1H-Indole-7-sulfonic acid, 3-((2,5-dichloro-4-((ethylamino)sulfonyl)phenyl)azo)-2-methyl-, monosodium salt 3-(4-(N-Ethylsulfamyl)-2,5-dichlorophenylazo)-2-methyl-7-indolesulfonic acid, sodium salt 67786-20-3