Red HE-3B or Reactive Red 120 has a formula of CHClNOS and a molecular weight of 1338.1 g/mol, containing two monochlorotriazine rings. It is highly soluble in water. The dehydrogenases binding ability of Red HE-3B is greater to NADP+ dependent dehydrogenases than NAD+ dependent dehydrogenases, vice versa for Cibacron Blue F3G-A.  It can be used to purify enterotoxins A, B, and C from Staphylococcus aureus using Procion Red HE-3B on sepharose, eluting out with 60 mM and 150 mM phosphate.