Use of Escherichia coli immobilized on amberlite XAD-4 as a solid-phase extractor for metal preconcentration and determination by atomic absorption spectrometry.

A sensitive solid-phase extraction technique (SPE) for the enrichment of Fe(III), Co(II), Mn(II) and Cr(III) prior to atomic absorption spectrometric analysis is described. Escherichia coli immobilized on Amberlite XAD-4 was used as a solid-phase extractor. The effects of the pH, amount of solid-phase, eluent type and volume of the sample solution on the recovery of the metal ions were investigated. The effect of diverse ions was also investigated. The recoveries of Fe(III), Co(II), Mn(II) and Cr(III) under the optimum conditions were found to be 99 +/- 2, 99 +/- 3, 98 +/- 2, 98 +/- 3%, respectively, at the 95% confidence level. The detection limits of the metal ions were found as to be 2.4, 3.8, 1.3 and 1.7 ng ml(-1) for Fe(II), Co(II), Mn(II) and Cr(III) respectively, by applying a preconcentration factor of 25. The proposed enrichment method was applied to the determination of analytes in Atatürk Dam water samples, and alloy samples (RSD < 5%). The accuracy of the method was verified on certified alloy samples (NBS SRM 85b and NBS SRM 59a). The analytes were determined with a relative error lower than 5% in water and alloy samples.     

Analyse und Optimierung von Gasphasen-Reaktionen,XVII. Selenoketen

Analysis and Optimization of Gasphase Reactions, XVII. — Selenoketene The thermal decomposition of 1,2,3-selenadiazole in the gaseous phase has been investigated by photoelectron and mass spectroscopy. At temperatures above 720 K selenoketene is formed, the PE spectrum of which can be assigned based on ab initio SCF calculations as well as on radical cation state comparison with the iso(valence) electronic heterocumulenes H₂C  C  O and H₂C  C  S. The 4-phenyl derivative decomposes above 820 K forming phenylacetylene.     

Preconcentration of trace elements from water samples on a minicolumn of yeast (Yamadazyma spartinae) immobilized TiO2 nanoparticles for determination by ICP-AES

A trace element preconcentration procedure is described utilizing a minicolumn of yeast (Yamadazyma spartinae) immobilized TiO₂ nanoparticles for determination of Cr, Cu, Fe, Mn, Ni and Zn from water samples by inductively coupled plasma atomic emission spectrometry. The elements were quantitatively retained on the column between pH 6 and 8. Elution was made with 5% (v/v) HNO₃ solution. Recoveries ranged from 98 ± 2 (Cr) to 100 ± 4 (Zn) for preconcentration of 50 mL multielement solution (50 μg L⁻¹). The column made up of 100 mg sorbent (yeast immobilized TiO₂ NP) offers a capacity to preconcentrate up to 500 mL of sample solution to achieve an enrichment factor of 250 with 2 mL of 5% (v/v) HNO₃ eluent. The detection limits obtained from preconcentration of 50 mL blank solutions (5%, v/v, HNO₃, n = 11) were 0.17, 0.45, 0.25, 0.15, 0.33 and 0.10 μg L⁻¹ for Cr, Cu, Fe, Mn, Ni and Zn, respectively. Relative standard deviation (RSD) for five replicate analyses was better than 5%. The retention of the elements was not affected from up to 500 μg L⁻¹ Na⁺ and K⁺ (as chlorides), 100 μg L⁻¹ Ca²⁺ (as nitrate) and 50 μg L⁻¹ Mg²⁺ (as sulfate). The method was validated by analysis of freshwater standard reference material (SRM 1643e) and applied to the determination of the elements from tap water and lake water samples.     

Kinetic and spectroscopic studies of the substitution reactions of [Rh(acac)(CO)2] with triphenylphosphite

Summary The substitution reactions of [Rh(acac)(CO)₂] with triphenylphosphite (P) to produce [Rh(acac)(CO)P], [Rh(acac)P₂] and [PhP₃P], were studied in detail using spectroscopic (n.m.r., i.r. and u.v.-vis.) and kinetic techniques. The kinetic data demonstrate that the first substitution process is very fast and followed by the rate-determining second step. The subsequent loss of acac is relatively slow. The activation enthalpy for the formation of [Rh(acac)P₂] is extremely low and possibly accounts for the catalytic nature of this system in hydrogenation and hydroformylation reactions.     

Preparation of hydrosol suspensions of elemental and core–shell nanoparticles by co-deposition with water vapour from the gas-phase in ultra-high vacuum conditions

In this study, efforts were placed in giving some in vitro key clues to the question on which is more efficient for the cancer hyperthermia between intracellular and extracellular modalities. Near infrared (NIR) photothermal responsive gold nanorods (GNRs) were adopted to cause cellular thermolysis either from inside or outside of cells. GNRs were synthesized with the size of 30.4?nm (in length)?×?8.4?nm (in width). Demonstrated by ICP-MS (inductively coupled plasmon mass spectroscopy), UV?CVis spectroscopy and transmission electron microscopy analyses, various cell uptake doses of nanoparticles were differentiated due to different molecular designs on GNRs surfaces and different types of cells chosen (three cancer cell lines and three normal ones). Under our continuous wavelengths (CW) NIR irradiation, it resulted that the cells which internalized GNRs died faster than the cells surrounded by GNRs. Furthermore, fluorescent images and flow cytometry data also showed that the NIR photothermal therapeutic effect was greater when the amount of internalized GNRs per cell was larger. Generally speaking, the GNRs assisted intracellular hyperthermia exhibited more precise and efficient control on the selective cancer ablation. To a larger degree, such a relationship between GNRs distribution and hyperthermia efficiency might be applied to wider spectra of cell types and heat-producing nanoparticles, which provided a promise for future cancer thermal therapeutic designs.