Ein Computerverfahren für die Massenspektrometrische Untersuchung Organischer Proben bei Fraktionierter Direktverdampfung

A procedure is described for use of an on-line digital computer to acquire and process low resolution mass spectra obtained by a fractionated evaporation technique. The procedure generates unambiguous spectra from uniform solid or liquid organic substances, and characteristic spectra from multicomponent organic solid or liquid samples. The system is realised with minimal hardware configuration.     

A fully automated mass spectrometer for the analysis of organic solids

Automation of a mass spectrometer—computer system makes it possible to process up to 30 samples without attention after sample loading. An automatic sample changer introduces the samples successively into the ion source by means of a direct inlet probe. A process control unit determines the operation sequence. Computer programs are available for the hardware support, system supervision and evaluation of the spectrometer signals. The most essential precondition for automation — automatic evaporation of the sample material by electronic control of the total ion current — is confirmed to be satisfactory. The system operates routinely overnight in an industrial laboratory, so that day work can be devoted to difficult analytical problems. The cost of routine analyses is halved.     

Asymmetric hydrogenation - influence of the structure of carbohydrate derived catalysts on the relative enantioselectivity QH/Me regarding acid and ester substrates and its inversion - selectivity increase in water by amphiphiles

4,6-O-Benzylidene protected 2,3-bis(O-diphenylphosphino)-δ-glycopyranoside rhodium(I) chelate precatalysts 1-4 e,f showed for the hyrogenation of methyl (Z)-2-N-acylamidoacrylates 6-8 a stepwise decrease of the enantioselectivity with increasing number of axially oriented hexopyranoside substituents. The decrease is even stronger for the analogous substrate acids 6h-8h resulting in an unusual low relative enantioselectivity Q=q_H/q_Me of 0.3 for the precatalysts 4e and 4f. Deprotected, 4,6-OH-group bearing catalysts 1-4g,h generally show smaller differences of %ee in methanol or benzene, however, not in water. Under addition of amphiphiles a in comparison with blanks b the relative enantioselectivity Q=q_a/q_b clearly increases for both groups of catalysts - in most cases to Q-values between 3 up to 8 - independent of a neutral or ionic nature of the amphiphile.     

Determination of boron and hydrogen in materials for multicrystalline solar cell production with prompt gamma activation analysis

Journal of Radioanalytical and Nuclear Chemistry - For the optimization of the manufacturing process of multicrystalline silicon (mc-Si) for solar cells in order to reduce energy consumption and...     

Identification of novel biomarker candidates by differential peptidomics analysis of cerebrospinal fluid in Alzheimer's disease

The objective of this work was the application of peptidomics technologies for the detection and identification of reliable and robust biomarkers for Alzheimer's disease (AD) contributing to facilitate and further improve the diagnosis of AD. Using a new method for the comprehensive and comparative profiling of peptides, the differential peptide display (DPD), 312 cerebrospinal fluid (CSF) samples from AD patients, cognitively unimpaired subjects and from patients suffering from other primary dementia disorders were analysed as four independent analytical sets. By combination with a cross validation procedure, candidates were selected from a total of more than 6,000 different peptide signals based on their discriminating power. Twelve candidates were identified using mass-spectrometric techniques as fragments of the possibly neuroprotective neuroendocrine protein VGF and another one as the complement factor C3 descendent C3f. The combination of peptide profiling and cross validation resulted in the detection of novel potential biomarkers with remarkable robustness and a close relation to AD pathophysiology.     

Korrelation massenspektroskopischer, IR-spektroskopischer und potentiometrischer Analysendaten zur Ermittlung der Stabilit?t von Metallchelaten

Zusammenfassung Neben den Stabilitätskonstanten und den Metall-Sauerstoff-Valenzschwingungen kann auch das Intensitätsverhältnis spezifischer Bruchstückionen im Massenspektrum als Maß für die Stabilität von Metallchelaten dienen, wie an Kupferchelaten alkylsubstituierter Acetessigsäureamide gezeigt werden konnte.

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Correlation of measurements by mass spectrometry, IR-spectrometry and potentiometry for the determination of the stability of metal chelates

The stability of copper chelates of alkyl substituted aceto-acetamides can be expressed not only by stability constants or by stretching vibrations of the metal-oxygen bonds, but also by the abundance ratios of specific ions in the respective mass spectra.

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Wir danken Herrn Dr. W. Schäfer, Institut für Biochemie der Universität München, für die Möglichkeit, am dortigen Komparator unsere Photoplatten auszuwerten.     

Removal of interfering elements in ICP–QMS for the determination of Pt, Rh, and Pd by chemically modified sample introduction capillaries

New on-line methods developed for the determination of Pt, Rh, and Pd by inductively coupled plasma– quadrupole mass spectrometry (ICP–QMS) include separation of elements which might lead to spectral interference in the quadrupole instrument. The fused-silica capillaries generally used for transport of the sample to μ-flow nebulizers have been chemically modified with ion-exchanger compounds to remove interfering elements such as Cu, Pb, or Hf. Characterization of the modification procedures by atomic-force microscopy showed that the quality of the quartz material and the kind of modification had a decisive influence on the yield of surface modification, and thus the exchange capacity of the capillaries.     

Statistical evaluation of uncertainty for rapid tests with discrete readings – examination of wastes and soils

 In the course of the colorimetric determination of analytes using a procedure with discrete readings the measurement uncertainly cannot be calculated in the normally practiced manner. The basic principle of the analytical method used is a stepwise and non-equidistant reading. Based on the fact that half a step can be estimated, a calculation of the measurement uncertainty for the 95% confidence level is possible; this is needed to allow a reliable decision of whether a critical value is exceeded or not. Received: 24 February 2000 / Accepted: 28 April 2000     

Vergleichende Stäbilitätsbestimmungen von Metallchelaten der Monothioacetessigsäureanilide mit Hilfe der Massenspektrometrie,der IR-Spektroskopie und der Potentiometrie

The stability of Ni(II), Co(II) and Fe(II) chelates of substituted thioacetoacetanilides can be expressed not only by stability constants or by stretching vibrations of the metal-oxygen and the metal-sulphur bonds, but also by the abundance ratios of specific ions of fragments in the respective mass spectra.