Description
This method describes quantitative determination of benzoic, sorbic acid and methyl, ethyl and propyl p-hydroxybenzoic acid esters. The preservatives are extracted from the food with a mixture of methanol and water. After filtration and iso-cratic reversed phase liquid chromatographic separation on a C-18 column, the preservatives are detected by means of a UV detector at 235 nm. Two different mobile phases are used, one for the separation of the free acids and one for the p-hydroxybenzoic acid esters. For the five preservatives the detection limit of the method is 5 mg/kg or lower.