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This paper reports the development of a method based on capillary electrophoresis with laser-induced fluorescence detection for the simultaneous determination of thiouracil (TU) and phenylthiouracil (PhTU) with high sensitivity (nanomolar range, i.e., attomoles detected). After derivatization with 5-iodoacetamidofluorescein, the analytes were separated by capillary zone electrophoresis using 20 mM phosphate buffer (pH 10.0) and quantified by fluorescence detection. The linearity range, precision, recovery, and detection limits were determined, and the method was shown to be applicable for the determination of TU and PhTU in spiked feed samples and urine. 相似文献
54.
两个新的氢键诱导液晶化合物的合成 总被引:3,自引:0,他引:3
通过4-丁氧基苯甲酸(4BA0与两个手性取代的苯乙烯基吡啶(VSZ及LSZ)间的氢键作用合成了2个新的液晶化合物,用DSC、偏光显微镜研究了其液晶行为,并由红外光谱证实了分子间氢键的存在,形成的复合物4BA-VSZ具有手性近晶C相。 相似文献
55.
Summary The solution conformations of 1,4-diaryl-tetrahydro-1H,3H-furo[3,4-c]furans were determined by means of the LIS technique using a modified LIS-simulation program specially designed for the requirements of the aromatic 1,2,3-trimethoxy arrangement as a bidentate coordination site for the NMR shift reagent. The resulting geometries were confirmed by force field calculations (MM2-87) and compared with X-ray derived structures. Reliable data for the conformations in solution allowed a quantitative estimation of the circular dichroism based on the coupled oscillator model.
Lanthanideninduzierte Verschiebungen von aromatischen 1,2,3-Trimethoxy-Verbindungen: Konformationsanalyse von Tetrahydrofurofuran-Lignanen in Lösung
Zusammenfassung Es wurden mittels der LIS-Technik die Konformationen von 1,4-Diaryl-tetrahydro-1H,3H-furo[3,4-c]furanen in Lösung bestimmt. Dazu mußte ein modifiziertes LIS-Simulationsprogramm entworfen werden, das auf die besonderen Verhältnisse der aromatischen 1,2,3-Trimethoxy-Gruppierung eingeht, welche in den untersuchten Verbindungen als zweizähnige Koordinationsstelle für das NMR-Verschiebungsreagens fungiert. Die resultierenden Geometrien wurden mittels Kraftfeldrechnungen (MM2-87) überprüft und soweit vorhanden auch mit Röntgenstrukturdaten verglichen. Für die Lösungskonformationen wurde eine quantitative Abschätzung des Circulardichroismus auf der Basis des Modells für gekoppelte Oszillatoren durchgeführt.相似文献
56.
Silica nanoparticles for separation of biologically active amines by capillary electrophoresis with laser-induced native fluorescence detection 总被引:1,自引:0,他引:1
This paper describes the analysis of biologically active amines by capillary electrophoresis (CE) in conjunction with laser-induced native fluorescence detection. In order to simultaneously analyze amines and acids as well as to achieve high sensitivity, 10 mM formic acid solutions (pH < 4.0) containing silica nanoparticles (SiNPs) were chosen as the background electrolytes. With increasing SiNP concentration, the migration times for seven analytes decrease as a result of increase in electroosmotic flow (EOF) and decrease in their electrophoretic mobilities against EOF. A small EOF generated at pH 3.0 reveals adsorption of SiNPs on the deactivated capillary wall. The decreases in electrophoretic mobilities with increasing SiNP concentration up to 0.3x indicate the interactions between the analytes and the SiNPs. Having a great sensitivity (the limits of detection at a signal-to-noise ratio (S/N) = 3 of 0.09 nM for tryptamine (TA)), high efficiency, and excellent reproducibility (less than 2.4% of the migration times), this developed method has been applied to the analysis of urinal samples with the concentrations of 0.50 +/- 0.02 microM, 0.49 +/- 0.04 microM, and 74 +/- 2 microM for TA, 5-hydroxytryptamine, and tryptophan, respectively. The successful examples demonstrated in this study open up a possibility of using functional nanoparticles for the separation of different analytes by CE. 相似文献
57.
《Surface and interface analysis : SIA》2003,35(3):263-267
The potential of a microline‐imaging laser‐induced plasma spectrometry (LIPS) system for surface and depth analysis of heterogeneous solid samples in air at atmospheric pressure has been demonstrated. A pulsed Nd : YAG laser beam operating at 532 nm, with a homogeneous energy distribution (flat top laser), was used to generate a microline plasma on the sample surface. Subsequent light from the microline plasma was resolved spectrally and spatially and detected with an imaging spectrograph and an intensified charged‐coupled device detector. A patterned metal sample was chosen as the most appropriate for this study. Three‐dimensional chemical maps of Ni and Cu from the edge connectors of a printed circuit board have been obtained. With this experimental configuration, the lateral resolution (limited by crater width) was 42 µm and the spatial resolution along the spectrometer slit was 17.4 µm. The results illustrate the capability of microline imaging for fast mapping of large‐area samples and for depth profiling purposes. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
58.
HeinzD. Roth 《Helvetica chimica acta》2006,89(12):2847-2860
Chemically induced dynamic nuclear polarization (CIDNP) observed during electron transfer (ET) reactions of tertiary amines such as DABCO ( 1 ) or Et3N ( 2 ) with a wide range of electron acceptors support the involvement of amine radical‐cations (e.g., 1. + or 2. + ) as key intermediates. Radical ions such as 2. + may be deprotonated, generating neutral aminoalkyl radicals (e.g., 2. ). When generated by reaction with an electron acceptor of energetically low triplet state such as naphthalene (1Naph*), the resulting pair 2. + /Naph.? reacts mostly by reverse electron transfer (RET) from triplet pairs populating the naphthalene triplet state. 相似文献
59.
Jingye Li Kohei Sato Saneto Asano Minoru Iida Yoneho Tabata Masakazu Washio 《European Polymer Journal》2005,41(3):547-555
Crosslinked and non-crosslinked polytetrafluoroethylene films (RX-PTFE and V-PTFE films, respectively) were irradiated by γ-ray and then grafted with styrene in liquid phase. Microscope FT-IR spectroscopy, TGA, solid state 13C CP/MAS and high resolution HS/MAS NMR spectroscopy, wide-angle X-ray diffraction (WAXD) study were used to get the structural information of the styrene grafted RX-PTFE and V-PTFE films. From microscope FT-IR spectra of the grafted RX-PTFE films, the “grafting front mechanism” was proved. TGA analysis showed that the grafted films have a small degradation step and two main degradation steps. In the 13C CP/MAS NMR spectra of the non-grafted films, there are no signal due to the absence of the hydrogen atom. While in the spectra of the grafted films, there are signals attributed to the polystyrene grafts. In the 13C HS/MAS NMR spectra of the grafted films, the relative intensity of the peaks attributed to the polystyrene grafts increased while the relative intensity of the peak attributed to PTFE matrix decreased with the increase in the DOG. From WAXD patterns, the intensity of the crystalline peak decrease with the increase in the DOG. The grafted films were sulfonated by chlorosulfonic acid and the results of highest IEC value exceeded 3.0. Those results will be reported in the near future. 相似文献
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