Chiral high-performance liquid chromatography analysis of α-amino acid mixtures using a novel SH reagent— N- R-mandelyl- l-cysteine and traditional enantiomeric thiols for precolumn derivatization

• Published in: Journal of Chromatography A 2007-12, Vol.1175 (1), p.89-95
• Main Authors: Chernobrovkin, M.G., Shapovalova, E.N., Guranda, D.T., Kudryavtsev, P.A., Švedas, V.K., Shpigun, O.A.
• Format: Article
• Language: English
• Subjects: Acetylcysteine - chemistry; Amino acid enantiomers in beer; Amino Acids - analysis; Amino Acids - chemistry; Chiral analysis; Chiral thiol; Chromatography, High Pressure Liquid; Cysteine - analogs & derivatives; Cysteine - chemistry; Indoles - analysis; o-Phthalaldehyde; o-Phthalaldehyde - chemistry; Polyaminum; Stereoisomerism; Sulfhydryl Compounds - chemistry; Sulfhydryl Reagents - chemistry; α-Amino acid mixtures
• ISSN: 0021-9673
• DOI: 10.1016/j.chroma.2007.10.034

Several chiral thiols, i.e. traditionally used enantiomerically pure SH reagents and novel N- R-mandelyl- l-cysteine ( R-NMC) containing additional chiral center, have been applied as co-reagents in precolumn derivatization with o-phthalaldehyde for enantiomeric HPLC analysis of individual α-amino acids and their mixtures. The R-NMC-derived isoindoles as well as adducts with other thiols have a characteristic absorption maximum at 340 nm, and are highly fluorescent allowing detection of 10 μg/l of an amino acid. Investigated 19 amino acids were analyzed separately and in a mixture by a gradient HPLC after precolumn derivatization. The chromatographic behavior of formed isoindoles substantially differs for each of the thiols used for modification. In contrast to traditional enantiomeric thiols application of diastereomeric R-NMC provides higher resolution for α-amino acid enantiomers, with l, d-elution order (except for Arg). Combined use of R-NMC and other thiol enlarges the possibilities of this method, allowing accurate chiral analysis of complex amino acid mixtures.