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Determination of lipoic acid, Trolox methyl ether and tocopherols in human plasma by liquid‐chromatography and ion‐trap tandem mass spectrometry
Author(s) -
Montero Olimpio,
Ramírez María,
SánchezGuijo Alberto,
González Constancio
Publication year - 2012
Publication title -
biomedical chromatography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.4
H-Index - 65
eISSN - 1099-0801
pISSN - 0269-3879
DOI - 10.1002/bmc.2683
Subject(s) - chemistry , chromatography , ion trap , tandem mass spectrometry , lipoic acid , trolox , tandem , mass spectrometry , ether , top down proteomics , selected reaction monitoring , antioxidant , biochemistry , organic chemistry , antioxidant capacity , materials science , composite material
A method for the simultaneous determination of lipoic acid and/or Trolox methyl ether, along with α ‐, γ ‐ and δ ‐tocopherol was developed using liquid chromatography–tandem 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 C 18 ‐bonded phase and methanol–aqueous ammonium acetate elution gradient. Linear correlations of the chromatographic peak area (r.u. × s −1 ) to the injected amount (ng) gave the slope values (r.u. × s −1 × ng −1 ) 2.34 × 10 4 for α ‐tocopherol, 5.05 × 10 4 for γ ‐tocopherol, 1.27 × 10 5 for δ ‐tocopherol, 8.86 × 10 5 for lipoic acid and 1.23 × 10 5 for Trolox methyl ether. The lower limit of quantification ranged between 0.02 and 1.22 ng for Trolox methyl ether and lipoic acid. MS 3 experiments of γ ‐ and δ ‐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. Copyright © 2012 John Wiley & Sons, Ltd.