Environmental analysis arsenic speciation

For the determination of organotin compounds (tributyltin, triphenyltin, triethyltin, and tetra-ethyltin) a MAE is proposed before the normal phase (NP) HPLC/UV analysis [35], In organotin and arsenic speciation studies, hydride generation is the most popular derivatization method, combined with atomic absorption and fluorescence spectroscopy or ICP techniques [25,36], Both atmospheric pressure chemical ionization (APCI)-MS and electrospray ionization ESI-MS are employed in the determination of butyltin, phenyltin, triphenyltin, and tributyltin in waters and sediments [37], A micro LC/ESI-ion trap MS method has been recently chosen as the official EPA (Environmental Protection Agency) method (8323) [38] it permits the determination of mono-, di-, and tri- butyltin, and mono-, di-, and tri-phenyltin at concentration levels of a subnanogram per liter and has been successfully applied in the analysis of freshwaters and fish [39], Tributyltin in waters has been also quantified through an automated sensitive SPME LC/ESI-MS method [40],... 

Laboratory methods. Huorimetry has been used widely for selenium analysis in environmental samples but is being superseded by more sensitive instrumental methods. Some of the instmmental methods used for arsenic speciation and analysis can also be used for selenium. In particular, HPLC and HG can separate selenium into forms suitable for detection by A AS, AFS (Ipolyi and Fodor, 2000), or ICP-AES (Adkins et al, 1995). Only Se(IV) forms the hydride, and so Se(VI) must be prereduced to Se(IV) if total selenium is to be determined. This is normally achieved using warm HCl/KBr followed by co-precipitation with La(OH)3 if necessary (Adkins et al., 1995). KI is not used, since it tends to produce some Se(0), which is not reduced by HG. La(OH)3 collects only Se(IV), so the prereduction step to include the contribution from Se(VI) is required before co-precipitation. Other methods of preconcentration include co-precipitation of Se(IV) with hydrous iron oxide or adsorption onto Amberlite IRA-743 resin (Bueno and Potin-Gautier, 2002). 

Cavicchioli A, La-Scalea MA, Gutz IGR (2004) Analysis and speciation of traces of arsenic in environmental, food and industrial samples by voltammetry a review. Electroanalysis 16 698-711... 

Terlecka, E. (2005). Arsenic speciation analysis in water samples a review of the hyphenated techniques. Environmental Monitoring and Assessment. Vol. 107, p>p. 259-284... 

Another intensively studied element in speciation analysis is arsenic. The biological and environmental effects of arsenic species and their transformation pathways have been studied in numerous papers.40- 42 Both arsenite and arsenate accumulate in living tissues because of their affinity for proteins, lipids and other cellular compounds.43 Arsenic species can undergo transformation via... 

Wang, R.Y., Hsu, Y.L., Chang, L.F., Jiang, S.J. Speciation analysis of arsenic and selenium compounds in environmental and biological samples by ion chromatography -inductively coupled plasma dynamic reaction cell mass spectrometer. Anal. Chim. Acta 590, 239-244 (2007)... 

Plasma emission spectroscopy is an elemental analysis technique that is, it provides no information on the chemical form or oxidation state of the element being determined. The identification of the chemical state of an element in a sample is called speciation. For example, in environmental samples, mercury may exist in a variety of species mercuric ion, mercurous ion, methymercury compounds, and the extremely toxic compound dimethyhnercury. Determination of mercury by ICP-OES results in total mercury concentration chemical speciation would teU us how much mercury is present in each of the different forms. Arsenic is another element of environmental and health interest because of its toxicity. Arsenic, like mercury, exists in multiple organoarsenic compounds and multiple oxidation states as inorganic arsenic ions. Why is speciation... 

Although it is beyond the scope of this article to consider detailed collection and sample preparation procedures for environmental samples, here are some general considerations for speciation analysis of air, water, biological material, and soils/sediments. The collection of samples in air has focused upon the determination of hydrides and methylated compounds of elements such as arsenic, lead, mercury, and tin. The sample may be introduced into a preevacuated container, or with a pump. The analytes may be isolated using cryotrapping techniques or adsorbent cartridges. For best results, it is recommended to collect the entire gas sample in a container, coated... 

When the environmentally most critical components within a complete project cycle are identified (e.g. by their property or total amount), the pathway(s) should be analyzed by which these substances may reach critical concentrations in both man and associated foodwebs. This type of risk estimation, known as critical pathway analysis, is primarily based on the evaluation of existing speciation data, as exemplified in Fig. 3.2 for arsenic and mercury (Preston and Portmann 1981). The differentiation of the most toxic forms of both metals unveils rather early the really critical forms and pathways which these metals may take to reach sensitive targets. To focus on total concentrations alone would fail to understand and predict their true nature or to find out the really relevant routes of exposure. 

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