Molecular Spectroscopic Analysis Of Organics In Environmental Samples

Detection of organic contaminents in environmental samples is an important topic of environmental analytical chemisty, however, traditional chemical analyis techniques often could not meet the demonds for real time and online monitoring. Molecular spectroscopy, with the advantages of no reagent requirements, real-time, online, in-situ and simultaneou detection, is considered to be a promising method. In this thesis, fluorescence spectrometry and infrared spectrometry, combined with mathematical processing and other techniques, were used to establish new methods for detecting environmental organic compounds. Main contents and results are as follows:1. Fluorescence spectrometry is a powerful tool for detecting polycyclic aromatic hydrocarbons (PAHs). However, both PAHs and natural dissolved organic compounds (DOM) in water can interference such a determination. Three-dimentional excitation-emission-matrix (EEM) combined with parallel factor algorighm can be used for extracting information from overlapping spectrum. As a result, viairous PAHs could be detected simultaneously. In addition, the interactions between different PAHs and DOM were demonstrated to be independent.2. The spectoelectrochemistry of benzoquinone, a model compound of DOM, was studied. Fluorescence spectroelectrochemistry could be used to monitor the real-time change of fluorescence intensity along with the electrochemistry process. The anion radicals produced by electrochemical reduction had a lower fluorescence intensity, while the dianion had the lowest intensity and a red-shift in emission spectrum.3. To resolve the problem of determing low concentration organic compounds in water by infrared method, an infrared-attenuated total reflections (ATR) chemical sensors based on planar silver halide waveguide coated on ethylene/propylene copolymer was established. This method was successfully used for detecting multiple organic contaminents (i.e., monocyclic aromatic hydrocarbons and chlorinated hydrocarbons) in water. Comparing to the conventional infrared system, our sensor system exhibits an extremely high senvitivity and selectivity, excellent reliability and in a wide dynamic range.4. The changing secondary structure of bovine serum albumin (BSA) and hemoglobin in the heating process was examined by using planar silver halide waveguide based infrared ATR. Information about the amide I region was extracted using curve fitting methods. From two-dimentional infrared correlation spectroscopy, the sequence order in the heating process was obtained.5. Preparing bio-oil from various biomass is an environment friendly method, but chemical compositions of bio-oil are extremely complex. Spectrometry, inculding infrared and EEM, were used to establish a method for the fast determination of bio-oil chemical compositon. Fractions in bio-oil with different polar could be distinguished qualitatively, and the results are consistent with the GC/MS results.