GLUTATHIONE AND CYSTEINE MEASUREMENT IN BIOLOGICAL SAMPLES BY HPLC WITH A GLASSY-CARBON WORKING DETECTOR

An HPLC method using a glassy carbon working detector for measuring cy steine and reduced glutathione (GSH) in biological samples was develop ed. Oxidized glutathione (GSSG) was also measured after reduction with glutathione reductase. This study was conducted in human plasma. Cyst eine and GSH standard curves were linear in the physiological range, p resenting detection limits of 22.0 pmol and 6.0 pmol respectively. Pla smatic results found were 43.92 +/- 4.15, 4.50 +/- 0.65, and 0.19 +/- 0.12 mM (means +/- SE), for cysteine, GSH and GSSG, respectively. Peak specificity for cysteine and reduced glutathione was certified by the ir disappearance after treatment with N-ethylmaleimide.