Biological buffering agent MES sodium salt is a derivative of MES buffering agent, with the Chinese name: Morpholine ethanesulfonic acid sodium salt. Like MES, it is a buffering agent with a wide range of applications in biological experiments. Its buffering range is between 5.5 and 6.5, and its conventional properties are white powder, which is convenient for transportation and storage. MES sodium salts have the advantages of strong stability, low absorption of ultraviolet and visible light, and can form weak bases with some metal ions, such as Ca, Mg, and Mn. Mixing MES sodium salt with MES can obtain the required pH, and its pH is not affected by temperature. The prepared solution is also colorless, clear, and transparent. Therefore, it is commonly used in biological experiments such as cell culture, electrophoresis, and protein purification. Preparation method of MES sodium salt: 1. Preparation materials: MES sodium salt powder, stirring rod, graduated beaker, deionized water; 2. Weigh the required amount of MES sodium salt and prepare a sufficient amount of deionized water; 3. Pour the weighed MES sodium salt and deionized water into the prepared beaker; 4. Use a stirring rod to stir the powder until it dissolves; 5. Adjust to the required pH value using concentrated HCl; 6. Add deionized water to the final volume; 7. After high-temperature sterilization, store at 4 ℃.