tellurium and sodium-borohydride

Cysteine and triethanolamine capped CdTe nanoparticles have been synthesized using a simple aqueous solution based method. This method involves the reaction of tellurium powder with sodium borohydride (NaBH(4)) in water to produce telluride ions (Te(2-)), followed by the simultaneous addition of an aqueous solution of cadmium chloride or other cadmium source (acetate, carbonate and nitrate) and solution of L-cysteine ethyl ester hydrochloride or triethanolamine. The effect of capping agent on the size, structure and morphology of the as-synthesized nanoparticles was investigated. The particles were characterized using optical spectroscopy, transmission electron microscopy (TEM), high-resolution TEM (HRTEM), X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy.

Topics: Ascorbic Acid; Borohydrides; Cadmium; Cadmium Compounds; Cysteine; Ethanolamines; Indicators and Reagents; Luminescence; Microscopy, Electron, Transmission; Nanoparticles; Particle Size; Spectrophotometry, Ultraviolet; Spectroscopy, Fourier Transform Infrared; Tellurium; X-Ray Diffraction

Speciation of tellurium can be achieved by making use of different kinetic behaviors of Te(IV) and Te(VI) upon their reaction with sodium borohydride using hydride generation. While Te(IV) can form H(2)Te, Te(VI) will not form any volatile species during the course of hydride formation and measurement by atomic absorption spectrometry. Quantitative reduction of Te(VI) was achieved through application of a microwave assisted prereduction of Te(VI) in 6.0 mol/L HCl solution. Enhanced sensitivity was achieved by in situ trapping of the generated H(2)Te species in a previously heated graphite furnace whose surface was modified using Pd or Ru. Overall efficiency for in situ trapping in pyrolytically coated graphite tube surface was found to be 15% when volatile analyte species are trapped for 60s at 300°C. LOD and LOQ values were calculated as 0.086 ng/mL and 0.29 ng/mL, respectively. Efficiency was increased to 46% and 36% when Pd and Ru surface modifiers were used, respectively. With Ru modified graphite tube 173-fold enhancement was obtained over 180 s trapping period with respect to ETAAS; the tubes could be used for 250 cycles. LOD values were 0.0064 and 0.0022 ng/mL for Pd and Ru treated ETAAS systems, respectively, for 180 s collection of 9.6 mL sample solution.

Topics: Borohydrides; Graphite; Palladium; Ruthenium; Spectrophotometry, Atomic; Tellurium; Water Pollutants, Chemical

A new, simple and sensitive method by combining headspace Pd(II)-coated graphite bar microextraction (GBME) with electrothermal vaporization-inductively coupled plasma mass spectrometry (ETV-ICP-MS) was developed for the determination of trace Se, Te and Bi in seawater and human hair. In this method, the graphite bar was coated with Pd(II) and then used for headspace trapping of the hydrides of Se(IV), Te(IV) and Bi(III). The graphite bar with enriched hydrides of analytes was inserted directly into the graphite tube and subsequently determined by ETV-ICP-MS according to the established temperature program. The experimental parameters, which may affect the extraction and vaporization of target analytes, were systematically investigated and the optimal experimental conditions were established. Under the optimal conditions, the detection limits of the method were 8.6, 2.6 and 0.2 ng l(-1) and the relative standard deviations (RSDs) were 7.0%, 6.2% and 8.0% (C=0.20 microg l(-1), n=7) for Se, Te and Bi, respectively. Linearity was obtained over the range of 0.05-20.00, 0.01-5.00 and 0.01-20.00 microg l(-1) with the correlation coefficients of 0.9942, 0.9997 and 0.9976 for Se, Te and Bi, respectively. The proposed method was successfully applied for the determination of trace Se, Te and Bi in seawater and human hair samples. In order to validate the method, the proposed method has also been applied for the determination of trace Se, Te and Bi in the certified material of GBW07601 human hair, and the determined values were in good agreement with the certified values.

Topics: Adsorption; Bismuth; Borohydrides; Chemical Fractionation; Graphite; Hair; Humans; Hydrogen-Ion Concentration; Mass Spectrometry; Palladium; Seawater; Selenium; Tellurium; Temperature; Time Factors; Volatilization