1. Basic Product Profile

• Full IUPAC Name: (2S)-2-amino-3-(1H-imidazol-4-yl)propanoic acid
• Aliases: L-His, L-2-Amino-3-imidazol-4-ylpropionic acid
• CAS Number: 71-00-1
• EINECS: 200-745-3
• Molecular Formula: C6H9N3O2
• Molecular Weight: 155.15
• Chemical Classification: Essential amino acid, protein building block, nutritional supplement, pharmaceutical injection raw material, biochemical buffer reagent
• Core Advantages
  L-type chiral amino acid containing imidazole heterocyclic side chain, dual acid-base amphiprotic property, strong metal ion chelating capacity. It is an essential amino acid for human growth, precursor of histamine and carnosine, key component of hemoglobin. Widely used in compound amino acid infusions, sports nutrition supplements, food fortifiers, cosmetic anti-aging raw materials and biological pH buffer systems. High crystal purity, stable storage property, excellent biocompatibility.

2. Physical & Chemical Properties

2.1 Physical Index

1. Appearance: White crystalline powder
2. Odor: Odorless, slight bitter taste
3. Solubility: Soluble in water; slightly soluble in ethanol; insoluble in acetone, ether, benzene
4. Melting Point: 277–288 °C (decomposes)
5. Specific Optical Rotation [α]D20: +8.0° ~ +10.0° (c=10, water)
6. pH (0.5% aqueous solution): 7.0–8.0 (near neutral amphoteric solution)
7. Hygroscopy: Slightly hygroscopic under high humidity
8. UV characteristic: Characteristic absorption peak at 210 nm

2.2 Chemical Properties

1. Molecular structure: α-amino carboxylic acid with imidazole side chain; imidazole ring contains both acidic N-H and basic nitrogen
2. Amphoteric ion characteristic: Has amino and carboxyl groups, forms internal salt; can generate soluble salts with acid or alkali
3. Chelation performance: Imidazole nitrogen coordinates with Fe, Zn, Cu, Ni metal ions to form stable complexes
4. Thermal stability: Stable below 220℃; decomposes above melting point to release ammonia and imidazole fragments
5. Acid & Alkali Stability: Stable in pH 4–9 medium; strong acid heating causes ring hydrolysis; strong alkali induces racemization
6. Photostability: Slightly yellow after long-term intense UV irradiation; light-proof storage suggested
7. Compatibility: Compatible with other amino acids, water-soluble excipients; incompatible with strong oxidants, concentrated mineral acids

3. Main Application Fields

3.1 Pharmaceutical Industry (Core Usage)

1. Raw material for compound amino acid injection, postoperative enteral nutrition liquid; supplements essential amino acid for critically ill patients
2. Chelating auxiliary for mineral oral preparations (zinc histidine, iron histidine) to improve mineral absorption efficiency
3. Adjuvant drug raw material for gastric mucosal protection, antioxidant liver protection formulations

3.2 Health & Sports Nutrition

1. Functional supplement raw material: Boosts immunity, promotes muscle repair, maintains hemoglobin content
2. Anti-aging oral raw material, inhibits oxidative damage via carnosine synthesis in vivo

3.3 Food Fortification Additive

3.4 Biochemical Laboratory Reagent

1. pH buffer component for enzyme catalytic reaction and protein electrophoresis
2. Metal chelating reagent for chromatographic separation and trace metal detection experiments

4. Quality Specification Table