DETERMINATION OF THE ENANTIOMERS OF ZOPICLONE AND ITS 2 CHIRAL METABOLITES IN URINE USING AN AUTOMATED COUPLED ACHIRAL CHIRAL CHROMATOGRAPHIC SYSTEM

The enantiomers of zopiclone and its two chiral N-desmethyl and N-oxid e metabolites were determined in urine using a coupled achiral-chiral liquid chromatographic method. After liquid-liquid extraction, zopiclo ne and its two metabolites were quantified on a cyanopropyl column. Af ter fluorimetric detection on the achiral system, the eluent was switc hed through a silica precolumn in order to trap and concentrate the an alytes. Each fraction was then backflushed separately onto a carbamate cellulose chiral stationary phase in order to determine the enantiome ric ratios. The coupled system was automated with an autosampler and a switching valve programmed by an integrator. The method was validated , and a first trial was performed on urine samples of a volunteer trea ted with 15 mg of racemic zopiclone.