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 μL, 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 × 10⁻⁴ to 2.0 × 10⁻² mol L⁻¹, with a slope of −53.1 ± 0.4 mV/decade and a detection limit of 8.0 × 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. © 1999 John Wiley & Sons, Inc. Lab Robotics and Automation 11: 234–239, 1999