title: High-throughput salting-out-assisted liquid-liquid extraction for the simultaneous determination of atorvastatin, ortho-hydroxyatorvastatin, and para-hydroxyatorvastatin in human plasma using ultrafast liquid chromatography with tandem mass spectrometry.
abstract: A high-throughput, specific, and rapid liquid chromatography with tandem mass spectrometry method was established and validated for the simultaneous determination of atorvastatin and its two major metabolites, ortho-hydroxyatorvastatin and para-hydroxyatorvastatin, in human plasma. A simple salting-out-assisted liquid-liquid extraction using acetonitrile and a mass-spectrometry-friendly salt, ammonium acetate, was employed to extract the analytes from human plasma. A recovery of more than 81% for all analytes was achieved in 1 min extraction time. Chromatographic separation was performed on a Kinetex XB C18 column utilizing a gradient elution starting with a 60% of water solution (1% formic acid), followed by increasing percentages of acetonitrile. Analytes were detected on a tandem mass spectrometer equipped with an electrospray ionization source that was operated in the positive mode, using the transitions of m/z 559.3 → m/z 440.2 for atorvastatin, and m/z 575.3 → m/z 440.2 for both ortho- and para-hydroxyatorvastatin. Deuterium-labeled compounds were used as the internal standards. The method was validated over the concentration ranges of 0.0200-15.0 ng/mL for atorvastatin and ortho-hydroxyatorvastatin, and 0.0100-2.00 ng/mL for para-hydroxyatorvastatin with acceptable accuracy and precision. It was then successfully applied in a bioequivalence study of atorvastatin.
authors.affiliation: Center for Drug Metabolism and Pharmacokinetics, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, P. R. China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Yang
authors.forename: Qiufang
authors.initials: Q
authors.lastname: Xu
authors.forename: Lei
authors.initials: L
authors.lastname: Zhou
authors.forename: Dafang
authors.initials: D
authors.lastname: Zhong
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Chen
mesh_terms: D000069059:Atorvastatin / Q000097:blood* / Q000737:chemistry / Q000302:isolation & purification*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D057166:High-Throughput Screening Assays / Q000379:methods*; D006801:Humans; D059625:Liquid-Liquid Extraction / Q000379:methods*; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D000069059:Atorvastatin
keywords: Atorvastatin; High-throughput analysis; Interconversion; Liquid-liquid extraction; Salting-out