L-Cysteine
CAS 52-90-4 C3H7NO2S
- CAS number
- 52-90-4
- EC number
- 200-158-2
- Formula
- C3H7NO2S
- Molar mass
- 121.16 g/mol
- HS code
- 2930.90
Supply of L-Cysteine
- Grades
- Food (FCC / E920) and pharmacopoeial (USP / EP / JP) grades, as the free base (CAS 52-90-4) or the hydrochloride, anhydrous (52-89-1) or monohydrate (7048-04-6). Source — fermentation or keratin hydrolysis — is declared per lot on request.
- Packaging
- 25 kg fibre drums or cartons with double PE liner · Smaller foil packs for pharma
- Documents
- CoA, SDS and TDS on request; certificate of origin where the destination requires it.
- Delivery
- Worldwide, including the United States, Canada, the United Kingdom, Germany and the rest of the EU, the United Arab Emirates, India, Singapore, Malaysia and Australia. Quoted EXW, FOB, CIF or DAP.
L-Cysteine is an amino acid that contains sulfur. Bakeries use it to soften dough so it mixes faster, flavour makers use it to create meaty and savoury flavours, and drug makers use it to produce medicines such as N-acetylcysteine. It is also used in hair and skin care.
Technical details
L-Cysteine is the amino acid that carries a thiol, the –SH group that makes it both a strong reducing agent and the source of the disulfide bridges that hold proteins in shape. Bakers use it to break some of those bridges in gluten, which relaxes a dough and shortens mixing; flavour houses use its sulfur to build meat and savoury notes in Maillard reactions; and pharma uses it as the starting material for N-acetyl-L-cysteine and carbocisteine. Because the thiol oxidises in air, most of the trade moves as the more stable hydrochloride. Ehlinar supplies food and pharmacopoeial grades, free base or hydrochloride, with the source declared.
Appearance: White crystals or crystalline powder with a faint sulfurous odour; soluble in water. The hydrochloride is the most widely traded form.
Applications
How we supply
- Certificate of Analysis (CoA), lot-specific where available
- Safety Data Sheet (SDS / MSDS)
- Technical Data Sheet (TDS)
- Certificate of Origin / Certificate of Conformity
Independent third-party inspection can be arranged on request, with the agency and scope agreed per trade. Representative samples can be requested for qualification, subject to supplier availability. We recommend incoming quality control against the agreed CoA.
Quoted on standard Incoterms (e.g. EXW, FOB, CIF, DAP) as agreed per trade. Delivery region, packaging and grade are confirmed per quote.
Documents and services above are subject to supplier availability and confirmed per quote; nothing here is an offer.
Typical / indicative values — not a binding specification
| Property | Typical |
|---|---|
| Assay (USP, HCl monohydrate) | ~98.5–101.5% |
| Water solubility | Freely soluble (hydrochloride) |
Also known as
L-Cys · (R)-2-amino-3-mercaptopropanoic acid · E920 · L-Cysteine hydrochloride (salt form)
Frequently asked questions
- Free base or hydrochloride?
- They are different products with different CAS numbers: the free base is 52-90-4, the hydrochloride anhydrous 52-89-1 and the hydrochloride monohydrate 7048-04-6. Most food and pharma buyers use the hydrochloride monohydrate; specify the form and the pharmacopoeia you test against.
- Is L-cysteine animal-derived?
- It can be. Much of the world's cysteine has historically been made by reducing L-cystine extracted from hydrolysed keratin, such as feathers or hair; fermentation-derived material also exists. If you need halal, kosher or vegan status, specify the source and ask for a declaration against the lot.
- What is the difference between L-cysteine and L-cystine?
- L-cystine is two cysteine molecules joined through a disulfide bond. It is far less soluble and is the form cysteine turns into when it oxidises. They are separate products with separate CAS numbers.
- How is L-cysteine stored?
- Sealed, cool and dry, away from oxidisers. In air and especially in neutral or alkaline solution the thiol slowly oxidises to cystine, so keep containers closed and make solutions up fresh.
Enquire about L-Cysteine
Related products
Figures and identifiers here are compiled from public references and provided for general information; they are indicative, not a specification. See all products.