title: Determination of M+4 stable isotope labeled cortisone and cortisol in human plasma by microElution solid-phase extraction and liquid chromatography/tandem mass spectrometry.
abstract: A sensitive microElution solid-phase extraction (SPE) liquid chromatography/tandem mass spectrometry (LC/MS/MS) method has been developed and validated for the determination of M+4 stable isotope labeled cortisone and cortisol in human plasma. In this method, M+4 cortisone and M+4 cortisol were extracted from 0.3 mL of human plasma samples using a Waters Oasis HLB 96-well microElution SPE plate using 70 microL methanol as the elution solvent, and chromatographed on a Waters Symmetry C18 column (4.6 x 50 mm, 3.5 microm). M+9 cortisone and M+9 cortisol were used as the internal standards. A PE Sciex API 4000 tandem mass spectrometer interfaced with the liquid chromatograph via a turboionspray source was used for mass analysis and detection. The selected reaction monitoring (SRM) of precursor --> product ion transitions were monitored at m/z 365.2 [M+H](+) --> 167.0 and at m/z 367.3 [M+H](+) --> 125.1 for M+4 cortisone and M+4 cortisol, respectively. The lower limit of quantitation was 0.1 ng mL(-1) and the linear calibration range was from 0.1 to 100 ng mL(-1) for both analytes. This method demonstrated to be very reproducible and reliable.
authors.affiliation: Department of Drug Metabolism, Merck Research Laboratories, Merck and Co., Inc., WP75A-303, West Point, PA 19486, USA. amy_yang2@merck.com
authors.forename: Amy Y
authors.initials: AY
authors.lastname: Yang
authors.forename: Li
authors.initials: L
authors.lastname: Sun
authors.forename: Donald G
authors.initials: DG
authors.lastname: Musson
authors.forename: Jamie J
authors.initials: JJ
authors.lastname: Zhao
mesh_terms: D001774:Blood Chemical Analysis / Q000379:methods*; D002250:Carbon Radioisotopes; D005591:Chemical Fractionation / Q000379:methods*; D002853:Chromatography, Liquid / Q000379:methods*; D003348:Cortisone / Q000097:blood*; D006801:Humans; D006854:Hydrocortisone / Q000097:blood*; D007553:Isotope Labeling / Q000379:methods; D013058:Mass Spectrometry / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D002250:Carbon Radioisotopes; D003348:Cortisone; D006854:Hydrocortisone