BYU

Abstract by Hyejung Lee

Personal Infomation


Presenter's Name

Hyejung Lee

Degree Level

Masters

Abstract Infomation


Department

Statistics

Faculty Advisor

Dennis Tolley

Title

Deconvolution of Chemical Species using Absorbance Ratios

Abstract

Liquid chromatography (LC) is one of the most common methods of analysis of chemical compounds in a sample. One method of detection of compounds as they elute from an LC system is to analyze their absorbance spectra. A simple, portable absorbance detector that has recently been developed at BYU provides absorbance at these two different light way lengths. This paper presents the statistical methods of deconvolving compounds that have overlapping elution patterns by using the known ratios of absorbances at the two light way lengths. Empirically, the form of the eluting peaks are an exponentially modified Gaussian (EMG) shape, rather than simply a Gaussian shape. Estimating the 3 parameters of this distribution entails an iterative technique. Here, I present the use of nonlinear least squares using the Levenberg-Marquardt algorithm to estimate the parameters of EMG distriburions observed at each of the way lengths. Using the known absorbance ratios at these two wave lengths provides a degree of freedom to seperate co-eluting peaks. Examples are presented for seepratign variaous opoiod compounds that have similar elution times using both simulated and real data.