邻苯二胺二盐酸盐（OPD）是一种显色底物，因为利用辣根过氧化物酶缀合物，因此可用于酶联免疫吸附试验（ELISA）程序。底物产生可溶的最终产物，其颜色为橙棕色，并且可以在450 m下通过分光光度计读取。可以用3N HCl或3M H2SO4终止OPD反应，并在492 nm处读取。 o -Phenylenediamine dihydrochloride (OPD) is a chromogenic substrate that can be used in enzyme-linked immunosorbent assay (ELISA) procedures as it utilizes horseradish peroxidase conjugates. The substrate produces a soluble end product that is orange-brown and can be read spectrophotometrically at 450 nm. The OPD reaction may be stopped with 3N HCl or 3M H2SO4 and read at 492 nm.