7-hydroxy-8-[[4-(6-methyl[2,6'-bibenzothiazol]-2'-yl)-2-sulphophenyl]azo]naphthalene-1,3-disulphonic acid, sodium salt

7-Hydroxy-8-[[4-(6-methyl[2,6'-bibenzothiazole]-2'-yl)-2-sulfophenyl]azo]-1,3-naphthalenedisulfonic acid/sodium,(1:x) salt