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 met hod involves protein precipitation with acetonitrile and reversed-phase chr omatography with ultraviolet detection at 304 nm. The mobile phase was 0.06 7 M phosphate buffer, pH 7.95-acetonitrile (55:45, v/v). Diazepam was appli ed as an internal standard. The method was tested for linearity (over the range 2.5-200.0 ng/mL). The r ecovery (mean +/- SD, n=7) was 96.76 +/- 1.89%. Inter- and intra-day precis ion 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 .