Ultratrace analysis of uranium and thorium in glass

Three methods of determination for uranium and thorium traces and ultratraces in glass were developed: a simple and powerful ICP-MS method exhibiting limits of determination in the one ng/g-range; a complex method with end-determination by classical photometry and a limit of determination for U and Th of 20 ng/g; and a method with chelate-complex formation for U and Th and subsequent GC-detection with a ⁶³Ni-ECD with limits of determination in the g/g-range. These methods are critically compared and tested for real type samples of special glasses.Abbreviations used AAS Atomic absorption spectrophotometry - ECD Electron capture detector - FOD 1,1,1,2,2,3,3-Heptafluoro-7,7-dimethyl-4,6-octanedion - GC Gas chromatography - HFA 1,1,1,5,5,5-Hexafluoro-2,4-pentanedione - ICP-AES, -MS Inductively coupled plasma-atomic emission spectrometry, metry, -mass spectrometry - LAS Liquid absorption spectrophotometry = classical photometry - NAA Neutron activation analysis - NIST National Institute of Standardization and Technology (Gaithersburg, U.S.A.) - TBP Tri-(n-butyl)-phosphate - TFA 1,1,1-Trifluoro-2,4-pentanedione - TTFA 1-(2-Thenoyl)-3,3,3-trifluoroacetone - XRS X-ray (fluorescence) spectrometry     

Beiträge zur Komplexchemie der Phosphine und Phosphinoxide. XXIII. Schwermetallkomplexe des Tetramethyl-biphosphins

On the coordination chemistry of phosphines and phosphinoxides. XXIII. Heavy metal complexes of tetramethyl-biphosphine The reactions of tetramethyl-biphosphine with salts of 3d elements including Cd and Hg, too, in THF, benzene, acetonitrile and alcohols, respectively, results in forming complexes of differing compositions: (MⁿX_n)₂{(CH₃)₂P? P(CH₃}₂)₃? Mⁿ = Ti^III, V^III, Cr^III, Fe^II, Ni^II, Cu^I; MX₂{(CH₃)₂P? P(CH₃)₂}₂? M = Co^II, Ni^II, Hg^II; MX₂ · (CH₃)₂P? P(CH₃)₂? M = Fe^II, Ni^II, Zn, Cd, Hg^II; X = Cl, Br, J. The partly intensively coloured complexes have low solubilities; this item complicates the performing of structure determining methods. Partial informations about the structures of the complexes are to be gained by magnetic and spectrophotometric measurements and X-ray investigations. The tendency of (CH₃)₂P? P(CH₃)₂ to form complexes with transition metals differs from that of other biphosphines. Splitting of the P? P bond due to metal salts does not occur. (CH₃)₂P? P(CH₃)₂ acts as a monodentate or bidentate ligand, like other members of the R₂P? PR₂ series do too. The forming of ligand bridges seems to be favoured in comparison to the chelate function.     

Linear codimerization of 2-cyclopropyl-1,3-butadiene with methyl acrylate catalyzed by iron and cobalt complexes

Conclusions The linear codimerization of 2-cyclopropyl-1,3-butadiene with methyl acrylate gave a mixture of methyl esters of 5-cyclopropyl-2Z,5Z- and 2E,5Z-heptadienoic acids.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2364–2366, October, 1984.     

High-speed liquid chromatography of polychlorinated biphenyls and related compounds.

High-speed liquid chromatography in the system silica gel-dry n-hexane has been used to characterize the behaviour of a series of commercially available mixtures of chlorinated biphenyls, viz., Aroclor 1221-1268. An attempt has been made to assign a large number of peaks in the chromatograms of the Aroclors to the individual constituents. To this end, retention times and UV spectra were recorded for 47 polychlorinated biphenyls. The dependence of retention and spectral characteristics on the chlorine content of the substituted biphenyls is discussed     

Differential capacity curves at adsorption of organic ions: Model approach I

Theoretical analysis of the double-layer model has been carried out in the presence of the specific adsorption of organic cations accompanied by considerable increase of the inner-layer dimensions. The formulae for calculation of the differential capacity curves of an electrode have been derived. A flat minimum at high negative charges, caused by the diffuse structure of the double layer, has been predicted on the capacity curves. The presence of such minima has been verified experimentally on the mercury and bismuth electrodes. By computer calculation it has been shown that, although. relatively good agreement of the theoretically calculated capacity curves with the experimental curves could he obtained, a physically unrealistic interaction parameter of the specifically adsorbed ions had to be used. As demonstrated, this result is a result of the double-layer model assuming linear dependence of the inner-layer integral capacity of the surface coverage and its independence from the electrode charge.     

Severine N-oxide and korsemine fromKorolkowia sewerzowii

Korsevine and the new alkaloids severine N-oxide and korsemine have been isolated from the combined alkaloids ofKorolkowia sewerzowii Regel. On the basis of the results of a study of the IR and NMR spectra of the alkaloids and also of a correlation with korseveriline and korsevine it has been established that base (I) is severine N-oxide and korsemine has the structure of korsevine 3β-D-glucopyranoside.     

On the morphology of polystyrene fractions,obtained by a multistep procedure from a radically polymerized sample

Summary A polystyrene sample obtained by free radical polymerization has been fractionated by preparative scale GPC and the structure and morphology of the fractions have been studied by¹³C-NMR spectroscopy, DSC and X-ray measurements. No changes in morphology in the course of fractionation have been obeyed. A distribution of syndiotacticity within the molecular weight distribution does not exist.

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Zusammenfassung Eine Polystyrolprobe, die durch radikalische Polymerisation hergestellt wurde, wurde mit Hilfe der präparativen Gelpermeationschromatographie fraktioniert; die Struktur und Morphologie der Fraktionen wurde mit¹³C-NMR-Spektroskopie, DSC und Röntgenbeugung untersucht. Im Verlauf der Fraktionierung traten keine Änderungen der Morphologie der Fraktionen auf. Innerhalb der Molekulargewichtsverteilung existiert keine Verteilung der Syndiotaktizität.

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List of abbrevations and symbols AIBN a, a-Azo-bis-(iso-butyronitrile) - D Dispersity, M _w /M _n - DSC Differential scanning calorimetry - EF Efficiency of fractionation - GPC Gel permeation chromatography - m mass of the fraction - M mass of the fractionated polymer sample - MWD Molecular weight distribution - P _r content of racemic dyads - PS Polystyrene - THF Tetrahydrofuran - U D-1 - U _ss U of the starting sample - U _f U of the fraction Auszug aus der Dissertation von U.-D. Standt: Zur Morphologie von Polystyrol, TU Braunschweig 1981.     

Insect pheromones and their analogs. VIII. Synthesis of the (Z) and (E) isomers of 2-methyloctadec-7-ene and of 2-methyl-7,8-epoxyoctadecane

A highly stereospecific method for the synthesis of racemic (Z)-disparlure has been developed which is based on the reduction of 2-methyloctadec-7-yne with the aid of 9-borabicyclo[3.3.1]nonane and the epoxidation of the resulting (Z)-2-methyloctadec-7-ene with p-methoxycarbonylperbenzoic acid. The¹³C NMR spectra of the (Z) and (E) isomers of 2-methyloctadec-7-ene and 2-methyl-7,8-epoxyoctadecane, which unambiguously confirm the structures of these compounds, are given. It has been established that (E)-2-methyloctadec-7-ene exhibits a moderate attractant activity while the (Z) isomer does not attract the gypsy moth. The addition of 5–25% of (E)-disparlure increases the biological activity of (Z)-disparlure.Institute of Chemistry, Bashkir Branch, Academy of Sciences of the USSR, Ufa. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 630–634, September–October, 1983.     

Use of non-segmented flow,post-columns reaction detection with miniaturized HPLC systems

Summary The use of non-segmented flow, post-column reaction detection is evaluated for use with miniaturized HPLC. Non-segmented open-tubular reactors with internal diameters 0.1 mm to 0.25 mm and packed-bed reactors with internal diameters of 1 mm, filled with 5 and 10 m particles are evaluated theoretically and experimentally with respect to band broadening and pressure drop characteristics. An integrated system consisting of miniaturized HPLC (1 mm i. d.) columns and compatible hardware is described. An example of the separation of catecholamines is given.