New approaches to the analysis of complex samples using fluorescence lifetime techniques and organized media

Fluorescence spectroscopy is a highly sensitive and selective tool for the analysis of complex systems. In order to investigate the efficacy of several steady state and dynamic techniques for the analysis of complex systems, this work focuses on two types of complex, multicomponent samples: petrolatums and coal liquids. It is shown in these studies that dynamic, fluorescence lifetime-based measurements provide enhanced discrimination between complex petrolatum samples. Additionally, improved quantitative analysis of multicomponent systems is demonstrated via incorporation of organized media in coal liquid samples. This research provides the first systematic studies of (1) multifrequency phase-resolved fluorescence spectroscopy for dynamic fluorescence spectral fingerprinting of complex samples, and (2) the incorporation of bile salt micellar media to improve accuracy and sensitivity for characterization of complex systems.;In the petrolatum studies, phase-resolved fluorescence spectroscopy is used to combine spectral and lifetime information through the measurement of phase-resolved fluorescence intensity. The intensity is collected as a function of excitation and emission wavelengths, angular modulation frequency, and detector phase angle. This multidimensional information enhances the ability to distinguish between complex samples with similar spectral characteristics. Examination of the eigenvalues and eigenvectors from factor analysis of phase-resolved and steady state excitation-emission matrices, using chemometric methods of data analysis, confirms that phase-resolved fluorescence techniques offer improved discrimination between complex samples as compared with conventional steady state methods.;In contrast to sample classification and discrimination, accurate quantitative determinations are difficult to obtain from fluorescence analysis of complex samples due to sample matrix effects and intermolecular interactions. Organized media can be used to minimize these unwanted processes by isolating the analyte molecules in a uniform microenvironment within the sample matrix. Utilizing complex coal liquid samples, the unique capabilities of bile salt micellar media to provide such uniform microenvironments for accurate and selective determinations, without physical separation or extraction, are compared with results for conventional detergent micelles and simple solvent solutions.