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991.
A rapid and reliable capillary zone electrophoresis method for the determination of inorganic cations was developed. The complete separation of K+, Ba2+, Ca2+, Na+, Mg2+, Mn2+, Ni2+, Cd2+, Li+ and Cu2+ can be achieved in 4 min with a simple electrolyte composed by 10 mM imidazole as the carrier buffer and background absorbance provider and acetic acid as the complexing agent (pH 3.60). Injection was performed hydrostatically by elevating the sample at 10 cm for 30 s. The running voltage was +25 kV at room temperature. Indirect UV-absorption detection was achieved at 185 nm. The detection limit was in the range between 0.06 mg/l (Mg2+) and 0.57 mg/l (K+) and the quantification limits ranged from 0.10 mg/l (Ni2+) to 0.80 mg/l (Cu2+). The calibration graphs were linear in the concentration range from the quantification limit till at least 1 g/l in K+, 10 mg/l in Ba2+, Ca2+, Mg2+, Mn2+, Ni2+ and Cd2+, 40 mg/l in Na+ and 12 mg/l in Li+ and Cu2+. The repeatability, intraday and interday analysis were ≤1.55% and ≤3.64% for migration time and ≤3.38% and ≤3.63% for peak area. The method developed has been applied to several beverage samples with only a simple dilution and filtration treatment of the sample. The proposed method is simple, fast, cheap and it is achieved with common products in either laboratory. For these reasons, it is a very useful method for routine analysis. 相似文献
992.
Valente Gómez-Benítez 《Tetrahedron letters》2006,47(29):5059-5062
[NiCl{C6H3-2,6-(OPPh2)2}] efficiently catalyzes the thiolation of iodobenzene with a broad scope of disulfides in the presence of zinc, the coupled products are obtained in excellent and in many cases nearly quantitative yields. 相似文献
993.
Nandi CK Parui PP Schmidt TL Heckel A Brutschy B 《Analytical and bioanalytical chemistry》2008,390(6):1595-1603
We have recently constructed a “DNA strut” consisting of two DNA-binding hairpin polyamides of Dervan-type connected via a
long flexible linker and were able to show that this strut can be used to sequence-selectively connect DNA helices. This approach
provides a second structural element (besides the Watson–Crick base pairing) for the assembly of higher-order DNA nanoarchitectures
from smaller DNA building blocks. Since none of the existing analytical techniques for studying this kind of system were found
suitable for detection and quantification of the formation of the resulting complexes, we chose fluorescence correlation spectroscopy
(FCS). In the present study we show that FCS allowed us in a versatile and fast way to investigate the binding of Dervan polyamides
to DNA. In particular it also shows its power in the quantitative detection of the formation of multimeric complexes and the
in investigation of binding under nonphysiological conditions.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
994.
Saturated aqueous solutions of 28 different salts have been studied as a potential mobile phases for salting-out thin-layer
chromatography, on silica gel, of a series of four mixed bis-aminocarboxylato cobalt(III) complexes. In addition, by linear
regression analysis of chromatographic data obtained for fifteen mixed aminocarboxylato Co(III) complexes (four series) with
solutions of ammonium chloride, three alkali metal chlorides, and four alkaline earth metal chlorides, four linear dependences
previously established on different adsorbents with (NH4)2SO4 solutions were confirmed. The qualities of the separations achieved with the salts were compared and Li+, Mg2+, and Ca2+ chlorides are proposed as the most suitable. 相似文献
995.
996.
概述了双苯并咪唑取代胺类、三苯并咪唑取代胺类及四苯并咪唑取代胺类配体及其金属配合物的研究和应用。研究报道,这些配体与人体必需的微量元素铜、锌、钴、镍、锰等金属形成的配合物能较好地模拟SOD分子中与金属离子配位的组氨酸的结构,且具有较好的拟SOD生物活性。 相似文献
997.
998.
《中国科学B辑(英文版)》2008,(12)
The magnetic exchange interactions between the dimanganese(II)-substituted complexes and the het-eropolymolyanion, [MnII2(Xn Mo9O33)2]2(n-10)-(X = PV(I), AsV(II) and SeVI(III)), are investigated by using density functional theory combined with broken-symmetry approach (DFT-BS) method. The calculated magnetic exchange coupling constant (J) of complex II is in reasonable agreement with the responding experimental value and the negative J values indicate that antiferromagnetic exchange interactions exist in these complexes. Furthermore, the influence of the central heteroatom on the exchange cou-pling within the dimanganese core unit is studied from standpoints of geometry, spin density and fron-tier orbitals. It demonstrates that the change of the heteroatom X via PV-AsV-SeVI elongates the dis-tances of Mn1···Mn2 and shortens the distances of Ob···Ob, and reduces the effectiveness of the super-exchange pathways, consequently, decreasing the magnitude of the antiferromagnetic coupling constant, J, of these species. 相似文献
999.
1000.
Mohamed GG Szesni N Fischer H 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2008,71(1):161-168
The fragmentation pathways of allenylidene and carbene complexes have been studied using FAB mass spectrometry in comparison with thermal analyses (TGA, DrTG and DTA). Both the decomposition modes are investigated and the possible fragmentation pathways are suggested. The use of mass and thermal analyses (TGA and DTA) in the analyses of allenylidene and carbene complexes allowed the characterization of the fragmentation pathways in MS. The major pathway includes successive loss of carbon monoxide followed by fragmentation of the organic part of the allenylidene or carbene molecules. This is also confirmed by thermogravimetric analysis (TGA) where the first step involves the loss of carbon monoxide followed by the organic ligand. The nature of each step; exothermic or endothermic, is also studied using DTA technique. The kinetic parameters of the thermal decomposition are also studied using the Coates-Redfern method. 相似文献