Speciation metalloids

In the case of Lysimeter Teuftal, most dissolved heavy metal and metalloid concentrations are directly correlated to electrical conductivity. The plot in Fig. 7 shows the relative dilution of different components during a rain event in comparison to that of electrical conductivity. The trend is independent of the speciation of these components. It should be noted that there are three notable exceptions, namely Ni(H), Co(II), and Cu(II). The common property of these cationic species is that they are extremely insoluble under the highly basic conditions encountered in the leachates of cement-stabilized residues (pH 12.8). It is possible that precipitation is the cause of such behaviour. 

Gardiner, P. E., Delves, H. T. The speciation of trace metals and metalloids in biological specimens, in Trace Metal Analysis in Biological Specimens (ed.) Stoeppler, M., Foster City, California, Biomedical Publications, in preparation... 

In 2006, the speciation of metals and metalloids (As, Bi, Hg, Pb, Sb, Se and Sn) associated with alkyl groups and biomacromolecules in the environment was critically reviewed by Hirner.85 More than 60 species of alkylated metals and metalloids have been found in different ecosystems and terrestrial locations all over the world.85-87 These alkylated metals or metalloids are of interest due to their toxicological properties (e.g. monomethyl mercury, MMHg, which gained worldwide attention during the Minamata tragedy, and are not only known to be produced by microbial methylation within most anaerobic compartments of the environment, but also in the course of enzymatic transformation during human metabolism.85... 

Multi-element trace analysis is an important prerequisite for the quality assurance of foodstuffs with respect to the characterization of non-essential, toxic and essential (nutrient) elements as pollutions or as mineral elements relevant to health. Contamination with heavy metals such as Cd, Pb or Hg has become a serious problem with increasing environmental (artificial) contamination e.g., due to industrial pollution. The increasing use of inorganic mass spectrometric techniques (especially of ICP-MS) in the analysis of foodstuffs for multi-element analysis of trace elements or the detection of selected elements and species at a low concentration level has resulted from advances in very sensitive and quantitative measurements of metals, metalloids and several non-metals, including their speciation. 

The number of analytical methods developed for the study of the distribution of metal- and metalloid-containing species in the last decade has been impressive. However, a majority of these are as yet to be applied to real biological materials. With the greater appreciation of the pre- and post-sampling factors that influence chemical speciation, and the development of appropriate quality control materials the results of these studies will become more reliable. Consequently, the use of chemical speciation data will become indispensable to accurate environmental impact assessment, and to our understanding of the roles that metals and metalloids play in biological systems. 

Pecheyran, C. (1997) Speciation of chemical forms of metals and metalloids in air challenges and perspectives. Analusis, 25, M41-M44. 

Another key factor in the popularity of the technique is its increasingly widespread use in speciation chemistry. The current awareness of the importance of the chemical form in which an element is present in food (e.g., the oxidation state, the nature of the ligands, and the molecular structure), on its possible absorption and fate inside the body, has made elemental speciation a prominent topic of present research in the food science. If speciation critically influences the bioavailability, essentiality, or toxicity of an element, the analytical techniques that enable species discrimination and quantification gather prominence. ICP-MS has the capability for quantifying metal (metalloid)-containing species in a chromatographic or capillary electrophoresis effluent or, as recently demonstrated, in a gel spot after SDS-PAGE via electrothermal vaporization (ETV) or laser ablation (LA) [4, 5]. Hence, it has firmly established as a sensitive,... 

Wine is a very complex matrix and the accurate, selective determination of species constitutes a challenge for analytical chemists. Furthermore, the speciation analysis of metals bound to biological ligands is a subject of increasing interest since complexation may reduce their toxicity and bioavailability. There is a limited number of studies concerning the speciation analysis of metals or metalloids in wines. Arsenite, arsenate, MMA, and DMA were separated in less than 10 min by means of an anion-exchange column [88], Arsenic species detection was accomplished by the direct coupling of the column effluent to an HG system and AFS was used for detection. LoDs in white wine were 0.16, 0.33, 0.32, and 0.57 ng ml-1 for As(III), DMA, MMA, and As(V), respectively. In real samples... 

ICP-MS this is the primary detection technique in the determination and speciation of trace elements. It has excellent selectivity, sensitivity, multielement and isotopic capability and easy coupling with different separation techniques (especially low-flow and low-volume chromatographic methods). Modem instruments enable practically interference-free response over the wide range of element concentrations in a variety of samples and quantification of metalloids and nomnetals. 

Speciation studies have been focused on relatively few elements, mainly aluminum, antimony, arsenic, chromium, lead, mercury, selenium, and tin. The primary species of these elements studied with ICP-MS detection are presented in Table 3 and they include different oxidation states, alkylated metal and/or metalloid compounds, selenoaminoacids, and selenopeptides. In addition, applications in studies of the pharmacokinetics of metal-based drugs (Pt, V, Au), metalloporphyrins (Ni, V, Fe, etc.), heavy metals in phytochelatins (Cd, Cu, Zn, Hg, etc.) and in humic substances should be mentioned. 

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