Beitrag zur Bestimmung von freiem Phenol, insbesondere im Bisphenol A

Zusammenfassung Es wird über ein gaschromatographisches Verfahren zur Bestimmung von Spuren Phenol, insbesondere im Bisphenol A (2,2-Bis-[4-hydroxyphenol]-propan) berichtet. Die beschriebene Methode erlaubt die Phenolbestimmung im Bisphenol A in wesentlich kürzerer Zeit als die bisher üblichen Methoden (z.B. Wasserdampfdestillation und jodometrische Endbestimmnung). Das gaschromatographische Verfahren benötigt für eine komplette Bestimmung 7–8 min. Ausserdem arbeitet das beschriebene Verfahren im ppm-Bereich mit größerer Genauigkeit. So wurde im Bereich von 75 ppm Phenol im Bisphenol A ein Wiederholstreubereich von ±6% rel. gefunden. In diesem Konzentrationsbereich sind die Abweichungen bei der bisher üblichen Methode zum Teil über 100% vom Sollwert.     

X-ray determination of the mean amplitudes of vibration and debye temperatures of some rare earth monochalcogenides

The x-ray diffraction intensities of Bragg reflections have been measured at room temperature for thulium selenide, samarium sulphide, samarium selenide and samarium telluride. On the basis of a common amplitude approximation, the Debye-Waller factor, the mean amplitude of vibration and the Debye temperature have been evaluated. The values of the Debye temperatures and mean amplitudes of vibration are 176±16°K, 0·185 ± 0·017 Å (TmSe), 155 ± 7°K, 0·244 ± 0·012 Å (SmS), 153 ± 14°K, 0·221 ± 0·020 Å (SmSe) and 151 ± 20°K, 0·204 ± 0·027 Å (SmTe).     

Analytik bakterientoxischer Effekte mit Hilfe genetisch konstruierter Leuchtbakterien

Zusammenfassung Leuchtbakterienteste stellen eine elegante Methode zur schnellen, reproduzierbaren Bestimmung bakterientoxischer Effekte dar. Einer allgemeinen Anwendung steht allerdings entgegen, daß die Luminescenzeigenschaften auf relativ wenige Bakterienfamilien mit zum Teil extremen Standortansprüchen beschränkt sind. Die Übertragbarkeit der Meßergebnisse auf interessierende Anwendungen ist deshalb in vielen Fällen nicht gegeben. In der vorliegenden Arbeit wird am Beispiel eines gentechnologisch konstruierten luminescenten Abwasserstammes gezeigt, daß durch Verwendung von anwendungsspezifischen Testorganismen das Anwendungsspektrum von Leuchtbakterientesten erweitert werden kann.

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Analysis of microbial toxicity using gentechnologically constructed luminescent bacteria

Summary Luminescent bacteria bioassays represent an elegant method for fast and reproducible determination of microbial toxicity. A general application of this method is however prevented by the fact that the capability for bioluminescence is restricted to a relatively small group of bacteria with extreme environmental demands. Therefore it seems questionable whether results obtained with those organisms can be used for all interesting applications. It is shown in this paper, that the field of applications for bacterial luminescent assays can be widened using gentechnologically constructed luminescent bacteria.

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Herrn Prof. Dr. H. Hartkamp zum 60. Geburtstag gewidmet     

Analysis of coefficient identification problems associated to the inverse Euler-Bernoulli beam theory

A rigorous investigation of the identification of a heterogeneousflexural rigidity coefficient in the Euler-Bernoulli steady-statebeam theory in the presence of a prescribed load is presented.Mathematically, this study is an extension to higher-order differentialequations of the coefficient identification problem analysedby Marcellini (1982) for the one-dimensional Poisson equation.In addition, various types of boundary conditions are discussed.Conditions for the well-posedness of these inverse problemsare established and, furthermore, numerical results obtainedusing a regularization algorithm are presented.     

A critical investigation of the effects of the radio frequency potential on the trapping of externally injected ions in ion trap mass spectrometry

The sensitivity of all ion trap mass spectrometry (ITMS) methods is dependent on the trapping efficiency of the instrument. For ITMS instruments utilizing external ion sources, such as laser desorption, trapping efficiency is known to depend on the phase and amplitude of the radio frequency (RF) potential applied to the ring electrode at the time of ion introduction. It is remarkable that, in a considerable body of literature, no consensus exists regarding the effects of these parameters on the efficacy of trapping externally generated ions. In this paper, a summary of the literature is presented in order to highlight significant discrepancies. New laser desorption ion trap mass spectrometry (LD-ITMS) data are also presented, from which conclusions are drawn in our effort to clarify some of the confusion. Copyright 1999 John Wiley & Sons, Ltd.     

Substituted tertiary phosphine Ru(II) organometallics: catalytic utility on the hydrolysis of etofibrate in pharmaceuticals

Some new organometallics of ruthenium(II) of the type [RuCl(2)(COD)(CO)L] (1a-f) and [RuCl(2)(COD)L(2)] (2a-f) (where L is substituted tertiary phosphines), have been synthesized by using precursors [RuCl(2)(COD)(CO)(CH(3)CN)] (1) and [RuCl(2)(COD)(CH(3)CN)(2)] (2) with the substituted tertiary phosphine ligands in 1:1 and 1:2 molar ratio. The organometallics (2a-f) have been further reacted with carbonmonoxide to produce compounds of the type [RuCl(2)(CO)L(2)] (3a-f). These compounds were characterized by elemental analysis, IR, NMR ((1)H, (13)C and (31)P), mass and electronic spectral data. The catalytic activity of all these organometallics were studied and found that they are efficient catalysts for hydrolysis of etofibrate. The hydrolyzed product was separated by column chromatography and the percent yields are found in the range of 98.6-99.1%.