Abstract:

The semimicro fractional distillation and the semiconducting refrigeration techniques were applied to the fast determination of sulfur  dioxide in foodstuffs. A novel distilling method which did not require mercuric  absorbent and cooling water was proposed. A fast distillation equipment which,  can complete the distillation of sulfur dioxide in foodstuffs in 15 min,  was developed. The effects of acidity, volume of sample solution, volume of distillate  and time of distillation on distillation yield of sulfur dioxide were studied. The calibration curve is linear at the mass SO₂ content  of 1.0-100.0 mg/kg sample,  the correlation coefficient is over 0.998, the lower limit of detection is 1.0 mg/kg.   With the method and the equipment mentioned above, the interference of the sample color and the pollution of the mercuric absorbent can be avoided, and the analysis of each sample can be completed in 30 min including the sample preparation time. More than 20 kinds of practical samples were analyzed.   The results  are in good agreement with the results obtained by the standard method, and the relative errors of determined values are less than 5% when the sulfur SO₂ concentrations are more than 10 mg/kg. 

Key words: Sulfur dioxide; Fast distillation; Food detection