Direct quantification of ethyl carbamate in distilled alcoholic beverages using a cold capillary injection system and optimised selected ion monitoring

Summary An integrated procedure is described which allows direct injection quantitative screening to single figure parts per billion (g/L) levels of ethyl carbamate in the natural matrix of distilled alcoholic beverage. Injection and detection performance was studied and optimized to allow this routine, reproducible, trace analysis without any sample pre-treatment. All aspects of the analysis including autosampler run sequences and automated internal standard report generation are initiated and controlled from a single GC/MS workstation.Excerpt from the Ph. D. Thesis (in preparation) of K. MacNamara, Universität Karlsruhe     

Natural flavours of wine: correlation between instrumental analysis and sensory perception

Summary The aroma of wine consists of 600 to 800 aroma compounds from which especially those, typical for the variety, are already present in the grapes. The aroma extracts — received by extraction with trichlorofluoromethane — are separated by gas chromatography. There are significant varietal differences between the aromagrams (fingerprint pattern). Thus the amount of some flavour compounds (key substances) shows typical dependence on the variety. Especially monoterpene compounds play an important role in the differentiation of wine varieties.The German white wines can be differentiated into three groups only by quantitative determination of 12 monoterpenes (terpene profile). These groups are: Riesling type, Muscat type and Silvaner-Weißburgunder type. Such terpene profiles are also useful for the separation of real Riesling wines from others called Riesling (e.g. Welschriesling, Kap Riesling, Emerald Riesling) but not produced from grapes of the variety Riesling. Including further components and by means of statistical methods as for example linear discriminant analysis even the different varieties within the mentioned groups (for instance the Riesling-group: Riesling, Kerner, Ehrenfelser, Bacchus, Müller-Thurgau) can be separated from each other.To identify compounds causing off-flavours the sniffing technique is the method of choice. The off-flavour is pinpointed during gas chromatography separation of the complex aroma mixture by effluent sniffing. Once allocated, the chemical nature of the off-flavours is elucidated by spectroscopic methods. Substances contributing to the green pepper taint, the strawberry note, mousiness, corkiness etc. in wine could be found in this way.     

Eignung der eindimensionalen immunologischen Geldiffusion nach Oudin zur quantitativen Erfassung von K?rpereiwei?en

Ohne Zusammenfassung     

Measurements referring to plasma focus scaling laws

In order to establish scaling laws and characteristic curves of a plasma focus device, the neutron output was measured as a function of the deuterium filling pressure, accelerator length and capacitor energy.     

Computer aided drug identification in toxicological analysis by means of EI and CI mass spectrometry

Ohne Zusammenfassung

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Computer aided drug identification in toxicological analysis by means of EI and CI mass spectrometry

     

Electrode effects on the neutron spectrum of a plasma focus

End-on neutron spectra of a plasma focus were measured by the time-of-flight method. Using an inner electrode with a specially shaped cavity instead of the normal solid or hollow electrodes caused the maximum of the neutron spectrum to shift from 2.66 MeV to 2.85 MeV. It is attempted to explain the effect by the interaction of the electrode, or the impurities emitted by it, with the compressed plasma.     

Synthetic approaches to 4,8‐dimethyl‐5′‐(N‐pyridiniummethyl)‐ 4′,5′‐dihydropsoralens and 4,8‐dimethyl‐5′‐ (N‐aminomethyl)‐ 4′,5′‐dihydropsoralens

New synthetic approaches to 4,8‐dimethyl‐5′‐(N‐pyridiniummethyl)‐4′,5′‐dihydropsoralens and 4,8‐dimemyl‐5′‐(N‐aminomethyl)‐4′,5′‐dihydropsoralens are described. The 5′‐halomethyl‐4′,5′‐dihydro‐psoralen precursors are formed by electrophilic ring closures of 4,8‐dimethyl‐6‐allyl‐7‐hydroxycoumarin. The ring‐closure reactions may also be applied to the synthesis of 5′‐halomethyl‐4‐methyl‐4′,5′‐dihydroangelicins. The compounds are potential therapeutic agents for improved psoralen ultraviolet A radiation treatment.     

Physics perspectives of heavy-ion collisions at very high energy

The structure of stretchable electronics is based on the buckling of a thin film on a compliant substrate. Under anisotropic biaxial prestrains, this structure may buckle into several patterns, including cylindrical, checkerboard, and undulating patterns. The displacement and energy of each pattern are deduced analytically. By comparing their minimum potential energies, the critical buckling condition of each pattern is determined. After secondary bifurcation, the checkerboard pattern occurs just above the critical prestrains, but the undulating pattern dominates other regions. The buckling amplitude and wavenumber of the undulating pattern are shown under biaxial prestrains. Even if the structure is under equi-biaxial prestrains, it may buckle into an asymmetric undulating pattern.