Our Amplite ADHP is a sensitive fluorogenic peroxidase substrate that has much lower background than the material from other commercial vendors. ADHP generates highly fluorescent resorufin that has maximum absorption of 571 nm and maximum emission of 585 nm. Unlike other HRP substrates such as dihydrofluoresceins and dihydrorhodamines, the air-oxidation of ADHP is minimal. So far ADHP has been known as the most sensitive and stable fluorogenic probe for detecting HRP and H2O2. ADHP has been widely used to detect HRP in many immunoassays. On the other hand, ADHP can also be used to detect trace amount of H2O2. The ADHP-based H2O2 detection is at least one order of magnitude more sensitive than the commonly used scopoletin assay for H2O2. Because H2O2 is produced in many enzymatic redox reactions, ADHP can be used in coupled enzymatic reactions to detect the activity of many oxidases and/or related enzymes/substrates or cofactors such as glucose, acetylcholine and cholesterol, L-glutamate, amino acids, etc.