Spectral Deconvolution and Quantification of Natural Organic Material and Fluorescent Tracer Dyes

Abstract

Fluorescent dyes have become an integral part of the study and management of ground water in karst environments. Researchers have striven to reduce detection limits and analyze multiple dyes in a single sample while minimizing dye concentrations for environmental, aesthetic and health reasons. The unambiguous separation from background, identification and quantification of fluorescent tracer dyes has increasingly taken on legal implications. Synchronous fluorescence spectroscopy and curve fitting software represent a major advances in the quantitative analysis of low levels of tracer dyes against naturally occurring background fluorescence. Determination of levels of detection (LOD) and levels of quantification (LOQ) are an important part of dye trace design and implementation. Factors that impact LOD and LOQ include levels of natural fluorescent compounds, absolute fluorescence of the specific dyes, the presence of multiple dyes with overlapping peaks and instrumental noise. Characterization of the spectral shapes and concentration dependences of the natural fluorescence background and applied tracer dyes are important to the determination of a positive dye trace result. Rather than representing noise, the natural fluorophores contain information about the flow environment. Spectral deconvolution with curve fitting software is an important tool in the karst researcher’s toolbox.