The More and Less Common Approaches to Enhancing Sensitivity in Capillary Electrophoresis

The determination of trace analytes in some types of samples by capillary electrophoresis (CE) requires their prior extraction from the sample matrix and preconcentration. The preconcentration step is the bottleneck of many analytical processes, which should ideally involve as few operations as possible in order to minimize potential errors and shorten analysis times. There is a growing search for more environmental friendly approaches capable of using smaller amounts of solvents and sample sizes. Although solid phase extraction (SPE) continues to be the most widely used concentration technique, some cleanup/concentration methodologies involving the use of membranes, electrophoretic preconcentration, chromogenic reagents, microdialysis (MD), solid phase microextraction (SPME), hollow fibres (HF), supercritical fluid extraction (SFE), cloud point extraction (CPE) and stir bar sorptive extraction (SBSE) have proved effective alternatives for preconcentration purposes. This paper reviews available preconcentration techniques for use in CE analysis (mainly with UV-Vis detection) and supplements the information contained in previously published reviews about this emerging field of analysis.