Proficiency testing

You are in an accredited laboratory, regularly audited by Cofrac. The latter requires you to take part in proficiency testing. Why this request? Why refer to ISO 17025 to justify it? What is the purpose of proficiency testing? What can you do if there are no proficiency tests for the analyte you're measuring?

Traceability of measurements made by physico-chemical or biochemical analysis laboratories is difficult to achieve, and specific solutions have had to be found, as explained in ISO 17025:

• carry out proficiency testing by interlaboratory comparison (CIL) ;

• manufacture certified reference materials (CRMs) ;

• identify primary analysis methods.

The aim of this sheet is to describe proficiency testing, which is the main method used by accredited laboratories to ensure traceability and comply with ISO 17025.