Claudia Schlagenhaufen

Arsenobetaine and other arsenic compounds in the National Research Council of Canada Certified Reference Materials DORM 1 and DORM 2

A silica-based cation-exchange column was used to determine the arsenic compounds in the National Research Council of Canada (NRCC) CRMs DORM 1 and DORM 2 (Dogfish Muscle). With a 20 mM aqueous pyridine mobile phase at pH 3.0, the concentration of arsenobetaine was only 10.7 mg kg–1 As in the extract of DORM 1. When the same extract was chromatographed on an anion-exchange column, 15.9±0.3 mg kg–1 As (arsenobetaine) were found. The calibration for arsenobetaine was linear from 0.5 µg dm–1 As to 10 mg dm–3 As. When the extracts were diluted with water the cation-exchange results approached the anion-exchange results. The multi-element capabilities of ICP-MS allowed the simultaneous monitoring of arsenic and alkali metals. Sodium and potassium were found to co-elute with arsenobetaine. When aqueous solutions of arsenobetaine with 250 mg dm–3 Na were chromatographed, the signal obtained for arsenobetaine was only 60% of the signal without sodium in the solution. When the pH of the 20 mM aqueous pyridine mobile phase was lowered, the alkali metals were separated from arsenobetaine and the results obtained from cation-exchange chromatography were not significantly different from the anion-exchange results. Because DORM 1 is no longer available, the arsenic compounds in DORM 2 were determined. No significant difference was found for the concentration of arsenobetaine (15.6±0.7 mg kg–1 As for DORM 1; 16.0±0.7 mg kg–1 As for DORM 2). The concentrations of the minor arsenic compounds (dimethylarsinic acid, arsenocholine, the tetramethylarsonium cation and an unknown arsenic compound) in DORM 2 were only half the concentrations in DORM 1.

Heavy metals in human hair samples from Austria and Italy: influence of sex and smoking habits

Hair samples from 79 young healthy adults from Vienna (Austria) and Rome (Italy) were analyzed for As, Cd, Co, Cr, Ni and Pb by ICP-MS. No differences were found between the two locations except for chromium, which was significantly higher in the Viennese population (P < 0.001). In both cities male hair contained higher arsenic (P < 0.001) and lower cadmium (P < 0.05) levels than female hair, and in Vienna lead concentrations were lower in males (P < 0.05). Striking differences appeared when smokers were compared with non-smokers. Geometric means (micrograms/g) of smokers versus non-smokers were: arsenic 0.081 vs. 0.065, cadmium 0.075 vs. 0.038 (P < 0.05), cobalt 0.025 vs. 0.010 (P < 0.05), chromium 0.84 vs. 0.72 (P < 0.05), lead 3.42 vs. 1.47 (P < 0.001) and nickel 0.64 vs. 0.32 (P < 0.005). Consideration of a large number of biological and behavioural factors minimizes bias inherent in unmatched sample composition.

Retention behavior of inorganic and organic selenium compounds on a silica-based strong-cation-exchange column with an inductively coupled plasma mass spectrometer as selenium-specific detector

Abstract The retention behavior of eight selenium compounds (selenous acid, selenic acid, selenocystine, selenohomocystine, selenomethionine, selenoethionine, trimethylselenonium iodide, and dimethyl(3-amino-3-carboxy-1-propyl)selenonium iodide) with aqueous solutions of pyridine (20 mmol/l) in the pH range 2.0–5.7 on a Supelcosil LC-SCX cation-exchange column was investigated. An inductively coupled plasma mass spectrometer was employed as the selenium-specific detector. To increase the nebulization efficiency, the Meinhard concentric glass nebulizer was replaced by a hydraulic high-pressure nebulizer. At pH 5.0, seven selenium compounds could be separated within 400 s, but selenohomocystine and selenomethionine had the same retention time. Selenomethionine can be separated from selenohomocystine with an aqueous solution of pyridine (20 mmol/l) adjusted with formic acid to pH 2.0. At 1 ng Se ml−1, the relative standard deviations (n=5) of the signal area for the eight selenium compounds ranged from 7 to 11%, and at 50 ng Se ml−1 from 0.6 to 2.6%.

Induction of structural and numerical changes of chromosome, centrosome abnormality, multipolar spindles and multipolar division in cultured Chinese hamster V79 cells by exposure to a trivalent dimethylarsenic compound

Dimethylarsine iodide (DMI) was used as a model compound of trivalent dimethylarsenicals [DMA(III)], and the biological effects were extensively investigated in cultured Chinese hamster V79 cells. When the cytotoxic effects of DMA(III) were compared with those of inorganic arsenite and dimethylarsinic acid [DMA(V)], DMA(III) was about 10,000 times more potent than DMA(V), and it was even 10 times more toxic than arsenite. Depletion of cell glutathione (GSH) did not influence the cytotoxic effects of DMA(III), whereas it enhanced the cytotoxicity of arsenite. Chromosome structural aberrations, such as gaps, breaks and pulverizations, and numerical changes, such as aneuploidy, hyper- and hypo-tetraploidy, were induced by DMA(III) in a concentration-dependent manner. Mitotic index increased 9-12h after the addition of DMA(III), and then declined. By contrast, the incidence of multinucleated cells increased conversely with the decrease in mitotic index at and after 24h of exposure. The mitotic cell-specific abnormality of centrosome integrity and multipolar spindles were induced by DMA(III) in a time- and concentration-dependent manner. Moreover, DMA(III) caused abnormal cytokinesis (multipolar division) at concentrations that were effective in causing centrosome abnormality, multipolar spindles and aneuploidy. These results showed that DMA(III) was genotoxic on cultured mammalian cells. Results also suggest that DMA(III)-induced multipolar spindles and multipolar division may be associated with the induction of aneuploidy. In addition, the centrosome may be a primary target for cell death via multinucleated cells.

Arsenic compounds in terrestrial organisms. III: Arsenic compounds in Formica from an old arsenic smelter site

Total arsenic concentrations in the freeze-dried pulverized ants (Formica sp.) and material from an ant-hill collected at a former arsenic roasting facility were determined by inductively coupled plasma mass spectrometry (ICP-MS) after microwave digestion with nitric acid and hydrogen peroxide. The ants contained 12.6 ± 0.9 mg As/kg dry mass, the ant-hill material 5420 ± 90 mg As/kg dry mass. Total arsenic concentrations in needles of Picea abies and Larix decidua (spruce and larch needles) were also determined, because needles are the main constituents of the upper layer of ant-hill material. Needles of Picea abies contained 1.17 mg As/kg dry mass and needles of Larix decidua 3.71 mg As/kg. The Formica sp. and ant-hill material were extracted with water or methanol/water (9:1). The extracts were chromatographed on a cation-exchange and an anion-exchange column. Water extracted 20% of the arsenic from the ants and only 3% from the ant-hill material. With methanol/water (9:1) only 7% of the arsenic was released by the ants and 0.5% by the ant-hill material. The arsenic compounds in the column effluents that were introduced into the plasma via a hydraulic high-pressure nebulizer (HHPN) were quantified on-line by ICP-MS. Arsenite and arsenate were the major arsenic compounds in the extract. Dimethylarsinic acid and traces of methylarsonic acid and arsenobetaine were also detected. The extracts of the ant-hill material contained the same compounds. Additionally, traces of trimethylarsine oxide were found. The presence of arsenobetaine was confirmed by spiking an extract of the ants with synthetic arsenobetaine bromide.

Can humans metabolize arsenic compounds to arsenobetaine

Arsenic compounds were determined in 21 urine samples collected from a male volunteer. The volunteer was exposed to arsenic through either consumption of codfish or inhalation of small amounts of (CH3)3As present in the laboratory air. The arsenic compounds in the urine were separated and quantified with an HPLC–ICP–MS system equipped with a hydraulic high-pressure nebulizer. This method has a determination limit of 0.5 μg As dm−3 urine. To eliminate the influence of the density of the urine, creatinine was determined and all concentrations of arsenic compounds were expressed in μg As g−1 creatinine. The concentrations of arsenite, arsenate and methylarsonic acid in the urine were not influenced by the consumption of seafood. Exposure to trimethylarsine doubled the concentration of arsenate and increased the concentration of methylarsonic acid drastically (0.5 to 5 μg As g−1 creatinine). The concentration of dimethylarsinic acid was elevated after the first consumption of fish (2.8 to 4.3 μg As g−1 creatinine), after the second consumption of fish (4.9 to 26.5 μg As g−1 creatinine) and after exposure to trimethyl- arsine (2.9 to 9.6 μg As g−1 creatinine). As expected, the concentration of arsenobetaine in the urine increased 30- to 50-fold after the first consumption of codfish. Surprisingly, the concentration of arsenobetaine also increased after exposure to trimethylarsine, from a background of approximately 1 μg As g−1 creatinine up to 33.1 μg As g−1 creatinine. Arsenobetaine was detected in all the urine samples investigated. The arsenobetaine in the urine not ascribable to consumed seafood could come from food items of terrestrial origin that—unknown to us—contain arsenobetaine. The possibility that the human body is capable of metabolizing trimethyl- arsine to arsenobetaine must be considered.

Occurrence of organo-arsenicals in jellyfishes and their mucus

Water-soluble arsenic compound fractions were extracted from seven species of jellyfishes and subjected to analysis by high-performance liquid chromatography-inductively coupled plasma mass spectrometry (HPLC-ICP-MS) for arsenicals. A low content of arsenic was found to be the characteristic of jellyfish. Arsenobetaine (AB) was the major arsenic compound without exception in the tissues of the jellyfish species and mucus-blobs collected from some of them. Although the arsenic content in Beroe cucumis, which preys on Bolinopsis mikado, was more than 13 times that in B. mikado, the chromatograms of these two species were similar in the distribution pattern of arsenicals. The nine species of jellyfishes including two species treated in the previous paper can be classified into arsenocholine (AC)-rich and AC-poor species. Jellyfishes belonging to Semaostamae were classified as AC-rich species.

Occurrence of a few organo-arsenicals in jellyfish

Water-soluble fractions containing arsenic compounds were extracted with chloroform-methanol (2:1) from two kinds of jellyfish, Aurelia aurita and Carybdea rastonii. After defatting, each water-soluble fraction was subjected to analysis by HPLC-GFAA (column: ODS 120-T) and HPLC-ICP MS (column: Supelcosil LC-SCX) for arsenicals. Arsenobetaine was detected with both analytical systems as the major arsenic compound. Besides arsenobetaine, the tetramethylarsonium ion and arsenocholine were also detected by HPLC-ICP MS. The major arsenical in each jellyfish purified by ionexchange chromatography using Dowex 50W x 8 (H + form) and Dowex 50W x 8 (pyridinium form) was confirmed to be arsenobetaine by thin-layer chromatography.

Priest, hunter, alpine shepherd, or smelter worker?

A sample of hair found with the man from the Hauslabjoch was made available for the determination of inorganic components particularly trace elements. Hair is known to preserve information about the trace element status of an organism. The sulfur (cysteine)-rich organic constituents of hair have high affinities for heavy metals. A high body burden of elements such as copper, lead, and arsenic should be reflected by high concentrations of these elements in hair1. Thus, high concentrations of arsenic in Napoleon’s hair were taken as indication that the emperor had been poisoned by arsenic2. Although nobody expects that the iceman was poisoned, the concentrations of elements in the hair samples could perhaps provide information about the nutritional status with respect to essential elements, about exposures to toxic elements, and about settings leading to such exposures.