The chromogen substrate HDAOS is a highly sensitive substrate in enzyme-linked immunosorbent assay, belonging to a new type of Trinder's reagent. Its detection principle is similar to TMB in ELISA, but it has differences. For example, in the detection of total cholesterol in serum, HDAOS is commonly used as a chromogenic substrate. Total cholesterol (TC) includes free cholesterol (FC) and cholesterol ester (CE). There are over a hundred methods for measuring TC, which can be divided into five categories: chemical reagent colorimetry, enzyme analysis, fluorescence, gas and high-performance liquid chromatography. Due to the high conditions of gas phase and high-performance liquid chromatography, enzymatic determination of total cholesterol using chromogen substrates such as HDAOS is currently the most conventional application method. Its advantages are fast, accurate, specific, small sample size, no need for extraction, and easy for automated analysis and batch determination. In the detection of total cholesterol in serum, chromogen substrates such as HDAOS, HRP or POD, as well as enzyme preparations such as cholesterol esterase and cholesterol oxidase, are indispensable reagent raw materials. As an established reagent manufacturer, Desheng can provide a variety of reagent raw materials including these.