4-methyl-2,6-bis[[2-(sulphooxy)ethyl]amino]-5-[[4-[[2-(sulphooxy)ethyl]sulphonyl]phenyl]azo]nicotinonitrile, sodium salt

4-Methyl-2,6-bis[[2-(sulfooxy)ethyl]amino]-5-[[4-[[2-(sulfooxy)ethyl]sulfonyl]phenyl]azo]-3-pyridinecarbonitrile/sodium,(1:x) salt