Comparison of GC and colorimetry for the determination of alkylresorcinol homologues in cereal grains and products

Cereal alkylresorcinols (ARs), a group of phenolic lipids mainly found in the outer parts of wheat and rye kernels, are currently being studied for possible use as biomarkers of intake of whole grain wheat and rye foods. Several different techniques have been used for quantitative AR analysis over the years, but with limited attempts to compare them. In this present study, two commonly used methods, gas chromatography and colorimetry, were evaluated and compared. Gas chromatographic and the colorimetric methods showed good agreement. The GC-method provides the total amount of AR and relative homologue composition, whereas the colorimetric method, which is based on azo-coupling of a Fast Blue salt to the hydroxyl group(s) in the alkylresorcinol molecule, only provides the total amount, but is much faster and does only requires a UV-spectrophotometer.