hexasodium 4,4'-bis[[4-chloro-6-[[3-[[1-(2,5-dichloro-4-sulphonatophenyl)-4,5-dihydro-3-methyl-5-oxo-1H-pyrazol-4-yl]azo]-4-sulphonatophenyl]amino]-1,3,5-triazin-2-yl]amino]stilbene-2,2'-disulphonate