Studies On Porous Plastic Optical Fiber Based On Quinine As Fluorescence Indicator

This dissertation consists of the following three chapters.Chapter 1 is a literature review. It summarizes the development of optical fiber chemical sensors and the basis of this dissertation from spectral method, probe and porous plastic optical fiber probe's advantages. It also summarizes the measuring methods to date for chloride determination in serum and for free SO2 determination in wine from both regular lab determination and chemical sensing technology, and emphasis is put on chemical sensing technology especially the research and development of fiber-optical chemical sensors.Chapter 2 is about theories and methods. It is an introduction to the theory of dynamic fluorescence quenching and the basis principle of porous plastic optical fiber probe. A detailed description is made in the process flow of probes and the influence on probes of parameters in the fabrication of probes. These parameters included types and quantities of every component in the polymerization, the temperature of polymerization and the degree of purification and airproof, etc. Chapter 3 is the development and applications of porous plastic optical fiber probes. In order to resolve the current problem that sensing probe indicator is easily leakable, the thesis proposes a new fabrication method for porous plastic optical fiber probes using the copolymerization of fluorescence indicator and monomer. A small segment of this porous plastic fiber has been applied to the determination of real sample with satisfactory results. This chapter consists of three sections. The first section is studies on halides-ion porous plastic optical fiber probe. A new porous plastic optical halides-ion fiber was developed through the copolymerization of fluorescence indicator quinine sulphate and monomer methyl methacrylate. Its response mechanism was studied and applied to the determination of halides-ion.Under the condition that the pH value was 1.3, the optical fiber's fluorescence remains constant and has a good response to halides-ion. The calibrated graphs for iodide was obtained in the range from 5.0×10-4 to 1.3×10-2 mol/L, from 8.0×10-4 to 1.5×10-2 mol/L for bromide and from 1.5×10-2 to 8.0×10-2 mol/L for chloride and their respective detection limits were 2.2× 10-4 mol/L for iodide, 5.2×10-4mol/L for bromide, and 1.2×10-2mol/L for chloride. Using the probe to determine the amounts of chloride ion in serum, the results were in good agreement with the results obtained from the traditional chloride ion-selective electrode method. The second section is studies on sulfur dioxide porous plastic optical fiber probe. Sulfur dioxide fiber was developed through the copolymerization of fluorescence indicator quinine and monomer styrene. Its response mechanism was studied and applied to the determination of SO2. Under the condition that the pH value was 1.3, the optical fiber's fluorescence remains constant and has a good response to sulfur dioxide. A good linearity in a wide concentration range of sulfur dioxide, 5.0×10-5～7.1×10-4 mol/L, was displayed. Its detection limit was 2.2×10-5mol/L. Using the probe to determine the amounts of free sulfur dioxide in wine, the results were in good agreement with the results obtained by the state standard direct iodometric method. The third section outlines some exist of problems in the studies of porous plastic optical fiber probes and comes up with their possible solutions.