Pyridinium, 1,1'-[sulfonylbis[3,1-phenyleneimino[6-[[3-[[3-carboxy-4,5-dihydro-5-oxo-1-(4-sulfophenyl)-1H-pyrazol-4-yl]azo]-4-sulfophenyl]amino]-1,3,5-triazine-4,2-diyl]]]bis[3-carboxy-, bis(inner salt), tetrasodium salt