A NEW NAFION-FREE BIPOLYMERIC SENSOR FOR SELECTIVE AND SENSITIVE DETECTION OF NITRIC-OXIDE

An amperometric/voltammetric sensor for the determination of nitric ox ide based on its oxidation on a glassy carbon (GC) electrode modified by polymerized nickel(II) tetrakis(4-hydroxy-3-methoxyphenyl)porphyrin (NiTHMPP) and additionally covered by polymerized eugenol (4-allyl-2- methoxyphenol) (PE) is described. Cyclic voltammetry was used to compa re the performance of Nafion and PE as selective membranes for NO sens ors. Our findings showed that the electrodes with PE can be successful ly applied to NO detection either by DPV (oxidation peak appeared at 0.75 V vs. Ag/AgCl) or by amperommetry at +0.8 V. The electrodes were very sensitive to NO : with detection limit of 85 nM (S/N = 3), and at the same time were also very selective against ureate (>10(4):1), asc orbate (>5 x 10(3):1) and nitrite (>10(3):1). Moreover: PE coated elec trodes, comparing with those with Nafion, displayed significantly bett er selectivity against positively charged species: dopamine (ca. 80:1) and epinephrine (ca. 150:1).