An improved colorimetric method for the determination of alkylresorcinols in cereals and whole-grain cereal products

A rapid analytical method was developed to study the content of alkylresorcinols (ARs) in cereal grain material and the effects of processing on their amount in food. This method is based on the fact that ARs coupled with diazotized Fast Blue B Zn salt form colored derivatives in acidified methanol that can be quantified colorimetrically. The presented method is simple, sensitive (>0.1 μg), fast, accessible, and inexpensive. The standard calibration curve of the assay showed acceptable linearity in the range of 0.1–7 μg of homologue C15:0 (equivalent to 0.3–20 nmols) with a correlation coefficient of 0.999. The stability of the reagent used in the procedure was improved (to 4 days). The stability of the products of the reaction between the ARs and Fast Blue B Zn salt after 1 h of incubation was lengthened (to 3 h). This is an important aspect, especially when we analyze numerous cereal grain samples or carry out long-term experiments in which the use of a constant experimental environment (e.g. equipment, reagents, etc.) is crucial. The modified procedure presented here appears promising for the analysis of 1,3-dihydroxybenzene derivatives in biological samples, especially when screening numerous samples in plant breeding and food analyses.