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Gas chromatographic–mass spectrometric analysis of the tripeptide glutathione in the electron-capture negative-ion chemical ionization mode
- Tsikas, Dimitrios, Hanff, Erik, Kayacelebi, Arslan Arinc, Böhmer, Anke
- Amino acids 2016 v.48 no.2 pp. 593-598
- amino acids, esters, gas chromatography-mass spectrometry, glutathione, ionization, laboratory techniques, liquid chromatography, thiols
- The dicarboxylic tripeptide glutathione (GSH) is the most abundant intracellular thiol. GSH analysis by liquid chromatography is routine. Yet, GSH analysis by gas chromatography is challenged due to thermal instability and lacking volatility. We report a high-yield laboratory method for the preparation of ²H-labeled GSH dimethyl ester ((d₃Me)₂-GSH) for use as internal standard (IS) which was characterized by LC–MS/MS. For GC–MS analysis, the dimethyl esters of GSH and the IS were derivatized with pentafluoropropionic (PFP) anhydride. Electron-capture negative-ion chemical ionization of the (Me)₂-(PFP)₃-GSH provided high sensitivity. We encourage increasing use of GC–MS in the analysis of amino acids as their Me-PFP derivatives in the ECNICI mode.