CR-3, or Coating Reagent 3, is an essential component in separation buffer that coats the inner channels of a microfluidic chip to prevent the adsorption and build-up of substrate peptides and other assay components. CR-3 is already present in ProfilerPro Separation Buffer (#760367) at a concentration of 0.1% and does NOT need to be added to Separation Buffer unless you are making your own formulation.