Custom TMB Substrate is a one bottle stabilized chromogenic substrate for use with horseradish peroxidase (HRP) immunoassays. It contains both 3,3,5,5 tetramethylbenzidine (TMB) and hydrogen peroxide (H2O2). Custom TMB Substrate develops a deep blue color in the presence of peroxidase labelled conjugate. This substrate has been optimized for use with microwell assays, especially ELISA. Custom TMB is not for use with assays requiring a precipitating substrate. Stable for a minimum of 36-months when stored at 2-8C.