Preparation of sample solution for determination of acid coal-tar dyes in confectionery by the matrix solid-phase dispersion method

A simple and rapid procedure for sample preparation has been developed for determination of acid coal-tar dyes in confectionery by the matrix solid-phase dispersion (MSPD) method. Confectionery samples spiked with food dyes (12 permitted and 4 non-permitted in Japan) were blended with octadecylsilyl (C18)-derivatized silica packing material pretreated with cetyltrimethylammonium bromide-methanol. A column containing the C18/confectionery matrix was first washed with water, then the dyes were eluted with methanol. The eluate from the column was free from interfering compounds as confirmed by thin-layer and high performance liquid chromatography with UV detection at 254nm. Recoveries of acid coal-tar dyes from confectionery spiked at 100μg/g were 76.7-102.4%.