Biological Buffers

HEPES | 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid)

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.
HEPES biological buffer molecular structure
Useful pH Range 6.8 - 8.2
Working concentration range 10mM-1M7-9
Chemical formula C8H18N2O4S

Find more buffer resources from our Biological Buffers Selection Guide.

        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 RDD002
PHG0001 RES6003H-B7 83264
HEPES sodium salt 75277-39-3 C8H17N2NaO4S 260.29 H7006 H3784 5380-OP H8651
RES6007H-A7  H3662 
HEPES hemisodium salt 103404-87-1 C8H17.5N2O4S • 0.5Na 249.30 H7637 H9897   RES6008H-A7  
HEPES potassium salt 82207-62-3 C8H17KN2O4S 276.39 H0527      


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