On-line sample concentration capillary electrophoresis for the analysis of metabolic intermediates in the cell

Abstract

About 300 small molecules to be found in the cell as metabolic intermediates are listed and classified according to the chemical characteristics. To develop a comprehensive analytical technique of these metabolic intermediates, capillary electrophoresis (CE) is considered to be a promising technique. A mixture of 22 phenylthiohydantoin (PTH) amino acids and that of 6 aromatic carboxylic acids were employed as standard samples to evaluate the CE method from a viewpoint of detection sensitivity. PTH amino acids were concentrated and separated by sweeping micellar electrokinetic chromatography (MEKC) under acidic conditions and only 5-fold increases in sensitivity were obtained for a single run separation of 22 PTH amino acids. The aromatic carboxylic acids were concentrated and separated either under alkaline conditions by capillary zone electrophoresis or under acidic conditions by MEKC. Detection limits of these carboxylic acids were 0.05-0.6ppm.