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4-(2-Hydroxyethyl)piperazine-1-ethanesulfonic acid,
N-(2-Hydroxyethyl)piperazine-N′-(2-ethanesulfonic acid),
N-(2-Hydroxy ethyl)-Piperazine ethane Sulfonic Acid

Technical Data

CAS Number: 7365-45-9
Molecular Formula: C8H18N2O4S
Molecular Weight: 238.30
Beilstein Registry Number: 883043
EC Number: 230-907-9

FabriChem Specifications

AppearanceWhite crystalline powder
Assay (dry basis)99.5% Min.
(1.0M solution in H2O)
260 nm 0.05 Max.
280 nm0.05 Max.
Identification (IR) Conforms to structure
Loss on Drying (105° C) 1.0% Max.
pH (1M solution in H2O) 5.0 – 6.5
pKa (at 25°C) 7.35 – 7.75
Residue on Ignition 0.3% Max.
(1M solution in H2O)
Clear, colorless and complete
Heavy Metals (as Pb) 0.002% Max.

Molecular Structure



HEPES [4-(2-Hydroxyethyl)piperazine-1-ethanesulfonic acid] is one of the known buffering agents used for biochemical and biological research. These buffering agents are now collectively referred to as “Good’s Buffers”. Good’s Buffers are important tools used in modern biological laboratories for a variety of their properties, including but not limited to being zwitterionic (aka hybrid or dipolar) compounds.