Thallium analysis

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. 

Extraction systems with following electrothermal atomic absorption spectroscopy (ET-AAS) may be useful in some cases. For example, Zendelovska and Stafilov (2001) used isoamyl acetate extraction with following ET-AAS for thallium analysis in sulfide minerals. Eleischer (1997) reported a detection limit of 0.8 JgL when using ET-AAS with matrix modification (uirmineralized urine, diluted 1 2). 

Zinc can be used as an internal standard in the analysis of thallium by differential pulse polarography. A standard... 

Titration Indicators. Concentrations of arsenic(III) as low as 2 x 10 M can be measured (272) by titration with iodine, using the chemiluminescent iodine oxidation of luminol to indicate the end point. Oxidation reactions have been titrated using siloxene the appearance of chemiluminescence indicates excess oxidant. Examples include titration of thallium (277) and lead (278) with dichromate and analysis of iron(II) by titration with cerium(IV) (279). 

Tri-n-butyl phosphate, ( -C4H9)3P04. This solvent is useful for the extraction of metal thiocyanate complexes, of nitrates from nitric acid solution (e.g. cerium, thallium, and uranium), of chloride complexes, and of acetic acid from aqueous solution. In the analysis of steel, iron(III) may be removed as the soluble iron(III) thiocyanate . The solvent is non-volatile, non-flammable, and rapid in its action. 

In room temperature phosphorescence, a treatment of the paper substrate with sodium dodecyl sulfate in conjunction with thallium acetate enhances the results and the technique can be used in routine environmental analysis of organic pollutants [156]. 

Yields in the above reactions can often be improved by the addition of 1 mole of triphenylphosphine directly to the trifluoroacetic acid solution of the reactants immediately before final work-up. It would appear that the triphenylphosphine functions as a scavenger for TTFA released in the metal-metal exchange reaction, thus protecting the final phenol from further electrophilic thallation and/or oxidation. Validation of the metal-metal exchange mechanism was obtained indirectly by isolation and characterization of an ArTlX2/LTTFA complex directly from the reaction mixture. NMR analysis revealed that this complex still possessed an intact aryl-thallium bond, indicating that it was probably the precursor to the transmetallation products, an aryllead tristrifluoroacetate and TTFA. 

The ac polarograms of the mixture at varying frequencies (Fig. 19) shows four ac summit peaks corresponding to reduction of T1(I), In(III), Cd(II), and Zn(II). The summit peaks for In(III) and Cd(II) are very close and so their ac waves are not very sharp. The first summit peak corresponding to T1(I) appears to be due to the combined reduction of lead and thallium ions, as is evident from the summit peak height. Hence, ac polarographic analysis only enables the identification of four metal ions out of seven and... 

From an analysis of their data, Materlik and co-workers were able to determine that for the ex situ case and in the absence of oxygen, the thallium atoms are located at twofold sites at a mean distance of 2.67 0.02 A. For the in situ case and again in the... 

The palladium and magnesium nitrates modifier has a substantial equalising effect on the atomisation temperature of the nine elements investigated. The optimum atomisation temperature for all but one element (thallium) is between 1900 and 2100 °C. This means that all elements can be determined at a compromise atomisation temperature of 2100 °C with a minimum sacrifice in sensitivity. Such uniform conditions for as many elements as possible are of vital importance if simultaneous multielement furnace techniques are envisaged. Moreover, in conventional graphite furnace AAS, uniform conditions for a number of elements can greatly facilitate and simplify daily routine analysis. 

In all 28 parameters were individually mapped alkalinity, aluminum, antimony, arsenic, barium, boron, bromide, cadmium, calcium, chloride, chromium, conductivity, copper, fluoride, hardness, iron, lead, magnesium, manganese, nitrate, pH, potassium, selenium, sodium, sulphate, thallium, uranium, and zinc. These parameters constitute the standard inorganic analysis conducted at the DENV Analytical Services Laboratory. 

Thallium may be analyzed by flame- and furnace- AA spectrophotometric methods and also by the ICP-AES methods. For the flame-AA analysis, an air-acetylene flame is satisfactory. The ICP- AES measurement may be carried... 

In their applications of A.C. oscillopolarographic titration for pharmaceutical analysis, Huang et al. reported a method for the titration of procaine hydrochloride with sodium tetraphenylborate [62]. Procaine hydrochloride was mixed with sodium tetraphenylborate in acetate buffer (pH 4.6). The precipitate was filtered off, and the unconsumed tetraphenylborate titrated with thallium sulfate by A.C. oscillo-polarography. The recovery was found to be 99.9 to 100.0%, and the coefficient of variation (n = 10) was 0.19%. The method could also be used to identify outdated samples of procaine hydrochloride injection solution, as its loss of water solubility is indicated by an incision in the titration curve. 

Many elements are present in the earth s crust in such minute amounts that they could never have been discovered by ordinary methods of mineral analysis. In 1859, however, Kirchhoff and Bunsen invented the spectroscope, an optical instrument consisting of a collimator, or metal tube fitted at one end with a lens and closed at the other except for a slit, at the focus of the lens, to admit light from the incandescent substance to be examined, a turntable containing a prism mounted to receive and separate the parallel rays from the lens and a telescope to observe the spectrum produced by the prism. With this instrument they soon discovered two new metals, cesium and rubidium, which they classified with sodium and potassium, which had been previously discovered by Davy, and lithium, which was added to the list of elements by Arfwedson. The spectroscopic discovery of thallium by Sir William Crookes and its prompt confirmation by C.-A. Lamy soon followed. In 1863 F. Reich and H. T. Richter of the Freiberg School of Mines discovered a very rare element in zmc blende, and named it indium because of its brilliant line in the indigo region of the spectrum. 

Thallium in Pyrite. In 1867 Dr. E. Carstanjen found that the flue dust from the pyrite-roasting kilns of L. Rohr s sulfuric acid plant at Oranienburg was unusually rich in thallium. It yielded on analysis 3.5 per cent of metallic thallium. By working up a large quantity of flue dust from several kilns, he prepared twenty or thirty pounds of the metal. 

Rapid exchange of alkyl groups occurs in thallium(III) alkyls as demonstrated by the proton NMR study of Maher and Evans (81). At low temperatures ( —85°) the multiplet structure expected for proton-thallium coupling is superimposed on the proton spectra of thallium alkyls. On warming, the multiplets collapse. Analysis of this collapse region [Eq. (29)] yielded a value of 6 1 kcal mole-1 for the exchange-activation energy... 

One of the most famous applications in forensic science is the analysis of Napoleon s hair by ICP-MS after mineralization in concentrated nitric acid whereby an arsenic concentration about 40 times higher than normal (about 40p,gg 1) was measured (see Section 9.5). Ingested arsenic is known to be stored in sulfydryl rich tissue, like hair, nails or skin. ETV-ICP-MS combined with isotope dilution has been employed to measure thallium in human scalp hair from a person poisoned by thallium compared to control subjects, whereby several longitudinal concentration gradients for the analyzed segments (length 10 mm) were obtained.28... 

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