Abstract
It is known that Blue No. 1 (B1; brilliant blue FCF) in an alkaline solution can be decomposed on heating. However, it is also known that the color tone of B1 when in alkaline solution form does not change at room temperature. In this study, the heating decomposition of B1 in an alkaline solution was examined using liquid chromatography/mass spectrometry (LC/MS) and HPLC. As a result, the generation of ethylamino subsidiary (B1sub-EA) and phenol subsidiary (B1sub-HP) colors that existed in commercial B1 were confirmed. The generation of B1sub-EA was very limited, and most of the decomposition of B1 was B1sub-HP that showed in a purplish-red color. It had been suggested that B1sub-HP should change into an oxocyclohexadienylidene subsidiary color (B1sub-OCD) when in an alkaline solution. It has been suggested that the isomerization of B1 should similarly proceed to the quarter ammonium hydroxide form of cyclohexadienylidene with the same maximum wavelength, The effect of temperature on decomposition was also observed. It is suggested that the color tone of B1 when in an alkaline solution should not change in a short time because the decomposition of B1 is slow at a low temperatures.
