Tellurium speciation

In aqueous chemistry, tellurium is mainly found as telluride (Te- ), tellurite (Te03 ), and tellurate (Te04 ). Zolotov et al. [19] developed an IC procedure for the separation of TeOi, and Te04 by a suppressed ion-chromatographic system. In the method, F interfered with the determination of TeO., while S04 " interfered with the determination of Te04. In a report by Chen et al. [20], a similar method was used to speciate tellurium. The detection limits for Te04 were very poor in both methods. The studies were confined only to standard solutions. 

Simultaneous speciation of inorganic selenium and tellurium in water samples by ICP-MS was performed after selective solid phase extraction (SPE), as discussed by Yu et al 9 Under acidic conditions Se (IV) and (TV) complexes with ammonium pyrrolidine dithiocarbamate were formed. The detection limits for Se and species in water samples were found to be 7ngl 1 and 3 ng 1 1, respectively. 

Tellurium speciation has been described by Klin-kenberg et al. [40] using reversed-phase LC-ICP-MS for the analysis of tellurium in samples from a wastewater treatment plant. A method was developed for the separation of Te03 and HTe04 and, although at least 11 different organic Te compounds were detected, no attempt was made to identify them. This is essentially a problem with ICP detection since all structural information is lost by plasma sample decomposition. 

Tellurium speciation in water samples from a treatment plant has been performed by Klinkenberg et al. [29]. Te032 and HTe04 were separated along with 11 unidentified organic Te compounds. More structural information was not available as a result of complete decomposition of the compounds in the plasma. 

The speciation of Te(IV) is less straightforward than that of Se(IV) but, probably, is dominated by TeO(OH) and Te(OH)J in acid solutions. In addition to the above-mentioned acidity effect, the Ce(IV)-Te(IV) reaction exhibits an inverse dependence on both [NO3 ] and [HSO4 ]. The l//Cobs versus l/[Te(IV)] or l/[Te(VI)] plots are linear, indicating complex formation with each. The reversible reaction through the pentavalent substrate species observed for Se(lV) is not observed in the tellurium system. In this system, the observed retardation effect of Ce(III) is attributed to complex formation with Te(IV) or Te (VI). 

In addition to mercury, AFS has been employed for the speciation of antimony, arsenic, selenium, and tellurium. Samples analyzed include environmental samples (sediments, water, etc.), food (fish, rice, etc.), and biological fluids (urine, blood, liver, etc.). It is anticipated that the applications of AFS will continue to increase because of the technique s favorable analytical characteristics. 

Arsenic, selenium, and tellurium can be determined at the trace level by cathodic stripping voltammetry (CSV) after having been reductively codeposited with copper. A characteristic of the stripping technique of these three elements is that only a single current peak which arises from the further reduction of the deposited analyte to As. Se" or Te " is observed. This method is suitable for the determination and speciation of As(V) and As(IlI) in water samples [36], selenium in minerals [38] and biological samples [68], and for the simultaneous determination of selenium and tellurium (Fig. 41) [37]. 

E. Ghasemi, N. M. Najafi, Sh. Seidi, F. Raofie and A. Ghassempour, Speciation and determination of trace inorganic tellurium in environmental samples by electrodeposition-electrothermal atomic absorption spectroscopy, J. Anal. At. Spectrom., 2009, 24(10), 1446-1451. 

N. M. Najafi, H. Tavakoli, R. Alizadeh and Sh. Seidi, Speciation and determination of ultra trace amounts of inorganic tellurium in environmental water samples by dispersive liquid-liquid microextraction and... 

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