SOFT - TIAFT 1998 Poster Session 3 Thursday October 8, 1998

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:

URINE (ETS): negative positive negative positive invalid* invalid* Total
BLOOD (GC): negative positive positive negative negative positive  
No. of cases: 284 149 48 4 26 3 514
* no result obtained by ETS

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.

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