Arsenic species

A novel interface to connect a ce system with an inductively coupled plasma mass spectrometric (icpms) detector has been developed (88). The interface was built using a direct injection nebulizer (din) system. The ce/din/icpms system was evaluated using samples containing selected alkah, alkaline earths, and heavy-metal ions, as well as selenium (Se(IV) and Se(VI)), and various inorganic and organic arsenic species. The preliminary results show that the system can be used to determine metal species at ppt to ppb level. 

The reactions discussed above show that arsenic(fV) is of redox amphoteric character and a stronger reducing agent than arsenic(in), but at the same time it is a stronger oxidant than arsenic(V). Partners of the oxidation-reduction reactions of arsenic(fV) known so far can be seen in Table 13. It follows from the redox amphoteric character that the oxidation potentials of couples involving arsenic species are in the order... 

Zheng, J., Kosmus, W., Pichler-Semmelrock, F., and Kock, M., Arsenic speci-ation in human urine reference materials using high-performance liquid chromatography with inductively coupled plasma mass spectrometric detection, /. Trace Elements Med. Biol., 13, 150, 1999. 

Onken B.M., Hossner L.R. Plant uptake and determination of Arsenic species in soil solution under flooded conditions. J Environ Qual 1995 24 373-381. 

Klane and Blum [69] showed that inductively coupled plasma spectrometry was able to determine below 1000 ng/1 of arsenic in seawater. Ion exclusion chromatography coupled with inductively coupled plasma mass spectrometry has been used to determine several arsenic species in seawater [ 947 ]. Down to 3 ng/1 arsenic can be determined using hydride generation prior to this technique. 

Another variation on the method [4] with slightly higher sensitivity (several ng/1) used the liquid nitrogen cold trap and gas chromatography separation, but used the standard gas chromatography detectors or atomic absorption for the final measurement. These workers found four arsenic species in natural waters. 

Organic arsenic species can be rendered reactive either by photolysis with ultraviolet radiation or by oxidation with potassium permanganate or a mixture of nitric acid and sulfuric acids. Arsenic (V) can be determined separately from total inorganic arsenic after extracting arsenic (III) as its pyrrolidine dithiocarbamate into chloroform [15]. 

The mechanisms of arsenical toxicity differ considerably among arsenic species, although signs of poisoning appear similar for all arsenicals (Woolson 1975 NRCC 1978 Pershagen and Vahter 1979 Eisler 1988, 1994 ATSDR 1992 Abernathy et al. 1997 SEGH 1998). 

Kurttio, R, H. Komulainen, E. Hakala, and J. Pekkanen. 1998. Urinary excretion of arsenic species after exposure to arsenic present in drinking water. Arch. Environ. Contam. Toxicol. 34 297-305. 

Lin, T.H. and Y.L. Huang. 1998. Arsenic species in drinking water, hair, fingernails, and urine of patients with blackfoot disease. Jour. Toxicol. Environ. Health 53A 85-93. 

Fig. 4. Arsenic species present in the impacted soil. TETRA C4Hi2Asl MMA CH3AsO(OH)2...

Smith, P.G. Koch, I. Gordon, R.A. Mandoli, D.F. Chapman, B.D., Reimer, K.J. 2005. X-ray absorption near-edge structure analysis of arsenic species for application to biological environmental samples. Environmental Science and Technology, 39, 248-254. 

Cores were collected from the NATA and adjacent wetland. Solid material was obtained from the aquifer beneath the NATA by filtering water samples from MW17. Pore water was squeezed from cores in a hydraulic press. Groundwater, surface and lake water samples were filtered (0.2 pm) in the field. Sub-samples were acidified to preserve cations. Arsenic species were separated on site by passing filtrate through SAX cartridges (Le et al. 2000). 

In Procedure 11.10, step 1 is designed to extract soluble species, carbonates, and species on exchange sites. Step 2 is designed to extract reducible iron and magnesium oxyhydroxides. Step 3 extracts oxidizable organic matter and sulfides, while step 4 extracts any metals remaining after the completion of the previous extractions. Sequential extraction methods have also been used to extract and quantify the amounts of various arsenic species, primarily as As(III) and As(IV) in soil [21],... 

This is a powerful method for the determination of the species of elements present in a specific environment. For example, it has been used to determine the arsenic species present in particular environmental conditions [16]. 

Generally, inorganic arsenic can occur in the environment in several forms but in natural waters and thus in drinking water, it is mostly found as trivalent arsenite or pentavalent arsenate. Organic arsenic species, abundant in seafood, are very much less harmful to health and are readily eliminated by the body5. 

An amount of 0.5 g of sorption material was shaken with 50 mL of carbonate buffered water (pH = 7, 10 mg/L sulfate, 14 mg/L chloride) containing 500 pg/L of each As(III) and As(V). Samples were taken in increasing time intervals to investigate the kinetics of the sorption process. The arsenic species were measured by IC-ICP-MS [5]. 

Columns with volume of 125 m3 were filled with different materials and the same water as described above was continuously percolated through the material. The flow rate was about 2-3 mL/min. Inlet and outlet water was sampled and analyzed for arsenic species daily. 

In Ganges Delta, groundwater contaminated with arsenic causes health risk of 40 million people.1 Since arsenic exists as both arsenite (As(III)) and arsenate (As(V)), removal methods for both arsenic species are desired to resolve the arsenic calamity in Ganges Delta.2 Granular adsorbents specific... 

Since properties of both phosphate and arsenate are very similar each other, the adsorption of phosphate was examined prior to the adsorption of arsenic species. Here, the feeding solution in the adsorption operation was 1 mM phosphate solution of pH3. Table 1 summarizes detailed experimental conditions and column performances during repeated adsorption-elution-regeneration cycles. Since supplied volumes of the feed are not constant (101 - 193 BV), it is not easy to judge the efficiency of the adsorption from total uptake of phosphate. Thus, removal of phosphate until 100 BV is listed at the last column of Table 1 as an index of the column performances. 

In this work, the column performances were examined by supplying 1 mM of arsenic species, which corresponds to 75 ppm of arsenic. Such a high level arsenic is rarely found in surface water. Since the highest concentration levels of arsenic in well water of Ganges Delta are ca. 2 ppm. Thus, the removal of arsenic form dilute arsenite solutions was tested. Figure 5 illustratively shows the results. 

B. Daus, J. Mattusch, R. Wennrich, H. Weiss (2002) Investigation on stability and preservation of arsenic species in iron rich water samples.- Talanta, in press... 

As H3As03+3H++3e < As(s)+3H20 0.247 V vs. SHE Trace inorganic arsenic species in groundwater and biological samples... 

The chemical form of arsenic in marine environmental samples is of interest from several standpoints. Marine organisms show widely varying concentrations of arsenic [4-6] and knowledge of the chemical forms in which the element occurs in tissues is relevant to the interpretation of these variable degrees of bioaccumulation and to an understanding of the biochemical mechanisms involved. Different arsenic species have different levels of toxicity [7] and bioavailability [8] and this is important in food chain processes, while physicochemical behaviour in processes such as adsorption onto sediments also varies with the species involved [9]. It has... 

Maher [13] has described a procedure for the determination of inorganic arsenic, monomethylarsenic and dimethylarsenic in marine organisms and estuarine sediments. The arsenic species are isolated by solvent extraction, separated by ion-exchange chromatography and selectively determined by arsine generation. Recoveries of spikes of 5 and lOpg of arsenic taken through the whole procedure were 92-96%. 

Table 13.3 Percentage recoveries of arsenic species in the ion-exchange separation...

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