Determination of some heterocyclic aromatic amines in soup cubes by ion-pair chromatography with coulometric electrode array detection

Abstract

An analytical method based on ion-pair chromatography with coulometric electrode array detection was developed for determination of four heterocyclic aromatic amines (IQ, MeIQx, 4,8-DiMeIQx and 7,8-DiMeIQx). These compounds are eluted isocratically (960 ml of a solution containing 30 mM trichloroacetic acid and 50 mM sodium acetate adjusted with glacial acetic acid to pH 2.5 are mixed with 40 ml tetrahydrofuran) from a phenyl–hexyl phase and are detected in a coulometric array detector. The working potentials of the four cells are set at +350, +690, +160 and +10 mV against modified palladium electrodes. The detection limits ( S/ N=3) depend on the working potential and are found between 0.1 and 1.1 ng injected. In commercial soup cubes, IQ, MeIQx and 4,8-DiMeIQx are present in concentrations between 0.3 and 2.8 ng/g. The recovery (54.8–100.9%) is influenced by the food matrix. The limits of quantitation are between 0.2 and 2.3 ng/g ( S/ N=5).