Abstract
Thin layer chromatography was applied ta the detection of benzoic, salicylic, dehydroacetic, and sorbic acids, ethyl, propyl and butyl esters af p-hydroxybenzoate and dulcin. Kieselgel G activated at 80°C for 30 minutes or Wakogel B-5 activated at 100°C for 30 minutes was used. For the detection of the spots, 1% ferric chloride solution, 0.1% bromcresolgreen alcohol solution and 1% potassium permanganate solution were successively sprayed. The chromatoplate was developed with chloroform-propionic acid (4: 1) mixture for the group separation of the esters, the acids and dulcin.
Chloroform-ethyl acetate (9: 1) mixture was used for the separation of sorbic acid from benzoic acid and dehydroacetic acid, and also for the identification of esters (as p-hydroxybenzoic acid). The preservatives were clearly separated with n-heptane-propionic acid (4: 1) mixture, by which the good separation of dehydroacetic acid from benzoic acid and sorbic acid has been achieved.
