A Novel Clomipramine and Paroxetine-Selective Membrane Sensors and their Applications in Pharmaceutical Analysis

Selective electrodes based on the reineckate drugs ion pairs in a polyvinyl chloride (PVC) matrix membrane is proposed for the determination of clomipramine (CLO) and paroxetine (PRX) hydrochlorides. The ion-pair complexes of drug cations with reineckate anion are either dissolved in tetrahydrofuran solvent or dispersed in a PVC matrix, with dioctylphthalate or dioctyl sebacat plasticizers, and used as the ion-exchange membranes. The electrochemical response characteristics of electrodes incorporating these types of membranes are evaluated with regard to the effect of pH, foreign basic compounds, effect of soaking time and lifespan. A well defined internal electrode potential was achieved using Ag/AgCl disc in contact with the ion-pair electroactive membrane phase. The electrodes display a stable fast Nernstian response in the concentration ranges 10-2-10-7 mol L-1 for the two drug cations over the pH range 2-5, a short static response time less than 60 s and response remain stable for at least 6 weeks. The lower limit of detection was 10-7 mol L-1 for both drugs. Determination of as low as 8 μg mL-1 of drugs hydrochloride shows an average recovery of 98.75 and 100.6% and a mean standard deviation of 0.70 and 0.35 for CLO and PRX drugs, respectively. Selectivity coefficients for CLO and PRX drugs relative to a numbers of potential interfering substances were investigated. The electrodes exhibit useful analytical characteristics for determining CLO and PRX in some illicit powders. The results agree fairly well with those obtained by gas-liquid chromatography. The proposed electrodes are simple easy to construct and behave as symmetric ion selective electrodes (ISEs).