ELECTROCATALYSIS AND MEASUREMENTS OF HYDRAZINE COMPOUNDS AT GLASSY-CARBON ELECTRODES COATED WITH ELECTROPOLYMERIZED 3,4-DIHYDROXYBENZALDEHYDE FILMS

Chemically modified electrodes exhibiting electrocatalytic response re wards hydrazine compounds were prepared by electroxidation of 3,4-dihy droxybenzaldehyde (3,4-DHB) on glassy carbon electrodes. The surface-c onfined quinone moiety accelerates the slow oxidation of hydrazine or its methylated analogs, and allows their convenient quantitation at ve ry low potentials. Cyclic voltammetry offers useful insights into the catalytic behavior. The electrocatalytic response is evaluated with re gard to pH, scan rate, applied potential, hydrazine concentration, flo w rate and other variables. When used as flow-injection detector, the 3,4-DHB modified electrode yields an extremely low detection limit of 5 x 10(-8) M (32 pg) hydrazine. Applicability to thick-film sensor str ips is also illustrated.