Learn how interlaboratory comparisons (ILCs) other than proficiency testing differ from PT schemes, their intended purposes, limitations, and how they support ISO/IEC 17025 compliance.

Interlaboratory comparisons, proficiency testing, ring tests, and round robins are often confused. Learn the correct terminology, key differences, and the importance of harmonized language in quality assurance.

Learn how proficiency testing providers assign reference values, estimate uncertainties, calculate performance scores, and interpret z, zeta, En, and percentage difference results.

Learn how proficiency testing providers calculate assigned values, uncertainty, and data dispersion, and how these statistics help laboratories interpret PT results correctly.

Learn how laboratories should investigate poor proficiency testing results, identify root causes, implement corrective actions, and improve quality management to prevent recurring issues.

Learn how surplus proficiency testing (PT) items can support method verification, analyst training, internal quality control, troubleshooting, and performance assessment in analytical laboratories.

Learn how post-acquisition workflows in ICP-OES and ICP-MS improve calibration evaluation, interference correction, QC review, and data reliability.

Learn how ISO/IEC 17043 applies to proficiency testing schemes for sampling, including evaluation models, statistical design, homogeneity, assigned values, and sampling uncertainty.

Pre- and post-analytical PT/EQA schemes help evaluate the entire routine chemical analysis process, from sampling and preparation to interpretation and reporting of results.

How to define a PT strategy? Eurachem guidance explains how to set scope, frequency, and risk-based participation while integrating PT with broader QA tools.