Analysis of Inorganic and Organic-Bound Arsenic in Marine Brown Algae

Abstract

Inorganic arsenic in brown algae was removed by distillation s the corresponding trichloride and assessed by absorption of the arsine-silver diethyldithiocarbamate complex. Severe digestion conditions for organicbound arsenic were found necessary to determine total arsenic analyzed subsequently by the silver diethyldithiocarbamate-pyridine reagent. Arsenic in the inorganic and organic forms ranged from 0.5 to 2.7 and 40.3 to 89.7 μg g" 1 dry weight respectively in 7 species of the Laminariaceae, 3 species of the Alariaceae and Lessoniaceae collected in British Columbia; providing levels of inclusion similar to commercially available brown seaweed products. By contrast Sargassum muticum contained 20.8 μg g~! dry weight of inorganic arsenic, about 38% of the total concentration, and a commercial specimen of Hizikia fusiforme contained 71.8 μg g" 1 inorganic arsenic, some 58% of the total concentration, suggesting the propensity of members of the Sargassaceae family to accumulate the inorganic form of arsenic.

Extraction and detection of arsenicals in seaweed via accelerated solvent extraction with ion chromatographic separation and ICP-MS detection

“…The inorganic fraction represents 27.8% of the extracted arsenicals and the ingestion of 1 g would be equivalent to the ingestion of 120 mL of water at the 0.05 mg/L As MCL. Whyte et al found 38% of the arsenic present as inorganic for the same seaweed [34]. The figure insert in Fig.…”

The main seaweed foods in Japan

“…The legally allowed amounts of arsenic contaminating the foods in Japan are formulated to be below 0.2 ppm for some beverages, below 1.0 ppm for some fruits and vegetables, and below 3.5 ppm for other fruits (Hosogai et al, 1978). Fortunately, the contents of the inorganic form in konbu and wakame are below this limit, but that of hiziki is far in excess of this (Whyte & Englar, 1983). Fortunately, the contents of the inorganic form in konbu and wakame are below this limit, but that of hiziki is far in excess of this (Whyte & Englar, 1983).…”

“…The presence of such large amounts of arsenic in popular Japanese foods is a serious problem for us. Among the typical seaweed foods in Japan, inorganic arsenic content is very high only in hiziki, Shimokawa et al (1971); b Whyte & Englar (1983); c mixture of arsenate and arsenite: Tagawa (1980); d mixture of methylarsenate and dimethylarsenate: Tagawa (1980). where it reaches as much as 72 ppm, while the organic form reaches 62 ppm. Several examples of seaweed arsenic contents are shown in Table 28.…”

Purification and Identification of Arsenic-containing Ribofuranosides from the Edible Brown Seaweed,Laminaria japonica(MAKONBU)

“…While there have been many reports concerning the total amount of arsenic in various algae, [4][5][6][7] the structural information on the arsenic compounds of algae is still very limited. 8 -10) We will report here the purification and identification of major water-soluble arsenic compounds from an edible brown seaweed, Laminariajaponica (MAKONBU in Japanese), which is one of the most heavily harvested seaweeds in Japan.…”