Biological buffer MES monohydrate, chemical name 2- (N-morpholine) ethanesulfonic acid monohydrate, is a white crystalline powder with a molecular formula of C6H13NO4S · H2O and a molecular weight of 213.26. It is easily soluble in water, has no irritating odor, and has good biocompatibility. MES monohydrate is widely used as a "Good" buffer in the fields of biology and biochemistry due to its important characteristics, including low UV absorbance, strong water solubility, pKa in the neutral range and not easily affected by temperature, stable pH value, and minimal interference with reactions. In addition, MES monohydrate does not penetrate the cell membrane and introduces low salt ion effects. MES monohydrate can be used as a non coordinating buffer in chemical reactions involving metal ions. It can also be used as an electrophoresis buffer for denatured gels.