FT-IR detection system for capillary electrophoresis & a novel deposition method for ATR
Todebush, Richard Andrew
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Research performed in this dissertation is concerned with the separation, identification, and structural determination of complex carbohydrates. To help facilitate this research, capillary electrophoresis (CE), Fourier transform infrared (FT-IR) spectrometry and attenuated total reflection (ATR) were employed. Fourier transform infrared spectrometric interfaces have been used for over forty years. The primary focus of these interfaces usually falls under the heading of separations, which includes gas chromatography (GC) and high performance liquid chromatography (HPLC). Over the past twenty years capillary electrophoresis has become a popular separation technique, however, the use of a FT-IR spectrometric detection system coupled to CE has not been previously reported. This dissertation focuses on the practicality and performance of an interface between a capillary electrophoresis system with a Fourier transform infrared spectrometric microscope instrument, that is, CE/FT-IR spectrometry. The instrument was then used to study oligosaccharides.|There are a number of factors that must be addressed in the design of the CE/FT-IR spectrometric interface. The most important of these is the creation and maintenance of electrical contact at the end of the capillary column. This was achieved through two different methods. The first method involved the use of a stainless steel tee, which was in contact with the end capillary column. The second, more successful method involved coating the exterior of the capillary column with silver paint, which allowed for more flexibility in the design of the interface.|The next important factor in the design of the interface involved selection of the appropriate CE electrolyte system for the separations, in this case monosaccharides, oligosaccharides, and carbohydrates. The electrolyte system should not have absorption bands in the mid-infrared region, due to interference with the sugar bands. Borate electrolytes are proven to separate these compounds very well, however they have a strong absorption in the IR and they are not very volatile, which are two definite drawbacks. The use of ammonium electrolyte systems provides the needed volatility, but does not produce sufficient separation of the monosaccharides, oligosaccharides, and carbohydrates. This problem should be solved with the use of capillary electrochromatography (CEC), which will provide both chromatographic and electrophoretic separations.|The final concern with the interface design is the ability to control the deposit size and the amount of sample deposited from the end of the capillary column. The smaller the deposition size of the sample, the greater the sensitivity of the FT-IR analysis.|Future studies related to this project include the use of a capillary electrochromatography (CEC)/FT-IR interface to allow for detection and separation of the underivatized oligosaccharides and carbohydrates.