MES, Sodium Salt (2-(N-Morpholino)ethanesulfonic acid sodium salt) is a zwitterionic N-substituted aminosulfonic acid known as a Good's buffer, active in the pH range 6-8 with a pKa of 6.10 at 25° C. With a pKa value near physiological pH, it is not absorbed through cell membranes, and it…

pKa (25°C): 6.15. The working pH range in aqueous solution is 5.5-6.7.