are produced by accredited institutions and is subject to strict testing. They typically contain a certificate with information on validated, methods, measurements uncertainty, and traceability. As per ISO/IEC 17025, accredited laboratories are required to use CRM.
Why Does a Lab Need Reference Materials?
Reference materials play an imperative role for the following laboratory tasks:
- Calibration of instruments: calibrating instruments and measurement systems
- Process control and quality assurance: ensuring the integrity of measurement quality assurance programs and process control
- Validation of methods: validating analytical methods and test procedures
- Training: training of employees
- Performance/proficiency testing: demonstrating analyst or laboratory proficiency and using as test materials for inter-laboratory comparisons
ISO 33405:2024— Reference Materials – Approaches For Characterization And Assessment Of Homogeneity And Stability is available on the ANSI Webstore.
