Potentiometric Determination of saccharin in Dietary Products Using a Coated-carbon Rod Ion-selective Electrode

Publisher Website
Google Scholar
Abstract
The construction and analytical evaluation of coated-graphite saccharin ion-selective electrodes, based on the ion pair formed between saccharinate anion and basic dye cations incorporated in a poly(vinylchloride)(PVC) matrix, are described. Several basic dyes such as brilliant green, crystal violet, malachite green, methylene blue, Nile blue, rhodamine B, toluidine blue O, Victoria blue B and violet gentian were used in the preparation of the coated electrodes as anion-exchanger. Of those, only electrodes constructed with toluidine blue O, methylene blue, violet gentian and rhodamine B presented good responses. The influences of membrane composition, pH and foreign food additives were investigated. The best electrode found was 5:30:65%m/m (toluidine blue O cation)(saccharinate anion)/dibutylphthalate/PVC, respectively. This electrode shows a Nernstian response over the saccharin concentration range from 8.1×10−5 to 1.4×10−2 mol L−1, a detection limit of 6.3 10−5 mol L−1, good selectivity, precision and a useful lifetime of at least nine months (over one thousand determinations for each polymeric membrane) with a decrease of 5% of their initial potentiometric response (slope) at pH 2.5 (McIlvaine buffer). Sucrose, glucose, fructose, aspartame, cyclamate, sorbitol, lactose, benzoic acid, citric acid, fumaric acid, ascorbic acid, phosphate, nitrate and chloride do not interfere even in significant amounts. Application of this electrode for the determination of saccharin in several dietary products is reported.