Specification Product Name SPADNS Synonyms 5-Dihydroxy-3-(4-Sulfophenylazo)-2,7-Naphthalenedisulfonic Acid trisodium salt; SPADNS; p-Sulfophenylazochromotropic Acid trisodium salt CAS NO. 23647-14-5 Molecular Formula C16H9N2Na3O11S3 Molecular Weight 570.42 Appearance Dark Reddish Brown Powder Structure     Tests    Limits Solubility 0.1% (dist. Water) - Clear Red Solution Absorptivity 1% / 1cm, at λ max.508.0 nm - >350 Dye Content (by spectrophotometry) - >80% Loss on Drying (110°C) - <10%         REVISED: 1-1-2012