title: Use of novel picolinoyl derivatization for simultaneous quantification of six corticosteroids by liquid chromatography-electrospray ionization tandem mass spectrometry.
abstract: Simultaneous quantification method of six corticosteroids, cortisone, cortisol, cortexolone, corticosterone, dehydrocorticosterone and deoxycorticosterone, by LC-electrospray ionization (ESI)-MS in a positive mode using novel picolinoyl derivatization was investigated. Conversion of each corticosteroid into the corresponding picolinoyl derivative was performed by mixed anhydride method using picolinic acids and 2-methyl-6-nitrobenzoic anhydride. Derivatization proceeded smoothly to afford the corresponding 21-monopicolinoyl derivatives. Positive ion-ESI mass spectra of the picolinoyl derivatives were dominated by the appearance of [M+H](+) as base peaks. The picolinoyl derivatives provided 5-10 times higher ESI response in the LC-ESI-MS-selected reaction monitoring (SRM) when compared to those of underivatized molecules in a positive LC-ESI-MS mode. The use of the picolinoyl ester, solid-phase extraction, and deuterium labeled internal standards enabled to determine the concentrations of these corticosteroids in human saliva simultaneously by LC-ESI-MS-SRM.
authors.affiliation: Faculty of Pharmaceutical Science, Tohoku Pharmaceutical University, 4-1 Komatsushima 4-Chome, Aoba-ku, Sendai 981-8558, Japan. kyama@tohoku-pharm.ac.jp
authors.forename: Kouwa
authors.initials: K
authors.lastname: Yamashita
authors.forename: Madoka
authors.initials: M
authors.lastname: Takahashi
authors.forename: Satoshi
authors.initials: S
authors.lastname: Tsukamoto
authors.forename: Mitsuteru
authors.initials: M
authors.lastname: Numazawa
authors.forename: Mitsunobu
authors.initials: M
authors.lastname: Okuyama
authors.forename: Seijiro
authors.initials: S
authors.lastname: Honma
mesh_terms: D000305:Adrenal Cortex Hormones / Q000032:analysis* / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D006801:Humans; D015394:Molecular Structure; D010848:Picolinic Acids / Q000737:chemistry*; D015203:Reproducibility of Results; D012463:Saliva / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D000305:Adrenal Cortex Hormones; D010848:Picolinic Acids