ABSTRACT
Two unknown dyes (purple and purplish-red) were detected by TLC in two pickled vegetable (sakura-zuke daikon) samples containing Acid Red 52 (AR) and New Coccine as food colorants. HPLC with diode-array detection and LC/MS analyses suggested that the purple dye is monobrominated AR and the purplish-red dye is its N-desethyl derivative, which would be generated mainly during sample preparation. For the identification of the purple dye, a reference compound was prepared by bromination of AR followed by isolation of the monobrominated AR, the structure of which was elucidated as 4′-brominated AR (4′BrAR) by LC/ToF-MS and 1H-NMR spectroscopy. The purple dye was confirmed as 4′BrAR by comparison of its retention time, ultraviolet-visible spectrum and mass spectrum with those of the prepared reference compound. To our knowledge, this is the first report of the detection of 4′BrAR in foods.
Acknowledgement
The authors thank Haruko Sekido of Kanagawa Prefecture Institute of Public Health for her kind support in LC/TOF-MS analysis.
Disclosure statement
No potential conflict of interest was reported by the author(s).