The TMB Substrate Set contains 110 ml TMB Substrate A and 110 ml TMB Substrate B, sufficient for twenty 96-well plates. It is formulated with 3, 3', 5, 5' tetramethyl benzidine (TMB). The substrate can be catalyzed with peroxidase to produce a pale blue color which can be read spectrophotometrically at 370 or 620-650 nm. The TMB reaction may be stopped with BioLegend's Stop Solution (Cat. No.?423001), and read at 450 nm.