Amperometric Sensor for Glutathione Based on a Mechanically Immobilized Cobalt Hexacyanoferrate Modified Electrode

A mechanically immobilized cobalt hexacyanoferrate modified electrode has been constructed. The modified electrode exhibits two reversible redox peaks in a 0.1 M NaCl medium, and can be used for the amperometric determination of glutathione. The modified electrode facilitates the catalytic oxidation of glutathione at a reduced overpotential compared with an unmodified graphite electrode. Glutathione was determined in the range of 4 × 10-5 to 5.2 × 10-4 M in 0.1 M NaCl and in 0.1 M KCl with correlation coefficients of 0.9991 and 0.9992, respectively. Relative standard deviations of 2.88% in NaCl and 3.27% in KCl were obtained for 4 × 10-4 M GSH (n = 10). The sensor exhibited excellent stability, reproducibility and immediate response, and can be used in flow-injection analysis.