Rapid Determination of Sulfur Dioxide in Foodstuffs by Single-Sweeping Oscillopolarography

In an acetate buffer of pH 5.0,sulfur dioxide was adsorbed on the dropping mercury electrode,producing a sensitive polarographic reduction wave at its peak potential (Ep) of -0.66 V (vs.SCE).The sensitivity of the 2nd derivative of its peak current (I″p) was raised by 0.81 times by the addition of N-cetyl pyridine chloride.Linear relationship between I″p and concentration of SO2 was obtained in the range of 0.2-6.0 mg·L-1,with a detection limit of 0.1 mg·L-1.Appropriate amounts of sulfide,nitrite and aldehydes were tolerable.In the application of the proposed method to the analysis of 18 kinds of foodstuffs,values of RSD′s (n=6) found were in the range of 0.1%-5.2%.Values of recovery found by the standard addition method were in the range of 90.0%-114.0%.