Benzodiazepines and metabolites from biological fluids by liquid chromatography electrospray tandem mass spectrometry

Solid-phase extraction and liquid chromatography-tandem mass spectrometry are invaluable techniques for the determination of benzodiazepines and metabolites in biological matrices. The reason for using tandem mass spectrometry is to increase limits of detection without the need for chemical derivatization. Here we describe a technique for the detection of 26 benzodiazepines and metabolites at a detection limit of approximately 1-2 ng/mL in blood and 1-5 ng/mL in urine when screened using a data-dependent scan method.

Extraction and analysis of flunitrazepam/7-aminoflunitrazepam in blood and urine by LC–PDA and GC–MS using butyl SPE columns

The forensic toxicology community has recognized flunitrazepam and its metabolite (7-aminoflunitrazepam) as compounds of concern for several years. In this procedure, the analytes were extracted from whole blood and urine onto single mode solid phase cartridges (butyl) using nitrazepam as an internal standard. The columns were washed with distilled water and hexane. All three compounds were eluted from the sorbent using an ethyl acetate-methanol solvent mixture. After collection and evaporation of the solvent, the residue was dissolved in A, 0.1% (v/v) aqueous trifluoroacetic acid for HPLC-PDA analysis or B, ethyl acetate for derivatization with pentafluoropropionic anhydride (PFPA) for analysis by gas chromatography-mass spectrometry (selected ion monitoring, SIM). A limit of quantitation for this method using HPLC-PDA was found to be 5 and 1.0 ng mL(-1) by SIM.

Simultaneous analysis of flunitrazepam and its major metabolites in human plasma by high performance liquid chromatography tandem mass spectrometry

A sensitive and specific high performance liquid chromatography-atmospheric pressure chemical ionization-tandem mass spectrometry (HPLC-APCI-MS-MS) method has been developed for the simultaneous determination of flunitrazepam and its major metabolites, 7-aminoflunitrazepam and N-desmethylflunitrazepam, in human plasma. After the addition of a deuterium labelled internal standard of flunitrazepam, plasma samples were extracted using Oasis(R) MCX solid phase extraction cartridges. The compounds were separated on a 5 microm Symmetry C18 (Waters) column (3.0 x 150 mm, i.d.) with a step gradient of acetonitrile-0.1% formic acid at a flow rate of 0.6 ml/min. The overall extraction efficiency was more than 89% for all three compounds. The limits of detection were 0.25 g/l for flunitrazepam, 0.5 microg/l for 7-aminoflunitrazepam, and 2.0 microg/l for N-desmethylflunitrazepam. Within-run accuracies for quality-control samples were between 92.5 and 101.3% of the target concentration, with coefficients of variation <8%. The proposed method enables the unambiguous identification and quantitation of flunitrazepam and its major metabolites in both clinical and forensic specimens.