This European Standard specifies an enzymatic method for the determination of the sulfite content, expressed as sulfur dioxide, in foodstuffs. Other sulfur-containing substances such as sulfate, sulfide or thiosulfate do not interfere with the determination. Carbonal-sulfite complexes react as free sulfites. Isothiocyanates occuring in, e.g. mustard interfere with the determination. The method is not applicable to cabbages, dried garlic, dried onions, ginger, leeks and soy protein. It has been shown that the analysis of isolated soy protein leads to false positive results.