title: Liquid chromatography-tandem mass spectrometric method for the determination of salivary 25-hydroxyvitamin D3: a noninvasive tool for the assessment of vitamin D status.
abstract: A sensitive liquid chromatography-electrospray ionization-tandem mass spectrometric (LC-ESI-MS/MS) method for the determination of 25-hydroxyvitamin D(3) [25(OH)D(3)] in human saliva has been developed and validated. The saliva was deproteinized with acetonitrile, purified using a Strata-X cartridge, derivatized with a Cookson-type reagent, 4-phenyl-1,2,4-triazoline-3,5-dione (PTAD), and subjected to LC-MS/MS. The PTAD derivative was much more easily ionized in positive-ESI-MS and efficiently produced a characteristic product ion during MS/MS, compared to the intact 25(OH)D(3). Methylamine was used as the mobile phase additive, and also effectively enhanced the assay sensitivity. Quantification was based on selected reaction monitoring, and 25-hydroxyvitamin D(4) was used as the internal standard. This method allowed the reproducible and accurate quantification of salivary 25(OH)D(3) using a 1.0-ml sample, and the limit of quantitation for 25(OH)D(3) was 2.0 pg/ml. The applicability of the developed method for clinical studies was then examined. There was a positive linear relationship (r (2) = 0.830) between the serum 25(OH)D(3) level, which is conventionally used as a means of assessing the vitamin D status, and the salivary 25(OH)D(3) level measured using the proposed method. The method also enabled the detection of the increase in the salivary 25(OH)D(3) level after the supplementation of vitamin D(3).
authors: Division of Pharmaceutical Sciences, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa, 920-1192, Japan. higashi@p.kanazawa-u.ac.jp
authors: Tatsuya
authors: T
authors: Higashi
authors: Yujin
authors: Y
authors: Shibayama
authors: Mihoko
authors: M
authors: Fuji
authors: Kazutake
authors: K
authors: Shimada
mesh_terms: D000328:Adult; D002112:Calcifediol / Q000008:administration & dosage / Q000032:analysis* / Q000737:chemistry; D002853:Chromatography, Liquid / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D015394:Molecular Structure; D009752:Nutritional Status; D012463:Saliva / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods; D053719:Tandem Mass Spectrometry / Q000379:methods; D014807:Vitamin D / Q000097:blood*
chemical_list: D014807:Vitamin D; D002112:Calcifediol