Biological Buffers


Synonym: N,N-bis[2-hydroxyethyl]-2-aminoethanesulfonic acid

BES is a zwitterionic buffer that is used in biochemistry and molecular biology research1. BES has been used to study versatile catalyst precursors for mild hydrocarboxylation of alkanes to carboxylic acids2. BES has also been used to determine that saline and buffers minimize the action of interfering factors in the bacterial endotoxins test3.
Useful pH Range 6.4 - 7.8
Working concentration range Not available


        Comparison of products by grade or quality level
Name CAS Molecular Formula Mol Wt Reagent Grades Life Science Grades PharmaGrade  Solution
BES 10191-18-1 C6H15NO5S 213.25 B9879 B4544 391334 B6420 14853    
BES sodium salt 66992-27-6 C6H14NNaO5S 235.23 B2891      


Interaction Comments

BES was found to diminish color development of the protein-BCA complex by 30-35% at 50 mM, and by <10% at 5 mM, measuring in the 1-10 mg range of BSA against protein-BCA complexes formed in water. This color loss may result from binding of Cu2+ to BES4.
Weak interaction with Co and Cu5



  1. Good, N. E., et al, Hydrogen Ion Buffers for Biological Research. Biochemistry, 5(2), 467-477 (1966).
  2. Kirillova MV, et al. Inorg Chem. 2012 May 7;51(9):5224-34.
  3. Fujita Y, et al. Anal Biochem. 2011 Feb 1;409(1):46-53.
  4. Kaushal, V., and Barnes, L. D. Anal. Biochem., 157(2), 291-294 (1986).
  5. Ferreira CM, Pinto IS, Soares, EV, Soares HM. 2015 Royal Society of Chemistry 30989- 31003.