title: Quantitative analytical method to evaluate the metabolism of vitamin D.
abstract: A method for quantitative analysis of vitamin D (both D2 and D3) and its main metabolites - monohydroxylated vitamin D (25-hydroxyvitamin D2 and 25-hydroxyvitamin D3) and dihydroxylated metabolites (1,25-dihydroxyvitamin D2, 1,25-dihydroxyvitamin D3 and 24,25-dihydroxyvitamin D3) in human serum is here reported. The method is based on direct analysis of serum by an automated platform involving on-line coupling of a solid-phase extraction workstation to a liquid chromatograph-tandem mass spectrometer. Detection of the seven analytes was carried out by the selected reaction monitoring (SRM) mode, and quantitative analysis was supported on the use of stable isotopic labeled internal standards (SIL-ISs). The detection limits were between 0.3-75pg/mL for the target compounds, while precision (expressed as relative standard deviation) was below 13.0% for between-day variability. The method was externally validated according to the vitamin D External Quality Assurance Scheme (DEQAS) through the analysis of ten serum samples provided by this organism. The analytical features of the method support its applicability in nutritional and clinical studies targeted at elucidating the role of vitamin D metabolism.
authors.affiliation: Department of Analytical Chemistry, Annex Marie Curie Building, Campus of Rabanales, University of Córdoba, Córdoba, Spain; University of Córdoba Agroalimentary Excellence Campus, ceiA3, Córdoba, Spain; Maimónides Institute of Biomedical Research (IMIBIC), Reina Sofía University Hospital, University of Córdoba, Córdoba, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Mena-Bravo
authors.affiliation: Phytoplant Research S.L. Rabanales 21, Science and Technology Park of Córdoba, Astrónoma Cecilia Payne Building, Córdoba, Spain.
authors.forename: C
authors.initials: C
authors.lastname: Ferreiro-Vera
authors.affiliation: Department of Analytical Chemistry, Annex Marie Curie Building, Campus of Rabanales, University of Córdoba, Córdoba, Spain; University of Córdoba Agroalimentary Excellence Campus, ceiA3, Córdoba, Spain; Maimónides Institute of Biomedical Research (IMIBIC), Reina Sofía University Hospital, University of Córdoba, Córdoba, Spain.
authors.forename: F
authors.initials: F
authors.lastname: Priego-Capote
authors.affiliation: Department of Fundamental Chemistry, Faculty of Sciences, University of La Coruña, La Coruña, Spain.
authors.forename: M A
authors.initials: MA
authors.lastname: Maestro
authors.affiliation: Department of Organic Chemistry, Faculty of Chemistry, University of Santiago, Santiago de Compostela, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Mouriño
authors.affiliation: Maimónides Institute of Biomedical Research (IMIBIC), Reina Sofía University Hospital, University of Córdoba, Córdoba, Spain; Mineral Metabolism Unit, Reina Sofia Hospital, University of Córdoba, Córdoba, Spain.
authors.forename: J M
authors.initials: JM
authors.lastname: Quesada-Gómez
authors.affiliation: Department of Analytical Chemistry, Annex Marie Curie Building, Campus of Rabanales, University of Córdoba, Córdoba, Spain; University of Córdoba Agroalimentary Excellence Campus, ceiA3, Córdoba, Spain; Maimónides Institute of Biomedical Research (IMIBIC), Reina Sofía University Hospital, University of Córdoba, Córdoba, Spain.
authors.forename: M D
authors.initials: MD
authors.lastname: Luque de Castro
mesh_terms: D001774:Blood Chemical Analysis / Q000379:methods*; D002138:Calibration; D002853:Chromatography, Liquid; D006801:Humans; D016014:Linear Models; D011786:Quality Control; D015203:Reproducibility of Results; D053719:Tandem Mass Spectrometry; D014807:Vitamin D / Q000097:blood* / Q000378:metabolism*
chemical_list: D014807:Vitamin D
keywords: Automation; DEQAS; LC–MS/MS; Metabolites; Serum; Vitamin D