title: A Method for Simultaneous Determination of 25-Hydroxyvitamin D3 and Its 3-Sulfate in Newborn Plasma by LC/ESI-MS/MS after Derivatization with a Proton-Affinitive Cookson-Type Reagent.
abstract: A method for the simultaneous determination of 25-hydroxyvitamin D3 [25(OH)D3] and its 3-sulfate [25(OH)D3S] in newborn plasma, which is expected to be helpful in the assessment of the vitamin D status, using stable isotope-dilution liquid chromatography/electrospray ionization-tandem mass spectrometry (LC/ESI-MS/MS) has been developed and validated. The plasma was pretreated based on the deproteinization and solid-phase extraction, then subjected to derivatization with 4-(4-dimethylaminophenyl)-1,2,4-triazoline-3,5-dione (DAPTAD). The derivatization enabled the accurate quantification of 25(OH)D3 without interference from 3-epi-25(OH)D3 and also facilitated the simultaneous determination of the two metabolites by LC/positive ESI-MS/MS. Quantification was based on the selected reaction monitoring with the characteristic fragmentation of the DAPTAD-derivatives during MS/MS. This method was reproducible (intra- and inter-assay relative standard deviations of 7.8% or lower for both metabolites) and accurate (analytical recovery, 95.4-105.6%). The limits of quantification were 1.0 ng/mL and 2.5 ng/mL for 25(OH)D3 and 25(OH)D3S, respectively, when using a 20-μL sample. The developed method was applied to the simultaneous determination of plasma 25(OH)D3 and 25(OH)D3S in newborns; it was recognized that the plasma concentration of 25(OH)D3S is significantly higher than that of 25(OH)D3, and preterm newborns have lower plasma 25(OH)D3S concentrations than full-term newborns.
authors.affiliation: Faculty of Pharmaceutical Sciences, Tokyo University of Science.
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Higashi
authors.affiliation: Faculty of Pharmaceutical Sciences, Tokyo University of Science.
authors.forename: Mai
authors.initials: M
authors.lastname: Yokota
authors.affiliation: Faculty of Pharmaceutical Sciences, Tokyo University of Science.
authors.forename: Ayaka
authors.initials: A
authors.lastname: Goto
authors.affiliation: Shizuoka Saiseikai General Hospital.
authors.forename: Kenji
authors.initials: K
authors.lastname: Komatsu
authors.affiliation: Shizuoka Saiseikai General Hospital.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Sugiura
authors.affiliation: Faculty of Pharmaceutical Sciences, Tokyo University of Science.
authors.forename: Shoujiro
authors.initials: S
authors.lastname: Ogawa
authors.affiliation: Divisions of Clinical Mass Spectrometry, Chiba University Hospital.
authors.forename: Mamoru
authors.initials: M
authors.lastname: Satoh
authors.affiliation: Divisions of Clinical Mass Spectrometry, Chiba University Hospital.
authors.forename: Fumio
authors.initials: F
authors.lastname: Nomura
keywords: 25-hydroxyvitamin D3; 25-hydroxyvitamin D3 3-sulfate; LC/ESI-MS/MS; derivatization; newborn plasma