Design and applications of coupled SPE-CE.

CE suffers from an inherent low concentration sensitivity. Analyte detection limits can be improved by combining CE with SPE. This paper presents an overview of coupled SPE-CE systems that have been reported in literature.

On-line coupling of SPE and CE-MS for peptide analysis.

An on-line SPE-CE-MS system has been developed for the analysis of peptides. Analytes are preconcentrated using a C(18) microcolumn (5 x 0.5 mm id), and then introduced into the CE system via a valve interface.

Coupling of sequential injection analysis and capillary electrophoresis - Laser-induced fluorescence via a valve interface for on-line derivatization and analysis of amino acids and peptides.

The on-line coupling of sequential injection analysis (SIA) and capillary electrophoresis (CE) via an in-line injection valve is presented. The SIA system is used for automated derivatization of amino acids and peptides. Dichlorotriazinylaminofluorescein serves as the derivatization agent, thus enabling sensitive laser-induced fluorescence detection of the derivatized analytes.

On-line coupling of size exclusion chromatography and capillary electrophoresis via solid-phase extraction and a Tee-split interface.

An on-line size exclusion chromatography (SEC)-solid-phase extraction (SPE)-capillary electrophoresis (CE) system using a Tee-split interface has been developed for the analysis of peptides in biological fluids. The SEC column fractionates the sample by molecular size and the low-molecular-weight fraction, which contains the peptides, is directed to a C(18) SPE microcolumn, where the peptides are trapped and concentrated. The SPE column is desorbed with 425 nL acetonitrile and the effluent is sent to the Tee-split interface, which hydrodynamically splits (1:40) the flow and, thus, allows appropriate injection of analytes into the CE system.

On-line multidimensional liquid chromatography and capillary electrophoresis systems for peptides and proteins.

Peptides and proteins are gaining increasing attention in biosciences and, consequently, in analysis. This overview highlights the different approaches to couple on-line various separation techniques for the determination of proteins and peptides. The first section discusses the liquid chromatography (LC)-LC coupling, the second one reviews the on-line LC-capillary electrophoresis (CE) coupled systems and the third section summarizes the strategies for on-line CE-CE.