Modified Method for the Determination of Sulfur Dioxide in Malt

A method suitable for the routine determination of residua) sulfur dioxide in large numbers of malt samples is described. The technique is a modification of an existing method and is rapid and simple in that it involves no distillation or nitrogen stripping. Sulfur dioxide is extracted from ground malt with a di lute solution of sodium tetrachloromercurate and a colored complex is formed with para-rosaniline hydrochloride. The technique is sensitive and offers repeatability that is comparable to that of existing methods. Coefficients of variation on malts with mean sulfur dioxide levels of 5.8, 18.4, and 27.2 mg/kg were 5.9, 6.6, and 5.7%, respectively. The mean coefficient of variation calculated from data on three similar malts accumulated over a several month period averaged 9.5%. Data obtained were comparable and correlated very highly with that obtained by three more elaborate techniques.