Description

Cysteine CAS NO 4371-52-2 is a sulfur-containing amino acid that serves as a versatile building block and biochemical intermediate. Its unique thiol group makes it a critical raw material for applications requiring antioxidant activity, metal chelation, or protein structure modification. This high-purity ingredient is essential for manufacturers in the pharmaceutical, nutraceutical, and food industries seeking reliable, high-quality intermediates for synthesis and formulation.

Application

• Pharmaceutical Synthesis: A key chiral intermediate in the production of active pharmaceutical ingredients (APIs), including N-acetylcysteine (NAC) and other thiol-based drugs.
• Nutraceutical & Dietary Supplements: Used as a precursor for glutathione synthesis and in formulations targeting antioxidant support and detoxification.
• Food & Flavor Industry: Employed as a processing aid and flavor enhancer, particularly in meat flavorings and bakery products, where it participates in Maillard reaction.
• Cosmetic & Personal Care: Incorporated into hair care formulations (permanent waving/straightening agents) and skincare products for its antioxidant and conditioning properties.
• Biochemical Research & Cell Culture: Used as a reducing agent to maintain sulfhydryl groups in proteins and as a component of cell culture media.
• Animal Nutrition: Serves as a feed additive to support animal health, feathering in poultry, and wool production in sheep.

Basic Information

Product Name	Cysteine
CAS No.	4371-52-2
Molecular Formula	C3H7NO2S
Molecular Weight	121.16 g/mol
Synonyms	L-Cysteine; (R)-2-Amino-3-mercaptopropanoic acid; 2-Amino-3-mercaptopropionic acid; Cys; C; Thioserine; β-Mercaptoalanine; Half-cystine; Cysteine free base; Cysteine hydrochloride (salt form)
EINECS	224-452-3

Quality Control

Our Cysteine is manufactured under strict quality management systems to ensure batch-to-batch consistency and high purity. It is typically tested to meet specifications aligned with USP, EP, and FCC monographs where applicable. Comprehensive testing includes assay, optical rotation, residue on ignition, heavy metals, and specific impurity profiles. A Certificate of Analysis (COA) documenting all test results is provided with each shipment.

Storage

Preserve in a tightly closed container, protected from light. Store in a cool, dry, well-ventilated area at controlled room temperature (15-25°C). This product is hygroscopic (moisture-sensitive) and easily oxidized; containers must be kept tightly sealed after opening to minimize exposure to air and moisture. For long-term storage, consider using an inert atmosphere.

Specification

Item	Specification
Appearance	White crystalline powder
Identification (IR)	Conforms
Assay (HPLC)	98.5% - 101.5%
Specific Rotation	+8.0° to +9.5°
Loss on Drying	≤ 0.5%
Residue on Ignition	≤ 0.1%
Heavy Metals (as Pb)	≤ 10 ppm
Related Substances (HPLC)	Individual impurity ≤ 0.5%; Total impurities ≤ 1.0%

Note: Specifications can be tailored. Please contact us for the detailed technical data sheet of a specific grade.