Determination of arsenic species in a freshwater crustacean Procambarus clarkii

The arsenic species present in samples of the crayfish Procambarus clarkii caught in the area affected by the toxic mine‐tailing spill at Aznalcóllar (Seville, Southern Spain) were analyzed. The total arsenic contents ranged between 1.2 and 8.5 µg g^?1 dry mass (DM). With regard to the different species of arsenic, the highest concentrations were for inorganic arsenic (0.34–5.4 µg g^?1 DM), whereas arsenobetaine, unlike the situation found in marine fish products, was not the major arsenic species (0.16 ± 0.09 µg g^?1 DM). Smaller concentrations were found of arsenosugars 1a (0.18 ± 0.11 µg g^?1 DM), 1b (0.077 ± 0.049 µg g^?1 DM), 1c (0.080 ± 0.089 µg g^?1 DM), and 1d (0.14 ± 0.13 µg g^?1 DM). The presence of two unknown arsenic species was revealed (U1: 0.058 ± 0.058 µg g^?1 DM; U2: 0.12 ± 0.12 µg g^?1 DM). No significant differences were seen with respect to the total arsenic contents between the sexes. However, significant differences in the total arsenic contents were revealed between the area affected by the spill and the area not affected, the contents being greater in the affected area. Copyright © 2002 John Wiley & Sons, Ltd.     

Arsenobetaine as the major arsenic compound in the muscle of two species of freshwater fish

The chemical form of arsenic contained in the muscle of certain freshwater fish was examined using cultured specimens of rainbow trout (Salmo gairdneri) and wild specimens of Japanese smelt (Hypomesus nipponensis). More than 95% of the total arsenic of both species was extracted with methanol and recovered in the water-soluble fraction. The major arsenic compound of both species was purified by cation-exchange chromatography on Dowex 50, gel filtration on Bio-Gel P-2 and HPLC on Asahipak GS-220H. Behavior in the above purification procedure and analyses of the purified compounds by HPLC–ICP and TLC confirmed that the major arsenic compound of both species was arsenobetaine. Arsenobetaine found in cultured rainbow trout seems to be derived from the commercial assorted feed containing arsenobetaine as the major arsenical. On the other hand, the result with wild Japanese smelt suggested that arsenobetaine is a naturally occurring compound in the freshwater environment.     

The discovery of hidden arsenic species in coastal waters

The analysis of ultraviolet (UV)-irradiated and untreated seawater samples has shown that the dissolved arsenic content of marine waters cannot be completely determined by hydride generation–atomic absorption spectrophotometry without sample pretreatment. Irradiation of water samples obtained during a survey of arsenic species in coastal waters during the summer of 1988 gave large increases in the measured speciation. Average increases in the measured speciation. Average increases in total arsenic, monomethylarsenic and dimethylarsenic were 0.29 μg As dm^?3 (25%), 0.03 μg As dm^?3 (47%) and 0.12 μg As dm^?3 (79%), respectively. Overall, an average 25% increase in the concentration of dissolved arsenic was observed following irradiation. This additional arsenic may be derived from compounds related to algal arsenosugars or to their breakdown products. These do not readily yield volatile hydrides when treated with borohydride and are not therefore detected by the normal hydride generation technique. This has important repercussions as for many years this procedure, and other analytical procedures which are equally unlikely to respond to such compounds, have been accepted as giving a true representation of the dissolved arsenic speciation in estuarine and coastal waters. A gross underestimate may therefore have been made of biological involvement in arsenic cycling in the aquatic environment.     

Tolerance,bioaccumulation and biotransformation of arsenic in freshwater prawn (Macrobrachium rosenbergii)

Tolerance bioaccumulation and biotransformation of arsenic compounds by a freshwater prawn (Macrobrachium rosenbergii) were investigated. M. rosenbergii was exposed to 10, 20, 30 and 35 μg As cm⁻³ of disodium arsenate [abbreviated as As(V)], 25, 50, 100 and 120 μg As cm⁻³ of methylarsonic acid (MMAA), or 100,200, 300 and 350 μg As cm⁻³ of dimethylarsinic acid (DMAA). Tolerances (50% lethal concentration: LC₅₀) of the prawn against As(V), MMAA, and DMAA were 30, 100, and 300 μg As cm⁻³, respectively. The prawn accumulated arsenic compounds directly from aqueous phase and biotransformed them in part. Both methylation and demethylation of the arsenicals were observed in vivo. Highly methylated and less toxic arsenicals were less accumulated in M. rosenbergii.     

The identification of some water-soluble arsenic species in the marine brown algae Fucus distichus

The extraction and clean-up procedures developed to isolate the water-soluble arsenic species present in the marine macroalga Fucus distichus, from British Columbia, Canada, are described. The arsenic species were extracted into methanol and then subjected to gel-permeation and ion-exchange chromatography. Fractions high in arsenic were identified by using graphite furnace atomic absorption spectroscopy (GF-AAS), and further investigated by using high-performance liquid chromatography coupled to inductively coupled plasma–mass spectrometry (HPLC–ICP MS). By using different HPLC columns and mobile-phase conditions, the four major arsenic-containing compounds present in the macroalga were positively identified as arsenosugars; one minor compound remained unidentified. © 1997 John Wiley & Sons, Ltd.     

Enzymatic digestion and chromatographic analysis of arsenic species released from proteins

A method combining gel filtration chromatography (GFC), protease digestion, and ion pair chromatography with inductively coupled plasma mass spectrometry detection was developed for the determination of arsenic species bound to proteins. The method was first established by examining the interactions of two model proteins, metallothionein (MT) and hemoglobin, with three reactive trivalent arsenic species. It was then successfully applied to the speciation of arsenic in red blood cells of rats. Inorganic arsenite (iAs^III), monomethylarsonous acid (MMA^III), and dimethylarsinous acid (DMA^III) were efficiently released from the proteins by protease digestion at pH 8.0, with the recovery ranging from 93% to 106%. There was no oxidation of iAs^III or MMA^III during the protease digestion process. Up to 61% DMA^III (the least stable arsenic species) was unchanged, and the rest was oxidized to the pentavalent dimethylarsinic acid (DMA^V). The arsenic species in the red blood cells of control rats was present as DMA^III complex with hemoglobin. The method enabling the determination of the specific arsenic species that bind to cellular proteins is potentially useful for studying arsenic distribution, metabolism, and toxicity.     

Determination of lipid‐soluble arsenic species in seaweed‐eating sheep from Orkney

This work is part of an ongoing research study towards an understanding of the complete metabolism of arsenosugars in mammalian organisms when ingesting seaweed, using the North Ronaldsay (NR) sheep as a model organism. We focus on the analysis of only those arsenic species bound to the lipids of the feed (Laminaria digitata), faeces and the tissues of the NR sheep using a novel enzymatic hydrolytic method that is simple and reliable. This rare breed of sheep, found in the remote Orkney Islands in the north of Scotland, live the entire year on the beaches and eat seaweed that is washed ashore (up to 3 kg daily). Previous studies on arsenic fractionation in muscle, kidney and liver tissues revealed that most of the arsenic is concentrated in the fat fractions of these tissues (muscle fat: 61%; liver fat: 66%; kidney fat: 25%) rather than in the non‐lipid fractions. Hence, this study was undertaken in order to determine the arsenic species bound to lipids in the muscle, kidney and faeces of NR sheep and to compare these with the arsenic species bound to the lipids of the L. digitata consumed. The enzymatic hydrolytic procedure has been successfully employed for the first time to cleave the arsenic species cleanly from the rest of the lipid structure. This makes the arsenic species water soluble and enables their direct determination by high‐performance liquid chromatography coupled with inductively coupled plasma mass spectrometry. Dimethylarsinic acid (DMA(V)) and monomethylarsonic acid (MA(V)) were found to be the major hydrolysed arsenic species bound to the kidney and muscle lipids, whereas arsenosugar‐1 was found to be the major hydrolysed arsenic species in L. digitata lipids. On the other hand, DMA(V) was found to be the major arsenical obtained after the enzymatic hydrolysis of the faeces lipids. These results seem to suggest that both direct absorption and biotransformation of the absorbed organoarsenicals are the likely reasons for their occurrence and accumulation in the NR sheep tissues. Copyright © 2003 John Wiley & Sons, Ltd.     

Arsenobetaine and other arsenic species in mushrooms

Arsenic species in arsenic accumulating mush- rooms (Sarcosphaera coronaria, Laccaria amethystina, Sarcodon imbricatum, Entoloma lividum, Agaricus haemorrhoidaius, Agaricus placomyces, Lycoperdon perlatum) were determined. HPLC/ICP MS and ion-exchange chromatogra- phy–instrumental neutron activation analysis (NAA) combinations were used. The remarkable accumulator Sarcosphaera coronaria (up to 2000 mg As kg^?1 dry wt) contained only methylarsonic acid, Entoloma lividum only arsenite and arsenate. In Laccaria amethystina dimethylarsinic acid was the major arsenic compound. Sarcodon imbricatum and the two Agaricus sp. were found to contain arsenobetaine as the major arsenic species, a form which had previously been found only in marine biota. Its identification was confirmed by electron impact MS.     

利用氢化物发生-冷阱捕集-原子吸收光谱联用技术测定雄黄染毒大鼠血中砷的含量

采用氢化物发生-冷阱捕集-原子吸收光谱法(HG-CT-AAS)测定了雄黄染毒大鼠血中不同形态砷的含量.结果表明,雄黄在大鼠体内的代谢产物为无机砷、一甲基胂酸和二甲基胂酸,其中二甲基胂酸是主要代谢产物;3种形态砷的精密度、准确度、回收率及线性关系良好.     

Distribution and cycle of arsenic compounds in the ocean

In order to understand the distribution and the cycle of arsenic compounds in the marine environment, the horizontal distributions of arsenic(V) [As(V)], arsenic(III) [As(III)], monomethylarsonic acid (MMAA) and dimethylarsinic acid (DMAA) in the Indian Pacific Oceanic surface waters have been investigated. This took place during cruises of the boat Shirase from Tokyo to the Syowa Station (15 November–19 December 1990), of the tanker Japan Violet from Sakai to Fujayrah (28 July–17 August 1991) and of the boat Hakuho-maru from Tokyo to Auckland (19 September–27 October 1992). Vertical distributions of arsenic in the west Pacific Ocean have also been investigated. The concentration of As(V) was found to be relatively higher in the Antarctic than in the other areas. Its concentration varied from 340 ng dm^?3 (China Sea) to 1045 ng dm^?3 (Antarctic). On the other hand, the concentrations of the biologically produced species, MMAA and DMAA, were extremely low in the Antarctic and southwest Pacific waters. Their concentrations in Antarctic waters were 8 ng dm^?3 and 22 ng dm^?3 and those in the southwest Pacific were 12 ng dm^?3 and 25 ng dm^?3. In the other regions the concentration varied from 16 ng dm^?3 (China Sea) to 36 ng dm^?3 (north Indian Ocean) for MMAA and from 50 ng dm^?3 (east Indian Ocean) to 172 ng dm^?3 (north Indian Ocean) for DMAA. As a result, with the exception of Antarctic and southwest Pacific waters, the percentages of each arsenic species in the surface waters were very similar and varied from 52% (east Indian Ocean) to 63% (northwest Pacific Ocean) for As(V), from 22% (northwest Pacific Ocean) to 27% (east Indian Ocean) for As(III) and from 15% (northwest Pacific Ocean) to 21% (north and east Indian Oceans) for the methylated arsenics (MMAA+DMAA). These percentages in Antarctic waters were 97%, 0.2% and 2.8%, respectively, and those in the southwest Pacific Ocean were 97% for As(V)+As(III) and 3% for MMAA+DMAA. The very low concentrations of the biologically produced species in Antarctic waters and that of methylated arsenic in southwest Pacific waters indicated that the microorganism communities in these oceans was dominated by microorganisms having a low affinity towards arsenic. Furthermore, microorganism activity in the Antarctic was also limited due to the much lower temperature of the seawater there. The vertical profile of inorganic arsenic was 1350 ng dm^?3 in surface waters, 1500 ng dm^?3 in bottom waters with a maximum value of 1700 ng dm^?3 at a depth of about 2000 m in west Pacific waters. This fact suggested the uptake of arsenic by microorganisms in the surface waters and the co-precipitation of arsenic with hydrated heavy-metal oxides in bottom waters. The suggested uptake of inorganic arsenic and subsequent methylation was also supported by the profile of DMAA, with a high concentration of about 26 ng dm^?3 in surface water and a significant decrease to a value of 9 ng dm^?3 at a depth of 1000 m.     

Methylated arsenic species in estuarine porewaters

Inorganic arsenic, monomethylarsenic and dimethylarsenic species have been observed in samples of sediment porewater collected from the Tamar Estuary in South-West England. Porewater samples were collected using in situ dialysis. The arsenic species were separated by hydride generation and concentrated by liquid nitrogen trapping, prior to analysis by directly coupled gas chromatography-atomic absorption spectroscopy. The predominant dissolved arsenic species present was inorganic arsenic (5-62 m?g dm^?3). However, this is the first time significant concentrations of methylated arsenic species have been quantified in estuarine porewaters (0.04–0.70 m?g dm^?3), accounting for between 1 and 4% of the total dissolved arsenic. The presence of methylated arsenic compounds in porewaters is attributed to in situ environmental methylation, although the possibility of methylated arsenic species being derived from biological debris cannot be excluded.     

The association mode of arsenic accumulated in the freshwater alga Chlorella vulgaris

Arsenic accumulated in living Chlorella vulgaris cells was solvent-fractionated with chloroform/methanol (2:1), and the fractions were analyzed for arsenic. A large part of the accumulated arsenic was localized in the extract residues. The extract residue from the same extraction of C. vulgaris, which had been, however, cultured in any arsenic-free Detmer medium (MD), adsorbed arsenic physico-chemically at a concentration of 1.1 mg As g^?1 dry weight. Arsenic was found to be combined with protein with molecular weight around 3000 in the arsenicaccumulated living cells. The arsenic-bound protein was analyzed for amino acids. The experimental results showed that no metallothionein-like protein was inductively biosynthesized in C. vulgaris on the exposure to arsenic.     

Intake of different chemical species of dietary arsenic by the japanese,and their blood and urinary arsenic levels

We calculated the intake of each chemical species of dietary arsenic by typical Japanese, and determined urinary and blood levels of each chemical species of arsenic. The mean total arsenic intake by 35 volunteers was 195±235 (15.8-1039) μg As day^?1, composed of 76% trimethylated arsenic (TMA), 17.3% inorganic arsenic (As_i), 5.8% dimethylated arsenic (DMA), and 0.8% monomethylated arsenic (MA): the intake of TMA was the largest of all the measured species. Intake of As_i characteristically and invariably occurred in each meal. Of the intake of As_i, 45-75% was methylated in vivo to form MA and DMA, and excreted in these forms into urine. The mean measured urinary total arsenic level in 56 healthy volunteers was 129±92.0 μg As dm^?3, composed of 64.6% TMA, 26.7% DMA, 6.7% As_i and 2.2% MA. The mean blood total arsenic level in the 56 volunteers was 0.73±0.57 μg dl^?1, composed of 73% TMA, 14% DMA and 9.6% As_i. The urinary TMA levels proved to be significantly correlated with the whole-blood TMA levels (r = 0.376; P<0.01).     

液相色谱-电感耦合等离子体质谱法测定稻米中的5种砷形态

建立了稻米中砷酸根[As（Ⅴ）]、亚砷酸根[As（Ⅲ）]、砷甜菜碱（AsB）、一甲基砷（MMA）和二甲基砷（DMA）的液相色谱-电感耦合等离子体质谱（LC-ICP-MS）检测方法。以0.3 mol/L硝酸水溶液为提取试剂,样品在石墨消解仪中于95 ℃消解1.5 h,上清液供LC-ICP-MS分析。5种砷形态采用Dionex IonPac AS19阴离子交换柱（250 mm×4 mm）分离,经ICP-MS检测。比较了4种提取液对稻米中5种砷形态的提取效率,并对提取溶剂的浓度、提取温度和提取时间等条件进行了优化。通过加标回收试验结合测定标准物质考察了方法准确度及精密度,在2个加标水平上各形态的回收率为89.6%~99.5%,RSD（n=5）不大于3.6%,大米标准物质中各形态之和的测定结果与其标准值吻合,5种砷形态的线性范围AsB和DMA为0.05~200 μg/L,As（Ⅲ）和MMA为0.10~400 μg/L,As（V）为0.15~600 μg/L,方法检出限为0.15~0.45 μg/kg。结果表明,本方法简单、灵敏、耐用,可用于稻米中5种砷形态的准确定量和风险评估。     

HPLC-ICP-MS测定植物样品中6种砷形态化合物

通过优化色谱分离、样品前处理条件,同时对比了电感耦合等离子体质谱的标准模式(STD)、碰撞模式(KED)、氧气反应模式(Oxygen-DRC)、甲烷反应模式(Methane-DRC)的检测结果,建立了一种有效分离植物样品中砷甜菜碱(AsB)、二甲基砷酸(DMA)、亚砷酸(As(Ⅲ))、砷胆碱(AsC)、一甲基砷酸(MM...     

Evaluation of the influence of arsenic species on the nitrogen metabolism of a model angiosperm: nasturtium,Tropaeolum majus

How the various organic and inorganic arsenic species affect the nitrogen metabolism of a model plant, Tropaeolum majus, was studied in order to evaluate the toxicological impact of the various chemical forms of arsenic. For this purpose, the effects on the (a) entire nitrogen pool, (b) protein fraction, and (c) non‐protein fraction were distinguished. The arsenic‐dependent effects on the nitrogen cycle were assessed by using ¹⁵N‐labelled KNO₃ as a nutritive substance and optical emission spectroscopy to analyse how ¹⁵N is incorporated into the nitrogen cycle. In addition to the ¹⁵N‐tracer experiments, the uptake and metabolization of the arsenic compounds were examined. The work shows that biochemical indicator systems like ¹⁵N‐tracer studies are able to characterize the degree of the influence of metabolic processes by arsenic species. For example, the incorporated ¹⁵N concentration decreased linearly and independently of the ¹⁵N fraction with increasing dimethylarsinate (DMA) concentrations. This behaviour indicates that DMA has prevented the uptake of ¹⁵N and hence the formation of amino acids and proteins. Arsenite‐treated plants exhibited an elevated concentration of non‐protein ¹⁵N, which could be an indication either for a stimulated uptake of nitrate or for an interrupted amino acid/protein synthesis. Copyright © 2005 John Wiley & Sons, Ltd.     

Uptake and excretion of total inorganic arsenic by the freshwater alga Chlorella vulgaris

Arsenic-tolerant freshwater alga Chlorella vulgaris which had been collected from an arsenicpolluted environment were tested for uptake and excretion of inorganic arsenic. Approximately half the quantity of arsenic taken up by C. vulgaris was estimated to be adhered to the extraneous coat (10 wt %) of the cell. The remainder was bioaccumulated by the cell. Both adhered and accumulated arsenic concentrations increased with an increase in arsenic(V) concentration of the aqueous phase. Arsenic(V) accumulation was affected by the growth phse: arsenic was most actively accumulated when the cell was exposed to arsenic during the early exponential phase and then accumulation decreased with an increase in culture time exposed to arsenic. The alga grew well in the modified Detmer (MD) medium containing 1 mg As(III) dm^?3 and the growth curve was approximated by a ‘logistic equation’. Arsenic(III) was accumulated up to the second day of the culture time and arsenic(III) accumulation decreased with an increase in the culture time after that. Arsenic accumulation was also largely affected by various nutrients, especially by managanese, iron and phosphorus compounds. A modified MD medium with the three nutrients was proposed for the purpose of effective removal of arsenic from the aqueous phase. Using radioactive arsenate (Na₂H⁷⁴AsO₄), the arsenic accumulated was found to be readily excreted under conditions which were unfavourable for the multiplication of C. vulgaris.     

Urinary arsenic species in an arsenic‐affected area of West Bengal,India (part III)

Arsenic contamination of groundwater has long been reported in the Mushidabad district of West Bengal, India. We visited 13 arsenic‐affected families in the Makrampur village of the Beldanga block in Mushidabad during 18–21 December 2001 and collected five shallow tubewell‐water samples used general household purposes, four deep tubewell‐water samples used for drinking and cooking purposes, and 44 urine samples from those families. The arsenic concentrations in the five shallow tubewell‐water samples ranged from 18.0 to 408.4 ppb and those in the four deep tubewell‐water samples were from 5.2 to 9.6 ppb. The average arsenite (arsenic(III)), dimethylarsinic acid (DMA), monomethylarsonic acid (MMA) and arsenate (arsenic(V)) in urine were 28.7 ng mg^?1, 168.6 ng mg^?1, 25.0 ng mg^?1 and 4.6 ng mg^?1 creatinine respectively. The average total arsenic was 227.0 ng mg^?1 creatinine. On comparison of the ratio of (MMA + DMA) to total arsenic, the average proportion was 86.7 ± 9.2% (mean plus/minus to residual standard deviation, n = 43). The exception was data for one boy, whose proportion was 8.0%. One woman excreted the highest total arsenic, at 2890.0 ng mg^?1 creatinine. When using 43 of the urine samples (the exception being the one sample obtained from the boy) there were significantly positive correlations (p < 0.01) between arsenic(III) and MMA, between arsenic(III) and DMA and between MMA and DMA. Copyright © 2005 John Wiley & Sons, Ltd.     

Identification of arsenic species in sheep‐wool extracts by different chromatographic methods

Sheep on the island of North Ronaldsay (Orkney, UK) feed mostly on seaweed, which contains high concentrations of dimethylated arsenoribosides. Wool of these sheep contains dimethylated, monomethylated and inorganic arsenic, in addition to unidentified arsenic species in unbound and complexed form. Chromatographic techniques using different separation mechanisms and detectors enabled us to identify five arsenic species in water extracts of wool. The wool contained 5.2 ± 2.3 µg arsenic per gram wool. About 80% of the arsenic in wool was extracted by boiling the wool with water. The main species is dimethylarsenic, which accounted for about 75 to 85%, monomethylated arsenic at about 5% and the rest is inorganic arsenic. Depending on the separation method and condition, the chromatographic recovery of arsenic species was between 45% for the anion exchange column, 68% for the size exclusion chromatography (SEC) and 82% for the cation exchange column. The SEC revealed the occurrence of two unknown arsenic compounds, of which one was probably a high molecular mass species. Since chromatographic recovery can be improved by either treating the extract with CuCl/HCl (CAT: 90%) or longer storage of the sample (CAT: 105%), in particular for methylated arsenic species, it can be assumed that labile arsenic–protein‐like coordination species occur in the extract, which cannot be speciated with conventional chromatographic methods. It is clear from our study of sheep wool that there can be different kinds of ‘hidden’ arsenic in biological matrices, depending on the extraction, separation and detection methods used. Hidden species can be defined as species that are not recordable by the detection system, not extractable or do not elute from chromatographic columns. Copyright © 2003 John Wiley & Sons, Ltd.     

Speciation and instrumental neutron activation analysis for arsenic in water samples

Ground water samples obtained from West Bengal, India were analyzed for total arsenic and its inorganic species contents by instrumental neutron activation analysis (INAA). Two anion exchange separation methods using Dowex 1X8 in chloride and acetate forms were standardized for the speciation of As(III) and As(V) using radiotracers. The method by Dowex 1X8 in the acetate form was validated using synthetic mixtures of As(III) and As(V), and applied to water samples; the species concentrations were determined by INAA. The accuracy of the INAA method was evaluated by analyzing the NRCC CRM DORM-2 for total arsenic.