Structural determination of the subsidiary colors in Food Blue No. 1 (Brilliant blue FCF) aluminum lake detected by paper chromatography

colors in fiscal year 1999 had a violet sub-spot during paper chromatograph y and was rejected. To clarify the orgin of the sub-spot, the violet subsid iary color (Sub-V) was isolated from the sample. On the basis of NMR and MS analyses and ion chromatography, the structure of the subsidiary color was elucidated to be 2-[[4-[N-ethyl-N-(3-sulfophenylmethyl)amino]phenyl][4-hyd roxyphenyl]methylio]benzenesulfonic acid. The relative content of Sub-V to that of m,m-B-1 in the rejected sample was determined to be 39.5% by HPLC. The relative contents in other submitted samples of B-1Al were in the range of 1.1-3.6%.