The coupling of capillary electrophoresis (CE) to chemiluminescence nitrogen detection (CLND), is presented here. Designing and implementing a novel pneumatic nebulizer as the interface, optimizing the operating parameters of the system, and demonstrating the utility of the system in modern analytical chemistry are some of the tasks undertaken and described in this dissertation. Interfacing CE, a liquid phase separation technique, to a commercial gas phase CLND system (ANTEK Instruments, Houston, TX) requires the design and development of an interface that does not adversely affect the separation nor hinder the detection.; To avoid aspiration on the CE capillary, a free-flow nebulizer was designed where the effluent of the CE capillary and the sheath liquid meet in a gap that separates the nebulizer nozzle from the CE capillary. This nebulizer reduces the separation efficiency (measured as theoretical plate count) in the combined CE-CLND system by only ∼10% of what would be achieved by using an on-line UV detector, while offering sensitive and selective detection of nitrogen containing species.; In order for a CLND to detect the small amount of analyte injected in CE, the sensitivity of the system had to be improved. To bring about the required improvement, attention was paid to the reaction chamber design, the nebulizer gas flow rate and O2 composition. A new inlet system was designed to improve mixing of the NO and O3 gas streams in the reaction chamber. Excess O2 in the NO stream, left over from the combustion step, was found to lower the signal from the chemiluminescence reaction, so the optimum composition was determined. The sensitivity, linearity, and reproducibility of the system are characterized here.; Applications of this new technique are reported as well. Aminoglycoside antibiotics were detected at the 0.2 ppm level using field amplified sample stacking as a preconcentration technique. Monomeric and polymeric hindered amine light stabilizers were also separated from one another and quantitated from both neat mixtures and a polyethylene sample.
展开▼
