title: Determination of carbocysteine in human plasma by liquid chromatography/tandem mass spectrometry employing precolumn derivatization.
abstract: A sensitive liquid chromatography/tandem mass spectrometry (LC/MS/MS) method was developed to determine carbocysteine in human plasma using 2-pyridylacetic acid as the internal standard (IS). The method employed derivatization with 10 M hydrochloric acid/methanol, which significantly improved the ionization efficiency of carbocysteine. After methanol-induced protein precipitation of plasma samples, carbocysteine and the IS were derivatized and subjected to LC/MS/MS analysis using atmospheric pressure chemical ionization. The method has a lower limit of quantitation of 20 ng/mL for a 0.2-mL plasma aliquot. The intra- and inter-day precision (RSD), calculated from quality control (QC) samples, was less than 7%. The accuracy, determined using QC samples, was within +/- 1%. The method offered increased sensitivity, selectivity and speed of analysis over existing methods. The method was utilized to support clinical pharmacokinetic studies of carbocysteine in volunteers following oral administration.
authors.affiliation: Laboratory of Drug Metabolism and Pharmacokinetics, Shenyang Pharmaceutical University, 103 Wenhua Road, Shenyang 110016, China.
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Chen
authors.forename: Dafang
authors.initials: D
authors.lastname: Zhong
authors.forename: Ying
authors.initials: Y
authors.lastname: Han
authors.forename: Zhiyong
authors.initials: Z
authors.lastname: Xie
mesh_terms: D002138:Calibration; D002233:Carbocysteine / Q000097:blood* / Q000493:pharmacokinetics; D002853:Chromatography, Liquid / Q000379:methods*; D006801:Humans; D013058:Mass Spectrometry / Q000379:methods*; D015394:Molecular Structure; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D002233:Carbocysteine