title: Enantioselective analysis of zopiclone in rat brain by liquid chromatography tandem mass spectrometry.
abstract: A new high-performance liquid chromatographic method with triple quadrupole mass spectrometry detection was developed and validated for the quantification of zopiclone enantiomers in rat brain samples. Zopiclone enantiomers were resolved on a CHIRALPAK AD column with a mobile phase consisting of acetonitrile/ethanol/methanol (60:20:20, v/v/v) at a flow rate of 1.3 mL min(-1). Moclobemide was used as internal standard. The sample treatment procedure was carried out employing solid-phase extraction, yielding mean absolute recoveries of 89.6 and 91.7% for each zopiclone enantiomer. The validated method showed linearity in the range of 0.29-344.8 ng g(-1), with quantification limits of 0.29 ng g(-1) for both enantiomers. Precision and accuracy were within acceptable levels of confidence (<15%). The method was applied in a pilot study of zopiclone kinetic disposition in rats. It could be observed that the levels of (+)-(S)-zopiclone were always higher than those of (-)-(R)-zopiclone, confirming the stereoselective disposition of zopiclone.
authors.affiliation: Department of Physics and Chemistry, Faculty of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Ribeirão Preto 14040-903 SP, Brazil.
authors.forename: Milena Araújo
authors.initials: MA
authors.lastname: Tonon
authors.forename: Valquíria A P
authors.initials: VA
authors.lastname: Jabor
authors.forename: Pierina Sueli
authors.initials: PS
authors.lastname: Bonato
mesh_terms: D000097:Acetonitriles / Q000737:chemistry; D000818:Animals; D053961:Azabicyclo Compounds / Q000032:analysis* / Q000494:pharmacology*; D001921:Brain / Q000187:drug effects*; D002623:Chemistry Techniques, Analytical; D002853:Chromatography, Liquid / Q000379:methods*; D000431:Ethanol / Q000737:chemistry; D006993:Hypnotics and Sedatives / Q000032:analysis / Q000494:pharmacology; D007700:Kinetics; D008297:Male; D000432:Methanol / Q000737:chemistry; D008956:Models, Chemical; D010879:Piperazines / Q000032:analysis* / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D015203:Reproducibility of Results; D013237:Stereoisomerism; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D000097:Acetonitriles; D053961:Azabicyclo Compounds; D006993:Hypnotics and Sedatives; D010879:Piperazines; C515050:zopiclone; D000431:Ethanol; D000432:Methanol; C032159:acetonitrile