Brilliant Blue FCF consists essentially of disodium α-(4-(N-ethyl-3- sulfonatobenzylamino) phenyl)-α-(4-N-ethyl-3-sulfonatobenzylamino) cyclohexa-2,5-dienylidene) toluene-2-sulfonate and its isomers and subsidiary colouring matters together with sodium chloride and/or sodium sulphate as the principal uncoloured components.
Chemical name: Disodium α-(4-(N-ethyl-3-sulfonatobenzylamino) phenyl)-α-(4-N- ethyl-3-sulfonatobenzylamino) cyclohexa-2,5-dienylidene) toluene-2- sulfonate
Appearance: Reddish-blue powder
Appearance of the aqueous solution: Blue