|SOFT - TIAFT 1998||Poster Session 3||Thursday October 8, 1998|
DETECTION OF BENZODIAZEPINES IN BLOOD USING CAPILLARY GC-ECD: RECOVERY, DAY-TO-DAY AND WITHIN-DAY VARIATIONS|
Jan Tytgat, Noël Bruneel and Paul Daenens
Laboratory of Toxicology, University of Leuven, E. Van Evenstraat 4, B-3000 Leuven, Belgium
|The benzodiazepine drugs are extensively prescribed and are the focus of a number of deaths associated with poisoning world-wide. It is therefore indispensable to have reliable methods for their detection, identification and quantification at the low levels encountered in body fluids. We recently have described the identification and quantification of 29 benzo-diazepines using capillary GC-ECD following extraction of these drugs from post-mortem blood with Na2CO3, diethylether and H3PO4 [Bruneel N., Tytgat J. & Daenens P. in: Proceedings of the 34th Triennial Meeting of TIAFT, Eds. Sachs H., Bernhard W. & Jeger A., Molinapress, Leipzig, Germany, 1996, pp. 122-126]. Based on this method, we report here the parameters affecting recovery, day-to-day and within-day variations for 7 selected benzodiazepines: alprazolam, bromazepam, brotizolam, clotiazepam, flunitrazepam, lorazepam and tetrazepam. In particular, we investigated whether an additional clean-up of the blood extract with 0.1 % H3PO4 was beneficial for extraction recovery of these drugs. Recovery was determined by comparing the representative peak heights of extracted blood with peak heights of standards prepared in methanol of the same concentration.
The following recoveries were obtained with and without 0.1 % H3PO4 clean-up respectively (n=5): 77 and 51 % (alprazolam), 57 and 22 % (bromazepam), 100 and 60 % (brotizolam), 91 and 60 % (clotiazepam), 75 and 58 % (flunitrazepam) and 31 and 18 % (lorazepam). Both day-to-day and within-day variations generally demonstrated a coefficient of variation less than 10 %.