Determination of reduced glutathione using an amperometric carbon paste electrode chemically modified with TTF–TCNQ

The development of an amperometric sensor for the determination of reduced glutathione (GSH) is described. The sensor is based on tetrathiafulvalene–tetracyanoquinodimethane (TTF–TCNQ) incorporated into the graphite powder/Nujol oil matrix. The electrooxidation of GSH was monitored amperometrically at 200 mV versus SCE (saturated calomel electrode). The amperometric response of the sensor was linearly proportional to the GSH concentration between 20 and 300 μmol l−1, in 0.1 mol l−1 phosphate buffer (pH 8.0), containing 0.1 mol l−1 KCl and 0.5 mmol l−1 Na2H2EDTA, as supporting electrolyte. tection limit, considering signal/noise ratio equal three, was 4.2 μmol l−1 for GSH and the repeatability obtained as relative standard deviation was of 5.1% for a series of 10 successive measurements.