Chinese Name: 4-Hydroxyethylpiperazine Ethanesulfonic Acid Synonyms: N-(2-Hydroxyethyl)piperazine-N'-2-ethanesulfonic Acid; N-2-Hydroxyethylpiperazine-N'-2-ethanesulfonic Acid; 4-(2-Hydroxyethyl)-1-piperazineethanesulfonic Acid; N-2-Hydroxyethylpiperazine-N'-2-ethanesulfonic Acid; 4-(2-Hydroxyethyl)-1-piperazineethanesulfonic Acid English Name: 2-[4-(2-Hydroxyethyl)piperazin-1-yl]ethanesulfonic Acid Abbreviation: HEPES Chemical Formula: C8H18N2O4S Molecular Weight: 238.30 CAS Number: 7365-45-9 EINECS: 230-907-9 Density: 1.07 g/mL Melting Point: 234-238 °C Appearance: White crystalline powder Solubility: Soluble in water Use: This product is a hydrogen ion buffer, capable of maintaining a constant pH range for an extended period.