Determination of zolpidem and zopiclone in serum by capillary column gas chromatography

A gas chromatographic method using a short, high-resolution capillary column connected to a specific thermoionic detector and requiring a simple and short extraction step without evaporation was developed for the rapid and precise determination of two new hypnotics, zolpidem and zopiclone, in serum at concentrations greater than 5 ng/mL. The assay was linear between 5 and 200 ng/mL, with coefficients of intra- and interassay variation less than 5% for both. The method was validated and then used to analyze zolpidem serum concentrations in nine rabbits after oral administration of 0.5 mg/kg and zopiclone serum concentrations in six patients treated orally with a 7.5-g dose.