Flow injection potentiometric determination of saccharin in dietary products with relocation of filtration unit

Abstract

A flow injection potentiometric procedure for saccharin determination in dietary products is proposed. Saccharin is precipitated as mercurous saccharinate and the excess of the mercurous cation is potentiometrically measured using a silver wire coated with a mercury film as the working electrode. A filter unit is used to avoid contact between the precipitate and the electrode surface. With relocation in the flow manifold, the accumulated precipitate is removed on-line. Sucrose, glucose, aspartame, sodium cyclamate and sodium benzoate do not interfere when present in amounts similar to those observed in commercial products. Results are comparable with those obtained by UV-spectrophotometry and the correlation coefficient between methods is equal to 0.9930. A linear relationship between Δ E (mV) and the logarithm of saccharin concentration was obtained in the saccharin concentration range 2 × 10 −3 - 1 × 10 −2 M. The sampling frequency is 60/hour and only 0.76 mg of Hg 2+ 2 is consumed in each determination.