Determination of lipoic acid, Trolox methyl ether and tocopherols in human plasma by liquid-chromatography and ion-trap tandem mass spectrometry

作者：Montero Olimpio^*; Ramirez Maria; Sanchez Guijo Alberto; Gonzalez Constancio

来源：Biomedical Chromatography, 2012, 26(10): 1228-1233.

DOI：10.1002/bmc.2683

• HPLC-MS
• tocopherols
• lipoic acid
• Trolox
• antioxidants

A method for the simultaneous determination of lipoic acid and/or Trolox methyl ether, along with alpha-, gamma- and delta-tocopherol was developed using liquid chromatographytandem mass spectrometry with negative electrospray ionization (HPLC-ESI-MS/MS) in an ion-trap mass spectrometer. Detection and quantification were accomplished by a multiple reaction monitoring method, using specific transitions from precursor ion to product ion for each analyte. Chromatographic separation was achieved in a 12?min run using a C18-bonded phase and methanolaqueous ammonium acetate elution gradient. Linear correlations of the chromatographic peak area (r.u. x s-1) to the injected amount (ng) gave the slope values (r.u. x s-1?x?ng-1) 2.34?x?104 for gamma-tocopherol, 5.05?x?104 for gamma-tocopherol, 1.27?x?105 for delta-tocopherol, 8.86?x?105 for lipoic acid and 1.23?x?105 for Trolox methyl ether. The lower limit of quantification ranged between 0.02 and 1.22?ng for Trolox methyl ether and lipoic acid. MS3 experiments of gamma- and delta-tocopherol suggest ion-radical reactions and dependence of the tocopherol fragmentation pattern on the phenolic ring methylation degree. The method is shown to be applicable to measurement of these metabolites in human serum after extraction.

• 出版日期2012-10