A new colorimetric method for determination of alkylresorcinols in ground and whole-cereal grains using the diazonium salt Fast Blue RR

A fast and inexpensive method was developed to determine the content of alkylresorcinols (ARs) in ground and whole-cereal grains. This method is based on the ability of ARs to couple with Fast Blue RR salt in alkaline medium, yielding coloured azo-derivatives that can be quantified colorimetrically. Good linearity was observed for olivetol in the range of 1–10 μg with methanol as solvent (λmax = 480 nm) and 1–7 μg with butanol as solvent (λmax = 530 nm). Sensitivity obtained in butanol was comparable to that obtained in the Fast Blue B based method (methanol as solvent, λmax = 520 nm). In the new colorimetric method described here, incubation time was reduced to 20 min and the stability of the reaction products was as long as 3 h. The method appears promising for the analysis of 1,3-dihydroxybenzene derivatives in samples from plant breeding and food analyses.