Introduction
The non-proteinogenic amino acid carbocisteine is used asan anti-inflammatory mucolytic agent for the treatment ofchronic obstructive lung disease (COPD) and asthma. UnlikeN-acetylcysteine, the substance seems to interfere with themetabolism of mucus producing cells [1–3] and not with thephlegm itself.Carbocisteine is synthesized by alkylation of l-cysteine withchloroacetic acid in aqueous sodium hydroxide solution [4,5]. Untiltoday the impurity profile of carbocisteine is assessed by meansof a thin layer chromatography (TLC) test on ninhydrin-positive