Combined extraction and paper chromatography of food preservatives

Food preservatives—sorbic, benzoic, p-hydroxybenzoic acid and p-hydroxybenzoates—have been extracted from foods directly on to chromatographic paper with ethyl ether. Paper chromatographic separation of the extracted compounds was effected on the same paper. Methyl, ethyl and propyl p-hydroxybenzoates have been separated from each other during ether extraction and from the critical pair, the butyl and benzyl p-hydroxybenzoates, on a paper impregnated with sodium hydroxide. An examination was made of the reactions which distinguish sorbic and benzoic acids when both are present.