Forensic Toxicology Proficiency Monitoring: Results, Experiences, and Comments

Two toxicology proficiency surveys were conducted, one during 1974 and the other during 1976. The surveys would not have been possible without our expressed agreement to confidentiality and anonymity of the results. Although several problems and objections were raised by the participating laboratories, the general response was favorable and their collective evaluation supported continuation of proficiency examinations by a neutral organization. The major findings of the surveys were that the toxicological laboratories associated with the medical examiners' or coroners' offices show significant interlaboratory and intralaboratory variations in identification and quantitation of drugs. These variations were found not to be caused by differences in methodologies or instrumentation since correct and incorrect results were reported using essentially similar methods. Technical and instrumental advances between 1974 and 1976 have not yet been reflected in the laboratory performance as measured by our survey. The vast majority of methodologies currently in use are the classical and accepted techniques of gas-liquid chromatography, thin layer chromatography, and absorption spectrophotometry. Some laboratories using classical methods do seem to significantly outperform the mean and do show exemplary performance when tested by blind proficiency samples, whereas other laboratories using essentially the same methodologies present a much less favorable picture of performance.