Effect of organic solvents and their dielectric constants on ion selective electrode potential

Summary The effects of mixtures of water with methanol, ethanol, acetone, dimethylsulfoxide (DMSO), andp-dioxane on the lead ion selective electrode potential have been studied. With the exception of DMSO which decreases the potential, other organic solvents stated above show an increased potential effect. Both the lead ion electrode and the silver arsenite electrode show an approximately linear decreasing relationship between the potential and the dielectric constant of organic solvents studied.

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Über die Wirkung organischer Lösungsmittel und ihrer Dielektrizitätskonstante auf das Potential ionenspezifischer Elektroden

Zusammenfassung Die Wirkung von wäßrigem Methanol, Äthanol, Aceton, Dimethylsulfoxid (DMSO) oderp-Dioxane auf das Potential einer bleispezifischen Elektrode wurde untersucht. Mit Ausnahme von DMSO, das dieses Potential vermindert, haben die angeführten organischen Lösungsmittel die entgegengesetzte Wirkung. Die bleispezifische Elektrode und die Silberarsenitelektrode zeigen ein etwa linear abnehmendes Verhältnis zwischen dem Potential und der Dielektrizitätskonstante der angeführten organischen Lösungsmittel.

     

N,N′-Bis(2-hydroxybenzyl)ethylenediamine-N,N′-dipropionic acid. A new chelating ligand for iron(III)

A new potentially chelating ligandN,N′-bis(2-hydroxybenzyl)ethylenediamine-N,N′-dipropionic acid, (HBEP) has been prepared in high yield and its ionization constants have been determined by potentiometric and spectrophotometric methods. The stability constant for the Fe^III-HBEP chelate has been determined spectrophotometrically, and the ligational behaviour of HBEP with iron(III) compared with that of its homologue, HBED (N,N′-bis(2-hydroxybenzyl)ethylenediamine-N,N′-diacetic acid). IPCL Communication No. 169.     

Separation and determination of small amounts of palladium and platinum

Summary A procedure is described for the separation of 20 to 100g of Pd(II) from 100 to 300g of Pt(IV) in a mixture. The method is based on the selective separation of Pd(II) on silica gel, leaving Pt(IV) in the solution phase. Complete recovery of Pt(IV) in the supernate has been checked with¹⁹⁷Pt as the radioactive indicator. The deposited palladium is extracted with dil. HCl, and the separated components are determined spectrophotometrically. A possible mechanism has been suggested.

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Zusammenfassung Die Trennung eines Gemisches aus 20 bis 100g Pd(II) und 100 bis 300g Pt(IV) wurde beschrieben. Sie beruht auf der selektiven Adsorption von Pd(II) an Kieselgel. Das vollständige Verbleiben von Pt(IV) in der Lösung wurde mit¹⁹⁷Pt radiochemisch erwiesen. Das adsorbierte Pd wird mit verd. HCl extrahiert und spektrophotometrisch gemessen. Eine mögliche Interpretation des Adsorptionsvorganges wird angeführt.

     

Gold nanoparticle formation during bromoaurate reduction by amino acids

The synthesis and characterization of water-soluble dispersions of gold nanoparticles by the reduction of a potassium tetrabromoaurate precursor solution using the amino acids L-tyrosine, glycyl-L-tyrosine, and L-arginine using alkaline synthesis conditions are reported. The particle sizes determined by small-angle X-ray scattering (SAXS) and high-resolution transmission electron microscopy (HRTEM) measurements are found to be inversely proportional to the rate of particle formation, which was determined by time-resolved UV-visible spectrophotometry measurements, and vary very slowly at intermediate gold concentrations and rapidly at the extremes. Dispersions produced with a mixture of the two amino acids glycyl-L-tyrosine and L-tyrosine showed particle sizes and particle size distributions which were directly proportional to the ratio of the two L-amino acids, thus offering the possibility for control over the properties of the gold nanoparticle dispersions.     

X-ray structures of iron(III) and cobalt(III) complexes containing 2-<Emphasis Type="Italic">S</Emphasis>-methyl-6-methyl-4-formylpyrimidine-<Emphasis Type="Italic">N</Emphasis>(4)-ethylthiosemicarbazone

Iron(III) and cobalt(III) complexes of types [Fe(LEt)₂]ClO₄·3/2C₆H₆ (1) and [Co(LEt)₂]ClO₄·2CH₂Cl₂ (2) with a new pyrimidine-derived thiosemicarbazone ligand, 2-S-methyl-6-methyl-4-formylpyrimidine-N(4)-ethylt-hiosemicarbazone (HLEt), having N, N, S donor centers have been synthesized and characterized by X-ray crystallography. The structural study shows distorted octahedral geometry for both 1 and 2 with MN₄S₂ chromophores. The space group of 1 is C2/c (monoclinic) and that of 2 is P2₁2₁2₁ (orthorhombic). The electrochemical electron transfer study in MeCN solutions shows a one-electron reductive response presumably due to a metal(III)–metal(II) couple.     

Bound D‐states of helium atom under Debye screening

We have investigated the 1snd^1,3D (3 ≤ n ≤ 7) state energies of helium atom embedded in weakly coupled plasma environments using the Rayleigh–Ritz variational method. The effect of the plasma environment is taken care of using a Debye screening model. A correlated wave function involving exponential expansion has been used to represent correlation between the charge particles. The bound 1snd^1,3D (3 ≤ n ≤ 7) state energies of helium for various Debye lengths along with the excitation energies of few singlet and triplet states are reported. Our results are useful references to atomic physics, plasma physics, and astrophysics research communities. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007     

Chemical and radiochemical separation of strontium and yttrium

Summary A procedure is presented for the chemical and radiochemioal separation of strontium and yttrium in mixtures which is based on the selective carrying of strontium by ignited barium sulphate leaving yttrium in the solution phase; the carried strontium is recovered by leaching with aqueous hydrochloric acid solution. In order to make strontium radiochemically free from yttrium activity, an initial isotopic dilution of the latter with 1 mg of inactive yttrium is an essential requirement. The method is applicable to chemical analysis of mixtures involving 1 to 3 mg of strontium and 1 to 16 mg of yttrium, both components being determined complexometrically after separation.

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Zusammenfassung Ein Verfahren zur chemischen und radioehemischen Trennung von Strontium und Yttrium in Gemischen wurde vorgeschlagen, das auf der selektiven Abscheidung von Sr mit geglühtem Bariumsulfat beruht, wobei Y in der Lösung zurückbleibt; Sr wird dann mit wäßriger Salzsäure ausgewaschen. Um jede radiochemische Y-Aktivität aus dem Sr zu entfernen, ist es wesentlich, vorher mit 1 mg Y-Isotop zu verdünnen. Das Verfahren ist für die chemische Analyse von Gemischen aus 1 bis 3 mg Sr und 1 bis 16 mg Y verwendbar. Die beiden Komponenten werden nach der Trennung komplexometrisch bestimmt.

     

Optical and magnetic properties of manganese-incorporated zinc sulfide nanorods synthesized by a solvothermal process

Manganese-incorporated ZnS (MnxZn1-xS) nanorods were synthesized by a simple solvothermal process. Synthesized nanorods were single crystalline. Manganese incorporation in the ZnS lattice induces a phase transformation from hexagonal wurtzite to cubic zinc blende structure. The diameter of the nanorods increased with the increase of Mn concentration. Intense orange luminescence at approximately 585 nm was observed for the nanorods. Six-line hyperfine splitting was observed in the EPR spectra for lower Mn concentrations, whereas broad Lorentzian-shaped EPR spectra were obtained for higher Mn concentrations because of the Mn-Mn cluster formation at higher Mn concentrations.     

The status of trace and minor elements in pulses: A PIXE measurement

The proton particle induced X-ray emission (proton PIXE) technique has been employed to study the heavy element status (essential and toxic) in five different varieties of pulses commonly cultivated and consumed in Bangladesh. In this analysis, the samples were irradiated in air with 2 MeV protons having 30 nA beam intensity for characteristic X-ray excitation. For 40 μC irradiations, the concentration of ten elements (K, Ca, Ti, Mn, Fe, Ni, Cu, Zn, Br, and Rb) was determined by comparison with a calibration obtained from the NBS orchard leaf standard, SRM 1571. In a comparative study with atomic absorption spectrophotometric (AAS) measurements of some elements in lathyrus sativus, the data were found to be in good agreement. The results obtained from the present study are discussed and compared with available data.     

The study of the Cd(NH3) 4 2+ /Cd*(NH3) 4 2+ exchange reaction in hydrous oxides of zirconium(IV), silicon(IV) and tin(IV)

Kinetics of the exchange reaction of cadmium(II)-ammine complex ion using radio-active isotope¹¹⁵Cd in the same chemical form in hydrous oxides of zirconium(IV), silicon(IV) and tin(IV) has been studied. It has been found that the major contribution in the overall exchange process is from the surface of the exchanger particles. It has also been found that the rate of exchange follows the order: hydrous ZrO₂>hydrous SnO₂>hydrous SiO₂