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91.
A new device has been developed for the trapping of volatile pollutants in trapping solvents. The device allows solvent recirculation and cryogenic trapping of evaporated volatiles to minimize the stripping effect and any losses of volatile analytes. Due to solvent recirculation, the trapping solvent column height remains constant during the extraction without any need for replenishment. Also mass transfer conditions are favorable due to the flattened shape of bubbles of CO2 and the longer extraction time. The bubbles have higher interfacial area and they have to pass a three times longer distance in the solvent column. The device produces more concentrated extracts, reduces solvent consumption, and reduces or eliminates its evaporation to the environment. The cryotrapping part reduces losses of volatile analytes and the stripping effect. It also enables single-phase extraction into much smaller solvent volumes. Due to constant and favorable extraction conditions, the precision of the method was also greatly improved (RSDs decreased from 2.2 to 0.8%). As proved by a set of rapid spiked-sample extractions of highly volatile compounds at very high flow rates, the relative standard deviation of the experiments performed in the new device is 3.5 times lower. 相似文献
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Stefan Söllradl Hanna Lührs Zsolt Révay Petra Kudejova Lea Canella Andreas Türler 《Journal of Radioanalytical and Nuclear Chemistry》2013,298(3):2069-2073
Prompt gamma activation analysis (PGAA) is especially sensitive for elements with high neutron-capture cross sections, like boron, which can be detected down to a level of ng/g. However, if it is a major component, the high count rate from its signal will distort the spectra, making the evaluation difficult. A lead attenuator was introduced in front of the HPGe-detector to reduce low-energy gamma radiation and specifically the boron gamma rays reaching the detector, whose thickness was found to be optimal at 10 mm. Detection efficiencies with and without the lead attenuator were compared, and it was shown that the dynamic range of the PGAA technique was significantly increased. The method was verified with the analyses of stoichiometric compounds: TiB2, NiB, PVC, Alborex, and Alborite. 相似文献
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Charles E. Carraher Jr. Michael R. Roner Cara Lea Carraher Ryan Crichton Kendra Black 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(11):867-886
Suitable structure characterization is assisted through the use of mass spectrometry. Polymer fragmentation can be achieved in many ways including application of heat and ionizing radiation. MALDI MS allows routine analysis of polymers allowing identification of several repeat units. Graphite as a matrix allows higher mass ions to be created with less interfering ion fragments formed in comparison to more utilized matrix materials. 相似文献
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Ludwig Maier Guenter Rist Peter J. Lea 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-3):349-352
Abstract The synthesis and properties of phosphinothricin derivatives which have different alkyl groups attached to phosphorus or bear a substituent on the nitrogen are described and their biological activities discussed. 相似文献
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