ep(HS)TMB-mA is a precipitating peroxidase substrate containing 3,3',5,5'-tetramethylbenzidine (TMB) and hydrogen peroxide in an aqueous buffer formulation. This product is supplied as a one component ready to use solution. Intact substrate is clear colorless to slightly yellowish in appearance. Positive reaction results in precipitating of insoluble permanent dark blue product at the sites of enzymatic HRP activity (where detecting HRP-labeled anti-analyte is bound). This product is in particular developed for using in High Sensitivity binding (Immuno)Assays designed in microArray/microChip format.