Spectrum Chemical manufactures and distributes fine chemicals with quality you can count on including those with CAS number 72-57-1, Whether you call it Trypan Blue, Direct Blue 14 , Congo Blue 3B , Niagara Blue 3B or Tetrasodium 3 -3'-[(3 -3'-dimethylbiphenyl-4 -4'-diyl)bisazo]bis[5-amino-4-hydroxynaphthalene-2 -7-disulphonate] you can be assured the Trypan Blue products offered by Spectrum, meet or exceed the grade requirements or specifications for each individual product.