Proficiency testing and ISO/IEC 17025: the outside check your laboratory needs

Internal quality control tells you whether your process is stable. It cannot tell you whether your results agree with the rest of the world. That is why ISO/IEC 17025 expects laboratories to monitor the validity of their results, and why participation in proficiency testing or other interlaboratory comparisons is one of the standard ways to do it.

Why an external benchmark matters

Robust quality control avoids the unnecessary rejection of acceptable products and stops defective ones from being released. To do that well, a laboratory needs benchmarks it does not control itself: independent proficiency testing and reference materials from credible third parties.

What to look for in a provider

• Competence demonstrated by accreditation to ISO/IEC 17043 for proficiency testing providers.
• Reference materials produced under ISO 17034.
• Schemes that run on a regular cycle, so trends and systematic errors can be detected.
• Clear, timely reports you can show to management, customers and your accreditation body.

Used consistently, proficiency testing is evidence of competence that regulators, customers and assessors recognise.