Application of pressurized sample preparation methods for the analysis of steels and copper alloys

Pressurized sample preparation devices (High Pressure Asher, Pressurized Microwave Digestion system, compared with a PTFE decomposition vessel) were used to dissolve certified metal alloy samples (steel, copper) for ICP analysis. Based on the results of the analysis it was established that both up-to-date devices can be advantageously applied to quickly and quantitatively dissolve metal alloy samples. To dissolve the samples, two different kinds of acid mixtures (A: nitric and hydrochloric acid; B: nitric and hydrochloric and sulphuric and phosphoric acid) were used. The sample preparation is simpler and less time-consuming than the earlier commonly used methods, sample loss and degree of contamination are also reduced. Steel samples containing tungsten, titanium and niobium (less than 0.5%) can only be analyzed using a mixture of the four acids. By dissolving steel samples in the nitric and hydrochloric acid mixture, the concentration of their most common elements (Cr, Ni, Mn, V, Cu) as well as their S and P content can be determined. Copper alloy samples can be dissolved quickly by the pressurized microwave decomposition device using hydrochloric acid and diluted (1:1) nitric acid.     

Optimization of Conditions for the HPLC Determination of Synthetic Dyes in Food

The retention of synthetic food dyes on the sorbent Kromasil C18 was studied under the conditions of reversed-phase and ion-pair high-performance liquid chromatography, depending on the concentrations of the ion-pair reagent (tetrabutylammonium dihydrophosphate) and organic solvent (acetonitrile) in the mobile phase and on the concentration and pH of the phosphate buffer solution. The optimum conditions were selected for the separation of ten dyes in the isocratic elution mode within 25 min. A procedure was developed for the determination of synthetic food dyes in foodstuffs; the detection limit was 10–30 g/L.     

Cycloaddition of fluorinated oxazoles

Cycloaddition reactions of polyfluorinated 1,3-oxazoles with cyclic and acyclic alkenes were studied. The results of these reactions were interpreted using quantum chemical calculations. An unusual product, viz., fluorine-containing acylpyrrole, was studied by X-ray diffraction. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1630–1635, July, 2005.     

Summer school in nuclear and radiochemistry at Brookhaven National Laboratory

Summary The Living Textbook of Nuclear Chemistry (http://livingtextbook.orst.edu) is a website, which is a collection of supplemental materials for the teaching of nuclear and radiochemistry. It contains audio-video presentations of the history of nuclear chemistry, tutorial lectures by recognized experts on advanced topics in nuclear and radiochemistry, links to data compilations, articles, and monographs, an audio course on radiochemistry, on-line editions of textbooks, training videos, etc. All content has been refereed.     

THE MOLECULAR WEIGHT OF HAEMATOPORPHYRIN DERIVATIVE, ITS GEL COLUMN FRACTIONS and SOME OF ITS COMPONENTS IN AQUEOUS SOLUTION

Abstract— The average molecular weights of haematoporphyrin derivative (HPD), the fractions of HPD that can he obtained by gel chromatography and of purified haematoporphyrin and protoporphyrin in aqueous solution have been determined by ultracentrifugation. The results show that HPD contains polymeric material with the excluded fraction from the gel column (HPD aggregate) having an average molecular weight of greater than 20000. The two remaining gel column fractions of HPD have lower molecular weights and their similarity indicates that these fractions do not separate because of molecular weight differences. Purified haematoporphyrin has a comparatively low molecular weight in aqueous solution but the data is not capable of discriminating between monomer, dimer or slightly higher oligomer. In contrast, protoporphyrin sediments to the bottom of the centrifuge tube under the conditions of sedimentation equilibrium indicating that it has an average molecular weight considerably greater than that of HPD aggregate.     

Zur komplexchemie von 4-zentren-π-systemen : XII. Glyoxaldiiminkomplexe: 1H-nmr-spektren und long range-kopplungen

Glyoxaldiimines (I) RN=CHCH=NR show in the NMR a downfield shift of glyoxalic protons (H_gly) when complexed to

(II: M = Mo, W), but increasing high field shifts when going to

(III) and

complexes (IV). In the tungsten complexes II H_glyW coupling satellites are resolved (J(WH) ≈4–6 Hz); in the phosphine compounds III, IV long range PH_gly coupling is clearly visible. Mechanisms of spinspin interaction are briefly discussed in connection with the EPR results on monoanionic radicals of II–IV.     

Rearrangement correction to higher polarizabilities of two-electron systems

In this paper we include the rearrangement correction (discussed in the preceding paper) in a coupled Hartree–Fock (CHF) calculation of atomic hyperpolarizabilities and other related properties. We have studied the effect of these corrections on properties like electric dipole hyperpolarizabilities, uniform electric field quadrupole polarizabilities and shielding factors in two-electron ions and have noticed significant changes in the computed values over the CHF results.     

p-Toluol- und Methansulfonamide substituierter Pyrazolcarbonsäuren

Zusammenfassung Es wird die Darstellung von Sulfonamiden aus Tosylamid-Na bzw. Mesylamid-Na und den Diketopiperazinen der 5-Methylpyrazol-3-carbonsäure, 4,5,6,7-Tetrahydroindazol-3-carbonsäure und Borneno[2,3-d]pyrazol-3-carbonsäure beschrieben.

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p-toluene- and methanesulfonamides of substituted pyrazolecarboxylic acids

Sulfonamides have been prepared from the diketopiperazines of 5-methylpyrazole-3-carboxylic acid, 4.5.6.7-tetrahydroindazole-3-carboxylic acid, borneno[2.3-d]pyrazole-3-carboxylic acid and tosylamide sodium and mesylamide sodium, resp.

     

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