Spectrophotometric Determination of Food Sulfite with Malachite Green

The optimum detecting conditions of sulfite determination in food were studied. The spectrophotometric method for sulfite determination in food was developed. The results showed that at 25℃ and in a solution of pH7.0 phosphate buffer medium, sulfite can cause a color-fading of the malachite green dye which has an absorption maxima at 615 nm. The determination of sulfite is carried out by measuring the intensity of color-fading. The linear range for determination of sulfite is found to be 0～ 0.6mg/L with a correlation coefficient of 0.9997 and the regression equation is ΔA=0.65C+0.0603. The detection limit and recovery rate of the method are 0.1μg/ml and 95.8%～103.1%, respectively. The proposed method is simple, convenient and highly sensitive, and has been applied to the determination of sulfite in food with satisfactory results.