Trace Amounts Of Tellurium Research Articles

Thermochromatography study of volatile tellurium species in various gas atmospheres

The adsorption interaction of tellurium species with fused silica was studied by thermochromatography. Trace amounts of tellurium were obtained by irradiating elemental tin with α-particles. Different tellurium species were obtained using carrier gases with varied redox potential. Adsorption enthalpies of the obtained species were calculated allowing for the identification of some species. Elemental tellurium or SnTe was deposited in thermochromatography experiments when using both dried and deoxygenated He and H2 as carrier gases. Tellurium dioxide was deposited in thermochromatography experiments when using dry oxygen as carrier gas. Tellurium dioxide was found to be significantly less volatile compared to elemental Te or SnTe. The deposition of a species with still lower volatility occurring under less oxidizing conditions was tentatively assigned to tellurium monoxide, TeO. Species more volatile than elemental tellurium or SnTe, most likely Te-hydroxides, were detected in experiments using moist H2 as carrier gas. In moist oxidizing gas, species more volatile than TeO2 were found, most likely Te-oxyhydroxides. The obtained results provide valuable input to design experiments for studying the volatility of tellurium’s heavier homologue polonium and its compounds, which represent one of the major radiological concerns for the use of lead–bismuth-eutectic as coolant and target material for innovative accelerator-driven systems or spallation sources.

Catalytic determination of ultra trace amounts of tellurium by 2.5-order differential oscillopolarography.

A highly sensitive and selective catalytic method with 2.5-order differential oscillopolarographic detection is described for the determination of tellurium, based on its activation effect on the slow Pd(II)-catalyzed reaction of sodium hypophosphite and methyl red in hydrochloric acid medium at 100 degrees C. Methyl red exhibited a sensitive 2.5-order differential polarographic wave at -0.35 V (vs. SCE) in the supporting electrolyte of pH 5.0 acetate buffer solution and was chosen as the indicating component for the indirect determination of tellurium. A calibration curve of tellurium in the range of 0.02-2.0 ng mL(-1) was obtained by the fixed-time procedure. The detection limit was 0.007 ng mL(-1). Possible interferences by co-existing substances were examined. The new method has been used to analyze trace tellurium in organs of white mice with satisfactory results. RSD was 0.54% to 2.10%, recovery 98.4% to 95.7%. The mechanism is also discussed.

Highly sensitive spectrophotometric determination of trace amounts of tellurium(IV) with the tungstate–basic dyes–poly(vinyl alcohol) system

Three highly sensitive spectrophotometric methods have been developed for the determination of tellurium(IV), based on its colour reactions with tungstate and basic dyes (BD) in aqueous solution in the presence of poly(vinyl alcohol).Tellurium(IV) reacts with tungstate and BD to form ion-association complexes. The molar absorptivities are between 1.76 × 107 and 3.33 × 107 dm3 mol–1 cm–1, the highest value being found with Nile blue. Suitable conditions for the reactions and the effects of foreign ions were investigated. The methods have been successfully applied to the spectrophotometric determination of trace amounts of tellurium(IV) in smoke ash samples.

Flow - Injection Spectrophotometric Determination of Trace Amounts of Tellurium by Catalytic Reduction of Toluidine Blue

Abstract Tellurium was determined spectrophotometrically at 635 nm and pH 5.3 based on its catalytic reduction of Toluidine Blue in the presence of Te(IV) by using a flow -injection system. Under the optimized experimental conditions, the detection limit is 60 ng/ml of tellurium ion and the linear range is 80–3800 ng/ml (110 μl, injection). The relative standard deviation of 10 replicate measurements is 1.5% for a 1.5 μg/ml of tellurium. The sampling rate is 25 h-1.

放射化分析による水酸化ナトリウム溶液中微量テルルの定量

水酸化ナトリウム溶液中テルルの分析として, Fe (OH) 3による共沈捕集前処理とMIBKを用いる放射化学分離中性子放射化分析〔130130Te (n, γ) 131Te〕によって微量のテルルを感度良く分析することができた。共沈捕集担体鉄の精製と主な元素の分離係数等について検討した。一定量のテルルを添加して調製した模擬試料を用いて分析し, 添加値に対して良い結果を得た。本法における検出限界は0.04ppbである。本法は高速炉冷却材ナトリウム中核分裂テルルの移行調査を目的とした分析に応用できる。

Determination of trace amounts of tellurium by the sub-superequivalence method of isotope dilution analysis

Trace amounts of tellurium in synthetic samples were determined by the redox sub-superequivalence method of isotope dilution analysis (SSE-IDA) and the results were compared with those of sub-stoichiometric isotope dilution analysis (Subst-IDA) in order to demonstrate the usefulness of SSE-IDA. 125mTeIV was separated from an HCl solution in which 125Sb and 125mTeIV were in radioactive equilibrium and 125mTe was used as a tracer. The reactant (TeIV) was oxidized sub-stoichiometrically with a solution of K2Cr2O7 in 0.1 mol dm–3 HCl, followed by the extraction of TeIV with 20% tributyl phosphate–kerosene solution (after changing the concentration of HCl to 5 mol dm–3) in order to separate TeIV and TeVI. Activities of TeVI in each aqueous phase were measured and the amount of tellurium was determined according to the graphical method of SSE or Subst-IDA. Under the conditions where Subst-IDA gives large errors, accurate determinations were possible using SSE-IDA with errors of less than 5–6 per cent. The limit of the determination was about 2 µg ml–1.

Determination of Tellurium in Urine by Graphite Furnace Atomic Absorption Spectrometry after Solvent Extraction

Trace amounts of tellurium in urine were determined by atomic absorption spectrometry using a graphite furnace atomizer. The urine was concentrated and digested with HNO 3 −HClO 4 . The bulk of salts and interfering elements were removed by 4-methyl-2-pentanone extraction procedure, and finally the organic phase was analyzed on a graphite furnace atomic absorption spectrometer equipped with an auto sampler having a concentration function. Recoveries of tellurium added to urine sample range from 90 to 103%; relative standard deviation was 9% at the 0.1 μg level. Tellurium contents in urine ranged from <0.1 to 1.2 μg/l

Spectrophotometric determination of trace amounts of tellurium(IV) with tetramethylthiourea

A spectrophotometric method for the determination of trace amounts of tellurium(IV) in dilute hydrochloric acid is described. Concentrations of between 0.2 and 7 µg ml–1 of tellurium(IV) in the final solution can be determined by measuring the absorbance at 382 nm of the complex formed by the reaction of tellurium(IV) with tetramethylthiourea (Iµ= 2.14 × 104 l mol–1 cm–1). The method is simple, reliable and sensitive. Those foreign ions that interfere in the determination of tellurium(IV) are bismuth(III), selenium(IV), iron(III) and copper(II).