A Design Of Capillary Thermostat For Fully Automated Quantitative Capillary Electrophoresis And Its Application

Capillary electrophoresis(CE)is a new type of liquid phase separation technology,using the elastic,fused silica capillary as the separation channel,and using electroosmotic flow as the driving force.The separation of a sample mixture in CE was achieved according to the each component’s electrophoretic mobility difference.It has the characteristics of high column efficiency,fast separation,less solvent consumption.CE has been predicted that it would take the place of HPLC and become the mainstream analysis instrument in micro separation field.Theoretical analysis shows that,due to the high electric field across the capillary,the electrolyte in the capillary generates Joule heat.The Joule heat will create temperature gradient in the capillary,i.e.,the temperature in the capillary center is higher than temperature near the capillary wall.Because the solution viscosity decreases exponentially with temperature increasing,the migration speed of solute molecule in the capillary center is faster than the molecule’s migration speed near the capillary wall,causing band broadening and column efficiency declining.Without capillary temperature control,capillary electrophoresis generally suffers from poor accuracy of quantitative analysis and unsatisfactory repeatability.In order to improve the accuracy and precision,a capillary electrophoresis instrument must consider the capillary’s temperature control.We designed the capillary thermostat which is a sub-project of the project on the development of the fully automatic quantitative capillary electrophoresis system.It was based on the semiconductor refrigeration and PID temperature control,with reasonable mechanical structure and electronic circuit.For reducing or eliminating the effect of Joule heat in the CE system,and therefore,improving the accuracy and the precision of the CE performance.This dissertation is divided into seven chapters:In chapter 1,we mainly introduced the background and significance of the project.The development history and characteristics of CE were summarized,also with the basic structure and the main influencing factors.We have also introduced the research and development of the whole automatic high precision quantitative capillary electrophoresis.In chapters 2,3,4 and 5,we mainly introduced how to design the capillary thermostat.In the second chapter,we introduced the capillary thermostat’s overall design.In chapter 3,4,and 5,we respectively introduced the designs of capillary thermostat’s hardware circuit,mechanical structure and software control.In addition,we investigated the technical parameters of the capillary thermostat and evaluated requirements of the design.In chapter 6 and chapter 7,we mainly presented the experimental results of the quantitative capillary electrophoresis as well as the capillary electrochromatography,both with capillary thermostat installed.We also have also investigated the practicability of capillary thermostat.