Identification of Non-Permitted Dye Orange II Used in a Pickled Vegetable

Abstract

Orange II (O-II), which is a non-permitted dye for use in food in Japan, was found in a pickled vegetable. It was difficult to identify O-II by usual analytical methods for food dyes such as paper and thin layer chromatographies, because there are three isomers in total, Orange I (O-I), Orange RN (O-RN), and O-II. In order to reliably identify the dye in a pickled vegetable, thin layer chromatography (TLC), thin layer chromatography/fast-atom bombardment mass spectrometry (TLC/FABMS) and high performance liquid chromatography with a photodiode-array detector (PDA-HPLC) were employed. The Rf value and TLC/FAB mass spectrum of the dye suggested that the dye was O-II or O-RN. The retention time and ultraviolet/visible spectrum of the dye coincided with those of standard O-II, but were different from those of O-RN. Therefore, we concluded that the dye in the pickled vegetable was O-II.