Potentiometric quantification of saccharin by using a selective membrane formed by pyrrole electropolymerization

Abstract

A selective membrane for direct quantification of saccharinate ion based on a polypyrrole-doped membrane is developed. The membrane is electrochemically prepared using stainless steel as working electrode. Potentiostatic variables for membrane growing such as pyrrole concentration, saccharinate concentration, applied potential and deposition time are optimized in order to maximize sensitivity. The optimized membrane was analytically characterized by means of calibration curves, the detection limit was found to be 3.6 × 10 −4 mol L −1 and the quantification limits were found between 5 × 10 −4 mol L −1 and over 1 mol L −1. Selectivity of the membrane is evaluated for different inorganic anions, resulting in the following selectivity coefficients: p K Saccharinate,Citrate = 3.4, p K Saccharinate, H 2 PO 4 = 3.4, p K Saccharinate, HPO 4 2 - = 3.4 and p K Saccharinate, HPO 4 2 - = 2.5 . These results demonstrate an adequate performance of the proposed selective polypyrrole membrane so it can be considered as an alternative to traditional analytical methods for the direct quantification of saccharin in diverse samples.