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Ultratrace analysis of environmentally important metals by volatile compound generation atomic spectroscopy
Goal: This project is focused on construction, assembly and optimization of the improved units for flow injection electrochemical and UV photochemical generation of volatile compounds for ultratrace elemental analysis by atomic spectroscopy (atomic absorption and fluorescence spectroscopy).
Novelty: Electrochemical and UV photochemical volatile compound generation techniques are among the most common techniques in atomic spectroscopy, due to their advantages compared with classical chemical generation. However, utilization of both techniques in analysis of environmental samples planned in the proposed work has not been sufficiently investigated.
Broader impacts: The proposed method development for analysis of real-world environmental samples has potential for improvement of environmental control on the release of toxic metals and other inorganic contaminants into the environment.
Background: Vapor generation coupled with atomic spectroscopic methods has been a routine technique for determination of As, Bi, Ge, Hg, Sb, Se, Sn, Te, and Pb for several decades. Furthermore, in recent years, the scope of volatile compounds generation has been expanded to include the determination of transition metals. Arsenic, antimony, lead and cadmium are heavy toxic metals with cumulative properties in living organisms. They are commonly used in up-to-date manufacturing. Their levels in the environment are gradually increasing, therefore sensitive and selective methods for their determination are desirable. The principal advantages of gas phase sample introduction are in the analyte separation from the sample matrix and in a higher introduction efficiency compared to liquid nebulization. A conventional and widely applied approach to the generation of volatile compounds is the chemical reduction using NaBH4. However, a simpler alternative approach utilizing electrochemical or UV photochemical reduction could be used to avoid the use of a chemical reductant.
Methods: In the first year of the project, the student will design and assemble new units for flow injection electrochemical and UV photochemical generation of volatile compounds. Arsenic will be used as a model analyte. Our laboratory has long-term experience with these techniques. In the next part of this project the student will optimize experimental conditions crucial for high sensitivities and low detection limits of determinations of all metals (As, Sb, Pb, Cd). In the second year, following the assembly and optimization, these units will be dedicated to the determination of generation efficiency of volatile forms of mentioned hydride forming elements. Apart from utilizing classical methods of determination of generation efficiency (comparison of slopes of calibration curves of photochemical and reference chemical generation; determination of residual analyte in waste), the efficiency of generation and transport of volatile forms will be also studied with the aid of radiotracers. In the third year of the project, the content of studied toxic metals will be determined in real-world samples (especially in river and waste water, slurry and sediments). The influence of potential interferences during generation of volatile forms of selected metals will be studied as well.