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Analysis of Arsenicals and their Sulfur Analogs Using HPLC with Collision Cell ICP-MS and ESI-MS
Citation:
KUBACHKA, K., C. GALLAWA, P. A. CREED, JOHN T. CREED, M. J. KOHAN, K. HERBIN-DAVIS, AND D. J. THOMAS. Analysis of Arsenicals and their Sulfur Analogs Using HPLC with Collision Cell ICP-MS and ESI-MS. Presented at International Symposium on Metallomics, Covington, KY, June 07 - 13, 2009.
Impact/Purpose:
Develop analytical approaches to quantify reactive intermediates within the metabolic pathway that biotransforms inorganic arsenic to DMA(V). The ability to quantify these species will enhance the mode of action (within NHEERL) and the bioavailability / bioaccessibility research (within NERL).
Description:
Recent metabolic and exposure assessment studies have found sulfur analogs (thioarsenicals) of common oxoarsenicals in environmental and biological systems. The occurrence of thioarsenicals raises questions regarding their origin and transport, and their roles in metabolism of arsenic. Definitive answers to these questions require speciation based methods that can separate and quantify oxo- and thioarsenicals in complex mixtures. Various LC methods are often necessary to separate such complex mixtures. Because thioarsenicals are often present in samples at low ng/g concentrations, elemental detection via ICP-MS is most commonly used for quantitation. Additionally, LC-ESI-MS/MS techniques have proven valuable for complementary verification of standards and confirmation of suspect peaks, because many arsenic standards and their sulfur analogs are not commercially available. An emerging area of arsenic metabolic research focuses on understanding of origin of thioarsenicals that are detected as excreted metabolites in many higher organisms, including humans. We have used an in vitro assay to examine the role of the anaerobic microbiota of mouse cecum in the metabolism of thio- and oxoarsenicals1-3. These studies have shown that there is considerable preabsorption metabolism of these arsenicals that is mediated by the anaerobic microbiota of mouse cecum. This presentation will summarize results from our studies on the conversion of dimethylarsinic acid and trimethylarsine oxide with an emphasis on utilizing ESI-MS/MS for identification. In addition, preliminary research on the role of the anaerobic microbiota in conversion of inorganic arsenic and monomethylarsonic acid to thioarsenicals will be presented.