trisodium 1-[5-[[4-[bis[2-[(2-chloroethyl)sulphonyl]ethyl]amino]-6-chloro-1,3,5-triazin-2-yl]amino]-2-methyl-3-sulphonatophenyl]-4,5-dihydro-5-oxo-4-[(2-sulphonatophenyl)azo]-1H-pyrazole-3-carboxylate