5-[[[3-carboxy-4-[[1-[(2-methoxy-5-sulphoanilino)carbonyl]-2-oxopropyl]azo]anilino]carbonyl]amino]-2-[[2-oxo-1-[(4-sulphoanilino)carbonyl]propyl]azo]benzoic acid, sodium salt

5-[[3-Carboxy-4-[1-[(2-methoxy-5-sulfophenyl)aminocarbonyl]-2-oxopropylazo]phenyl]aminocarbonylamino]-2-[2-oxo-1-[(4-sulfophenyl)aminocarbonyl]propylazo]benzoic acid/sodium,(1:x) salt