Hartley transform based algorithm for the qualitative and quantitative analysis of multi-component mixtures with the use of emission excitation matrices

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Virginia Tech

Rapid advances in computer technology over the last few years and their integration into analytical instruments have led to tremendous increases in data collection rates. The need for tools to assist analytical chemists, and especially spectroscopists, in their task of interpreting such vast quantities of data is immediate.

This work focuses on the development of an algorithm based on an alternative to the Fourier transform, the Hartley transform, for the qualitative and quantitative analysis of multi-component mixtures using Excitation Emission Matrices. The algorithm involves the reverse search of a compressed reference spectral library for the identification of possible components of the mixture and the method of Non-Negative Least Squares for the quantification of the components.

A number of techniques for pre-processing of three dimensional fluorescence spectra along with several spectral encoding methods for the compression of the spectra were investigated. Both simulated and real data collected with a fluorescence spectrophotometer were used in this study.

The algorithm proved capable of analyzing mixtures of five components with relative concentrations ratio of about 100:1 and significant spectral overlap. At the same time a compression ratio of about 10:1 for the spectra in the reference library was achieved.

Finally, a library of three dimensional fluorescence spectra of some aromatic and poly-aromatic hydrocarbons was developed to be used with the algorithm. Such a library, along with the algorithm, provides a tool for the quick and simple qualitative and quantitative determination of mixtures of aromatic and poly-aromatic hydrocarbons.