title: Simultaneous quantitative analysis of nine vitamin D compounds in human blood using LC-MS/MS.
abstract: OBJECTIVE
  It has been suggested that each member of the family of vitamin D compounds may have different function(s). Therefore, selective quantification of each compound is important in clinical research.
  
  
  METHODS
  Development and validation attempts of a simultaneous determination method of 12 vitamin D compounds in human blood using precolumn derivatization followed by LC-MS/MS is described. Internal standard calibration with 12 stable isotope labeled analogs was used to correct for matrix effects in MS detector.
  
  
  CONCLUSIONS
  Nine vitamin D compounds were quantifiable in blood samples with detection limits within femtomole levels. Serum (compared with plasma) was found to be a more suitable sample type, and protein precipitation (compared with saponification) a more effective extraction method for vitamin D assay.
authors.affiliation: School of Pharmacy, The University of Queensland, QLD 4072, Australia.
authors.forename: Nur Sofiah
authors.initials: NS
authors.lastname: Abu Kassim
authors.affiliation: School of Pharmacy, The University of Queensland, QLD 4072, Australia.
authors.forename: Fabio P
authors.initials: FP
authors.lastname: Gomes
authors.affiliation: School of Pharmacy, The University of Queensland, QLD 4072, Australia.
authors.forename: Paul Nicholas
authors.initials: PN
authors.lastname: Shaw
authors.affiliation: School of Pharmacy, The University of Queensland, QLD 4072, Australia.
authors.forename: Amitha K
authors.initials: AK
authors.lastname: Hewavitharana
mesh_terms: D002853:Chromatography, Liquid / Q000379:methods; D006801:Humans; D057230:Limit of Detection; D015203:Reproducibility of Results; D053719:Tandem Mass Spectrometry / Q000379:methods*; D014807:Vitamin D / Q000097:blood*
chemical_list: D014807:Vitamin D
keywords: LC–MS/MS; plasma; protein precipitation; saponification; serum; vitamin D