Background: Arsenic-containing carbohydrates (arsenosugars) are common constituents of marine algae, including those species used as human food. The toxicology of these compounds has not been fully evaluated. Methods: Arsenic metabolites in human urine were monitored over a 4-day period after ingestion of a synthetic specimen of arsenosugar. The metabolites were determined by HPLC-inductively coupled plasma mass spectrometry, and structural assignments were confirmed with liquid chromatography-electrospray ionization mass spectrometry. Results: Approximately 80% of the total ingested arsenic was excreted in the urine during the 4 days of the experiment. There was a lag-period of ∼13 h before substantial quantities of arsenic appeared in the urine, and the excretion rate peaked between 22 and 31 h. At least 12 arsenic metabolites were detected, only 3 of which could be positively identified. Dimethylarsinate (DMA) was the major metabolite, constituting 67% of the total arsenicals excreted. A new urinary arsenic metabolite, dimethylarsinoylethanol, represented 5% of the total arsenicals, whereas trimethylarsine oxide was present as a trace (0.5%) constituent. One other significant metabolite cochromatographed with a reduced DMA standard, and hence was possibly dimethylarsinous acid. The second most abundant metabolite in the urine (20% of the total arsenic) remained unidentified, whereas the rest of the excreted arsenic was made up of several trace metabolites and small amounts of unchanged arsenosugar. Conclusions: Arsenosugars are biotransformed by humans to at least 12 arsenic metabolites, the toxicologies of which are currently unknown.

Two lichens and 12 green plants growing at a former arsenic roasting facility in Austria were analyzed for total arsenic by ICP-MS, and for 12 arsenic compounds (arsenous acid, arsenic acid, dimethylarsinic acid, methylarsonic acid, arsenobetaine, arsenocholine, trimethylarsine oxide, the tetramethylarsonium cation and four arsenoriboses) by HPLC-ICP-MS. Total arsenic concentrations were in the range of 0.27 mg As (kg dry mass) À1 (Vaccinium vitis idaea) to 8.45 mg As (kg dry mass) À1 (Equisetum pratense). Arsenic compounds were extracted with two different extractants [water or methanol/water (9:1)]. Extraction yields achieved with water [7% (Alectoria ochroleuca) to 71% (Equisetum pratense)] were higher than those with methanol/water (9:1) [4% (Alectoria ochroleuca) to 22% (Deschampsia cespitosa)]. The differences were caused mainly by better extraction of inorganic arsenic (green plants) and an arsenoribose (lichens) by water. Inorganic arsenic was detected in all extracts. Dimethylarsinic acid was identified in nine green plants. One of the lichens (Alectoria ochroleuca) contained traces of methylarsonic acid, and this compound was also detected in nine of the green plants. Arsenobetaine was a major arsenic compound in extracts of the lichens, but except for traces in the grass Deschampsia cespitosa, it was not detected in the green plants. In contrast to arsenobetaine, trimethylarsine oxide was found in all samples. The tetramethylarsonium cation was identified in the lichen Alectoria ochroleuca and in four green plants. With the exception of the needles of the tree Larix decidua the arsenoribose (2'R)-dimethyl[1-O-(2',3'-dihydroxypropyl)-5-deoxy-b-D-ribofuranos-5-yl]-arsine oxide was identified at the low mg kg À1 level or as a trace in all plants investigated. In the lichens an unknown arsenic compound, which did not match any of the standard compounds available, was also detected. Arsenocholine and three of the arsenoriboses were not detected in the samples.

A silica-based cation-exchange column was used to determine ence of arsenocholine in DORM 1 was questioned and suggested to be the tetramethylarsonium cation.6 the arsenic compounds in the National Research Council of Canada (NRCC ) CRMs DORM 1 and DORM 2 (Dogfish This paper reports the arsenic compounds identified in the dogfish reference materials DORM 1 and DORM 2 [separation Muscle). With a 20 mM aqueous pyridine mobile phase at pH 3.0, the concentration of arsenobetaine was only on anion-or cation-exchange columns, arsenic-specific detection by inductively coupled argon plasma mass spectrometry 10.7 mg kg−1 As in the extract of DORM 1. When the same extract was chromatographed on an anion-exchange column, (ICP-MS)] and a method to prevent the reduction of the signal for arsenobetaine by the matrix components Na and K. 15.9±0.3 mg kg−1 As (arsenobetaine) were found. The calibration for arsenobetaine was linear from 0.5 mg dm−1 As to 10 mg dm−3 As. When the extracts were diluted with water the cation-exchange results approached the anion-exchange EXPERIMENTAL results. The multi-element capabilities of ICP-MS allowed the Reagents and solutions simultaneous monitoring of arsenic and alkali metals. Sodium and potassium were found to co-elute with arsenobetaine.DORM 1 and DORM 2 (Dogfish Muscle Tissue) were When aqueous solutions of arsenobetaine with purchased from the NRCC,

Background-Inorganic arsenic, a carcinogen at high exposure levels, is a major global health problem. Prospective studies on carcinogenic effects at low-moderate arsenic levels are lacking.

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