Development Of Microfluidic Capillary Electrophoresis Systems

In capillary electrophoresis (CE) systems, the separation is usually performed in capillaries with separation lengths of several tens centimeters, separation times of several tens minutes, with the advantages of low sample consumption, high analysis speed, high separation efficiency and ease of automation. The high-speed capillary electrophoresis (HSCE) systems using short capillaries, high separation field strengths and narrow sample plugs, can achieve the CE separation with high speed and high separation efficiency.In chapter 1, the developments of conventional CE, microfluidic chip-based CE and short capillary-based CE systems for protein separation in the recent years are reviewed.In chapter 2, we developed a high-speed sodium dodecyl sulfate capillary gel electrophoresis (SDS-CGE) system for protein separation based on a short capillary and slotted-vial array. A partial translational spontaneous injection approach was proposed for high-viscosity buffer solution system used in protein separation under CGE mode, to obtain narrow injection volume in the picoliter range. Several factors affected the sample injection process were investigated, including the shape of the capillary inlet and the moving speed of the platform. A sample injection plug length of～65μm (corresponding to～500 pL) was obtained under the optimized conditions. Five fluorescein isothiocyanate (FITC)-labled proteins were separated within 60 s with an effective separation length of 1.5 cm. The theoretical plates per meter ranged from 258,000 to 1,280,000 (corresponding to 0.78μm-3.88μm plate heights). The RSD of the migration time was less than 1.3%(n=5). A good linear correlation with the logarithm molecular weight versus migration time was obtained in the molecular weight range of 17,200 to 500,000, which demonstrated the present system could be applied in protein molecular mass determination. The separation speed and separation efficiency of the system was comparable to most of the reported microfluidic chip-based on HSCE systems for protein separation.In chapter 3, we developed a capillary electrophoresis analyzer toward space experiment based on sequential injection analysis (SIA) and "T" configuration channel sample introduceion system. The analyzer integrated closed liquid manipulation system, automated injection and separation system, high voltage power supply, laser-induced fluorescence (LIF) detection system, data collection, recording, storage system and control system. The factors affected the performance of the analyzer were investigated, including separation field strength, SI injection sample volume, the carrier flow-rate and the liquid difference. Under the MEKC separation mode, three fluorescein isothiocyanate (FITC)-labled chiral animo acids were separated within 320 s with an effective separation length of 13 cm. The repeatabilities for the migration time, peak height and peak area were 0.70%-0.86%, 3.23%-4.33% and 3.82%-5.39%(n=8), respectively. In the test for working stablility, the analyzer continuously worked for 19 h. We expect the capillary electrophoresis analyzer has good application potential in space experiment.