Determination of sulfur dioxide in food by ion chromatography

A method was developed for determination of sulfur dioxide residue in food by ion exchange method with conductivity detection.The sample was distilled under acidic conditions,received by oxidation in 3% hydrogen peroxide,and then determination by ion chromatography with conducting detection.The quantification was performed by external standard.IonPac AS11-HC(250 mm×4.0 mm i.d.) analytical column and AG11-HC(50 mm×4.0 mm i.d.)guard column was used,15 mmol/L KOH was used as mobile phase at a flow rate of 1 mL/min.The column temperature was set at 30 ℃,the detection cell temperature was set at 35 ℃.The calibration curves were linear between the peak area and the concentration in the range of 0.05～2 mg/L for sulfur dioxide,the correlation coefficients were greater than 0.999.The average recoveries spiked in food at the three concentration levels ranged from 88.29%～96.89% with the relative standard deviations of 3.29%～7.45%.