2,7-Naphthalenedisulfonic acid, 5-((1,8-dihydroxy-3,6-disulfo-2-naphthalenyl)azo)-4-hydroxy-3-((8-hydroxy-3,6-disulfo-1-naphthalenyl)azo)-, hexasodium salt 3810-39-7 Calcichrome Calcion Calcion IREA EINECS 223-283-4 NSC 141149 Sodium 5-((1,8-dihydroxy-3,6-disulphonaphthalen-2-yl)azo)-4-hydroxy-3((8-hydroxy-3,6-disulphonaphthalen-1-yl)azo)naphthalene-2,7-disulphonate