Axial distribution of analyte emission in inductively coupled argon plasma

Summary Using a spectrometer, ICP axial profiles of analyte emission for a large number of atom and ion lines with different excitation and ionization potential have been studied. Obtained experimental results for axial distribution of atom and ion lines can be correlated with some of the proposed models for excitation mechanisms of analytes in argon ICP. On the basis of experimental data it can be concluded that in the case of simultaneous multielement analysis the observation heights between 14 and 17 mm above the load coil can be recommended. Experimental data show that there is no simple correlation between maximum intensity of lines and their excitation and ionization potential. Experimental results for axial distribution for ionic lines show that there is agreement between measured axial profile and calculated Boltzmann distribution of excited ionic state population.

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Axialverteilung der Analytemission im induktiv gekoppelten Argonplasma

Zusammenfassung Die ICP-Axialprofile der Analytemission wurden mit Hilfe eines Spektrometers für eine große Anzahl von Atom- und Ionenlinien mit verschiedenem Anregungs- und Ionisierungspotential untersucht. Die erhaltenen Ergebnisse können zu einigen Modellen für den Anregungsmechanismus im Argon-ICP in bezug gebracht werden. Aus den experimentellen Daten wird geschlossen, daß bei der simultanen Multielementanalyse Beobachtungshöhen zwischen 14 und 17 mm über der geladenen Wendel zu empfehlen sind. Es ergab sich, daß zwischen der Maximalintensität der Linien und ihrem Anregungs- bzw. Ionisierungspotential keine einfache Beziehung besteht. Die Untersuchung der Axialverteilung bei den Ionenlinien zeigte, daß Übereinstimmung besteht zwischen den gemessenen Axialprofilen und der berechneten Boltzmann-Verteilung.

     

Supported oxorhenate catalysts prepared by thermal spreading of metal Re for methanol conversion to methylal

TiO₂-anatase and SiO₂ supported oxorhenate catalysts were prepared by an original and simple technique based on the oxidative dispersion of metallic rhenium under dry conditions. The dispersion process of the supported oxorhenate phase as a function of the rhenium coverage and the support properties are discussed on the base of in situ characterization. The structures of the as prepared catalysts were found to be comparable to those of materials prepared using the incipient wetness impregnation technique. The absence of water in the preparation technique has made it possible to highlight the role of the hydration level on the rhenium oxide volatilization. The as-prepared Re/TiO₂ catalysts were found to be effective for the direct conversion of methanol to methylal.     

New fused pyrazines. Synthesis of pyrido[3′,2′:4,5]‐thieno[2,3‐e]pyrrolo[1,2‐a]pyrazine derivatives

The synthesis of the title compounds was achieved using the key intermediate ethyl 4,6‐dimethyl‐3‐(pyrrol‐1‐yl)thieno[2,3‐b]pyridine‐2‐ carboxylate 2. This latter compound was obtained via the interaction of the thienopyridine amino ester 1 with 2,5 dimethoxytetrahydrofuran in acidic medium.