EVALUATION OF MULTIPOINT KINETIC DATA FOR QUANTITATION OF AMINO ACIDS AND MULTIWAVELENGTH ABSORPTION DATA FOR QUANTITATION OF POLYNUCLEAR AROMATIC HYDROCARBONS
Abstract
This thesis consists of three chapters and one appendix. Chapter I describes the evaluation of a predictive-kinetic method for the quantitation of amino acids based on reaction with ninhydrin. Conditions are developed for which reactions are pseudo-first-order in amino acid. Absorbance vs. time data from the kinetic region of the reaction (1-3 half-lives) are fit to a first-order model to predict the total absorbance change that would occur if the reaction were monitored to completion. Kinetic dependencies of all parameters were evaluated and results are virtually independent of change in temperature ((+OR-)1(DEGREES)C) and ninhydrin concentration ((+OR-)3.0 x 10('-3) M) Chapter II describes the evaluation of the predictive-kinetic method for the simultaneous quantitation of mixtures of amino acids based on significantly different apparent first-order rate constants for various amino acids; different data ranges were evaluated for two-component mixtures. A comparison between a nonlinear regression method and a so-called multiple linear regression method showed that both methods give the same results regardless of the number of components and fitted data range. Chapter III describes the use of multiwavelength first- and second-derivative spectra with matrix-least-square data processing to resolve mixtures of components with overlapping absorption spectra. Procedures are evaluated for polynuclear aromatic hydrocarbons in the presence of light-scattering components. Results show that the multiwavelength first- and second-derivative spectra offer higher degrees of selectivity than absorption spectra, permit the resolution of mixtures of components with overlapping spectra, and yield improved signal-to-noise ratio relative to single wavelength data. Polynuclear aromatic hydrocarbons in two- and three-component mixtures are quantified in the range from 0.2 to 2.0 (mu)g/ml with uncertainities in the range of 0.005 (mu)g/ml.
Degree
Ph.D.
Subject Area
Analytical chemistry
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