Results of multiyear international interlaboratory comparison program for mercury in human hair.

Since 1990, Laboratory Services, First Nations and Inuit Health Branch (Health Canada) conducted an interlaboratory comparison program for mercury in human hair. Laboratory Services initiated this program to compare the performance of participating laboratories, analyzing mercury in human hair samples by a variety of analytical methods and instrumental detection techniques. The results of the quality assurance program, which included 31 participants on four continents, are described. Of the participating laboratories, 92% consistently meet QA/QC performance limits for the determination of Hg in human hair. A variety of analytical methods using different digestion and instrumental techniques gave similar results. The most frequently used instrumental techniques were: CV-AA, CV-AFS, and ICP-MS. A summary of results from 24 rounds is provided. The feedback from this program has assisted some laboratories in improving their results and solving some of their analytical problems.