Studies On Microfluidic Chemiluminescence Detection System Based On Liquid Core Waveguide

Microfluidic analysis has been developed fast since it was proposed for its advantages such as low sample and reagent consumption, fast analysis speed, high efficiency, automation and integration. With the development of miniaturized microfluidic analysis systems, the sensitivity of the detector is required to be higher for samples in much less volume. Chemiluminescence (CL) analysis has been widely used in microfluidic analysis for its simple structure, requiring no light source, having no stray light, and therefore a high signal-to-noise ratio will lead to high sensitivity. Liquid core waveguides (LCWs) have the properties of conducting light direction and decreasing light loss during light propagation. When used in CL analysis, a LCW can act both as the light transmission conduit and the flow-through cell, and effectively improve the detection sensitivity. For the very fast CL reactions, the LCW can effectively collect and transfer the CL emission. In this paper, based on silver-coated LCW, a microfluidic CL detection system combined with automated sampling device has been developed, which features simple structure, low consumption, fast analysis speed and easy operation.In chapter1, several optical detection techniques widely used in microfluidic analysis system were reviewed, including absorption spectrophotometric detection, fluorescence detection and chemiluminescence detection. The LCWs and their applications in chemiluminescence detection were introduced; and the hydrogen peroxide analysis by CL was introduced. Finally, the purpose and design of this paper were proposed.In chapter2, a microfluidic CL detection system based on silver-coated LCW was established. The LCW capillary acting as sampling probe was combined with a rotary sampling device, so that continuously automated sample introduction could be achieved. The deposition methods of silver cladding and the sampling introduction methods were investigated. The LCW capillary with a high numerical aperture was applied to microfluidic CL detection system, and the analytical performance of the system was demonstrated with luminol-hydrogen peroxide-Cu (II) assay. The flow rate, the volume of luminescence reagent and sample, the concentration of luminol and Cu (II), the pH of the buffer solution and the diameter of the LCW tube were optimized. The liner range was4.4×10-6～4.4×10-3mol/L, and regression equations for the standard curve was y=-31.2+7.0x (10-5mol/L, r=0.9988). The LOD was2.2×10-7mol/L (3σ) with the sample throughput of30～60samples per hour, and a precision of5.8%RSD (n=5) was obtained. The carryover was so little that it can be neglected. The method was applied to the determination of hydrogen peroxide in rain water as well as in running water, and the recoveries were93.4～107.4%and90.3～106.4%for each.In chapter3, the microfluidic CL detection system based on LCW was summarized.