52-90-4Acetylcysteine EP Impurity B

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Catalogue No.:	VE005991
CAS No.:	52-90-4
Mol. Formula:	C3H7NO2S
Mol. Weight:	121.16 g/mol

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Additional information on CAS 52-90-4

Parent drug

Acetylcysteine

IUPAC Name

(2R)-2-Amino-3-sulfanylpropanoic acid

Pharmacopeial Synonyms

L-Cysteine

Synonyms

N/A

Smiles

NC(CS)CC(=O)O

InChI

InChI=1S/C4H9NO2S/c5-3(2-8)1-4(6)7/h3,8H,1-2,5H2,(H,6,7)/t3-/m1/s1

Description

Acetylcysteine EP Impurity B corresponds to L-cysteine, CAS 52-90-4, a sulfur-containing amino acid with molecular formula C3H7NO2S and molecular weight 121.16 g/mol. In acetylcysteine drug substance, it is typically associated with incomplete acetylation, hydrolytic deacetylation, or precursor carryover from synthesis. As a non-mutagenic process-related impurity rather than a nitrosamine or genotoxic species, its relevance is primarily pharmacopeial and compositional. Determination commonly relies on LC-MS/MS, ion-pair or derivatized HPLC, and occasionally capillary electrophoresis for resolution of closely related thiol species.

References

Toussaint, B., et al. “Quantitative Analysis of N-Acetylcysteine and Its Pharmacopeial Impurities in a Pharmaceutical Formulation by Liquid Chromatographya-UV Detection-Mass Spectrometry.” Journal of Chromatography A, vol. 896, no. 1-2, Oct. 2000, pp. 191-99, https://doi.org/10.1016/s0021-9673(00)00741-x.