Determination of Carbinoxamine Maleate in Pharmaceuticals by Direct and Differential Pulse Polarography

A new, simple method for the determination of carbinoxamine maleate in pharmaceuticals, based on differential pulse polarography (DPP) and direct current polarography (DCP) in phosphate buffer pH = 1.69 are proposed. Diffusion currents (i(d)) and peak currents (I(p)) were measured on dropping mercury electrode (DME), static mercury dropping electrode (SMDE) and hanging mercury dropping electrode (HMDE) vs. Ag/AgCl. The half wave potential (E(1/2)) and peak potential (Ep) for the reduction of carbinoxamine maleate were occurred over the range from -645 to -650 mV. The calibration curves i(d) = f(C) and I(p) = f(C) were linear over the ranges 12.0-238.0 mu g mL(-1) and 0.95-476.2 mu g mL(-1) with the relative standard deviations (RSD) of 2.5 and 4.3% on DME using DCP and DPP, respectively. The proposed method was applied for the direct determination of carbinoxamine maleate in some pharmaceutical formulations (tablets, capsules, syrup and oral drops) by DPP in phosphate buffer pH=1.69 using DME, SMDE and HMDE. The obtained results showed that the difference between the expected and the found results values were less than 4% in the worst case and the RSD was less than 2.0%. Therefore, this polarographic method can be, for the first time, applied successfully for the determination of carbinoxamine maleate in pharmaceuticals.