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The flow-injection spectroscopic speciation of aluminum, mercury, selenium and sulfur
The development and evaluation of some new procedures for the determination of various chemical forms of aluminum, mercury, selenium, and sulfur are described in this dissertation. Studies of the biological and environmental transformations of elements are underpinned by the provision of reliable information about the relative concentrations of various chemical forms of the elements. ^ Here, the final measurements were made by graphite furnace atomic absorption spectrometry (GFAAS), cold vapor atomic absorption spectrometry (CVAAS), molecular emission spectrometry (MES) and atomic fluorescence spectrometry (AFS). These measurement techniques were preceded by selective chemical reactions based on liquid-liquid extraction (LLE), chemical vapor generation (CVG) [in particular, hydride generation (HG)] and selective redox chemistry. ^ For the selenium and sulfur speciation techniques, the atomic fluorescence instrument was adapted to monitor molecular sulfur emission and selenium fluorescence simultaneously through two of the instrument's channels. The analyte elements in a sodium tetrahydroborate matrix were merged with a hydrochloric acid stream in a flow-injection manifold, chemical vapor generation was used to introduce the analytes into an argon-hydrogen diffusion flame in the form of hydrogen selenide and hydrogen sulfide. ^ A speciation procedure was developed based on the reactivity towards borohydride at low acid concentrations and the amalgam trapping of both mercury and methylmercury hydride. Spectroscopic discrimination between the methylmercury and inorganic mercury was made by using an amalgam trap. When the amalgam trap was bypassed, no signal for methylmercury was observed. This method was applied to the determination of inorganic and methylmercury in river water tap water, and urine matrices. Validation was performed by analysis of the standard reference materials TORT-2, DOLT-2 and DOMR-2 CRMs. ^ An automated flow-injection approach for the speciation of aqueous aluminum species in waters is suggested. It is intended that the flow-injection manifold be used to identify three types of aluminum; acid reactive (Alr), labile monomeric (Ala) and nonlabile monomeric (Alo). Initial results have been obtained for flow-injection liquid-liquid extraction interfaced with GF-AAS. (Abstract shortened by UMI.)^
Christopher David Palmer,
"The flow-injection spectroscopic speciation of aluminum, mercury, selenium and sulfur"
(January 1, 2001).
Doctoral Dissertations Available from Proquest.