هپس

HEPES (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid) is a zwitterionic buffering agent commonly used in biological and biochemical research to maintain stable pH in solutions. It is part of the Good’s buffer family and is particularly effective in the pH range of 6.8 to 8.2. It is favored in cell culture media for maintaining physiological pH independently of CO₂ levels.

🏭⚗️ Production
HEPES is synthesized chemically and is commercially available as a white crystalline powder. It is highly soluble in water (approximately 40 g per 100 mL at 20 °C). Buffers are typically prepared by dissolving HEPES powder in distilled water and adjusting pH with sodium hydroxide or hydrochloric acid as needed.

🔬 Properties
HEPES is a zwitterion, containing both positive and negative charges but overall neutral in charge. It has minimal absorbance in UV and visible light, making it suitable for spectrophotometric studies. Its pKa is approximately 7.5 at 25°C, giving it strong buffering capacity near physiological pH. HEPES is membrane-impermeable, chemically stable, and does not significantly bind metal ions. However, in the presence of light and riboflavin, it may produce hydrogen peroxide, so light exposure should be minimized.

🧪 Applications
• Biological research: Commonly used in cell culture media, protein purification, and enzymatic reactions.
• Molecular biology: Supports electrophoresis, live-cell imaging, and lysis buffers with stable pH.
• Biochemistry: Maintains pH in sensitive biochemical assays.
• Pharmaceutical development: Employed in drug formulation buffers for pH control.
• Analytical chemistry: Used in UV-sensitive assays and reactions involving metal ions due to minimal chelation.