Rapid and simple method for the determination of zopiclone in plasma by HPLC

A simple, accurate, and reproducible high performance liquid chromatography method for the determination of zopiclone in plasma is presented. This method involves protein precipitation with acetonitrile and reversed-phase chromatography with ultraviolet detection at 304 nm. The mobile phase was 0.067 M phosphate buffer, pH 7.95-acetonitrile (55:45, v/v). Diazepam was applied as an internal standard. The method was tested for linearity (over the range 2.5-200.0 ng/mL). The recovery (mean +/- SD, n=7) was 96.76 +/- 1.89%. Inter- and intra-day precision was less than 3% (n=6). The described method has been applied to the quantitative determination of zopiclone in plasma and should be useful for bioavailability investigations.