GC Determination of Dehydroacetic Acid in Food with Capillary Column

Gas chromatography with capillary column was applied to the determination of dehydroacetic acid (DHA) in food. For samples containing less moisture, DHA was separated from 5.000 g of sample by extraction from a solution containing 10 mL of sat′d NaCl solution (saturated also with acetonitrile), 4-5 g of NaCl, 200 μL of glacial acetic acid and 5 mL of acetonitrile. After vigorous shaking and centrifugation, 2.00 mL of the supernatant were taken and treated with 80 μL of 50 g·L-1 benzoic acid solution and 300 mg of anhydrous MgSO4 by centrifugation. Benzoic acid was added as a protectant for the analyte. For wet samples, 10.000 g of the sample were taken and the extraction was carried out in a solution containing 250 μL of glacial acetic acid, 10 mL of acetonitrile, 1 g of NaCl and 4 g of anhydrous MgSO4. After shaking and centrifugation, 2.00 mL of the supernatant were taken and treated further as described above. The supernatant finally obtained was used for the GC analysis. HP-5 capillary column and flame ionization detector were adopted in the determination. Linearity range for DHA was found between 2.5-1 000 mg·L-1 with the lower limit of determination (10S/N) of 0.005 g·kg-1. Recovery and precision were tested on 3 kinds of food at 4 concentration levels, giving results of recovery ranged from 84.3% to 107.9% and RSD′s (n=6) ranged from 2.6% to 4.5%.