2008 Volume 25 Pages 134-138
Commercial dried Hijiki, Sargassum fusiforme1), was soaked in 30 volumes of water for 20 min at various temperatures (0-75°C). The total amount of arsenic was determined by thermal neutron activation analysis and the types of the arsenic compounds released were determined by an ICP-MS instrument equipped with HPLC.
The ratios of the total arsenic amounts retained in the swollen Hijiki tissues to those released into water indicated validity of the water-soaking process as a method to diminish arsenic levels in Hijiki. The higher the temperature, the more arsenic was extracted from the Hijiki tissues within a short time. Out of the arsenic compounds extracted at 30°C, 60 % was arsenate and the rest (40 %) was an organic arsenic compound, X1, having a chromatographically corresponding retention time to arsenobetaine. Other components were less than a few percentage of the total arsenic.
Those arsenic compounds seem to exist in a dispersed form in the tissues, because the observation under a scanning electron microscope did not show any peak of arsenic by line analysis, selected area analysis and/or particle analysis.
