[Nomenclature and Identification Method of Non-Permitted Dyes of Patent Blue Group]

Violation of the Food Sanitation Act regarding detection of Patent Blue V, which is one of the non-permitted dyes for food in Japan, in imported food occurs every year. With respect to the identification of dyes of Patent Blue group, in some cases, each dye has several different names, and in other cases, different dyes have the same name. Thus, there is a risk that the detected dye is misidentified with other dyes of Patent Blue group. In this study, nine commercial available dyes of Patent Blue group, including a reagent with unclear product information, were analyzed by TLC, HPLC and LC-MS/MS. The result showed that with all three methods, the dyes could be clearly identified into one of four types of blue dyes, i.e. Patent Blue V, Azure Blue VX, Isosulfan Blue and Alphazurine A. Unification of nomenclature would reduce the risk of misidentification of dyes of Patent Blue group.