Biological Buffers

HEPES

Synonym: 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid)
 

HEPES is a zwitterionic biological buffer and is one of Good's buffers. HEPES is better at maintaining physiological pH in cell culture when compared to bicarbonate buffers despite the changes in carbon dioxide concentration1. HEPES buffer, with pH values ranging from 6.8 - 8.2, can be prepared at a wide variety of ratios.
Useful pH Range 6.8 - 8.2
Working concentration range 10mM-1M7-9

 

        Comparison of products by grade or quality level
Name CAS Molecular Formula Mol Wt Reagent Grades Life Science Grades PharmaGrade  Solutions
HEPES (free acid) 7365-45-9 C8H18N2O4S 238.30
HEPES sodium salt 75277-39-3 C8H17N2NaO4S 260.29
HEPES hemisodium salt 103404-87-1 C8H17.5N2O4S · 0.5Na 249.30    
HEPES potassium salt 82207-62-3 C8H17KN2O4S 276.39      

 

Interaction Comments
 

HEPES does not bind magnesium, calcium or manganese(II) ions2.
HEPES is not recommended for certain protein applications; it interferes with the Folin-Ciocalteu protein assay. The Biuret protein assay is unaffected3.
HEPES shows low absorbance in the UV range, but it does interfere with the Lowry protein assay giving false positive results3
Is oxidized by Cu (II).5
Can form radicals, not suitable for redox studies4

 

Literature References

  1. Baicu SC, Taylor MJ. Cryobiology 45 (1): 33–48 (2002)
  2. Good, N.E. and Izawa, S., Methods in Enzymology, 24B, 53 (1972).
  3. Himmel, H.M. & Heller, W.: J. Clin. Chem. Clin. Biochem. 25, 909-913 (1987)
  4. Grady, J. K.; Chasteen, N. D.; Harris, D. C. (1988). "Radicals from "Good's" buffers". Anal. Biochem. 173 (1): 111–115.
  5. Fengjiang W, Lawrence MS "Oxidation of Tertiary Amine Buffers by Copper". Inorganic Chemistry 1989 (28; 2): 168-169
  6. Ferreira CM, Pinto IS, Soares, EV, Soares HM. 2015 Royal Society of Chemistry 30989- 31003
  7. Downs SM, Mastropolo AM, Culture Conditions Affect Meiotic Regulation in Cumulus Cell-Enclosed Mouse Oocytes, Molecular Reproduction and Development 1997(46) 551-566
  8. Gupta B, Taha M, Lee M-J, Buffers more than buffering agent: introducing a new class of stabilizers for the protein BSA, Phys.Chem.Chem.Phys 2015(17) pp 1114-1133
  9. Kebede N, Francis PS, Barbante GJ, Hogan CF, Electrogenerated chemiluminescence of tris (2,2’ biopyridine) ruthenium (II) using common biological buffers as co-reactant, pH buffer and supporting electrolyte, Royal Society of Chemistry 2015(140) pp7142-7145