Electrocatalysis of NADH oxidation at a glassy carbon electrode modified with pyrocatechol sulfonephthalein

The pyrocatechol sulfonephthalein (PS) modified glassy carbon (PS/GC) elect rode, which was prepared by adsorption of PS on glassy carbon electrode sur face, shows electrocatalytic activity toward NADH oxidation with an overpot ential of ca. 310 mV lower than that of the bare electrode and a great enha ncement of the anodic currents. The electrocatalytic rate constant (k) was determined using rotating disk electrode measurements in Britton-Robinson b uffer solution at pH 7.0. It is found that the k is dependent on NADH conce ntration, the relation between k(-1) and c(NADH) can be fit to the line reg ression equation: 10(5) k(-1) (dm(3) mol(-1) s(-1))(-1) = 1.62286 + 0.65286 c(NADH) (mmol dm(-3)) with correlation coefficient of 0.99964. The experime ntal results also indicate that the presence of Ca2+ and Mg2+ in electrolyt e can drastically enhance the electrocatalytic currents of NADH oxidation. (C) 2000 Elsevier Science B.V. All rights reserved.