Field ionization mass spectrometry as a facile method for the study of the thermal formation of radicals

Electron impact spectra of thermolysis products of organic salts heated in the ion source of a mass spectrometer may give rise to organic ions corresponding to the cation of the salt. Field ionization mass spectrometry has been used as a facile method for detemining whether such an ion is due to ionization of the corresponding radical present in the gas phase, or to an electron impact induced fragmentation of a reaction product of higher mass. By comparison of the electron impact and field ionization spectra of a series of N-methyl pyridinium, tropylium and 1,2-dithiolylium salts it has been found possible to identify the radicals formed thermolytically, when present.     

First experiments on transmutation studies of129I and237Np using relativistic protons of 3.7 GeV

First experiments on the transmutation of long-lived¹²⁹I and²³⁷Np using relativistic protons of 3.7 GeV are described. Relativistic protons generate in extended Pb-targets substancial neutron fluences. These neutrons get moderated in paraffin and are used for transmutation as follows:¹²⁹I(n,)¹³⁰I and²³⁷Np(n,)²³⁸Np. The isotopes¹³⁰I (T _1/2-12.36 h) and²³⁸Np (T _1/2=2.117 d) were identified radiochemically. One can estimate the transmutation cross-section (n,) in the given neutron field as (¹²⁹I(n,))=(10±2)b and (²³⁷Np(n,))=(140±30)b The experiments were carried out in November 1996 at the Synchrophasotron, LHE, Dubna, Russia. The investigation has been performed at the Laboratory of High Energies, JINR, Dubna.     

Planar defects in β-alumina

Sodium β-alumina crystals were elaborated by melting of a mixture of Na₂CO₃ and Al₂O₃ or by PbO flux evaporation and were studied by transmission electron microscopy. They exhibit regular planar defects lying in the {11.0} prismatic planes. These defects are described as antiphase boundaries for the cationic sublattice with fault vectors $\text{1}\text{2}\text{〈10.0〉}$ (such faults do not affect the anionic sublattice). As a consequence it would be interesting to study precisely the structure of the sodium β cationic lattice in the vicinity of the melting point.     

Magnetic beads as interfacial nanoprobes

We use paramagnetic beads to probe strongly localized magnetic fields from one-dimensional nanomagnets. Using a polarization microscope in reflection mode, we find that light reflected from beads exhibits intensity fluctuations which may help us understand Brownian motion near interfaces. We estimate the height fluctuations and femtonewton forces acting on the beads.     

Chelat-Sandwichkomplexe des Tripod-Liganden Tris(diethoxyphosphoryl)phosphan mit zweiwertigen Kationen von Mangan,Eisen, Cobalt und Nickel

Chelate-like Sandwich Complexes of the Tripod Ligand Tris(diethoxyphosphoryl)phosphane with Bivalent Cations of Manganese, Iron, Cobalt, and Nickel P[P(O)(OR)₂]₃ ( 1 , R ? C₂H₅) and the transition metal hexafluoroarsenates M(SO₂)₂(AsF₆)₂ (M ? Mn, Fe, Co, Ni) form the remarkably stable 2:1 complexes M{P[P(O)(OR)₂]₃}₂ (AsF₆)₂ 2–5 in liquid SO₂. Two tripod chelate ligands are arranged like a sandwich around the metal cation. Spectroscopic and magnetic properties of the compounds are discussed.     

Improved determination of flavour compounds in butter by solid-phase (micro)extraction and comprehensive two-dimensional gas chromatography

The practicability and potential of comprehensive two-dimensional gas chromatography (GC x GC) coupled to both conventional flame ionisation (FID) and time-of-flight mass spectrometric (TOF-MS) detection, were compared with those of conventional one-dimensional (1D) GC, with the determination of flavour compounds in butter as an application. For polar flavour compounds, which were collected from the aqueous fraction of butter by means of solid-phase extraction (SPE), it was found that GC x GC dramatically improves the overall separation. Consequently, quantification and preliminary identification based on the use of ordered structures, can be performed more reliably. The improvement effected by replacing 1D-GC by GC x GC is considerable also in the case of TOF-MS detection, as illustrated by the high match factors generally obtained during identification. GC x GC was also used successfully for the characterisation of volatile flavour compounds in the headspace of butter collected by solid-phase microextraction (SPME) and to study the effect of heat treatment on the composition of butter samples in more detail.     

Synthesen von Heterocyclen, 124. Mitt.: Über Reaktionen des Isatosäureanhydrids mit Thioamiden und Amiden

Zusammenfassung Beim Verschmelzen von Isatosäureanhydrid (1) mit Thioamiden bilden sich 2-substit.-4(3H)-Chinazolinone (3a-h).

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Syntheses of heterocycles, CXXIV.: Reaction of isatoic anhydride with thioamides and amides

The reaction of isatoic anhydride with thioamides yields 2-substituted 4(3H)-quinazolinones (3a-h).

     

An analytically useful coulometric generation of micro amounts of metal ions : Part I. Electrogeneration of bismuth(III)

Bismuth(III) can be generated in a solution by electrolytically oxidizing dilute bismuth amalgam. Oxygen present in the solution contacting the amalgam also oxidizes the amalgam. Therefore normal coulometric circuits are not suitable for the generation of trace quantities of bismuth(III), even after prolonged passage of nitrogen. A procedure is described by which the interference of oxygen is eliminated so that amounts of bismuth(III) down to 5·10^-8 moles (in 30 ml) can be generated with 100% current efficiency.     

Synthesen von Heterocyclen, 146. Mitt.: Zur Synthese polymerer Indigofarbstoffe mit potentiellen Halbleitereigenschaften

Zusammenfassung Die Darstellung von polymeren Indigofarbstoffen (PI) nach dem Verfahren vonZiegler undKappe ^{2, 3} wird beschrieben. Ausgehend von Benzidin (1 a) und Tolidin (1 b) erhält man so diePI 6 a bzw.6 b. In analoger Weise wird aus Tetrahydrochinoxalin (7), der N,N-überbrücktePI 12 gewonnen.

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Syntheses of heterocycles, CXLVI: The synthesis of polymeric indigos with potential semiconductor properties

The synthesis of polymeric indigos (PI) according to the procedure ofZiegler andKappe ^{2, 3} is described. Starting with benzidine (1 a) or tolidine (1 b) thePI 6 a and6 b, resp., are obtained. In a similar way the N,N-bridgedPI 12 is synthesized from tetrahydroquinoxaline (7).

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Aus den Dissertationen vonH. G. Foraita undL. F. Werner, Universität Graz, Januar bzw. Juni 1963.     

Isotachophoretic separation of alkylsulfonates and determination of methanesulfonic acid as main component and as trace component in pharmaceutical drug substances

Alkylsulfonates from methanesulfonic acid to decanesulfonic acid were separated by isotachophoresis with conductivity detection in a common electrolyte system at pH 4.8. The electrolyte system consisted of 10 mM HCl buffered with epsilon-aminocaproic acid (pH 4.8) and 0.1% methylhydroxyethylcellulose (MHEC) acting as the leading electrolyte. The terminating electrolyte was 20 mM caproic acid also containing 0.05% MHEC. Current settings of 250 microA for the first and 50 microA for the second capillary were applied. On one hand, the method was applied to the determination of the content of methanesulfonate as the salt forming agent (mesilate) in a recently registered drug substance. The results obtained by ITP were compared with an orthogonal titration method. On the other hand, due to the column-coupling configuration of the electrophoretic instrument, the method could be extended to the trace determination in the ppm range in order to monitor methanesulfonic acid as an impurity in a drug substance. The validation confirmed the linearity of the method between 1 and 10 mg/l, limits of detection and quantification below 1 mg/l, recovery rates from 92.4 to 95.4%, and repeatability with a R.S.D. of 3.8% (six runs with a 4 mg/l spiked sample). Finally, three batches of a newly produced drug substance could be checked for methanesulfonic acid giving results of below 0.0014% (concentration related to the drug substance).