| The toxicological and biological characteristics of many trace elements depend to a great degree on their quantities as well as their oxidation states and chemical forms. Currently, it is not sufficient to just quantitate the total amount of the trace element, but rather information on the "form" of the trace element is essential since different forms of the same metal may exhibit widely different effects. From here stems the importance of speciation which is defined as the separation and quantitation of the different chemical forms of a particular trace element.;While solution nebulization is the most common type of sample introduction used for plasma mass spectrometry, chromatographic techniques such as high-performance liquid chromatography (HPLC) provide the separation scheme necessary for speciation while maintaining the integrity of the individual species in the sample. Speciation by coupling the HPLC to Inductively Coupled Plasma Mass Spectrometry (ICP-MS) is an attractive approach with excellent sensitivity, and high selectivity.;Conventional coupling of HPLC to ICP-MS generally involves the use of a concentric nebulizer. The nebulizer-spray chamber set-up not only contributes additional dead volume to the system, but is also less than 5% efficient in analyte transfer to the plasma. The first part of the dissertation research involves the evaluation of a direct injection nebulizer (DIN) in coupling HPLC to ICP-MS for the speciation of chromium. A home-made DIN is designed and constructed. The capillary of the DIN is connected to the analytical column to allow the transfer of the column's effluent to the plasma. The separation of the the two chromium species Cr(III) and Cr(VI) is accomplished on a 4 mm mixed-mode column with 120 ;The second part of the dissertation involves the development of chromatographic methods for the analysis of dye samples with mass spectrometric detection. The coupling of HPLC to ICP-MS provides trace detection levels needed for speciation of metal-complexed dyes and their breakdown products present in environmental samples. Methods developed for the speciation of inorganic dyes, mainly Acid Blue 158, and Acid Blue 193, are discussed along with the different chromatographic techniques that are used.;The last section of the dissertation involves the use of Electrospray Mass Spectrometry (ES-MS) for elemental analysis. Currently there is renewed interest in electrospray ionization as an atmospheric ionization source for mass spectrometric detection. Potential advantages of ES-MS over ICP-MS include its low cost, compatibility with organic solvents, capability to determine elements which suffer from argon plasma interferences (Ca, K, Fe, Se, and As), and the ability to directly determine speciation information. The characterization of the electrospray ion source and the potential for elemental analysis studies through the use of well defined solutions of simple inorganic analytes provides the framework for the results presented in this section. (Abstract shortened by UMI.)... |
