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  • 15 kg drum
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Assay (titr.): ≥ 99.5% | CAS No: 7365-45-9 | Useful pH range: 6.8 – 8.2 

Hopax is among the world's largest manufacturers and suppliers of HEPES (CAS 7365-45-9), a zwitterionic biological buffer often used in biological and biochemical research.

Uses of HEPES Buffer:

  • This Good's buffer is a very popular buffering agent in cell culture medias.
  • Used in electroporation.
  • Used as a running buffer in gel electrophoresis (occasionally with Tris Buffer - also manufactured by Hopax).
  • Used in studies related to the pH effects on seed germination.
  • Used as a grinding buffer in plant studies.
  • Used as a binding buffer for protein studies.
  • Used as an eluent during cation exchange chromatography.

Tips for HEPES handling and storage:

  • HEPES powder is resistant to high temperatures with its melting point reaching 200℃.
  • If exposing HEPES aqueous solution to the ambient light for three hours, it would produce cytotoxic hydrogen peroxide (H2O2), so it should be noted that HEPES aqueous solution must be kept away from light so as not to affect the experimental results.

Metal binding: (Compare with other buffers)

  • Negligible metal ion binding

Solubility in water: (Compare with other buffers)

  • 70.36g/100ml

Saturation at 0°C: (Compare with other buffers)

  • 2.25 M


  • Store at room temperature
Basic Information


Assay (titration)

≥ 99.5%

Useful pH range

6.8 – 8.2
Compare with other buffers

pKa (25°C)

7.45 – 7.65


White powder

Molecular formula


Molecular weight

238.3 g/mol

Solubility (1M in H2O)

Clear and Complete

Moisture (LOD)

≦ 0.5%

pH (5% in H2O)

5.0 – 6.5

UV (1M in H2O) A260nm

≦ 0.05

UV (1M in H2O) A280nm

≦ 0.04

UV (1M in H2O) A405nm

≦ 0.01

UV (33% in H2O)A290nm

≦ 0.05


≦ 0.1%

Heavy Metals (as Pb)

≦ 5 ppm

Customized specifications are available for bulk requests. Contact us to discuss your requirements.

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Synonyms/Similar names:

  • 4-(2-Hydroxyethyl)piperazine-1-ethanesulfonic acid
  • N-(2-Hydroxyethyl)piperazine-N′-(2-ethanesulfonic acid)
  • HEPES Free Acid
  • Hydroxyethylpiperazine Ethane Sulfonic Acid

What we offer:

  • Certificate of Analysis (CoA)
  • Small and bulk quantities available in stock
  • Analytical tests (DNase, RNase, protease activity, heavy metals and others upon request


  • Product registered under the European Chemicals Agency's REACH regulation

Related product:

Useful pH range chart
Use our interactive chart below to compare the useful pH range of this product with other buffers’. Click in the product name to access more information about it.