Volumetric determination of Pt(IV) in the presence of Ir,Pd, and Rh with ferrous ammonium sulfate in alkaline mannitol medium

A potentiometric reductimetric method for the determination of platinum (Pt(IV)Pt(II)) with a standard Fe(II) solution in an alkaline medium of mannitol is described. The method, the error of which does not exceed 2%, can be used in the presence of palladium, iridium, and rhodium.     

Zur Chemie in Schmelzlösungen. V. Darstellung kristalliner Halogenowolframate und Halogenomolybdate MeO · MeWO4 · nMeX2 bzw · MeO · MeMoO4 · nMeX2

Preparation and crystal growth of halogenotungstates and halogenomolybdates from molten salt solutions are described. Characteristic properties of this new class of compounds are communicated.     

Rapid determination of protein in plant material by flow injection spectrophotometry with trinitrobenzenesulfonic acid

The rapid determination of protein in plant material based on spectrophotometric determination of amino acids in protein hydrolysates with trinitrobenzenesulfonic acid has been adapted to flow injection analysis. With the manifold described, a routine sampling rate of 120 samples/h is possible, though this, as well as sensitivity, can easily be varied. The method was calibrated against the Kjeldahl method and a good correlation was obtained between the two methods over a wide range of protein values for beans.     

Membrane extraction of pertechnetate with quaternary ammonium salts comparison with solvent extraction

The liquid membrane extraction (MX) and the solvent extraction (SX) of pertechnetate with Aliquat 336 as a carrier has been studied. From the results of SX the percentage of pertechnetate in the inner solution in experiment with LM was proposed. It has been found that the pertraction of pertechnetate depends on the inner solution used and the most effective solutions were those with ClO ₄ ^– and SCN^–. Effects of the carrier concentration in membranes and outer phase composition have been studied too. The results of these experiments were kinetic curves with a minimum, which may be interpreted as a result of competing processes in the systems.     

A simple laboratory generator for low concentrations of sulphur dioxide

The generator is based on permeation of sulphur dioxide through silicone rubber tubes immersed in a buffered, thermostated solution of sodium hydrogensulphite. The generator contains three (or more) permeation tubes of different lengths immersed simultaneously in the generation solution. The tubes can be connected stepwise to the carrier gas source, so that three (or more) different concentrations of SO₂ in the carrier gas can be obtained from a single solution. The tested generator produced 1.25–25.4 ng s^?1 SO₂, depending on the hydrogensulphite concentration in the solution. Long-term stability was tested for the production of 10.49 ng s^?1 over 50 h; the relative standard deviation was 1.57%. The experimental conditions affecting the production of SO₂ are discussed. An equation is derived for estimating the SO₂ production for various solution compositions and surface areas of the permeation tubes.     

Effects of genesis and ionizing radiation on the kinetics of reduction of NiO-CeO2 mixed oxides with hydrogen

The reduction of mixed oxides NiO-CeO₂ of various composition with hydrogen was studied at 290–470° by means of thermogravimetry. Some physicochemical properties of the system were also investigated and compared with earlier studied analogous samples of different “origin”. The degree of mutual interaction of the two components, the reduction kinetics and the sensitivity to the different sorts of radiation (gamma-rays, fast neutrons and electrons), applied in different doses, are strongly affected by the “pre-history” and by the composition in both compared series of mixed oxides.     

Beitrag zur mikroskopischen Identifizierung organischer Stoffe nach L. Kofler. V

Zusammenfassung In Fortsetzung früherer Untersuchungen zum Zweck der Ergänzung und Erweiterung der Identifizierungs-Tabelle nachKofler werden für 62 Substanzen die thermomikroskopischen Konstanten mitgeteilt und die gegebenenfalls notwendigen Zusatzreaktionen beschrieben. Bei Nicotinamid, das auf Grund seiner Fähigkeit, mit vielen Stoffen wie organischen Säuren, Säureestern, Phenolen u. a. Komplexverbindungen zu bilden, häufig als Reagens in Betracht kommt, wird das polymorphe Verhalten erläutert und das Auftreten von sieben Modifikationen beschrieben.

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Contribution to the microscopic identification of organic materials after L. Kofler. V

Summary In continuation of earlier investigations for the purpose of supplementing and extending the identification tables ofKofler, the thermomicroscopic constants are given for 62 substances and when necessary the supplementary reactions are described. In the case of nicotinamide, which because of its ability to yield among other things complex compounds with organic acids, acid esters, phenols, is frequently considered as reagent, the complex behavior is illustrated and the occurrence of 7 modifications is described.

     

Tritium volume activity in natural waters of the NPP Temelín region

With the use of the tritium monitoring network the samples of river water, air humidity and precipitation are collected and analysed for HTO in the vicinity of Temelín nuclear power plant.     

Gold(III) complexes with imidazole,benzoxazole, purine and pyrimidine derivatives

Summary The synthesis and characterization of Au^III complexes with several heterocyclic ligands are reported. The compounds have general formula [AuX₃(L)], where L =N-methylimidazole (N-MeIz),N-ethylimidazole (N-EtIz),N-propylimidazole (N-PrIz), benzoxazole (BO), 2-methylbenzoxazole (2-MeBO), 2,5-dimethylbenzoxazole (2,5-diMeBO), 2-amino-pyrimidine (2-APm), 4(6) -hydroxy-pyrimidine [4(6)-hydrPm] or hypoxanthine (Hypox) and X = Cl or Br. Elemental analysis, conductivity measurements and spectral studies were used for the characterization of the complexes. A square-planar geometry withN-bonded heterocyclic ligands is suggested.     

Study of the drying zirconia gel-precipitates using thermal analysis

Thermoanalytical techniques (TG, DTG, DTA and EGA) can be helpful in studying gel compositions and relating the chemical history and the role of the precipitant to the chemical properties of gels. The objective of our work was to determine the influence of the initial conditions in the reaction mixture on the product characteristics. Zirconia gels were prepared by the gelprecipitation method by the hydrolysis of zirconium tetrachloride dissolved in methanol. The substitution of water by methanol was chosen in order to obtain a reaction medium in which better control of the hydrolysis and condensation reactions of the zirconium precursor were achieved and thus also better control of the final properties of the dried zirconia gel-precipitates could be obtained. The nature of the hydrated zirconia gels obtained during the gelation process is strongly influenced by the conditions of the reaction mixture, e.g. concentration of the zirconium precursor, the mixing rate and particularly by the amount of water added. To distinguish between various types of water in the gel-precipitates, the furnace atmosphere and the partial water pressure were altered appropriately. It was shown that initial zirconium to water molar ratio has a significant effect on the properties of the final products. It was assumed that, according to the preparation conditions, three different types of water are present in the formed zirconia gel-precipitates. Modification of the dehydration processes of zirconia gel-precipitates enables control of the final microstructural and surface properties of the dried gels which are suitable for further catalysts support as well as mixed oxide preparation.