title: Measurement of 25-hydroxyvitamin D2, 25-hydroxyvitamin D3, 24,25-dihydroxyvitamin D2 and 25,26-dihydroxyvitamin D2 in a single plasma sample by mass fragmentography.
abstract: A specific and sensitive assay for the measurement of the concentration of 25-hydroxyvitamin D2, 25-hydroxyvitamin D3, 24,25-dihydroxyvitamin D2 and 25,26-dihydroxyvitamin D2 in a single plasma sample is described, using stable isotope dilution mass fragmentography. After addition of appropriate deuterium-labelled internal standards, plasma samples were treated with acetonitrile to precipitate protein, and vitamin D metabolites were extracted on prepacked microparticulate reverse-phase cartridges. Further purification was achieved using straight-phase cartridges and high-performance liquid chromatography. Gas chromatography-mass spectrometry was carried out after appropriate derivatisation of samples and standards. The method has been evaluated in terms of specificity, recovery of added standards, and reproducibility.
authors.affiliation: Department of Chemical Pathology, London Hospital Medical College, UK.
authors.forename: R D
authors.initials: RD
authors.lastname: Coldwell
authors.forename: D J
authors.initials: DJ
authors.lastname: Trafford
authors.forename: M J
authors.initials: MJ
authors.lastname: Varley
authors.forename: D N
authors.initials: DN
authors.lastname: Kirk
authors.forename: H L
authors.initials: HL
authors.lastname: Makin
mesh_terms: D002112:Calcifediol / Q000097:blood; D002762:Cholecalciferol / Q000097:blood; D004872:Ergocalciferols / Q000097:blood; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D006887:Hydroxycholecalciferols / Q000097:blood* / Q000302:isolation & purification
chemical_list: D004872:Ergocalciferols; D006887:Hydroxycholecalciferols; D002762:Cholecalciferol; D002112:Calcifediol