title: Determination of 22-oxacalcitriol, a new analog of 1alpha,25-dihydroxyvitamin D3, in human serum by liquid chromatography-mass spectrometry.
abstract: A sensitive and specific liquid chromatographic-mass spectrometric assay has been developed for the determination of 22-oxacalcitriol (OCT), which is a new analog of 1alpha,25-dihydroxyvitamin D3. The analyte was isolated from serum by two solid-phase extraction steps on a C18 cartridge and NH2 cartridge. The recovery of OCT through two extraction steps was more than 90%. A related substance (ED-94), i.e. OCT with the side-chain shortened by one carbon, was used as an internal standard. Extracts were chromatographed on a C18 reversed-phase column interfaced to the electrospray ionization source. The mass spectrometer was operated in the positive-ion mode of selected reaction monitoring. The chromatographic run-time for one injection was less than 6 min. The intra- and inter-assay coefficients of variation for the lowest concentration examined (30 pg ml[-1]) were 9.83 and 10.67, respectively. And the analytical recovery of OCT added to serum was quantitative. Assay linearity was obtained in the range of 20-640 pg ml(-1).
authors.affiliation: Drug Metabolism and Pharmacokinetic Laboratory, Chugai Pharmaceutical, Tokyo, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Ishigai
authors.forename: Y
authors.initials: Y
authors.lastname: Asoh
authors.forename: K
authors.initials: K
authors.lastname: Kumaki
mesh_terms: D002117:Calcitriol / Q000031:analogs & derivatives* / Q000097:blood / Q000737:chemistry / Q000627:therapeutic use; D002138:Calibration; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D002940:Circadian Rhythm; D006727:Hormone Antagonists / Q000097:blood* / Q000737:chemistry / Q000627:therapeutic use; D006801:Humans; D006962:Hyperparathyroidism, Secondary / Q000188:drug therapy; D016014:Linear Models; D013058:Mass Spectrometry / Q000379:methods*; D010281:Parathyroid Hormone / Q000037:antagonists & inhibitors; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014316:Tritium
chemical_list: D006727:Hormone Antagonists; D010281:Parathyroid Hormone; D014316:Tritium; D002117:Calcitriol; C051883:maxacalcitol