Survey of arsenic content in edible seaweeds and their health risk assessment.

Since humans are especially sensitive to arsenic exposure, predominantly through diet, a strict control of the most widely consumed seaweeds is mandatory. Total arsenic contents and arsenic species in twenty-five different seaweeds from five different origins were studied. Seaweeds selected, included Phaeophyta (brown seaweed), Chlorophyta (green seaweed) and Rhodophyta (red seaweed) genera. The highest arsenic content appears in the Phaeophyta seaweed in the range from 11 to 162 mg kg-1 dried weight. Arsenosugars were found to be the predominant species of arsenic in most seaweeds, being up to 99.7% of total arsenic in some samples. The arsenic dietary intakes for seaweeds studied were assessed and the Target Hazard Quotients (THQ) and the Target Cancer Risk (TCR) were calculated, taking into account inorganic arsenic contents (iAs). iAs species in seaweeds showed low risk of arsenic intake except for Hizikia fusiforme samples.

Arsenosugar extracted from algae: Isolation by anionic exchange solid-phase extraction.

Obtaining reliable speciation data for evaluating dietary exposure, and increasing understanding of arsenic biochemistry in algae, are hindered by the availability of suitable standards of arsenosugars, the major species in these types of samples. Moreover, chemical syntheses of such compounds have been reported to be complex and tedious. The aim of this work was to investigate the feasibility of the anionic exchange SPE cartridges (SAX and WAX) as an easy and quick alternative for the isolation and preconcentration of arsenosugars. Two commercial silica-based SPE cartridges strong anion exchange sorbent (DSC-SAX) and weak anion exchange sorbent (DSC-NH2) were compared for the SPE of three arsenosugars (PO4-Sug, SO3-Sug and SO4-Sug). The effect of pH, ionic strength, type of salt and elution solvent on the elution protocols of these arsenosugars are studied. Eluted solutions from SPE were analyzed by ICP-MS for total arsenic content and IC-ICP-MS for the study of arsenic speciation. The developed SPE procedure allows to obtain a solution containing the three arsenosugars isolated from other arsenic species with recoveries over 75% for SO3-Sug and SO4-Sug, whereas for PO4-Sug were around 45%.