Selectivity enhancement in capillary electrophoresis by means of two-dimensional separation or dual detection concepts.

For the identification and quantification of analytes in complex samples, highly selective analytical strategies are required. The selectivity of single separation techniques such as gas chromatography (GC), liquid chromatography (LC), or capillary electrophoresis (CE) with common detection principles can be enhanced by hyphenating orthogonal separation techniques but also by using complementary detection systems. In this review, two-dimensional systems containing CE in at least one dimension are reviewed, namely LC-CE or 2D CE systems. Particular attention is paid to the aspect of selectivity enhancement due to the orthogonality of the different separation mechanisms. As an alternative concept, dual detection approaches are reviewed using the common detectors of CE such as UV/VIS, laser-induced fluorescence, capacitively coupled contactless conductivity (C4D), electrochemical detection, and mass spectrometry. Special emphasis is given to dual detection systems implementing the highly flexible C4D as one detection component. Selectivity enhancement can be achieved in case of complementarity of the different detection techniques.