Benzodiazepine findings in blood and urine by gas chromatography and immunoassay

Gas chromatography (GC) and immunoassay techniques applied to blood and uri ne specimens were compared for the screening of benzodiazepines in postmort em forensic toxicology. Five hundred and six such successive postmortem cas es in which both urine and peripheral blood was sent for toxicological anal ysis by the medical examiners were selected. The urine specimens were teste d by the Emit(R) d.a.u.(TM) Benzodiazepine Assay, and in parallel, the bloo d and urine specimens were screened for benzodiazepine drugs and their meta bolites by an established automated dual-column GC method. The lowest numbe r of positives (153) was obtained when immunoassay was performed without en zyme hydrolysis. When urine samples were hydrolysed before immunoassay, the number of positives increased to 175. The highest number of positives (200 ) was obtained in urine by GC, and the screening of blood by GC yielded 185 quantitative results. Despite the urine GC screening produced the most pos itives, the quantitative screening of the blood by GC appears to be the mos t efficient approach in postmortem forensic toxicology, considering the fac t that although urine findings confirm the presence of the drug, quantitati ve results in urine are irrelevant to acute toxicity. (C) 2000 Elsevier Sci ence Ireland Ltd. All rights reserved.