4-(2-Hydroxyethyl)Piperazin-1-Ylethanesulphonic Acid, often called HEPES, belongs to the family of zwitterionic buffers broadly used in biological and biochemical research. It presents a stable buffering capacity in the pH range typically suited for cell culture work and enzyme assays, offering reliability in laboratory conditions. The structure includes both a hydroxyethyl group and a piperazine ring, connecting via an ethanesulfonic acid linkage. This structure promotes solubility in aqueous solutions and favorable interaction in cellular environments, which matters for maintaining pH during experiments across a broad temperature range.
The substance appears as a white crystalline solid under standard laboratory conditions, but it sometimes comes in the form of flakes, fine powder, or even pearls depending on how it’s manufactured or processed. In terms of physical characteristics, HEPES feels free-flowing to the touch and resists caking, even if left in storage for extended periods or exposed to laboratory air. Bulk density commonly ranges between 0.5 and 0.7 g/cm³, providing consistency in solution preparation or reagent blending. As a raw material, it melts around 234 to 238°C with minimal decomposition, so researchers rarely encounter stability issues during typical handling or storage.
HEPES carries the chemical formula C8H18N2O4S and displays a molecular weight of about 238.3 g/mol, based on values found on quality control sheets from manufacturers. The molecular structure ensures minimal interaction with proteins or metal ions, minimizing the risk of interference during spectrophotometric studies or cell-based assays. Its zwitterionic nature—both positive and negative charges present on the molecule—makes it resistant to oxidation, and less likely to disrupt sensitive measurements in labs that rely on accuracy and repeatability.
Customs and logistics use the Harmonized System (HS) Code 2933.59 for this acid. The classification underlines that it qualifies among heterocyclic compounds, respecting international trade regulations and guiding safe handling during global shipments. Importers and distributors rely on this HS Code when planning shipments or tracking compliance with chemical export controls, which matters for both manufacturers abroad and research organizations sourcing specialty chemicals.
Dissolving HEPES in water leads to a clear solution, for concentrations common in biology and biochemistry labs. It comes with low UV absorbance at wavelengths above 260 nm, preventing signal interference in DNA or protein analysis. Even in concentrations exceeding 1 M, the solution stays free of particulate matter or cloudiness, which can’t always be said of alternative buffers. Chemists, lab technicians, and grad students know that the consistent behavior of HEPES cuts down troubleshooting time and that its capacity to buffer remains strong across variable temperatures—key for mammalian cell work and enzyme-based research.
In shipping and storage, HEPES is often found as a free-flowing powder, though some suppliers offer it as crystalline flakes or even pearls for easier measuring and handling in automated settings. It does not liquefy unless exposed to highly elevated temperatures, so accidental spillage leads only to easy clean-up with a brush or vacuum. Some suppliers offer ready-made HEPES solutions (often at 1 M or 2 M strength, sometimes pH-adjusted), allowing lab staff to spend less time on reagent prep and more time on actual experiments. Mixing powder into distilled water and adjusting pH with NaOH or HCl works for nearly any biology lab work, with shelf lives of several months at room temperature for dry forms, and weeks for aqueous solutions kept in a refrigerator.
HEPES presents a low hazard profile in terms of acute toxicity. Safety Data Sheets typically assign it only mild irritation risk to eyes or skin, especially compared to strong acids or organic solvents. The major concern comes from inhalation of fine dust, so a fume hood or dust mask serves for larger-scale weighing jobs. No evidence links this buffer to mutagenic, carcinogenic, or reproductive risk at the concentrations used in research. Disposal follows local chemical waste guidelines—dilute solutions can often be poured down the drain in academic or clinical labs, pending approval. Bulk waste or unused solid goes in chemical collection drums, so minimal environmental impact results. Wearing gloves and goggles gets recommended for any chemical reagent, even one with a good safety record, to prevent accidental exposure or cross-contamination.
Across cell biology, molecular biology, and protein chemistry, 4-(2-Hydroxyethyl)Piperazin-1-Ylethanesulphonic Acid fills a central role as a buffering agent. It provides stable pH environments that support living cells over long periods, powers reproducible enzyme reactions, and minimizes drift in test outcomes. The material touches almost every corner of experimental science, so supply chain reliability and high quality make a difference to labs everywhere. Researchers depend on clear labeling, documentation, and trustworthy material origin because contamination or variability can lead to lost weeks of labor or false research conclusions. As more institutions focus on traceability, batch numbering and COA (Certificate of Analysis) records improve day-to-day confidence. These details support efforts to reproduce breakthroughs across labs and make results trustworthy for the wider public.
