|SOFT - TIAFT 1998||Poster Session 3||Thursday October 8, 1998|
COMPARISON OF THE RESULTS FROM BENZODIAZEPINE URINE IMMUNOASSAY WITH QUANTITATIVE GC BLOOD ANALYSIS|
Ilpo Rasanen, Ilkka Ojanperä and Erkki Vuori
Department of Forensic Medicine, P.O. Box 40, FIN-00014 University of Helsinki, Finland
|The presence of benzodiazepines is usually tested by screening urine samples by immunochemical techniques followed by confirmation by chromatographic methods such as GC, HPLC or GC/MS. On many occasions it is necessary to perform also a quantitative benzodiazepine determination in the blood. This study investigates if post mortem blood samples alone could be used for quantitative screening for benzodiazepines by advanced GC methods. |
In the present study, 514 such successive medical examiner's cases were selected where urine and blood were available. Urine specimens were analysed by Emit d.a.u. Benzodiazepine Assay (ETSPLUS) using a 200 ng cutoff-value. Blood samples (1 ml) were screened for 21 benzodiazepine drugs or metabolites by a dual-column gas chromatographic method using DB-5 and DB-17 capillary columns, EC detectors and advanced software for the interpretation of the dual-column results. The limit of detection of the GC method was from 3 to 50 ng/ml depending on the compound.
The results are summarised in the following table:
The following drugs were detected in cases where urine was negative and blood positive: diazepam (18 times: range 20-700 ng/ml), desmethyldiazepam (18 times: range 20-7000 ng/ml), oxazepam (13 times: range 10-400 ng/ml), temazepam (19 times: range 10-300 ng/ml), alprazolam (2 times: 20 ng/ml), and lorazepam (1 time: 10 ng/ml). In three of the cases where urine was positive and blood negative, oxazepam and temazepam were found and in one case only oxazepam was found after further analysis by GC/MS. The results suggest that in post mortem forensic toxicology benzodiazepines are more reliably detected in the blood by a modern GC than in urine by immunoassay. Furthermore, the GC method used allows simultaneous quantitation of the drugs.