Identification of non-protein nitrogen compounds separated by CZE without derivatization from TCA extract from salted herring meat

Abstract

Capillary zone electrophoresis (CZE) is a good method for separation of small charged molecules like amino acids and small peptides. However, their identification in biological samples is quite difficult. Proteolysis products in salted fish are usually determined by chemical methods and there is no suitable simple and quick direct instrumental method. In this work the identification of compounds in trichloroacetic extracts from salted herring meat separated by CZE with direct UV detection was performed. There were determined theoretical migration time of amino acids and peptides based on the Offord’s model and experimental migration time of 67 standards. Standards were separated individually, in the mixture and with samples (increasing concentration). On the electrophoregram of salted herring meat extract there were noticed 36 peaks, divided into 4 fields A–D. Among them there were identified in sequence: (A) creatinine, Lys, Arg and His, (B) creatine, (C) Trp, Met, Tyr and Phe and (D) cystine. Described method may be suitable for fast monitoring of the salted herring ripening process.