ASSAY OF MIDAZOLAM IN HUMAN PLASMA BY GAS-LIQUID-CHROMATOGRAPHY WITH NITROGEN-PHOSPHORUS DETECTION

A sensitive and specific method is described for the determination of midazolam in human plasma. The drug was extracted from 1 mL of carbona te buffered plasma (pH 9.6) with 8 mt of diethyl ether. Famprofazone w as used as internal standard. The organic phase was evaporated to dryn ess. The residue was dissolved in methanol for the direct analysis by gas chromatograph-nitrogen phosphorus detector system. In the concentr ation range of 1-5000 ng/mL, the calibration curve was linear. The coe fficients of variation from the precision test were <6% at the range o f the concentration of 0.10-2.00 mu g/mL and the detection limit for m idazolam in 1 mL of plasma was 0.5 ng. This assay is more sensitive, s elective, simple and rapid than earlier methods. Plasma midazolam conc entrations were determined by this method after administration of mida zolam.