Evaluation of an HPLC method for the determination of sulphiting agents in foods

Abstract

A method based upon a combination of a modified Monier‐Williams procedure and an HPLC separation and quantitation of sulphite, has been developed. Its efficiency has been tested, in comparison with the Monier‐Williams method, for the SO₂ recovery in various foods. Desorption of SO₂ from different matrices is obtained by distillation in strongly acid solution. Gaseous SO₂, collected and oxidized to sulphate with hydrogen peroxide, is neutralized with sodium hydroxide. The neutralized solutions are diluted and injected by an autosampling injector into an HPLC apparatus consisting of a strong anion exchange column, eluted with a potassium hydrogen phthalate solution (0.15 g/1, pH 5.7) at a 3 ml/min flow rate and detected at 280 nm by an UV spectrophotometer. The combined method shows a good detection limit as well as high chromatographic resolution, avoiding potential interference of other volatile compounds. It is also time‐saving and utilizes basic laboratory equipment.

Keywords:

• sulphiting agents
• food
• HPLC analysis