Determination of antimony in wine by hydride generation graphite furnace atomic absorption spectrometry

 A method was developed for the determination of Sb in wine by electrothermal atomic absorption spectrometry, based on preconcentration by hydride generation with collection directly in the graphite furnace. Thiourea was added for prereduction of Sb(V) to Sb(III). The hydride was directly generated from diluted wine. Palladium was used as modifier in the collection step; the overall efficiency of the hydride/trapping system was found to be 67%. Sb was determined in several samples of red wine; the concentrations found were in the range 0.6 to 5.7 μg/L Sb. The detection limit of the method was 39 pg Sb, corresponding to 0.13 μg/L Sb in wine when 0.3 mL wine was analyzed. Received: 3 November 1995/Revised: 22 February 1996/Accepted: 24 February 1996     

Polyazaphosphorus macrocycles: Synthesis,reactivity, complexation

A general synthesis of various polyazaphosphorus macrocycles involving [1 + 1], [2 + 2], or [3 + 3] cyclocondensations is reviewed, as well as the attempted synthesis of cryptands. Selective reduction (imino functions) methylation (PS groups), silylation (PO groups) are reported. Preparations of some macrocycle complexes are described.     

An Ab Initio Study of C2H2.H2, C2H2.N2, and C2H2.Ar Complexes

Ab initio calculations at the post Hartree–Fock level were performed on complexes of acetylene with hydrogen, nitrogen, and argon. Total energies, optimum geometries, and binding energies were calculated, using the 6-311G** and the 6-31+G(2df,2pd) basis sets. Calculations showed the complexes to be more stable than the separate entities, with the exception of the acetylene–hydrogen complex.     

Scattering properties of agarose gels

Static light scattering and small angle neutron scattering measurements are reported for agarose hydrogels prepared under various conditions of concentration and temperature. For the wide range of transfer wave vector explored, these measurements show that the gels do not display fractal behaviour. Their structure is better described by a stretched exponential form, in which the value of the exponent is n = 0.2. As found by other authors, a maximum in the scattering intensity is observed in the light scattering spectra. The position of the maximum, q_max, depends on the concentration and on the thermal history of the sample. The inverse length 1/q_max is in good agreement with published measurements of the pore size D in this system. Preliminary measurements by small angle scattering indicate that the sol-gel transition is not of spinodal type.     

Ab Initio Calculations for FO3, FO 3 + , and FO 3 - Complexes Formed by Fluorine with Ozone

Complexes formed by fluorine with ozone, featuring neutral, positive, and negative species, as well as the decomposition reactions of the complexes are investigated with quantum chemical calculations, using the 6-311G* and the 6-311+G* basis sets, with the Moller-Plesset method. The most stable structures of the complexes are identified and the energies of the reactions of the complexes' formation and decomposition are obtained.     

Principle and applications of a floating energy analyser

We describe a new type of energy analyser suitable for the use in plasmas having no external potential reference like ICPs and microwave discharges. It can be used to determine the ion distribution function (IDF) at a negatively biased surface and the high energy tail of the plasma electron distribution function (EDF). The EDF is measured without distortions by ion currents. This analyser was tested in a dc glow discharge and its results compared to measurements with Langmuir probes and a analyser with grounded reference. Some preliminary measurements were also performed in a rf parallel plate discharge. Dedicated to Prof. Jan Janča on the occasion of his 60th birthday, in remembrance of a fruitful and friendly European co-operation. This work was supported by the Deutsche Forschungsgemeinschaft Bonn by Sonderforschungsbereich 191 and by the Directorate-General XII Science, Research and Development of European Commission, under Grant ERBCIPACT924034.     

Benzofuro[2,3-d]pyridazines IV. Etude de la chloro-4 benzofuropyridazine

[1] Benzofuro[2,3-d] pyridazone was synthesized by three methods namely8: catalytic dehalogenation of the 4-chlorobenzofuro [2,3-d] pyridazone; removal of the hydrazono group of 4-hydrazinobenzofuro [2,3-d] pyridazine and desulphurization of benzofuro [2,3-d] pyridazine and desulphurization of benzofuro [2,3-d] pyridazine-4(3H) thione. The 4-substituted derivatives were obtained by nucleophilic attack of the 4-chlorobenzofuro[2,3-d] pyridazine. Tetrazolo[1,5-b]- and s-triazolo-[1,2-b] benzofuro [2,3-d] pyridazones. The structural assignment of the benzofuro[2,3-d]pyridazones was made by the Noe effect.