The modification of glassy carbon (GC) with conducting polymer polypyrrole (PPy) by electrochem. technique, and the study on doping effect of Br-, and electrochem. behavior of PPy film electrode are reported. A new kind of Br- ion selective electrode was prepared successfully. The mechanism of the electrode potential response is based on the doping effect of anion in the conducting polymer. Effect of polymerisation conditions on the potential response characteristics is investigated in detail. The PPy-Br- ion selective electrode has the advantages of low resistance, fast response, resistance to poison and easy to make. The electrode shows a Nerst response for 1 ?10-4 - 1 ?10-1 MBr- with detection limit of 7 ?10-5 M and the slope of 61 mV/pBr-.

Key words: SENSORS, BROMIDE ION, CHEMICAL MODIFIED ELECTRODE, THIN FILM ANODES, POLYPYRROLE, CONDUCTING POLYMER, ELECTROCHEMICAL METHOD, DOPE EFFECT, GLASSY CARBON ELECTRODE