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 2,7-Naphthalenedisulfonic acid, 5-[(1,8-dihydroxy-3,6-disulfo-2-naphthyl)azo]-4-hydroxy-3-[(8-hydroxy-3,6-disulfo-1-naphthyl)azo]-, hexasodium salt 3810-39-7 Calcichrome Calcion Calcion IREA NSC141149