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AN INVESTIGATION OF CHEMICAL STABILITY OF ARSENOSUGARS IN EXTRATION SOLVENTS UTILIZED TO QUANTITATIVELY EXTRACT ARSENICALS FROM SEAFOOD PRODUCTS USING IC-ICP-MS AND IC-ESI-MS/MS
Citation:
Gallagher, P A., C A. Schwegel, J T. Creed, B. M. Gamble, X. Wei, AND A. Heck. AN INVESTIGATION OF CHEMICAL STABILITY OF ARSENOSUGARS IN EXTRATION SOLVENTS UTILIZED TO QUANTITATIVELY EXTRACT ARSENICALS FROM SEAFOOD PRODUCTS USING IC-ICP-MS AND IC-ESI-MS/MS. Presented at European Winter Conference on Plasma Spectrochemistry, Lillehammer, Norway, February 4-8, 2001.
Impact/Purpose:
The goal is to develop an extraction protocol that mimics the human digestive tract and then to use it to assess the bioavailable fraction of arsenic from complex dietary mixtures such as a daily composite -- to move current methods toward a better human physiologically-based exposure estimate method which approximates the "true" bioavailability of arsenic within an environmental or dietary matrix.
Description:
Arsenosugars are commonly associated with seaweed products which have total arsenic concentrations that can exceed 50 ppm on a dry weight basis. Arsenosugars are also present in other seafood products but the associated concentrations are usually considerably lower. The analytical problems generated by the extraction of these sugars from seafood matrices prior to arsenic speciation are two fold. The first problem is that the sugars require an analyte free chromatographic retention window if an ICP-MS is used as the chromatographic detector. For some seafood, the sugars can be extracted, separated, and detected without degradation by-products when relatively mild extraction conditions are utilized. However, due to poor extraction efficiencies in certain seafood products a more chemically aggressive extraction solvent needs to be investigated in order to assure a more quantitative extraction procedure. The second analytical problem is that the need to use a more agressive extraction solvent may produce arsenosugar degradation by-products. These by-products could further complicate the chromatographic separation. Therefore, characterizing the extent to which the arsenosugars degrade under a more aggressive extraction condition is essential to developing an arsenic speciation methodology for seafood. Thus, the goal is to establish a set of extraction conditions which allows for quantitative extraction of arsenicals from seafood and does not produce arsenosugar degradation by-products. This presentation will report on the stability of arsenosugars (purified from kelp xtracts) in acidic extraction environments (below pH 3). The effect of heat and overall extraction time will be investigated. The degradation by-products will be characterized via IC-ESI-MS/MS and their retention times will be reported using ICP-MS detection. Preliminary extraction conditions will be reported which maximize the quantitative nature of the extraction process while minimizing unwant arsenosugar degradation by-products.