2,7-Naphthalenedisulfonicacid,4-amino-6-[2-[4-[[[4-[2-(2,4-dihydroxyphenyl)diazenyl]phenyl]amino]sulfonyl]phenyl]diazenyl]-5-hydroxy-3-[2-(4-nitrophenyl)diazenyl]-,lithium salt (1:2)