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Title:A Stopped-Flow Analyzer for Kinetic Methods Development - Automated Implementation of Guggenheim's Methods
Author(s):Seiler, Brian Douglas
Department / Program:Chemistry
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Chemistry, Analytical
Abstract:Accessories have been designed and constructed which directly transform a conventional single-beam spectrophotometer into a versatile stopped-flow kinetic analyzer. A relatively inexpensive microcomputer system serves as a dedicated controller/data processor for the instrument. The design employed features preservation of the optical configuration and geometry of the original spectrophotometer. Thus, abilities related to the performance of precise, absolute absorbance measurements have been retained. Additionally, kinetic response curves can be reproducibly generated, primarily due to efficiencies on solution transport and mixing components built into the "stopped-flow module". The hybrid nature of the instrument, allowing reliable collection and processing of responses from both kinetic and equilibrium phases of reactions, is seen as a powerful attribute.
The instrument has been carefully evaluated and found to be particularly well-suited for kinetic methods development. Long-term drift is reasonably small, and relative photometric error is evidently limited by fundamental photon noise. A high degree of linearity has been observed for absorbance measurements up to 2 o.d., and signal-to-noise ratios typically observed are large enough to permit routine calculations of kinetic parameters that are especially noise-sensitive. The versatility of the analyzer has been demonstrated by its conventional application in kinetic determination methods of environmental, pharmaceutical, and clinical interest. Color-forming reactions, a "redox" degradation reaction, and enzyme-catalyzed reactions have been investigated, with measurements taken in the visible and ultraviolet regions of the spectrum.
Automated calculation procedures, related to the classical "Guggenheim Method", have been successfully applied to pseudo-first-order kinetic response curves. Apparent first-order rate constants and analyte-proportional kinetic parameters have been abstracted with typical precision (between run relative standard deviation) on the order of ten per cent or better. If the kinetic form of a particular reaction system is not made to deviate largely from a simple first-order model, significant modifications of reaction conditions can be detected by monitoring changes in the derived apparent rate constant. Thus, for kinetic methods, potential determination errors caused by reaction condition changes can often be diagnosed "within-run".
Issue Date:1983
Description:255 p.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1983.
Other Identifier(s):(UMI)AAI8324641
Date Available in IDEALS:2014-12-15
Date Deposited:1983

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