Amperometric determination of ascorbic acid on screen-printing ruthenium dioxide electrode

Ruthenium oxide (RuO2) is commonly used in resistive pastes for screen prin ting. The electrochemical properties of a screen-printing planar RuO2 elect rode have hardly been studied. In this communication, planar electrochemica l sensors with a RuO2 working electrode, an AglAgCl reference electrode and a RuO2 counter electrode are fabricated by screen printing. The electro-ox idation of ascorbic acid, uric acid, and hydrogen peroxide on these RuO2 el ectrodes is investigated by means of cyclic voltammetry. Compared to uric a cid and hydrogen peroxide, ascorbic acid can be easily oxidized at the low operating potential ( < 150 mV versus AglAgCl). The amperometric measuremen t of ascorbic acid at 100 mV on a RuO2 electrode shows fast response and go od linearity in the 0-4 mM range. Meanwhile, the electrochemical interferen ce from uric acid and hydrogen peroxide at this potential is very small. (C ) 2000 Elsevier Science S.A. All rights reserved.