| Several applications of computer-based modeling methods to analytical chemistry are described. Areas of application include reaction-rate methods of analysis, response surface modeling, and liquid chromatography.;Two reaction-rate methods of analysis are introduced which attempt to minimize the effect of between-sample variations in the pseudo-first-order rate constant. The first method uses two rate measurements during the reaction and is therefore called the two-rate method. A model for the propagation of random errors for this method is developed and shown to be valid. The second method introduced is based on the extended Kalman filter, a recursive analog to nonlinear least squares fitting. Chemical systems are used to show that both methods are less susceptible to between-run variations in the rate constant than traditional methods. The Kalman filter is also shown to enhance the capabilities of differential kinetic methods, those reaction-rate methods which take advantage of differences in the rate constant to determine two or more analytes simultaneously.;A comparison of traditional and optimized reaction-rate methods of analysis, including the two-rate method, is presented for reactions following first-order kinetics. The comparison focuses on the susceptibility of seven reaction-rate methods to rate constant variations and their precision in the absence of those variations. To aid in this comparison, models are developed which illustrate the dependence of each method on systematic errors in the rate constant.;Response surface modeling is an important area of many scientific disciplines and a new approach to this technique, based on the Kalman filter, is described. The new method has numerous advantages over traditional approaches to linear least squares modeling, including speed, simplicity, and adaptability. The new method is applied to three chemical systems to demonstrate its utility.;A theoretical model for recycle heartcut chromatography (RHC) is developed to evaluate its potential. The model shows that RHC is only useful for obtaining resolution improvements if long heartcut loops are used and/or dispersion in the heartcut loop can be reduced. The utility of RHC for enhancing chromatographic selectivity is demonstrated, however.;Also presented in this work are a program for nonlinear curve fitting and a summary of methods for generating normally distributed random numbers for simulation. |
