A NEW ULTRAMICROSENSOR FOR NITRIC-OXIDE BASED ON ELECTROPOLYMERIZED FILM OF NICKEL SALEN

A new amperometric ultramicrosensor for the determination of nitric ox ide (NO) is described. The ultramicrosensor, which is based on an elec tropolymerized film of ethylenebis(salicylideneiminate) nickel [Ni(sal en)] and Nafion, shows a low detection limit, high selectivity and sen sitivity to NO determination. The oxidation current (measured by a dif ferential pulse amperometric method) is linear with NO concentration r anging from 1.0 x 10(-8) to 4.0 x 10(-6) mol/L with a calculated detec tion limit, at a signal to noise ratio of three, equal to 5.0 x 10(-9) mol/L. Some endogenous electroactive substances in biological tissues , such as dopamine, 5-HT and nitrite do not interfere with NO determin ation at the concentrations higher than those in biological systems. T he ultramicrosensor could be employed for in vivo measurements of NO. The mechanism of the response of the ultramicrosensor to NO is also st udied.