Structural and Quantitative Analyses of 4-Chloroaniline-Derived Oligomers

Abstract

The oxidation of 4-chloroaniline by a peroxidase resulted in eight oligomeric products. A reverse-phase high performance liquid chromatography (HPLC) method was developed so that substrate disappearance and the corresponding product formations could be quantitatively monitored. The product mixture was isolated from the aqueous reaction solution with solid-phase extraction and the extract components were separated by thin-layer chromatography (TLC). The individual TLC bands were extracted for mass spectrometric and proton nuclear magnetic resonance analyses. The product mixture was found to contain dimers, trimers, and tetramers with benzoquinone monoimine, benzopuinone di-mine, diaminobenzene, and azobenzene structures. Analytical methodologies were specific for the study of the oxidative transformation of 4-chloroaniline, but they should be applicable to other anilinederived oligomers.     

Quantification of docetaxel and its main metabolites in human plasma by liquid chromatography/tandem mass spectrometry

Docetaxel is an antineoplastic agent widely used in therapeutics. The objective of this study was to develop and validate a routine assay, using liquid chromatography coupled to tandem mass spectrometry (LC/MS/MS), for the simultaneous quantification of docetaxel and its main hydroxylated metabolites in human plasma. A structural analogue, paclitaxel, was used as the internal standard. Determination of docetaxel and four metabolites (M1, M2, M3 and M4) was achieved using only 100 microL of plasma. Liquid-liquid extraction was used for sample preparation, with extraction efficiency of at least 90% for all analytes. Detection used positive-mode electrospray ionization in selected reaction monitoring mode. The lower limit of quantification (LLOQ) was 0.5 ng/mL for all analytes. The assay was linear in the calibration curve range 0.5-1000 ng/mL and acceptable precision and accuracy (<15%) were obtained with concentrations above the LLOQ. This method was sufficiently selective and sensitive for quantification of metabolites in plasma from cancer patients receiving docetaxel chemotherapy, and is suitable for routine analyses during pharmacokinetic studies.     

NOE difference spectroscopy of some 5-substituted and 5,5-disubstituted hydantoins

The nOe difference (NOED) spectra of twelve 5-substituted- and 5,5-disubstituted hydantoins were recorded in deuteriochloroform. The nOe's observed from the interaction of substituents on C-5 with the proton on N-1 are more reliable than the chemical shift of the N-1 proton for structure determination.     

Tagungsberichte: Bericht über das nationale Symposium “Traceranwendung in der Industrie”. Veranstalter: Zentralinstitut für Isotopen- und Strahlenforschung der AdW der DDR 705 Leipzig,Permoserstraße 15

The results of tritium measurements of atmospheric water vapour and precipitation samples for 1982 and 1983 are presented. The data were used to establish a simple model describing the tritium continental effect taking into account re-evaporation of tritium from the continental land surfaces. Some comments on man made tritium are given.     

Zur quantitativen Auswertung von Autoradiogrammen mit elektronischen Hilfsmitteln

Bei autoradiographischen Untersuchungen stellt die quantitative Auswertung der erhaltenen Aufnahmen einen wesentlichen Faktor dar. Einige grundsätzliche Aspekte dazu werden aufgezeigt und verschiedene Möglichkeiten zur zweidimensionalen Auswertung mit eleklronischen Mitteln diskutiert. Neben der Konzeption und ausführlichen Beschreibung des im Institut für angewandte Radioaktivität, Leipzig, gebauten speziellen Gerätes “Densitron I” wird dessen praktischer Einsatz für eine Reihe autoradiographischer Untersuchungen an Hand entsprechender Aufnahmen demonstriert. Da das Gerät nicht nur für die Auswertung von Autoradiogrammen geeignet ist, sind auch andere hier mit dem Gerät durchgeführte Untersuchungen kurz dargestellt.     

The Jones-Witten invariant for flows on a 3-dimensional manifold

The Jones-Witten functional for knots is generalized for smooth flows on 3-dimensional manifolds. Explicit computations for the abelian case are given.     

Santiagonamine: a new aporphinoid alkaloid incorporating a phenanthridine skeleton

Santiagonamine (6), the first phenanthridine alkaloid, has been isolated from $\text{Berberis darwinii}$ Hook (Berberidaceae).     

Soil radon levels measured with SSNTD's and the soil radium content

The source of the radon gas ²²²Rn in the ground air is the soil and the bedrock underneath. The potential radon level in the ground is given by the content of ²²⁶Ra in the ground. The presence of ²²⁶Ra is in turn dependent on the amount of ²³⁸U in the ground, and these two isotopes are not always found to be in equilibrium in a sample of soil or bedrock. Especially if the soil is washed out, the radium content may be reduced. When the soil is the relevant source of the radon gas, it is interesting to look for a possible relation between the radon level and the radium content of the soil.

In this paper we report on measurements of soil radon level carried out with SSNTDs at several European sites. Soil samples were collected at these sites and analysed with gamma spectrometry to determine their radium content. A comparison of the different degree of disequilibrium of radon, defined as the ratio between the actual and the secular equilibrium-with-radium soil radon concentration, found at the different sites and depths is presented. The influence on the result of soil type and climate is briefly discussed.