Characterization of 15N-TNT residues after an anaerobic/aerobic treatment of soil/molasses mixtures by solid-state 15N NMR spectroscopy. 1. Determination and optimization of relevant NMR spectroscopic parameters
| Autor: | Heike Knicker, Dirk Bruns-Nagel, Eberhard von Löw, Klaus Steinbach, Oliver Drzyzga |
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| Přispěvatelé: | Lower Saxony State Government, Federal Ministry of Education and Research (Germany) |
| Rok vydání: | 1999 |
| Předmět: |
chemistry.chemical_classification
Magic angle Analytical chemistry chemistry.chemical_element General Chemistry Nuclear magnetic resonance spectroscopy Condensation reaction complex mixtures Nitrogen chemistry.chemical_compound Aniline chemistry Magic angle spinning Environmental Chemistry Humic acid Organic matter |
| Zdroj: | Digital.CSIC. Repositorio Institucional del CSIC instname |
| Popis: | 7 pages, 4 figures, 4 tables, 25 references. Solid-state 15N NMR was applied to a humic acid, extracted from 15N-2,4,6-trinitrotoluene (TNT) enriched soil treated in an anaerobic/aerobic composting system to characterize the nitrogen functionality of the transformation products bound to the soil organic material. Signals assignable to aniline derivatives and condensation products were identified, indicating that the anaerobic/aerobic treatment caused a reduction of nitro groups followed by condensation reactions with the soil organic material. Relevant parameters for routine application of the cross polarization magic angle spinning technique were determined and optimized. The proton spin-lattice relaxation times of all peaks in the 15N NMR spectrum of the humic acid did not exceed 30 ms. Due to the fast relaxation, the application of 15N NMR spectroscopy to soils with lower enrichment of 15N-TNT is feasible. The influence of spinning sidebands on the intensity distribution was shown to be minimal at spinning speeds between 5.5 and 6.5 kHz. Contact times between 0.7 and 1 ms resulted in spectra with representative intensity distribution of all visible 15N-TNT transformation products. However an underestimation of unreacted TNT must be considered. The results imply that CPMAS 15N NMR is a valuable tool for the examination of bound residues of TNT in soils. (Figure 1). This work was supported by the Federal Ministry of Education, Science, Research and Technology (BMBF), by the state of Lower Saxony and the Industrieverwaltungsgesellschaft AG(IVG), Bonn, Germany. |
| Databáze: | OpenAIRE |
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