Laboratory capacity building through the use of metrologically traceable reference values in proficiency testing programmes

There is an increasing need for laboratory capacity building through the organisation of proficiency testing programmes with metrologically traceable reference values in the Asia-Pacific region. Stakeholders such as the regional metrology organisation, metrology institutes, and accreditation bodies are increasingly aware that consensus values of proficiency testing programmes could sometimes be significantly biased if the participating laboratories do not have clear understanding of their measurement capabilities and measurement uncertainties. In this article, we provide a review of the effectiveness of the use of reference values obtained from international comparisons among metrology institutes for performance evaluation in associated proficiency testing programmes. Important issues are discussed including determination of assigned values, the main methods employed by national metrology institutes/designated institutes and field analytical laboratories for analysis, estimation of measurement uncertainty, and guidance on analytical challenges presented by these studies. Application of measures such as appropriate matrix reference materials, particularly from incurred sources, for assessing extraction efficiencies and other measurement procedural issues, and proper knowledge of the uncertainty budgets are essential tools leading to effective and reliable measurements.