The full name of MAOS is N-ethyl-N - (2-hydroxy-3-sulfopropyl) -3,5-dimethylaniline sodium salt, which belongs to the new Trinder's reagent and has strong water solubility. It is a white powder. It holds a pivotal position in many application fields, such as water-soluble reagents that can be used for enzymatic spectrophotometric determination of hydrogen peroxide and for detecting 4-AA coupling substrates. Trinder's reagent powder is not easily interfered with and oxidized, but when formulated as a solution, it is easily affected by air and produces red or yellow substances after oxidation. So after preparing the solution, it is necessary to seal and refrigerate it as much as possible, using as much as possible. Once the solution is exposed to high temperature air for a long time, it is highly susceptible to gradual oxidation, leading to discoloration of the solution. In addition, MAOS is extremely sensitive to light and humidity, so during storage, it is necessary to refrigerate at a temperature between 0 and 10 degrees Celsius, and freeze it below 0 degrees Celsius. If there is no clear requirement for storage, the principle is to store it in a cool place below 15 ℃.