Blue MX-R or Reactive Blue 4 has a formula of  CHClNOS and a molecular weight of 637.4 g/mol. It contains dichlorotriazine ring to the chromophore unlike Cibacron Blue F3GA. For a large scale protein purification, Blue MX-R can be used to purify protein such as lactate dehydrogenase (LDH). In fast-protein liquid chromatography (FPLC) using Blue MX-R immobilized on poly(glycidyl methacrylate-co-ethylene dimethacrylate) beads, it was seen to separate lysozyme and bovine serum albumin (BSA), purified lysozyme from chicken albumin.