L-Cysteine HCL Monohydrate USP


l-cysteine hydrochloride monohydrate, cysteine hydrochloride monohydrate

Technical Data

CAS Number: 7048-04-6
Molecular Formula: HSCH2CH(NH2)COOH · HCl · H2O
Molecular Weight: 175.63
Beilstein Registry Number: 5158059
EC Number: 200-157-7

FabriChem Specifications

AppearanceWhite powder
IdentificationAs per USP36
Specific Rotation+5.7° to +6.8°
Loss on Drying8.0 to 12.0%
Residue on IgnitionNMT 0.4%
SulfateNMT 0.03%
IronNMT 0.003%
Heavy MetalsNMT 0.0015%
Total ImpuritiesNMT 2.0%
Each Individual ImpurityNMT 0.5%
Organic Volatile ImpuritiesAs per USP36
Residual SolventsAs per USP36
Assay98.5 to 101.5%
Total Plate CountNMT 1,000 CFU/g
Yeast & MoldNMT 100 CFU/g
E. ColiNegative
Staph. AureusNegative/10g

Molecular Structure



Cysteine is a sulfur-containing amino acid found in foods like poultry, eggs, dairy, red peppers, garlic and onions. It works as an antioxidant, in the production of collagen (a component of hair, skin and nails) and is also used in the body to create glutathione, another important antioxidant.

L-Cysteine is a non-essential standard amino acid that can be synthesized by the human body under normal physiological conditions if a sufficient quantity of methionine is available.

In the cosmetics industry, it can be used for hair perming formulations.