Amperometric assay of glutathione in whole blood and serum

The anodic steady state current by a sulfhydryl compound in concentrations about 10 muM at a dialysis membrane covered phthalocyanine-embedded carbon paste electrode (mCoPCPE) completely vanished after the addition of N-ethylmaleimide (NEM) in double concentrations of the sulfhydryl compounds. The concentrations of reduced glutathione (GSH) in whole blood and serum were determined by measuring the current decrease at 150 mV after the addition of NEM in blood solutions of pH 6.8. This method has the advantage of eliminating the procedures for deproteinization. The correlation coefficients between the GSH concentration determined in this method and those by a spectrometric measurement were 0.98 and 0.90 for 10 whole blood and 15 serum samples, respectively.