Spectrum Chemical manufactures and distributes fine chemicals with quality you can count on including those with CAS number 23647-14-5, Whether you call it SPADNS or 4 -5-Dihydroxy-3-(4-sulfophenylazo)2 -7-naphthalenedisulfonic Acid Trisodium Salt you can be assured the products offered by Spectrum, meet or exceed the grade requirements or specifications for each individual product.