For the two exercises completed to date, substances to be determined were limited to cocaine, benzoylecgonine, and morphine. Samples sent to the participating laboratories included hair from drug users, drug-free hair, and hair into which drugs had been soaked. For the first exercise, the hair samples were sent as powders; for the second, they were in the form of short segments. Results from these studies have shown that the laboratories, with a few exceptions, have performed well qualitatively; however, scatter in quantitative results was high. Various approaches were used to liberate drugs from the hair, with the most commonly used being acid extractions and enzyme digestions; they produced similar results. Laboratories that used gas chromatography/mass spectrometry (GC/MS) generally performed well and reported no false positives. In contrast, one laboratory that analyzed hair directly by using MS/MS without extractions produced three of the four false positives and the worst quantitative results. 3 tables, 3 figures, and 2 references
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