TMB Membrane Substrate is a ready to use solution. It contains 3,3′,5,5′-tetramethyl-benzidine (TMB) in a mildly acidic buffer in a one bottle format. TMB Membrane Substrate develops an insoluble, permanent dark blue reaction in the presence of peroxidase. The formulas are ready-to-use substrates featuring long-term stability and room temperature storage. These substrates are optimized for use with western blot, dot blot, and line assays. This substrate is not recommended for micro well or immune histochemical applications.