A CARBON-PASTE ELECTRODE CHEMICALLY-MODIFIED WITH A PHENOTHIAZINE POLYMER DERIVATIVE FOR ELECTROCATALYTIC OXIDATION OF NADH - PRELIMINARY-STUDY

A new kind of chemically modified electrode for electrocatalytic oxida tion of NADH is described. Carbon paste (graphite : paraffin oil) elec trodes are chemically modified with the addition of an aqueous insolub le polymer containing a covalently bound phenothiazine dye, Toluidine Blue O, through an amide linkage between a primary amine group of the Toluidine Blue O moiety and the polymer backbone. Some basic propertie s of this chemically modified carbon paste electrode for the electroca talytic oxidation of NADH are described, using cyclic voltammetry, as are the properties when the electrode is used as an amperometric senso r for NADH in a flow injection system. At an applied potential of +100 mV vs. Ag/AgCl, the detection limit for NADH was 0.4 muM.