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Improved chemical vapor generation methods for the determination of cadmium, lead and mercury in biological and environmental materials by flow injection atomic spectrometry

by Chuachuad, Wipharat

Abstract (Summary)
New methods for the determination of cadmium and lead by flow injection chemical vapor generation atomic absorption spectrometry with tetrahydroborate immobilized on an anion-exchanger were developed. Both flow injection and hydride generation parameters were optimized. The method has less suppression by some coexisting elements than the generation by the reaction with tetrahydroborate in aqueous solution, and smaller amounts of reagents are required. The developed method was successfully applied for the determination of trace amounts of cadmium and lead in environmental and biological materials. A method for the determination of trace concentrations of cadmium, by electrothermal atomic absorption spectrometry with flow injection chemical vapor generation from a terahydroborate-form anion-exchanger with in-atomizer trapping on a Zr-Ir coated graphite tube atomizer, was developed. Both electrothermal atomization and flow injection hydride generation parameters were optimized. A detection limit of 2 ppt was obtained. The method was successfully applied to the analyses of various types of environmental and biological samples. The cold vapor generation of mercury from tin chloro anion complexes immobilized on an anion exchanger was successfully developed for the first time. A purer tin(II) chloride reagent was obtained by passing solution through the anion-exchange column. The method was applied to the determination of trace amounts of total and inorganic mercury in different types of sample matrices with satisfactory results. A procedure for the speciation of mercury from the immobilized tetrachlorotin(II)- and tetrahydroborate-form anion-exchange columns was developed. Better tolerance of some coexisting elements was found compared to that of conventional cold vapor generation techniques. The method was applied for the speciation of mercury in canned fish and seafood samples and in some standard reference materials. A mercury speciation procedure for environmental and biological samples based on in-atomizer trapping on a gold-coated graphite tube atomizer and electrothermal atomic absorption spectrometry was developed. Both types of immobilized reducing agent gave satisfactory results. A new method for preconcentration of trace inorganic mercury in water samples as the anionic-chloro complex on anion-exchanger with reductive elution with tetrahydroborate solution was developed. The detection limit was 0.8 ppt. The method was applied to the analysis of natural water, spring water, drinking water, tap water and seawater samples. Cadmium and lead were determined in Typha angustifolia and Lemna minor in support of phytoremediation studies. Typha angustifolia is a suitable plant for the phytoremediation of lead contaminated soil. The interaction of cadmium and lead on the phytoextraction by Typha angustifolia in contaminated soil was investigated. The methods developed required only a small sample size from Lemna minor plants, so that multiple samples from the same plant could be taken.
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School:University of Massachusetts Amherst

School Location:USA - Massachusetts

Source Type:Master's Thesis

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Date of Publication:01/01/2005

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