A membrane sensor for selective determination of bisacodyl in tablets

Abstract

A novel PVC membrane sensor for bisacodyl based on bisacodyl-phosphotungstate ion pair complex was prepared. The influence of membrane composition (i.e. percent of PVC, plasticizer, and ion-pair complex), pH of test solution and foreign cations on the electrode performance were investigated. The optimized membrane demonstrates Nernstian response (60.3 +/- 2.1 mV per decade) for bisacodyl cations over a wide linear range from 8.0 x 10(-5) to 5.0 x 10(-3) M at 25 degrees C. The potentiometric response is independent from the pH of the solution in the pH range of 1.5-3.5. The proposed sensor has the advantages of easy preparation, good selectivity, fast response time, and small interferences from hydrogen ions. It was successfully used for determination of bisacodyl in tablets, and the results obtained with the electrode were in good agreement with the official chromatographic method.