Multidimensional liquid-phase separations combining both chromatography and electrophoresis - A review

•Non-gel MD technologies comprising both liquid chromatography and electrophoresis are reviewed.•LC separation modes include RPLC, IEC and SEC.•Electromigration separation modes include CE/MCE, FFE, MEKC, EC and IEF.•A special focus has been paid to interfacing technologies.•Various detection techniques are discussed with mass spectrometry being the most widely used.

Described as intrinsically powerful building blocks for two-dimensional separations by Giddings [Anal. Chem., 56 (1984) 1258A-1270A], the coupling of chromatography and electrophoresis has been proven to enhance the resolution of a wide array of molecules in complex biological, environmental and food samples. This review provides a comprehensive overview of multidimensional chromato-electrophoretic (LC - E) and electrophero-chromatographic (E - LC) separation systems from inception to the most recent published examples. LC separation modes include reversed phase, ion exchange, and size exclusion. Electromigration separation modes include capillary, microchip or free flow electrophoresis; micellar electrokinetic chromatography; electrochromatography; and isoelectric focusing. The advantages and disadvantages of various non-gel based off-line and on-line hyphenation technologies of LC - E and E - LC are discussed, with conditions and system characteristics also provided.

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