A reference material is a substance or object with one or more defined (known) properties, for use as a measure or reference value in measurement processes . Reference materials can be solids , liquids or gases of all kinds.
Reference materials are indispensable for chemical analyzes and material tests, as well as for quality control . The term reference standard is also used in pharmacy .
Many material tests and most chemical analyzes are comparative measurements, not absolute measurements. The measuring device only supplies a relative signal that has to be related to a known value ( calibration ). Reference materials are required for this reference.
The quality of reference materials is important for the accuracy and comparability of analysis results. For a precise analysis, the relevant properties of the materials should fluctuate only slightly. In the case of reference materials for chemical analyzes, the composition and homogeneity are very important, as is the traceability of these quantities. Defined reference materials are therefore produced by authorities or internationally recognized institutes and are called “certified reference materials”. The production and characterization is regulated by numerous guidelines and is subject to strict tests. A certificate is supplied by the manufacturer for each of the certified materials, with information on the properties described, their fluctuation and testing.
In Germany, the development of certified reference materials is a task of the Federal Institute for Materials Research and Testing (BAM) in Berlin. At the European level there is the Institute for Reference Materials and Measurements (IRMM) in Geel (Belgium).
In the USA, reference materials (SRM = Standard Reference Material ) are developed and offered by the National Institute of Standards and Technology (NIST), among others .
The European Pharmacopoeia divides the reference standards into:
- chemical reference substances (CRS),
- Vegetable reference standards (HRS)
- biological reference preparations (BRS) and
- Reference spectra (e.g. infrared spectrum ).
Such reference standards are used to identify samples in pharmacy, and are sometimes mandatory. The reference standards are available from the European Directorate for the Quality of Medicines (EDQM) of the Council of Europe in Strasbourg .
- ISO Guide 31, Contents of certificates of reference materials, 2000
- ISO Guide 32, Calibration in analytical chemistry and use of certified reference materials, 1997
- ISO Guide 33, Use of certified reference materials, 2000
- ISO Guide 34, General Requirements for the Competence of Reference Material Producer. Second edition, 2009
- ISO Guide 35, Reference materials - General and statistical principles for certification. Second edition, 2006
- Guidelines for the production and certification of BAM reference materials, 1997
- ASTM Designation E 826-90, Standard Practice for Testing Homogeneity of Materials for the Development of Reference Materials
- International Database of Certified Reference Materials (In English)
- Main page for reference materials at BAM
- European Reference Materials Website
- NIST website
- Herbert Feltkamp, Peter Fuchs, Heinz Sucker (editors): Pharmaceutical Quality Control , Georg Thieme Verlag, 1983, pp. 58–61, ISBN 3-13-611501-5 .
- NIST – SRM access 
- European Pharmacopoeia , Deutscher Apotheker Verlag Stuttgart, 8th edition, 7th supplement, 2016. Official German edition, ISBN 978-3769263299 , p. 8149.