L-Cysteine CAS 52-90-4

L-Cysteine is a white crystalline powder with a slight sulfur odor, easily soluble in water. As a natural amino acid containing sulfhydryl group (-SH), it is widely used in the food industry (bread improver, antioxidant) and cosmetics (perm, whitening ingredient). Its reducing properties and biocompatibility are outstanding, but it needs to be protected from light and sealed to prevent oxidization and deterioration.

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Model:
52-90-4
Brand:
Futurechemical
Code:
52-90-4

Product Description

L-Cysteine Basic information
Product Name:	L-Cysteine
CAS:	52-90-4
MF:	C3H7NO2S
MW:	121.16
EINECS:	200-158-2
Mol File:	52-90-4.mol
L-Cysteine Chemical Properties
Melting point	240 °C (dec.) (lit.)
alpha	8.75 º (c=12, 2N HCl)
Boiling point	293.9±35.0 °C(Predicted)
bulk density	300kg/m3
density	1.197 (estimate)
FEMA	3263 \| L-CYSTEINE
refractive index	8.8 ° (C=8, 1mol/L HCl)
storage temp.	Store below +30°C.
solubility	H2O: 25 mg/mL
pka	1.92(at 25℃)
form	Solid
color	White
PH	4.5-5.5 (100g/l, H2O, 20℃)
Odor	sulfury
Odor Type	sulfurous
optical activity	Optical rotation: +8° to +9° (c = 5, 1 N HCl, 20°C).
biological source	non-animal source
Water Solubility	280 g/L (25 ºC)
λmax	λ: 260 nm Amax: 1.5
λmax	λ: 280 nm Amax: 0.2
Sensitive	Air Sensitive
Merck	142,781
JECFA Number	1419
BRN	1721408
Stability:	Stability Stable, but may be air sensitive. Incompatible with oxidizing agents, bases.
LogP	-2.49
CAS DataBase Reference	52-90-4(CAS DataBase Reference)
NIST Chemistry Reference	L-Cysteine(52-90-4)
EPA Substance Registry System	L-Cysteine (52-90-4)

Item	Standard	Result
Appearance	Colorless to light yellow clear liquid	Colorless liquid
Assay	99-101%	99.34%
PH	4.5-5.5	4.8
Specific Rotation （α） D20	+8.3°~ +9.5°	+8.8°
Transmittance T430	≥98.0%	98.8%
Chloride(CI)	≤0.1%	＜0.1%
Ammonium(NH4)	≤0.02%	＜0.02%
Sulfate(SO4)	≤0.02%	＜0.02%
Iron (Fe)	≤10ppm	＜10ppm
Heavy Metals(Pb)	≤10ppm	＜10ppm
Arsenic A_B2_O3	≤1ppm	＜1ppm
Loss on drying	≤0.50%	0.24%
Residue on Ignition	≤0.1%	0.04%
Conclusion	Qualified

L-Cysteine CAS 52-90-4 C3H7NO2S Bread improver Nutritional supplement antioxidant Color protector

Quality Assurance

Full-Process Quality Control: From incoming raw material inspection to in-process monitoring and final outgoing checks, every batch is inspected at each production stage against strict acceptance standards.
Third-Party Certified & Tested: Our quality management system is certified to ISO 9001, and products are regularly tested by accredited laboratories (e.g. SGS, TÜV). Test reports are available on request.
100% Batch Traceability: Each batch carries a unique lot number that links raw material records, production parameters, and test results, enabling complete traceability from factory to final delivery.
Pre-Shipment Inspection: Every order passes a final pre-shipment inspection, with inspection photos and reports shared before dispatch.

FAQ From Customers

Q1: What is the minimum order quantity?

A: There is no quantity limit for the first sample or trial order. Just tell us the actual quantity you need.
Q2: How can I confirm that the quality meets the requirements?

A: Provide your specifications, and our technical team will check them or customize them for you; we can provide TDS, MSDS, and COA, and accept third-party testing.
Q3: How do you ensure stable quality?

A: We manufacture under an ISO 9001 quality system, test every batch before release, and retain samples for 24 months for traceability.
Q4: Do you provide samples?

A: Yes — Free samples are available; freight is at buyer's expense for express delivery.