A sensitive and reliable method was developed for the identification and quantitation of cannabinoids in blood. Samples were screened by fluorescence polarization immunoassay. Analysis was completed on a benchtop mass selective detector using selected ion monitoring. The limits of detection were 0.2 ng/mL for delta9-tetrahydrocannabinol (THC and 11-hydroxy-THC and 2 ng/mL for 11-nor-9-carboxy-THC. Extensive method validation is presented, including within-run variation, between-run variation, and results from external proficiency testing. Sample stability was studied over a 6-month period. Several derivatives and extraction techniques were evaluated to determine optimum performance. Data from a blind study of 217 samples were used to determine the predictive value of the screening procedure. The procedure is used routinely in the laboratory on samples from drivers issued a citation for impaired driving and also on postmortem blood from death investigations.

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An automated colorimetric microprocedure, suitable for screening purposes, has been developed for the determination of blood uric acid levels. The method uses 2O-µl. whole-blood (capillary) samples and is based on the AutoAnalyzer measurement of the absorbance of the colored uric acid-phosphotungstic acid complex. The dilution inherent in the sampling procedure necessitated a modification of the existing AutoAnalyzer method to increase the sensitivity. The proposed method is evaluated for precision and accuracy by comparison with the standard AutoAnalyzer macro-method.

THE INCEEASING number of requests to clinical laboratories during the past 10 years for serum cholesterol determinations reflects the growing awareness by physicians of the possible relationship between serum choles¬ terol levels and cardiovascular disease. Greater