Application of 4-Phenyl-1, 2, 4-triazoline-3, 5-dione for the Analysis of Sorbic Acid in Foods

Sorbic acid isolated from foods through steam distillation was extracted with ether, followed by the addition of dioxane and concentration under reduced pressure until the ether vapor was removed. Sorbic acid in the resulting solution was treated with 4-phenyl-1, 2, 4-triazoline-3, 5-dione in dioxane at 70°C, followed by methylation of the resultant Diels-Alder adduct with an ethereal diazomethane to give the corresponding methyl ester as a volatile compound for the determination using the GC method. Compared with the detection by FID, that by FTD was found to be about 100 times, since the volatile compound has three nitrogen atoms which are characteristic for FTD in the molecule. Accordingly, the GC method using 4-phenyl-1, 2, 4-triazoline-3, 5-dione is applicable to the microanalysis of sorbic aci