Simultaneous determination of eight synthetic permitted and five commonly encountered nonpermitted food colors in various food matrixes by high-performance liquid chromatography.

A simple and sensitive HPLC method has been developed for the simultaneous determination of eight permitted food colors and five commonly encountered nonpermitted colors in various food commodities, including sugar-, fat-, and starch-based food matrixes. The method uses a specific food category-based cleanup/treatment procedure before color extraction to avoid the interference of food matrixes, and to obtain the optimal color extraction. Analysis was performed on a reversed-phase C18 micro-Bondapak column with ammonium acetate and acetonitrile gradient elution as the mobile phase; a programmable lamda max-specific visible detection was used to monitor colors to obtain the higher sensitivity and expanded scope needed for multicolor blends having diverse absorption maxima. All colors showed good linearity, with regression coefficients of 0.9974-0.9999. The LOD and LOQ values ranged from 0.01 to 0.12 mg/L, and from 0.04 to 0.83 mg/L or mg/kg, respectively. The intraday and interday precision tests produced good RSD values, and the recoveries from different food matrixes ranged from 82 to 104%. The method offers high sensitivity for analysis of a wide variety of food matrixes containing a broad scope of multicolor blends. Two nonpermitted colors, orange II and metanil yellow, were found. Also, a number of samples contained permitted colors at levels two- to seven-fold higher than those prescribed.