Shandong Huashang Chemical Co., Ltd. is a high-tech enterprise focused on industry of fine chemicals research and develop, produce and sale. Shandong Huashang Chemical Co., Ltd. is located in Shan Dong Ji Nan China. we have the ability to provide you high quality products. More than 90 % of our products are exported to developed countries and regions such as north America, Europe, Japan, South Korea and the Middle East
1. Basic Information
Name: L-Cysteine
Alias: 2-Amino-3-mercaptopropanoic acid
CAS No.: 52-90-4
Molecular Formula: C3H7NO2S
Molecular Weight: 121.16
2. Physical and Chemical Properties
Physical Properties
- Appearance: White crystalline powder
- Odor: Faint sulfur peculiar odor, slight sour taste
- Solubility: Soluble in water, dilute acid and dilute alkali; slightly soluble in ethanol; insoluble in acetone, ether, benzene
- Melting Point: 225 °C (decomposes)
- Specific Rotation: [α]D2? +8.0° ~ +10.0° (1mol/L HCl solution)
- Hygroscopicity: Slightly hygroscopic under high humidity air
- Crystal form: Orthorhombic crystal grain
Chemical Properties
- Molecular structure: L-type sulfur-containing amino acid, carries free sulfhydryl (-SH), amino group and carboxyl group, amphoteric compound
- Reducing characteristic: Sulfhydryl group has strong reducibility, easily oxidized by air to form L-cystine disulfide dimer, product turns yellow after oxidation
- Metal chelation: -SH can chelate heavy metal ions to form insoluble mercaptide precipitates
- Acid-base property: Dissolves in both acid and alkali solution to generate corresponding amino acid salts
- Thermal stability: Stable below 100 °C; long-term heating above 150 °C causes desulfurization and decomposition, releasing sulfur-containing irritant gas
- Photostability: Sensitive to air and light; long-term exposure accelerates oxidation discoloration
- Compatibility: Compatible with common amino acids, food and cosmetic raw materials; incompatible with strong oxidants, heavy metal salts, peroxide
3. Main Application Fields
1. Food Industry Additive (Core Application)
- Dough improver for flour, reduces gluten strength, improves baking texture of bread and pastry
- Antioxidant and color fixative for fruit, beverage and meat products, prevents browning
- Nutritional fortifier of sulfur amino acid in functional food
2. Pharmaceutical Raw Material
- Raw material for compound amino acid infusion, oral amino acid preparations
- Detoxification auxiliary raw material for heavy metal poisoning antidote; precursor for glutathione synthesis
- Excipient for pharmaceutical formulations as antioxidant stabilizer
3. Cosmetic Active Ingredient
Hair perm reducing agent; skin brightening antioxidant raw material, inhibits melanin formation
4. Biochemical Culture Medium
Nitrogen and sulfur source for microbial fermentation medium
4. Quality Specification Table
| Test Item | Standard Index |
| CAS Number | 52-90-4 |
| Molecular Formula | C3H7NO2S |
| Molecular Weight | 121.16 |
| Appearance | White crystalline powder |
| HPLC Purity | Food/Pharma Grade ≥99.0%; Reference Standard ≥99.5% |
| Water Content (KF) | ≤0.30% |
| Residue on Ignition | ≤0.10% |
| Heavy Metals (Pb) | ≤10 ppm |
| Arsenic (As) | ≤2 ppm |
| Packaging | 25kg PE lined fiber drum, nitrogen-filled aluminum foil inner bag |
| Storage Condition | Hermetic, light-proof dry warehouse below 25 °C; isolate air and oxidants to avoid oxidation |
| Transportation Requirement | Sulfur-containing amino acid solid, sealed dust-proof packaging |
| Shelf Life | 24 months under intact nitrogen-filled sealed packaging |
Safety Warning
Low oral toxicity within standard dosage. Dust irritates respiratory tract, eyes and skin. Sulfur odor may cause discomfort during operation; wear dust mask and chemical-resistant gloves in ventilated environment. Must be sealed and isolated from air during storage to prevent oxidation and efficacy loss. Avoid mixing with hydrogen peroxide, bleach and other oxidizing substances.
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