Analysis of Alkylresorcinols in Wheat Germ Oil and Barley Germ Oil via HPLC and Fluorescence Detection: Cochromatography with Tocols
2016
Moreau, Robert A. | Fang, Xuezhi
Alkylresorcinols are long-chain phenolic compounds that have been reported to be localized in the outer layers of the kernels of wheat, rye, barley, and other grains. A sensitive HPLC method with fluorescence detection was recently reported for the quantitative analysis of alkylresorcinols in cereal grains and products. Using this new HPLC method we report for the first time that wheat germ oil contains moderate levels of alkylresorcinols, approximately 800-1,300 pg per gram of oil. We also found that commercial wheat germ oil and some experimental samples of wheat germ oil and barley germ oil also contained three unknown peaks. Upon further evaluation of these peaks it was found that the peaks appeared to be tocopherols (one peak of a-tocopherol, one peak of 5-tocopherol, and a peak with the combination of B- and y-tocopherol), even though the excitation and emission wavelengths for alkylresorcinols (excitation 274 nm and emission 300 nm) are different than those for tocols (excitation 294 nm and emission 326 nm). We also found that with this HPLC system one alkylresorcinol, AR17, had the same retention time (7.6 min) as 5-tocotrienol and that another alkylresorcinol, AR19, had the same retention time (10.8 min) as a-tocotrienol.
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