Some Fundamental Experiments on the Differential Determination of Several Kinds of Preservatives in Foods by Steam Distillation Method

For the purpose of the simple and rapid determination of preservatives in foods, the combination method of the procedures of steam distillation and ultraviolet absorption spectra was studied. As the preservatives, five kinds of substances were taken up, namely benzoic acid (BA), p-hydroxybenzoic acid ester (PHBE), sorbic acid (SOA), dehydroacetic acid (DHA) and salicylic acid (SA). The steam distillation was done under the conditions of the addition of tartaric acid and magnesium sulfate or sodium chloride. The maximum wave lengths of each preservative in the aqueous solution at pH 2.0 were as follows: BA 230mμ, PHBE 255mμ, SOA 265mg, DHA 225mμ and 308mμ, SA 235mμ and 303mμ. In the case of the coexistence of the preservatives more than two kinds, the synthetic spectra of mixed preservatives are needed to be prepared previously. The interference by the scorch of the sample and the absorption appeared by the substances except preservatives were able to be almost excepted by the ether extraction of the distillate.