Development and validation of a micromethod for fast quantification of 5-n-alkylresorcinols in grains and whole grain products

Abstract

A 96-well plate micromethod was developed to measure 5-n-alkylresorcinols (5nARs) in cereal grains and food derived products. The 5nARs reacted in alkaline alcoholic medium with Fast Blue RR ½ZnCl2 salt to yield coloured azo-derivatives. The highest sensitivity for 5nARs was obtained at 490nm with 0.025% ethanolic Fast Blue RR and 5% K2CO3. This reaction showed good linearity for olivetol (0.05–0.20μg). Contents of 5nARs determined in cereal grains and derived products by the new Fast Blue RR micromethod were highly correlated (R2=0.9944) with those obtained by a Fast Blue B method currently used. A Bland–Altman analysis indicated a small positive bias near to zero (R2=0.0401), suggesting that the methods can be interchangeably used. The new reaction is completed in 15min and the coloured products are read within the 15min after completion. The micromethod offers a fast analysis of 5nARs in cereal grains and derived products with low consumption of reagents and solvents.