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UBC Theses and Dissertations

Towards development of optimal sequential injection analysis methods Kester, Michael Dean


Currently, several research groups in the pulp and paper industry are actively pursuing the development of improved detection strategies for priority pollutants. A new technique in analytical chemistry called sequential injection analysis, may be able to provide a robust, inexpensive, automated method for detection of resin acids (known fish toxins) with appropriate use of immunochemical sensing. Most new analytical techniques, however, require fundamental studies in order to understand and optimize the physical processes that occur during the analysis. Towards this end, a dual-channel sequential injection analyzer has been designed and used for fundamental studies of dispersion. In an attempt to simplify the development of sequential injection methods, a unique graphical user interface with a virtual manifold has been proposed and implemented for control of the analyzer. The software is able to automatically and systematically manipulate over 20 instrumental parameters in search of optimal operating conditions; all information is recorded in a comprehensive database for rapid recall and display. The first dataset to be collected on the analyzer includes over 6,800 experimental dispersion profiles that were created by injection of a tracer dye. The effects of injection volume, flow rate, and manifold geometry were examined and quantified using peak moments. The random-walk model was shown to hold for sequential injection peak profiles which undergo multiple flow reversals of varying length. Optimization of the mutual penetration between two sequentially injected zones was investigated using several new descriptors for zone penetration, sensitivity, throughput and reagent economy. When the combined conditions of maximum zone penetration and sensitivity were considered, the optimal sample and reagent injection volumes were shown to be independent of manifold length and flow rate. To gain further insight into the sequential injection technique, a computer simulation based on the random-walk model was proposed and implemented. A unique injection procedure was demonstrated, which simulates the sequential loading of multiple zones, in addition to the flow reversal process. Simulated dispersion profiles agree well with experimental dispersion profiles created under laminar flow conditions. Visualization of the theoretical concentration profiles which occur during injection and flow reversal allowed prediction of improved sensitivity at the point of zero net fluid movement.

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