To quantify glutathione (GSH), cysteine (CSH) as well as their respective disulfides GSSG and CSSC in cereal products and erythrocytes a stable isotope dilution assay was developed. Internal standards labelled with stable isotopes in different positions were used to study thiol-disulphide interchange reactions during sample preparation. The method included alkylation of free SH-groups using iodoacetic acid, acylation of amino groups with Dansyl chloride as well as separation and quantification by LC-tandem mass spectrometry. Thiol-disulphide interchange reactions were suppressed or at least minimized by dissolving the standard substances in perchloric acid. The new method was suitable to determine the concentrations of GSH, CSH, GSSG and CSSC in cereal products such as wheat, bread, germinated grains and also in human erythrocytes. It was shown that GSSG concentrations in erythrocytes, if detectable, were very low (lower µmol/L range).
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To quantify glutathione (GSH), cysteine (CSH) as well as their respective disulfides GSSG and CSSC in cereal products and erythrocytes a stable isotope dilution assay was developed. Internal standards labelled with stable isotopes in different positions were used to study thiol-disulphide interchange reactions during sample preparation. The method included alkylation of free SH-groups using iodoacetic acid, acylation of amino groups with Dansyl chloride as well as separation and quantification b...
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