[Use of gas chromatography for determining benzoic and sorbic acid levels in orange beverage and tomato concentrate].

Conditions of simultaneous determination of benzoic and sorbic acid in orange drink and tomato concentrate by gas chromatography method were developed and tested. Preservatives were isolated by extraction of the samples with diethyl ether in acidic media, and then converted into methyl esters with thionyl chloride. Methyl esters were separated on column packed with 15% EGA coated on 80-100 mesh Chromosorb W AW DMCS. The smallest amount of preservatives detectable on chromatography column is 20 ng for benzoic acid and 16 ng for sorbic acid. The recovery rate of the method ranged from 96-97% for benzoic acid and 89-92% for sorbic acid, while the variability coefficient was from 1.7-3.5% for benzoic acid and 4.5-6% for sorbic acid.