Rasanen I., Ojanperä I., Vuori E.

Department of Forensic Medicine, P.O. Box 40, FIN-00014 University of Helsinki, Finland

A dual-column method for quantitative gas chromatographic screening of benzodiazepine drugs and metabolites in blood with DB-1701 and DB-17 capillary columns and electron capture detection is described. The method includes simple liquid-liquid extraction with ethylacetate and derivatization of compounds having active hydrogens in their structures with N-methyl-N-(tert-butyldimethylsilyl)-trifluoroacetamide (MTBSTFA) with 1% TBDMSCl. The compounds are identified as their retention indices (RI) using a series of benzodiazepine RI standards. The data processing is performed with SC-WorkStation 3.0 software which automatically identifies the internal RI standards by pattern recognition, calculates the temperature programmed (linear) RI values of detected compounds and compares them with library data. The programme produces a combination report where only those compounds that are identified with both columns are listed. Quantitative (recovery, limit of detection, limit of quantitation, linearity) and qualitative (precision of identification) validation data for twenty-four compounds is presented and interferences are discussed.