The Chinese name of DAOS is N-Ethyl-N - (2-hydroxy-3-sulfopropyl) -3,5-dimethylaniline sodium salt, and the English name is N-Ethyl-N - (2-hydroxy-3-sulfopropyl) -3,5-dimethylaniline sodium salt. CAS number 83777-30-4, molecular formula C13H20NNaO6S, molecular weight 341.36. DAOS is a novel Trinder's reagent widely used as a chromogenic substrate in biochemical assay kits due to its high water solubility, stability, and wide range of applications. Compared with other chromogenic substrates, it has high water solubility, stable aniline like properties, and a wide range of pH applications. In the colorimetric determination of hydrogen peroxide activity, it has several advantages over conventional colorimetric reagents. The principle of DAOS finished product detection is that in the presence of hydrogen peroxide and peroxidase, the new Trinder's reagent forms a very stable purple or blue dye during the oxidative coupling reaction with 4-aminoantipyrine (4-AA) or 3-methylbenzothiazolesulfone hydrazone (MBTH). The molar absorbance of MBTH coupled dyes is 1.5-2 times higher than that of 4-AA coupled dyes. The substrate is oxidized by its oxidase enzyme to produce hydrogen peroxide, and the concentration of this hydrogen peroxide corresponds to the substrate concentration. Therefore, the amount of substrate can be determined by colorimetric oxidation coupling reaction. It is necessary to experiment with different types of novel Trinder's reagents for developing the optimal detection system for specific substrates. When using DAOS, it is necessary to dissolve it in an appropriate buffer to prepare a detection solution. The specific preparation method may vary depending on the application, but typically 10ml PBS buffer is used to dissolve a certain amount of DAOS to prepare a 6.6mM DAOS solution. The concentration can be adjusted as needed.