CHARACTERIZATION AND QUANTITATIVE-DETERMI NATION OF TOCOPHEROLS AND GALLATES IN ESSENTIAL OILS

Antioxidants: butylhydroxyanisole, butylhydroxytoluene, propyl-, octyl - and dodecyl- gallates, and natural or synthetic tocopherols, can be legally used in essential oils with a maximal amount of 1 g . kg(-1). Detection and quantitative determination of tocopherols and gallates r equire specific analyses. High performance liquid chromatography (HPLC ) and capillary gas chromatography (GC) have been used to test 13 esse ntial oils. HPLC chromatograms after direct injection of the essential oils show, in most samples, peaks with retention times corresponding to those of the studied antioxidants. However, the UV spectra recorded on a photodiode array detector were different from the reference ones . GC analyses for the tocopherols were carried out by direct injection of samples, and after silylation fair the gallates. There was no inte rference between the antioxidants and the essential oils constituents. After optimization of the separation, the quantitative GC determinati ons could be carried out using hexacosanol as internal standard for th e alpha-tocopherol determination, and cholesterol in the case of the g allates. The regression lines and correlation coefficients were determ ined for alpha-tocopherol, and the propyl-, octyl-, dodecyl- gallates; the detection limits were found to be respectively 120 and 60 mg . kg( -1) for the alpha-tocopherol and the gallates.