The degradation pathway of E133 dye was investigated, when a commercial beverage containing the dye was subjected to summer sunlight and temperature. The study employed HPLC-DAD and HPLC–MS n analyses, conducted on both the beverage and model solutions subjected to sunlight irradiation.The results indicate that E133 was not present in the beverage after 16 days of irradiation and that the degradation products are formed only after long exposure times. Possible structures are proposed but their identification was made difficult by the formation of adducts with other ingredients present. Solid Phase Extraction (SPE) was developed to lower the matrix interferences.