Flow injection potentiometric determination of saccharin in dietary products using a tubular ion-selective electrode

The construction and analytical evaluation of a tubular ion-selective electrode coated with an ion pair formed between saccharinate anion and toluidine blue O cation incorporated on a poly(vinylchloride) (PVC) matrix was constructed and adapted in a flow-injection (FI) system. The optimum experimental conditions found were an analytical path of 120 cm, an injection sample volume of 500 mu L, a pH of 2.5, a flow rate of 2.3 mL min(-1), and a tubular electrode length of 2.5 cm. The linear response to saccharin concentration ranged from 1.0 x 10(-4) to 2.0 x 10(-2) mol L-1, with a slope of - 53.2 +/- 0.4 m V/decade and a detection limit of 8.0 x 10(-5) mol L-1. The analytical frequency was 40 determinations h(-1) , and this system was used with success for saccharin determination in several dietary products. (C) 1999 John Wiley & Sons, Inc.