EnzymaticDigestion,Solid-PhaseExtraction,and Gas Chromatography/Mass Spectrometryof DerivatizedIntactOxazepam in Urine

was used to release intact oxazepam from urine samples containing the d5-analog internal standard. The resulting specimens were extracted with Du Pont PREP Type W cartridge (processed by a PREP Automated Sample Processor), Bond Elut Certify”, and J. T. Baker “spe” columns for comparison of the columns ’ extraction recov-ery and overall effectiveness. Methyl iodide/tetrahexylam-monium hydrogen sulfate and N,O-bis(tnmethylsilyl)tri-fluoroacetamide/trimethylchlorosilane (10 g/L) were used for the methylation and trirnethylsilylation studies. We used a Hewlett-Packard HP 5790 mass-selective detector equipped with a 13-rn J & W DB-5 column (5 % phenyl polysiloxane phase) for gas chromatography/mass spec-troscopy (GC/MS) analysis and the Thru-Put Target#{174} software package for data processing. After several ex