[Simultaneous determination of three probe drugs by reversed-phase high performance liquid chromatography]

A reversed-phase high performance liquid chromatographic method was developed for the simultaneous quantitative determination of caffeine, dapsone and chlorzoxazone. The operation was carried out on a C18 column (250 mm x 4.6 mm i.d., 5.0 microns) with the mobile phase of acetonitrile-phosphate buffer (including 0.02 mol/L KH2PO4 and 0.02 mol/L (C2H5)3N, pH 6.5) (25:75 in volume ratio). The eluate was detected at 265 nm in 0 min-12 min and at 280 nm in 12 min-25 min. Excellent linearity was observed over the effective concentration ranges in plasma. This method is simple, fast and can be applicable to clinical safe prescription.