General questions

What is a CRM?

In a nutshell, a certified reference material (CRM) is a material which is used for method development, method validation, in particular to check for method bias, or for calibration. The formal answer - as defined in the Vocabulary of Metrology – is: a CRM is a reference material, accompanied by a certificate, one or more of whose property values are certified by a procedure which establishes traceability to an accurate realisation of the unit in which the property values are expressed, and for which each certified value is accompanied by an uncertainty at a stated level of confidence.

What is the difference between CRM, RM, SRM, ERM?

Reference material (RM) is the generic term for a group of either pure substances or matrix materials, which are used for calibration, method validation, the establishment of metrological traceability, method development, and various quality control purposes (proficiency testing, charting, etc). If the reference material fulfils a number of requirements (proven homogeneity and stability, characterisation of the property values using suitable, well-described and validated methods) this information may be summed up in a certificate, thus being a certified reference material (CRM).

SRM® is a trademark registered by the US National Institute for Standards and Technology (NIST) for the certified reference materials they produce and stands for Standard Reference Material. Any ERM® is a trademark of the European Communities for CRMs produced by partners of the European Reference Material (ERM) co-operation and fulfilling stringent quality criteria.

Where can I find reference materials?

Main sources to locate reference materials are:

Where can I buy reference materials of the European Commission?

CRMs can be bought directly from IRMM or from one of our authorised distributors (LGC Promochem, Fluka, RTC)
IRMM: http://www.irmm.jrc.be
LGC Promochem: http://www.lgcpromochem.com
RTC: http://www.rt-corp.com
Fluka: http://www.fluka.ch

Are CRMs generally produced under an accreditation scheme?

The appropriate standard for the production of reference materials is ISO Guide 34 “General quality requirements for the production of reference materials”, but it is understood that measurements must comply with the provisions of ISO 17025. There are only very few reference material producers accredited to ISO Guide 34 yet. The Reference Materials Unit of IRMM was the first organisation in Europe to achieve accreditation to ISO Guide 34 for the production of CRMs.

Can I purchase bulk volumes of CRMs?

IRMM does not sell bulk volumes of reference materials, but rather individually labelled samples (‘units’) of CRMs.

Why do certified values and uncertainties of replacement batches differ from the first released batch of a CRM?

Replacement batches are usually produced from different raw materials than the first batch of a CRM. Therefore, they do not have the same property values (analyte content etc.).

Although we try to match the first batch, this is sometimes impossible or even not desirable: changes in the analyte content routinely encountered in the laboratory should be reflected by changes in the concentration levels of the CRM.




Last Update 10/02/2006