Portable capillary-based (non-chip) capillary electrophoresis

Miniaturized, portable instrumentation has been gaining popularity in all areas of analytical chemistry. Capillary electrophoresis (CE), due to its main strengths of high separation efficiency, relatively short analysis time and low consumption of chemicals, is a particularly suitable technique for use in portable analytical instrumentation. In line with the general trend in miniaturization in chemistry utilizing microfluidic chips, the main thrust of portable CE (P–CE) systems development is towards chip-based miniaturized CE. Despite this, capillary-based (non-chip) P–CE systems have certain unmatched advantages, especially in the relative simplicity of the regular cylindrical geometry of the CE capillary, maximal volume-to-surface ratio, no need to design and to fabricate a chip, the low costs of capillary compared to chip, and better performance with some detection techniques. This review presents an overview of the state of the art of P–CE and literature relevant to future developments. We pay particular attention to the development and the potential of miniaturization of functional parts for P–CE. These include components related to sample introduction, separation and detection, which are the key elements in P–CE design. The future of P–CE may be in relatively simple, rugged designs (e.g., using a short piece of capillary fixed to a chip-sized platform on which injection and detection parts can be mounted). Electrochemical detection is well suited for miniaturization, so is probably the most suitable detection technique for P–CE, but optical detection is gaining interest, especially due to miniaturized light sources (e.g., light-emitting diodes).