Pyridinium, 1-[4-[[4-[(4-amino-9,10-dihydro-9,10-dioxo-3-sulfo-1-anthracenyl)amino]cyclohexyl]amino]-6-[(2,5-disulfophenyl)amino]-1,3,5-triazin-2-yl]-3-carboxy-, inner salt, sodium salt (1:3)