Potentiometric Flow Injection Analysis of Drotaverine Hydrochloride in Pharmaceutical Preparations

Abstract

 Five poly (vinyl chloride) (PVC) membrane electrodes for the determination of drotaverine hydrochloride (DvCl) were constructed and fully characterized in terms of composition, life span, response time, usable pH range, working concentration range, and temperature. The membranes of these electrodes consist of drotaverinium‐silicotungstate (Dv‐ST), silicomolybdate (Dv‐SM), phosphotungstate (Dv‐PT), phosphomolybdate (Dv‐PM), or tetraphenylborate (Dv‐TPB) ion associations dispersed in PVC matrix with dibutyl phthalate plasticizer. The electrodes showed near‐Nernstian response over the concentration range of 2.0 × 10⁻⁶ to 1.0 × 10⁻² M DvCl and were applied to the potentiometric determination of drotaverinium ion in pharmaceutical preparations in steady‐state and flow injection (FI) conditions with average recoveries of 98.1–102.2% and relative standard deviation of 0.308–1.310%. The electrodes exhibit good selectivity for DvCl with respect to a large number of inorganic cations, organic cations, sugars, and amino acids. The sensitivities of these electrodes are high enough to measure as low as 0.87 µg/mL of DvCl which permits the determination of the K _sp values of the ion associates used.

Keywords:

• Drotaverine hydrochloride
• ion‐selective electrode
• ion exchanger
• flow injection analysis
• urine
• PVC membrane