Abstract
The construction and electrochemical response characteristics of Poly(vinyl chloride) membrane sensors for chlorpromazine HCl (CPZ) are described. The sensing membranes incorporate ion association complexes of chlorpromazine cation and phosphomolybdic acid (PMA) (sensor 1) or phosphotungstic acid (PTA) (sensor 2) or silicotungstic acid (sensor 3) as electroactive materials. The sensors display a fast, stable and near-Nernstian response over a relative wide chlorpromazine concentration range (1 x 10(-2) to 7.5 x 10(-5), 1 x 10(-2) to 6.0 x 10(-5), 1 x 10(-2) to 7.0 x 10(-6) M), with detection limits of 5 x 10(-5), 3 x 10(-5) and 5.0 x 10(-6) M for sensor 1, 2 and 3, respectively over a pH range of 3.0-6.0. The sensors show good discrimination of chlorpromazine from several inorganic and organic compounds. The direct determination of 200 mu g/ml of chlorpromazine show an average recovery 98.5, 99.0 and 98.5% and a mean relative standard deviation of 1.7, 1.5 and 1.7% for sensors 1, 2 and 3 respectively. The proposed sensors have been applied for direct determination of chlorpromazine in some pharmaceutical preparations. The results obtained by determination of chlorpromazine in tablets using the proposed sensors are comparable favorably with those obtained using the US Pharmacopeia method. The sensors have been used as indicator electrodes for potentiometric titration of chlorpromazine.