High-performance liquid chromatographic detection of side reactions in peptide synthesis.

High-performance liquid chromatographic systems with chemically bonded packing materials were elaborated for monitoring synthetic stages during peptide coupling, purity control of peptides produced by solid-phase methods and detection of impurities formed as a consequence of side reactions such as oxidation, desulphation, racemization, transpeptidation, alkylation and decomposition. The technique was applied to the analysis of peptide hormones, neuropeptides, cyclopeptides, isopeptides and branched polypeptides based on poly-lysine. The mobile phases were methanol-acetonitrile-water mixtures containing phosphate, acetate, carbonate buffers or trifluoroacetic acid (pH 2-9). After optimization, baseline separations could be achieved for some critical peptide separations.