The total concentrations of four sulfur amino acid (SAA) metabolite redox couples (reduced
and oxidized forms of homocysteine, cysteine, glutathione, and cysteinylglycine) in human
blood are assayed with a simple and sensitive method by liquid chromatography–
electrospray positive ionization–tandem mass spectrometry. To prevent ex vivo thiol
oxidation, iodoacetamide (IAM) is used immediately following the blood draw. To selectively
enrich for S-carboxyamidomethylated SAA, and other cationic amino acids metabolites …