gerBerns, Anne ElisabethSchäffer, AndreasStruktur- und Bindungsuntersuchungen nichtextrahierbarer 15 N- und 14 C-Simazinrückstände im Bodeninfo:eu-repo/classification/ddc/570BodenPestizidrückstandSimazinIsotopenmarkierungStickstoff-15Kohlenstoff-14RückstandsanakyseNMR-SpektroskopieBiowissenschaften, Biologie15N- und 14C-Simazine15N-abgereicherter Kompost15N-CPMAS-NMRnichtextrahierbare RückständeSilylierungab initioBerechnungenThe aim of the presented study was the characterization of the structure and binding modes of non-extractable residues (NER) of the triazine herbicide simazine. The chemical environments of unaltered as well as metabolized simazine compounds can be observed directly in soil or compost matrix by 15N-NMR spectroscopy. As the 15N-isotope has a very low sensitivity and natural abundance 15N-labeled simazine was used. To further enhance the signal to noise ratio and sensitivity of the NMR experiment a compost of 15N-depleted maize and wheat as model soil was used to reduce background noise. Furthermore reactive extraction methods as NaOH extraction and silylation of the organic matrix in combination with the 14C-radiotracer technique were applied to elucidate the structure of NER. To verify and interprete the obtained spectra ab initio calculations of simazine and its metabolites as well as of a model of NER were carried out. At first 15N-depleted wheat and maize plants were grown on sand and composted after harvest. Characterization of this artificial compost proved its similarity to a natural compost. After 224 days analysis of the compost revealed a 15N-content of 267 ppm corresponding to a depletion factor of 13.7. Dilution series with the sieved 15N-depleted compost matrix and 15N-labeled simazine revealed an enhancement of the S/N-ratio compared to a dilution series with soil. Due to low amounts of NER the 15N-spectra gave only weak signals, which were attributed to the presence of free chlorinated, mono- and/or didealkylated simazine metabolites. Nevertheless the improved sensitivity made it possible to obtain interpretable NMR signals in contrast to experiments with 15N-simazine on native soil where no signals were detectable. Extraction with NaOH and silylation of the NER revealed that the largest part of the NER was tightly bound to the organic matrix, but sequestration contributed only to a small extent to the binding. Probably binding to the matrix was due to a combination of different binding mechanisms like covalent binding, ionic and hydrophobic interactions. This repartition on several binding types caused a dispersal of signal intensities resulting in a poor NMR traceability. Finally ab initio calculations of the metabolites confirmed the NMR assignments of the corresponding experimental spectra. The calculated NMR shifts of a modelled ester bond between hydroxysimazine and benzoic acid, as a model for a humic matter component, was not detected in the experimental spectra. But due to the low signal intensities no conclusions can be drawn from the absence of a signal.Aachen : Publikationsserver der RWTH Aachen University V, 139 S : graph. Darst. (2003). doi:10.18154/RWTH-CONV-123544 = Aachen, Techn. Hochsch., Diss., 2003info:eu-repo/semantics/doctoralThesisinfo:eu-repo/semantics/publishedVersionPublikationsserver der RWTH Aachen University2003info:eu-repo/semantics/openAccessDEhttps://publications.rwth-aachen.de/record/61934https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-123544%22StudentsStudent Financial Aid ProvidersTeachersResearchersinfo:eu-repo/semantics/altIdentifier/doi/10.18154/RWTH-CONV-123544info:eu-repo/semantics/altIdentifier/urn/urn:nbn:de:hbz:82-opus-6315