The perturbation of fluorescence in both bovine and human serum albumin caused by chloride, iodide, acrylamide and N-bromosuccinimide was studied under various experimental conditions. Serum albumin fluorescence lifetime changes induced by pH and added solutes were also studied, both in acid solutions and in powders. In general, the two proteins behave similarly. During the N-F transitions, the fluorescence lifetimes and the fluorescences intensities decrease in the same qualitative manner. Chloride binding enhances the fluorescence intensity, but has little or no effect on the fluorescence lifetimes. Chloride enhances the human serum albumin fluorescence intensity much more than it enhances that of bovine serum albumin. Iodide and acrylamide quench both the fluorescence intensities and lifetimes. Acrylamide quenching is hardly affected by pH changes, but is sensitive to the protein concentration. In acrylamide quenching, acrylamide molecules are partitioned into the protein matrix, causing both dynamic and static quenching. Iodide quenching is sensitive to pH, with a maximum quenching at pH 4.0. Iodide quenching decreases with increased ionic strength and with increased protein concentration. The Stern-Volmer plots obtained with iodide as the quencher are downward curving in both proteins. The downward curvature is a result of iodide binding, the main quenching mechanism. Both tryptophans in bovine serum albumin tryptophans and the single human serum albumin tryptophan are very close to the surface of the protein. The environments of the bovine serum albumin tryptophans are not very different from each other. The fluorescence lifetimes of serum albumin powders separated at pH 6.0 are very sensitive to hydration, while the lifetimes of powders separated at pH 2.0 are not. Acrylamide and iodide quench the fluorescence lifetimes of bovine serum albumin powders, even in the driest samples. Quenching is maximum at a hydration approximately equal to that required for monolayer coverage.

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Uranium (U) contamination can be introduced to the environment as a result of mining and manufacturing activities related to nuclear power, detonation of U-containing munitions (DoD), or nuclear weapons production/processing (DOE facilities). In oxidizing environments such as surface soils, U predominantly exists as U(VI), which is highly water soluble and very mobile in soils. U(VI) compounds typically contain the UO22+ group (uranyl compounds). The uniquely structured and long-lived green luminescence (fluorescence) of the uranyl ion (under UV radiation) has been studied and remained a strong topic of interest for two centuries. The presented research is distinct in its objective of improving capabilities for remotely sensing U contamination by understanding what environmental conditions are ideal for detection and need to be taken into consideration. Specific focuses include: 1) the accumulation and fluorescence enhancement of uranyl compounds at soil surfaces using distributed silica gel, and 2) environmental factors capable of influencing the luminescence response, directly or indirectly. In a complex environmental system, matrix effects co-exist from key soil parameters including moisture content (affected by evaporation, temperature and humidity), soil texture, pH, CEC, organic matter and iron content. Chapter 1 is a review of pertinent background information and provides justification for the selected key environmental parameters. Chapter 2 presents empirical investigations related to the fluorescence detection and characterization of uranyl compounds in soil and aqueous samples. An integrative experimental design was employed, testing different soils, generating steady-state fluorescence spectra, and building a comprehensive dataset which was then utilized to simultaneously test three hypotheses: The fluorescence detection of uranyl compounds is dependent upon 1) the key soil parameters, 2) the concentration of U contamination, and 3) time of analysis, specifically following the application of silica gel enhancing material. A variety of statistical approaches were employed, including the development of multiple regression models for predicting both intensity and band structure responses. These statistical models validated the first two listed hypotheses, while the third hypothesis was not supported by this dataset. The combination of inadequate moisture levels and reaction times (≤ 24 hrs) greatly limited the detection of varying levels of U, depending on the soil.