title: Simultaneous determination of endogenous and 13C-labelled cortisols and cortisones in human plasma by stable isotope dilution mass spectrometry.
abstract: This study describes a capillary GC-MS method for the simultaneous determination of endogenous cortisol and cortisone and their 13C-labelled analogues, [1,2,4,19-13C4]cortisol (cortisol-13C4) and [1,2,4,19-13C4]cortisone (cortisone-13C4), in human plasma. [1,2,4,19-13C4,1,1,19,19,19-2H5]Cortisol (cortisol-13C4,2H5) and [1,2,4,19-13C4,1,1,19,19,19-2H5]cortisone (cortisone-13C4,2H5) were used as analytical internal standards. A double derivatization (bismethylenedioxy-pentafluoropropionate, BMD-PFP) with good GC behavior was employed for the GC-MS analysis of cortisol and cortisone. Quantitation was carried out by selected-ion monitoring of the molecular ions ([M]+*) of the BMD-PFP derivatives of cortisol and cortisone. The sensitivity limit of the present GC-MS-SIM method was found to be 150 pg per injection for cortisol (s/n=5.0) and 50 pg for cortisone (s/n=8.1). The within-day reproducibility in which the amounts of unlabelled and labelled cortisols and cortisones determined were in good agreement with the actual amounts added, the relative errors being less than 3.07%. The inter-assay coefficients of variation (C.V.) were less than 1.80% for unlabelled and labelled cortisols and cortisones.
authors.affiliation: Department of Medicinal Chemistry and Clinical Pharmacy, School of Pharmacy, Tokyo University of Pharmacy and Life Science, Hachioji, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Furuta
authors.forename: N
authors.initials: N
authors.lastname: Eguchi
authors.forename: H
authors.initials: H
authors.lastname: Shibasaki
authors.forename: Y
authors.initials: Y
authors.lastname: Kasuya
mesh_terms: D002247:Carbon Isotopes; D003348:Cortisone / Q000097:blood* / Q000493:pharmacokinetics; D003903:Deuterium; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D006801:Humans; D006854:Hydrocortisone / Q000097:blood* / Q000493:pharmacokinetics; D007201:Indicator Dilution Techniques; D007553:Isotope Labeling; D012044:Regression Analysis; D015203:Reproducibility of Results
chemical_list: D002247:Carbon Isotopes; D003903:Deuterium; D003348:Cortisone; D006854:Hydrocortisone