Arsenosugar standards extracted from algae: Isolation, characterization and use for identification and quantification purposes.

Sulfate (SO ₄ -sug) and sulfonate (SO ₃ -sug) arsenosugar standard solutions were obtained using preparative liquid chromatography. Several commercial algae samples were characterized (total contents and speciation) to select the most appropriate in relation to their arsenosugar contents. Water extracts from the selected sample (Fucus vesiculosus) were fractionated using a Hamilton PRP-X100 preparative column, and the presence of arsenic species in the isolated fractions was ascertained by IC-ICP-MS. Two of the fractions successfully presented only one arsenic species corresponding to sulfate and sulfonate arsenosugars at suitable concentrations. To unequivocally confirm the presence of both compounds, high-resolution mass spectrometry (ESI-TOF/MS) was used and the exact mass determined with errors lower than 0.5 ppm. The standard solutions obtained were successfully used to identify and quantify SO ₄ -sug and SO ₃ -sug in several edible algae samples purchased in local market. Total arsenic content for analyzed samples ranged from 34 to 57 mg kg ^-1 , concentration values found for SO ₃ -sug ranged from 5 to 36 mg As kg ^-1 and SO ₄ -sug was only found in fucus with a concentration of 9.3 mg As kg ^-1 .
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