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71.
Summary The formation of V2O5 fibrous microcrystals in the V2O5-NH3-H2O system has been investigated by electron microscopy. The morphology of these microcrystals is dependent on the concentration of the particular components in the colloidal system and on the time of aging. In some colloid systems the orientation of V2O5 fibrous crystals with their long axes parallel to one another is also possible. The microcrystal growth in these systems can be attributed to very effective conditions for the recrystallization of vanadium pentoxide crystals in equilibrium with ammonium vanadate in solution.With 3 figures 相似文献
72.
Maleš Željan Plazibat Miško Vundać Vjera Bilušić Žuntar Irena Pilepić Kroata Hazier 《平面色谱法杂志一现代薄层色谱法》2004,17(4):280-285
JPC – Journal of Planar Chromatography – Modern TLC - The flowering tops of Hypericum hirsutum, H. montanum, H. perforatum subsp. angustifolium, H. perforatum subsp. perforatum, and H.... 相似文献
73.
E. Gjeçi 《Journal of Radioanalytical and Nuclear Chemistry》1996,213(3):165-174
The use of crown ethers is a simple and rapid method for the separation and determination of strontium in various samples. After sample dissolution oxalate precipitation was carried out to remove K. Chromatographic separation of strontium from most inactive and radioactive interference was done with a crown ether. The chemical recovery was determined gravimetrically. Radiostrontium was then determined by liquid scintillation counting. 相似文献
74.
Zusammenfassung Die Reaktion von 2-Nitroso-1-naphthol mit Resorcin bzw. Orcin in Äther bei Anwesenheit von HNO3 liefert Benzo[c]phenoxazon-(9) (I), Benzo[c]phenoxazon-(9)-12-oxid (II), Methyl-benzo[c]phenoxazon-(9) (III) sowie 11-Methyl-benzo[c]phenoxazon-(9)-12-oxid (IV). Die Struktur der isolierten Substanzen wurde durch Reduktion mittels TiCl3 sowie durch die UV- und IR-Spektren gestützt.
Mit 1 Abbildung 相似文献
The reaction of 2-nitroso-1-naphthol with resorcinol and orcinol in ether solution in the presence of nitric acid has been studied. From the reaction mixture the benzophenoxazones I–IV have been isolated. Structures were assigned on the grounds of UV and IR spectra and partly by using TiCl3 as a reducing agent.
Mit 1 Abbildung 相似文献
75.
The present paper deals with the application of direct injection enthalpimetry (DIE) in the study of the kinetics of azo coupling reactions. On the example of the coupling of diazotized aniline-4-sulphonic acid with 1,8-dihydroxynaphthalene-3,6-disulphonic acid, it was verified that the rate constants determined using DIE are comparable with those determined using spectrophotometry. Advantages result from the application of DIE in the study of the kinetics of azo coupling reactions. 相似文献
76.
P. M. Nikolić Lj. Milković P. Mihajlović B. Lavrenčić 《Czechoslovak Journal of Physics》1978,28(4):456-459
Zone center optical phonons in SnSe were investigated using Raman scattering data obtained here and previously reported far infrared reflectivity measurements. The values of the ratio of the pairs of interlayer force constants were calculated te be between 3·3 and 4·5. Thus it can be concluded that SnS is a layer like semiconductor but less layer like than GeS, GeSe or SnS. 相似文献
77.
A CZE method was developed and validated for the analysis of Olmesartan medoxomil (OLMD) in tablets. The influences of pH, buffer concentration, applied voltage and capillary temperature on the migration time of OLMD were investigated. About 50 mM pH 6.5 phosphate buffer were used as background electrolyte. The optimum instrument parameters were found to be 30 °C temperature with 30 kV applied voltage and diode array detection was carried out at 210 nm. OLMD was hydrodynamically injected (P inj = 50 mbar, t inj = 3 s) and an internal standard, diflunisal (IS), was used to improve the precision and repeatability. Under these conditions, the migration time of OLMD was 2.32 min and the total analysis time was shorter than 5 min. Linearity range for the developed method was found to be 2.0–50.0 μg mL?1 and the limit of detection was 0.5 μg mL?1. The developed method was applied for the analysis of OLMD in pharmaceutical tablet formulations. 相似文献
78.
Carbene complexes : IV. Far infrared and 31P NMR spectra of palladium and platinum carbene complexes
Infrared bands mainly associated with v(M—X2) stretching modes (M = Pd or Pt, and X = Cl, Br, or P) have been identified in the spectra of 35 carbene complexes. Based on these results and on |1J| (31 P—195 Pt) the trans-influence of the carbene ligands is assessed. 相似文献
79.
Zusammenfassung Bei der Titration von Zink aus dem Niederschlag von Natrium-Zinkuranylacetat wird statt des früher vorgeschlagenen Indikators Eriochromschwarz T der Indikator Dithizon verwendet. Dadurch wird auch bei Titrationen mit 0,001-m Lösungen ein scharfer Umschlag erzielt.
Summary Dithizone is used in place of Eriochrome black T previously suggested as indicator in the titration of zinc contained in the precipitate of sodium-zinc-uranyl acetate. A sharper change is thus observed even with 0.001M solutions.
Résumé Lors du titrage du zinc dans le précipité d'acétate d'uranyle de zinc et de sodium, les auteurs emploient comme indicateur la dithizone au lieu du Noir Eriochrome T qui avait été précédemment recommandé. Il est ainsi possible d'obtenir un virage très net, même pour des titrages effectués avec des solutions 0,001M.相似文献
80.
V. Kontrimavičiūtė H. Breton F. Barnay J. C. Mathieu-Daudé F. M. M. Bressolle 《Chromatographia》2006,63(11-12):533-541
A specific and sensitive liquid chromatography-electrospray ionization mass spectrometry method was developed for the determination of ibogaine and noribogaine in human urine. The work-up procedure involved a solid phase extraction of the compounds and the internal standard (fluorescein) using Oasis HLB columns. The system used a Zorbax eclipse XDB C8 analytical column packed with 5µm diameter particles as the stationary phase. The mobile phase consisted of a 20-min gradient (mobile phase A: 0.02% (v/v) trimethylamine in acetonitrile, mobile phase B: 2 mM ammonium formate buffer (pH 3)). Mass spectrometric data were acquired in single ion monitoring mode at m/z 311.1, 297.2 and 333 for ibogaine, noribogaine and fluorescein, respectively. The drug/internal standard peak area ratios were linked via a quadratic relationship to concentrations (1.78?358 μg L?1 for ibogaine; 2?400 μg L?1 for noribogaine). Precision ranged from 5.8 to 14.8% and accuracy was between 93.2 and 112.9%. Mean extraction recoveries of ibogaine, noribogaine and fluorescein were 70.0, 81.7 and 94.8%, respectively. The extraction efficiency was independent of concentration over the range studied. The lower limits of quantitation were 1.78 μg L?1 for ibogaine and 2 μg L?1 for noribogaine. In this paper, extensive stability testing was undertaken using a wide range of storage conditions. This method was found suitable for urine analysis of a poisoning involving ingestion of drink made from powdered root of shrub Tabernanthe iboga. 相似文献