The chromogen substrate DA64 has more advantages in the detection system of peroxidase, with molecular formula C19H23N4NaO3, molecular weight 378.39, full name N - (carboxymethyl amino carbonyl) -4,4 '- bis (dimethylamino) diphenylamine sodium, appearance white to green brown or gray green, crystalline powder to powder. Every 100g of water can dissolve 40mg of DA64, dissolved in water at a concentration of 1 mM or more. From a molecular structure perspective, DA64 is similar to Trinder's reagent or TMB, both containing aniline structures. After POD catalytic oxidation, it can generate color products with specific absorption wavelengths. The maximum absorption wavelength of DA64 λ Max (color rendering wavelength)=727 nm, ε/ H2O2 (extinction coefficient of one H2O2 molecule)=9 × 104. Most chromogenic substrates have wavelengths in the range of 400 to 550, while DA64 is as high as 727 nanometers, much higher than MAOS known for its long chromogenic wavelength (630nm). It has stronger anti-interference ability for complex samples and higher sensitivity for trace detection. In addition to quantifying hydrogen peroxide with AD64, it can also be used to detect peroxidase activity. Although other substrates such as Trinder's reagent or luminescent substrate Luminol can be used for detection, DA64 is compatible with water solubility and higher sensitivity, and does not require equipment requirements like luminescent and fluorescent reagents. Only a simple colorimeter is needed. Desheng R&D produces a variety of chromogen substrates and can provide new Trinder's reagents, DA64, DA67, luminol, and more.