RAPID HPLC DETERMINATION OF SACCHARIN BENZOIC ACID SORBIC ACID AND CAFFEINE IN FOODSTUFFS

HPLC is applied to the separation and determination of saccharin, benzoic acid, sorbic acid and caffeine in foodstuffs. A pretreatment of the sample with dilute sodium hydroxide solution and zinc sulfate solution to render the above mentioned compounds becoming water soluble as sodium salts and to remove the co-existing proteins and starch by precipitating with zinc sulfate. The filtrate is further filtered with filtering membrane of 0. 45 μm, and an aliquat of 20 μL is taken for the HPLC analysis. Hypersil-ODS2-C18 is used as the chromatographic column, and a solution, containing methanol and 0. 02 mol·L-1 ammonium acetate solution mixed in the ratio of 35 to 65, is used as the mobile phase. The four compounds mentioned above are separated and determined simultaneously. Qualitative analysis is performed according to the retention time, and quantitative analysis is carried out according the values of peak height. The detection limits obtained are as follows: saccharin 0. 14 mg·L-1, benzoic acid 0. 20 mg·L-1, sorbic acid 0. 22 mg·L-1 , caffeine 0. 21 mg·L-1, The precision and accuracy of this method are satisfactory.