Arsenic K-edge X-ray absorption spectroscopy of arsenic in seafood

It is well known that seafood contains high levels of arsenic. For marine animals arsenic is predominantly present as arsenobetaine and related compounds which are not metabolized and are thought to present no toxic hazard to humans. With edible seaweeds, arsenic is present in different forms, of which arsenosugars are the best known. These species may be metabolized by mammals, and the high arsenic contents of these materials represent a significant environmental source for human exposure to arsenicals in some Populations. In this work, we explore the utility of As K-edge X-ray absorption near-edge spectroscopy as an in situ probe of the chemical forms of arsenic in seaweeds. We find that three different chemical types of arsenic are present, consistent with arsenate, an arsenosugar or tetraalkyl-arsonium species, and a trivalent arsenic species.