QUANTITATIVE HIGH-PERFORMANCE THIN-LAYER CHROMATOGRAPHIC DETERMINATION OF ORGANIC-ACID PRESERVATIVES IN BEVERAGES

A simple quantitative HPTLC method for determination of sorbic acid, b enzoic acid, dehydroacetic acid in beverages without extraction or cle anup is described. Aliquots of samples and standards are chromatograph ed on preadsorbent silica gel or C-18 bonded silica gel plates contain ing fluorescent indicator, and the zones, which quench fluorescence, a re compared by scanning densitometry. Recoveries of the acids from win e and juices spiked at 50-300 ppm averaged 98%, and the coefficient of variation of replicate analyses ranged from 2-5%. Commercial sodas co ntaining unknown amounts sodium benzoate and iced teas containing pota ssium benzoate were analyzed by the method, and the tea analyses were validated by standard addition. The advantages of the TLC method relat ive to current HPLC and absorption spectrometric procedures are descri bed.