Proficiency tests: a tool for improvement and testing analytical performance at Gamma-Ray Spectroscopy Laboratory

Participation in proficiency tests is an essential requirement of ISO/IEC 17025 for testing and calibration laboratories. These tests aim to evaluate performance of laboratories for specific analytical methods, identify problems and assist in initiating corrective actions for improvement, find source of error in measurement result and validate uncertainty. The accredited Gamma-Ray Spectroscopy Laboratory at the Lebanese Atomic Energy Commission, participates yearly in proficiency test organized by the International Atomic Energy Agency (IAEA)-ALMERA Network-Analytical Laboratories for the Measurements of Environmental Radioactivity and the Department of Energy-USA, Mixed Analyte Performance Evaluation Program (MAPEP-DOE-USA). This paper showed how proficiency tests had helped the laboratory to improve adopted analytical protocol through the corrective actions implemented for unacceptable results, and to provide advanced experience to the laboratory staff through the lessons learned. The Results were evaluated based on accuracy and precision criteria. The relative bias, Z-score and precision score values since 2005 are presented and discussed. The laboratory showed high performance over years with acceptable values for different radionuclides in various matrices.