Electrochemical Response Characteristics and Analytical Application of Papaverine Ion‐Selective Membrane Electrodes

The construction and electrochemical response characteristics of poly(vinyl chloride) matrix ion‐selective electrodes (ISEs) for papaverine hydrochloride are described. The membranes incorporate ion association complexes of papaverine with tetraphenylborate {[B(C6H5)4]−}, picrate {[C6H2(NO2)3O]−}, tetraiodomercurate [(HgI4)]2−, tetraiodobismuthate [(BiI4)−], Reinecke salt {[Cr(NH3)2(SCN)4]−} and heteropolycompounds of Keggin structure–molybdophosphoric acid [H3(PMo12O40)], tungstophosphoric acid [H3(PW12O40)], molybdosiliconic acid [H4(SiMo12O40)], and tungstosiliconic acid [H4(SiW12O40)] as electroactive materials for ionometric sensor controls. These ISEs show linear response for papaverine hydrochloride over the range from 1×10−5 up to 5×10−2 mol/l with cationic slopes from 42 up to 58 mV per concentration decade. These ISEs exhibit fast response time (up to 1 min), low determination limit (up to 1×10−5 M), good stability (3–5 weeks) and reasonable selectivity. The ISEs were used for direct potentiometry and potentiometric titration {Na[B(C6H5)4]} of papaverine hydrochloride in pharmaceutical preparations. Results with mean accuracy of 98.6±0.9% of nominal were obtained, which correspond well to data obtained with the European Pharmacopoeial method.