Abstract
The chemical form of arsenic in Laminaria japonica Aresh. (Japanese name: “makonbu”, Laminariaceae) was investigated and the following results were obtained.
1) The arsenic in “makonbu” is easily extracted with water-methanol (4:1) mixture (the recovery was more than 90%).
2) Ultrafiltration indicated that the water-methanol soluble arsenic compounds have low molecular weight (MW 500-1, 000).
3) In activated charcoal column chromatography, the arsenic compounds in “makonbu” were eluted with water-ethanol (4:1) mixture, but not with water (column recovery 99.2%). In QAE-Sephadex A-25 (Cl type) column chromatography, the arsenic compounds in “makonbu” were eluted with acetic acid-methanol (1:25) mixture (column recovery 80.1%). After both procedures, the content of arsenic in the eluate reached 2.78%.
4) The arsenic compounds gave negative reactions with ninhydrin, dithizon and phenol-sulfuric acid reagent.
