CAS 66019-20-3 appears in our catalog under these names: Sodium 3-[2-(2-arsonophenyl)diazenyl]-4,5-dihydroxy-2,7-naphthalenedisulfonate (3:1), Arsenazo I, Arsenazo I Trisodium Salt, >90.0%(T). Offered by: Chemat, GLPBio, TCI. Available pack sizes: 1g, 5g.