Ion selective electrode for potentiometric determination of saccharin using a thin film of silsesquioxane 3-n-propylpyridinium chloride polymer coated-graphite rod

A polymer coated graphite rod ion selective electrode for saccharin was constructed and evaluated for the determination of saccharin in artificial table top sweeteners. The polymer consists of a thin film of silsesquioxane 3-n-propylpyridinium chloride. The electrode response was based on the ion pair formed between saccharinate acid the 3-n-propylpyridinium cation from the silsequioxane polymer. The electrode exhibits a Nernstian response for saccharin concentrations between 6.9x10(-6) and 5.3x10(-3) mol L-1 and a detection limit of 5.5x10(-6) mol L-1. The electrode response for saccharin was fast (10-20 s) and the potential independent of pH in the range of 3 to 7. The selectivity coefficients K-A,B(pot) for several anions usually present in commercial table top sweeteners were determined following the IUPAC recommendations. The potentiometric method with the ion selective electrode was validated by the HPLC reference method, through the determination of saccharin in commercial samples of table top sweeteners. The ion selective electrode is proved suitable for the routine quality control of table top sweeteners by potentiometry.