2-Naphthalenesulfonic acid, 6-(acetylmethylamino)-4-hydroxy-3-((3-phosphonophenyl)azo)-, diammonium salt 6-(Acetylmethylamino)-4-hydroxy-3-((3-phosphonophenyl)azo)-2-naphthalenesulfonic acid, diammonium salt 70815-22-4