Multiplexed electrophoretic systems for the detection and identification of small ions

Capillary electrophoresis (CE) is regarded as a powerful separation technique that is an alternative or complementary technique to more traditional methods such as gel electrophoresis and liquid chromatography. When applied to the separation of inorganic species, capillary electrophoresis still continues to take second place to other competitive techniques such as ion chromatography (IC) and elemental mass spectrometry. CE is often touted as having several obvious advantages over chromatographic techniques (mostly IC) including high resolving power, speed, instrumental simplicity, flexibility and cost‚ÄövÑv™efficiency. On the other hand, CE is frequently cited as having a number of comparative disadvantages such as poor reproducibility and sensitivity. The work undertaken in this thesis describes technical innovations to harness the inherent advantages of CE whilst minimising the disadvantages as part of the development of a system for the rapid determination of common small environmental anions and cations. It is unique in its capability to analyse directly from a sample flow, making it especially attractive for monitoring purposes. To enable a move from a capillary to a chip‚ÄövÑv™based system, simple, low cost techniques for the manufacture of polymeric microchips and the incorporation of detection electrodes were developed using limited resources to provide further improvements in speed and reduce resource consumption. A multiplexed polymeric microchip system was developed employing a novel hydrodynamic injection mechanism to reduce sample matrix effects and injection bias, and to improve the quantitative performance of the system. Finally, a compact multipurpose microfluidic platform is developed to support future research interests.