Overoxidized poly{pyrrole-co-[3-(pyrrol-1-yl)propanesulfonate]}-coated platinum electrodes for selective detection of catecholamine neurotransmitters

The cation-exchange and anion-exclusion properties of the poly{pyrrole-co-[3-(pyrrol-1-yl)propanesulfonate]}-(PPy-PS) copolymer are exploited for imparting higher selectivity to measurements of primary neurotransmitters in the presence of ascorbic acid. Such incorporation of ionizable sulfonated groups in the pyrrole ring prior to its electropolymerization leads to effective rejection of the anionic ascorbate species and preferential collection of the cationic dopamine and norepinephrine. Overoxidized PPy-PS films thus offer better discrimination against ascorbic acid than Nafion or overoxidized polypyrrole coatings. Experimental variables influencing the permselective behavior of the PPy-PS layer, including the electropolymerization time and solution pH, were explored. The selectivity and sensitivity improvements associated with the increased electrostatic character of overoxidized polypyrrole films hold promise for neurochemical electrochemical studies.