Abstract: Objective To establish a method for determination of the concentration of oxazepam in human plasma by HPLC. Methods The plasma samples were extracted with ether. The ether extraction was evaporated under nitrogen stream at 55℃ in water bath, and the residue was dissolved in methanol. Shim-pack CLC-CN(150 mm×6.0 mm, 5 m) was used as the analytical column. Mobile phase consists of n-hexane:methanol: ethanol(80:17:3, V/V/V), with a flow rate of 1.10 mL·min-1. The temperature of chromatographic separation was 30℃, and the drug was detected at 230 nm by an ultraviolet detector. Results A good linearity was obtained from 0.02 to 5.0 mg·L-1 with a correlation of 0.9996. The recovery of oxazepam was nearly 100%. Intraday RSD and interday RSD were both less than 5%(n=5). Conclusion The method is suitable for monitoring oxazepam in human plasma.

Key words: HPLC, oxazepam, plasma drug level