I. Speciation and identification of selenium compounds in biological matrices. II. Speciation of bromine compounds in aqueous/acidic matrices

There is an ever increasing awareness that particular chemical species of an element can dictate its toxicity, transport bioavailability and metabolism. Therefore, it is no longer sufficient to rely on total element determinations. Speciation science strives to identify and characterize elemental species in order to understand the environmental and biological implications of individual elements, and is a discipline of great relevance to a vast scientific group. Often, the "target" species is as yet undiscovered and problematic because of the complexity of real world systems. The determination of specific species of elements is considerably more challenging than determination of total element contents. Unfortunately, no "universal" technique nor procedure exists for speciation analysis. Hybrid techniques, such as chromatographic separation coupled to an element-selective detector like inductively-coupled plasm mass spectrometry (ICP-MS) are usually required.;Selenium is an essential trace element at very low concentrations, yet toxic outside of this range. Therapeutic potential has been witnessed with selenium-containing compounds in the treatment of cancer, tumors, and cardiovascular disease. Very little is known about the uptake and metabolism of selenium. Extremely low concentrations in a complex matrix, insufficient knowledge of chemical structure, and relatively low sensitivity of usual detectors have hindered to progress of selenium speciation in biological matrices. This research focused on the speciation and identification of selenium-containing metabolites in human urine using on-line HPLC-ICP-MS, and organic MS and MS/MS techniques. It was anticipated that identification of these selenium-containing metabolites will help in the elucidation of selenium metabolic pathways, thereby enhancing its therapeutic potential.;Ozonation is becoming a preferred drinking water disinfection technique. Bromate is an ozone disinfection by-product, and has been labeled as a potential carcinogen at low m g/L concentrations. There is also a concern about bromate in processed foods and beverages. The detection of low m g/L of bromate is hampered by the insufficient sensitivity of current analytical techniques. The ability to detect trace levels of bromine-containing compounds in phosphoric acid matrices is even more challenging. Research has focused on the speciation of bromine-containing compounds in both aqueous and phosphoric acid matrices using ion exchange chromatography (IEC) coupled with ICP-MS detection.