On-Line Electrophoretic, Electrochromatographic, and Chromatographic Sample Concentration in CE-MS

On-line sample concentration in capillary electrophoresis–mass spectrometry (CE-MS) is a specialized area in separation science. The sample is processed within the liquid stream that passes through the CE and then into the MS system. The electrophoretic and electrochromatographic sample concentration or stacking techniques in CE-MS with mainly an electrospray ionization (ESI) interface are described in this chapter. The mechanisms of stacking are discussed, and some examples for real sample analysis are presented. In addition, there is a final section on chromatographic sample concentration by on-line and in-line solid-phase extraction in CE-MS.