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Trimethylarsine Oxide (trimethylarsine + oxide)

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Chemistry	100%

Selected Abstracts

Organoarsenic compounds in plants and soil on top of an ore vein

APPLIED ORGANOMETALLIC CHEMISTRY, Issue 5 2002
Anita Geiszinger
Abstract Plants and soil collected above an ore vein in Gasen (Austria) were investigated for total arsenic concentrations by inductively coupled plasma mass spectrometry (ICP-MS). Total arsenic concentrations in all samples were higher than those usually found at non-contaminated sites. The arsenic concentration in the soil ranged from ,700 to ,4000,mg kg,1 dry mass. Arsenic concentrations in plant samples ranged from ,0.5 to 6,mg kg,1 dry mass and varied with plant species and plant part. Examination of plant and soil extracts by high-performance liquid chromatography,ICP-MS revealed that only small amounts of arsenic (<1%) could be extracted from the soil and the main part of the extractable arsenic from soil was inorganic arsenic, dominated by arsenate. Trimethylarsine oxide and arsenobetaine were also detected as minor compounds in soil. The extracts of the plants (Trifolium pratense, Dactylis glomerata, and Plantago lanceolata) contained arsenate, arsenite, methylarsonic acid, dimethylarsinic acid, trimethylarsine oxide, the tetramethylarsonium ion, arsenobetaine, and arsenocholine (2.5,12% extraction efficiency). The arsenic compounds and their concentrations differed with plant species. The extracts of D. glomerata and P. lanceolata contained mainly inorganic arsenic compounds typical of most other plants. T. pratense, on the other hand, contained mainly organic arsenicals and the major compound was methylarsonic acid. Copyright © 2002 John Wiley & Sons, Ltd. [source]

Nitrogen purity influences the occurrence of As+ ions in high-performance liquid chromatography/electrospray ionization mass spectrometric analysis of four common arsenosugars

RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 7 2003
Doris Kuehnelt
High-performance liquid chromatography coupled to electrospray ionization mass spectrometry (HPLC/ESI-MS) can provide both elemental and molecular information and, therefore, is a very useful tool for the identification of arsenic compounds. When a method for the identification of four arsenosugars was employed in our laboratory with an HPLC/ESI-MS system equipped with a Whatman model 75-72 nitrogen generator, a signal at m/z 75 (As+) could not be observed. When the HPLC/ESI-MS system was operated with nitrogen 5.0 (nitrogen of a purity of at least 99.999%) all four arsenosugars gave a signal at m/z 75. Because of this observation the influence of the quality of the nitrogen drying gas on the fragmentation of the four arsenosugars was systematically investigated. Standard solutions containing the four arsenosugars (0.5 ng As each) were separated on an anion-exchange column and detected with ESI-MS in the positive ion mode by monitoring the signals for [M+H]+, m/z 237, 91, and 75. Nitrogen with defined oxygen concentrations was used as drying gas. The purity of the nitrogen ranged from 99 to 99.999% (10,400 to 10 ppm oxygen impurity). The nitrogen with 99% purity gave no signal at m/z 75, but signals were obtained at m/z 91, 237, and for [M+H]+. When higher purity nitrogen (99.9%) was used, a signal was obtained at m/z 75, which accounted for 0.8,1.1% (depending on the kind of arsenosugar) of the sum of the signals for m/z 75, 91, 237 and [M+H]+. As the level of oxygen in the nitrogen decreased, the m/z 75 signal increased to 2.0,3.1%. This was accompanied by a concomitant decrease in the m/z 91 signal from 5.2,6.6% to 0.7,1.5%, whereas the signals for [M+H]+ and m/z 237 were essentially unchanged. Signals at m/z 75 with intensities comparable with those observed for the 99.9% pure nitrogen were also obtained for all the arsenosugars when the HPLC/ESI-MS system was operated with a Domnick Hunter Nitrox UHPLCMS18 nitrogen generator. Dimethylarsinic acid, arsenobetaine, trimethylarsine oxide, arsenocholine and the tetramethylarsonium cation also gave no signal at m/z 75 when they were analyzed with the Whatman model 75-72 nitrogen generator, but clear signals at m/z 75 were observed with the Domnick Hunter Nitrox UHPLCMS18 nitrogen generator. A nitrogen quality of at least 99.9% is required to obtain elemental information (m/z 75) when arsenic compounds are investigated by HPLC/ESI-MS. Molecular and elemental information from one chromatographic run is a valuable tool for the characterization of unknown arsenic compounds. Copyright © 2003 John Wiley & Sons, Ltd. [source]

Distribution and fate of biologically formed organoarsenicals in coastal marine sediment

APPLIED ORGANOMETALLIC CHEMISTRY, Issue 8 2005
Mio Takeuchi
Abstract Marine organisms, including phyto- and zoo-plankton, macroalgae, and animals, concentrate arsenic in various organic forms. However, the distribution and fate of these organoarsenicals in marine environments remains unclear. In this study, the distribution of organoarsenicals in coastal marine sediment in Otsuchi Bay, Japan, has been determined. Methylarsonic acid, dimethylarsinic acid, trimethylarsine oxide, arsenobetaine, arsenocholine and other unidentified arsenic species were detected in marine sediment by high-performance liquid chromatography,inductively coupled plasma mass spectrometry analysis of methanol,water extracts. Arsenobetaine was the dominant organoarsenical at four of the seven stations where tests were carried out, and unidentified species or dimethylarsinic acid dominated at the other stations. Total organoarsenicals (as arsenic) in the surface sediment amounted to 10.6,47.5 µg kg,1 dry sediment. Core analysis revealed that concentrations of organoarsenicals decreased with depth, and they are considered to be degraded within 60 years of deposition. These results show that organoarsenicals formed by marine organisms are delivered to the sediment and can be degraded within several decades. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Organoarsenic compounds in plants and soil on top of an ore vein

Comparison of three methods for the extraction of arsenic compounds from the NRCC standard reference material DORM-2 and the brown alga Hijiki fuziforme

APPLIED ORGANOMETALLIC CHEMISTRY, Issue 6 2001
Doris Kuehnelt
Abstract The NRCC standard reference material DORM-2 and the marine brown alga Hijiki fuziforme were extracted with water, methanol/water (9,+,1), and 1.5 M orthophosphoric acid. The extracts from DORM-2 were analyzed by HPLC,ICP-MS for arsenobetaine, arsenocholine, trimethylarsine oxide, and the tetramethylarsonium cation and the extracts from H. fuziforme for arsenous acid, arsenic acid, dimethylarsinic acid, methylarsonic acid, and four arsenoriboses. Almost no differences between the three extractants were observed when DORM-2 was investigated. Only arsenobetaine was slightly better extracted with 1.5 M orthophosphoric acid or methanol/water (9,+,1) than with water. The sum of all extractable compounds (arsenobetaine, the tetramethylarsonium cation, and a formerly unknown compound recently identified as the trimethyl(2-carboxyethyl)arsonium ion) accounted for 94% of the total arsenic when 1.5 M orthophosphoric acid was used, for 92% when methanol/water (9,+,1) was used, and for 87% when water was used. Significant differences in the extraction yields obtained for the alga were observed for arsenic acid and one of the arsenoriboses (,glycerol-ribose'). Orthophosphoric acid removed twice as much of this ribose from the algal material than water and three times more than methanol/water (9,+,1). Arsenic acid was 1.2 times better extracted with orthophosphoric acid than with water and ten times better than with methanol/water (9,+,1). Almost no differences in the extraction yields were found for dimethylarsinic acid and the other three riboses. Orthophosphoric acid extracted 76%, water 65%, and methanol/water 33% of the total arsenic from H. fuziforme. Copyright © 2001 John Wiley & Sons, Ltd. [source]

Metabolism of dimethylarsinic acid in rats: production of unidentified metabolites in vivo

APPLIED ORGANOMETALLIC CHEMISTRY, Issue 6 2001
Kaoru Yoshida
Abstract Our previous study revealed that two unidentified metabolites, M-1 and M-2, were excreted in urine after long-term oral administration of dimethylarsinic acid (DMA), the main metabolite of inorganic arsenic. In the present study, we attempted to clarify the mechanism of production of these unknown metabolites. Male F344/DuCrj rats were administered a single dose of DMA (50,mg kg,1) orally or intraperitoneally with or without pretreatment with L -buthionine-SR-sulfoximine (BSO), which inhibits glutathione (GSH) synthesis. Urine was collected by forced urination at various time points after administration of DMA. Arsenic metabolites in urine were analyzed by ion chromatography with inductively coupled plasma mass spectrometry (IC,ICP-MS). The unidentified metabolites M-1 and M-2 were excreted later than elimination of DMA and trimethylarsine oxide (TMAO). GSH depletion decreased in TMAO elimination, suggesting that GSH plays important roles in the methylation of DMA to TMAO in rats. There was no difference in the amount of production of either M-1 or M-2 between BSO-pretreated rats and controls, suggesting that M-1 and M-2 cannot be formed during methylation in the liver. The amounts of elimination of M-1 and M-2 were less after intraperitoneal administration than after oral administration. Male F344/DuCrj rats were given 100,mg As l,1 DMA via drinking water for 20 weeks. Urine and feces were collected forcibly and were analyzed by IC,ICP-MS. A new unidentified metabolite, M-3, was detected only in feces as a metabolite of DMA after 20 weeks exposure to DMA, although M-1 and M-2 were found in both urine and feces. The unidentified metabolites M-1, M-2, and M-3 were excreted mainly as fecal metabolites along with unmetabolized DMA. This finding also suggests that M-1, M-2, and M-3 might be produced in the intestinal tract. Copyright © 2001 John Wiley & Sons, Ltd. [source]

Enteric bacteria may play a role in mammalian arsenic metabolism

APPLIED ORGANOMETALLIC CHEMISTRY, Issue 6 2001
Koichi Kuroda
Abstract The cecal content of rats administered dimethylarsinic acid for 6 months via drinking water was cultured in GAM medium with 10,mg l,1 of dimethylarsinic acid. Arsenic compounds in the culture were analyzed by ion chromatography with inductively coupled plasma mass spectrometry (IC,ICP-MS). Dimethylarsinic acid was metabolized. Two bacterial Escherichia coli strains, A3-4 and A3-6, were isolated from the culture. These strains metabolized dimethylarsinic acid and yielded two unidentified arsenic compounds, M-2 and M-3. A3-6 methylated dimethylarsinic acid to trimethylarsine oxide. Both strains metabolized trimethylarsine oxide and yielded an unidentified arsenic compound, M-1. These unknown arsenic compounds were the same compounds as detected in the urine and the feces of rats administered dimethylarsinic acid. The strains reduced arsenate to arsenite efficiently. Cysteine was required for metabolism of dimethylarsinic acid by these bacteria, but glutathione was not required. These results strongly suggested that the intestinal bacteria have a different arsenic metabolism from that in mammals and that they may play a possible role in mammalian arsenic metabolism. Copyright © 2001 John Wiley & Sons, Ltd. [source]