Thallium emission

In contrast to the small world production of thallium of about 10-15 tons per year, the annual amount of thallium in waste material is estimated to be about 600 tons (Micke et al. 1983). The main anthropogenic occurrence of thallium in the environment results from emissions of the highly volatile metal and its compounds from some industrial processes for example, the smelting of chalcogenic ores - especially lead and zinc sulfides - yields thallium emissions. 

Perez Ruiz et al. [26] determined penicillamine and tiopronin in pharmaceutical preparations by flow injection fluorimetry. The procedure is based on the oxidation of these drugs by thallium(III), whereupon the fluorescence of T1(T) produced in the oxidation of penicillamine is monitored using excitation at 227 nm and emission at 419 nm. A linear calibration graph for penicillamine was obtained between 3 x 10-7 and 8 x 10 5 6 M. 

Berndt et al. [740] have shown that traces of bismuth, cadmium, copper, cobalt, indium, nickel, lead, thallium, and zinc could be separated from samples of seawater, mineral water, and drinking water by complexation with the ammonium salt of pyrrolidine- 1-dithiocarboxylic acid, followed by filtration through a filter covered with a layer of active carbon. Sample volumes could range from 100 ml to 10 litres. The elements were dissolved in nitric acid and then determined by atomic absorption or inductively coupled plasma optical emission spectrometry. 

Haapakka and Kankare have studied this phenomenon and used it to determine various analytes that are active at the electrode surface [44-46], Some metal ions have been shown to catalyze ECL at oxide-covered aluminum electrodes during the reduction of hydrogen peroxide in particular. These include mercu-ry(I), mercury(II), copper(II), silver , and thallium , the latter determined to a detection limit of <10 10 M. The emission is enhanced by organic compounds that are themselves fluorescent or that form fluorescent chelates with the aluminum ion. Both salicylic acid and micelle solubilized polyaromatic hydrocarbons have been determined in this way to a limit of detection in the order of 10 8M. 

Dilsizian V, Perrone-Filardi P, Arrighi JA, Bacharach SL, Quyyumi AA, Freedman NM et al. Concordance and discordance between stress-redistribution-reinjection and rest-redistribution thallium imaging for assessing viable myocardium. Comparison with metabolic activity by positron emission tomography. Circulation 1993 88 941-952... 

Tamaki N, Ohtani H, Yamashita K, Magata Y, Yonekura Y, Nohara R et al. Metabohc activity in the areas of new fill-in after thallium-201 reinjection comparison with positron emission tomography using fluor-ine-18-deoxyglucose. J Nucl Med 1991 32 673-678... 

Berman DS, Kiat H, Friedman JD, Wang FP, van TK, Matzer L et al. Separate acquisition rest thallium-201/ stress technetium-99m sestamibi dual-isotope myocardial perfusion single-photon emission computed tomography a clinical validation study. J Am Coll Cardiol 1993 22 1455-1464... 

The complexes exhibited different behavior in solution. The gold-thallium derivative showed a shift of the emission to 536 nm when the measurement was carried out in frozen solution. This was explained by a higher aggregation of [Aull(MTP)2] units in the solid state compared to the situation in solution. In the case of the Au-Pb compound, the emission spectrum showed a strong dependence on the aggregation state and temperature. Thus, the emission band in TH F solution, which appeared at 555 nm (298 K) (x = 57 ns), was shifted to 480 nm in frozen solution (x = 2.3 ps) or appeared at 752 nm in solid state (x = 22 ns). As with the thallium complex, the shift to high energy in solution may have been related to the polymeric structure of the complex in the solid state that was not reproduced in solution. 

A radioactive element is an element that disintegrates spontaneously with the emission of various rays and particles. Most commonly, the term denotes radioactive elements such as radium, radon (emanation), thorium, promethium, uranium, which occupy a definite place in the periodic table because of their atomic number. The term radioactive element is also applied to the various other nuclear species, (which arc produced by the disintegration of radium, uranium, etc.) including (he members of the uranium, actinium, thorium, and neptunium families of radioactive elements, which differ markedly in their stability, and are isotopes of elements from thallium (atomic number 81) to uranium (atomic number... 

In an interlab oratory study involving 160 accredited hazardous materials laboratories reported by Kimbrough and Wakakuwa [28], each laboratory performed a mineral acid digestion on five soils spiked with arsenic, cadmium, molybdenum, selenium and thallium. Analysis of extracts was carried out by atomic emission spectrometry, inductively-coupled plasma mass spectrometry, flame atomic absorption spectrometry and hydride generation atomic absorption spectrometry. 

Atomic absorption spectrometry has been used to determine thallium in soil [220]. This element has also been determined in multi-metal mixtures by emission spectrometry (Sect. 2.55). 

Van Laar et al. [223] have reviewed methods for the determination of thallium in soils. The determination of thallium is also discussed under Multi-Metal Analysis of Soils in Sect. 2.55 (emission spectrometry). 

Its absorption spectrum shows one band at 320 nm (e = 2900 M 1cm 1), assigned to the cti - ct2 transition localized in the Au-Tl moiety. The emission spectrum in the solid state at 77 K shows a band at 602 nm, which is attributable to a transition between orbitals that appear as a result of the metal-metal interaction. In this sense, Fenske-Hall molecular orbital calculations indicate that the ground state is the result of the mixing of the empty 6s and 6pz orbitals of gold(I) with the filled 6,v and the empty 6pz orbitals of thallium(I). In frozen solution, this derivative shows a shift of the emission to 536 nm, which has been explained by a higher aggregation of [AuT1(MTP)2] units in the solid state if compared to the situation in solution. 

As commented above, different compositions lead to different emission energies, and these systems emit at 646, 609, 620, 606, and 683 nm, respectively, by excitation at 550 nm. Furthermore, there is no correspondence of the emissions with the gold-thallium lengths since all of them range from 2.9 to 3.1 A or with the environment around the thallium centers. As a plausible explanation it was reported that each 2D or 3D network could probably lead to different excited states, and the formation of such networks might be influenced by the presence or absence of coordinating solvents in their structures. 

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