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81.
研究开发的一种新型的元素光度检测器主要用于锗、砷、锡和锑的氢化物气相色谱检测,具有高灵敏,高选择性。它是在普通火焰光度检测器的基础上加装了特制的滤光片改制而成的。对锗、砷、锡和锑的检测限分别为3.0×10 ̄(-11)g、7.0×10 ̄(-11)g、7.0×10 ̄(-10)g和1.1×10 ̄(-8)g,相对标准偏差分别为1.8%、2.4%、2.6%和3.0%。 相似文献
82.
苯乙烯(St)为单体,二乙烯基苯(DVB)为交联剂,在致孔剂甲苯和十二醇存在下,直接以Ф4.6×50mm色谱柱管为模具,同时在整个反应过程中通过氩气对反应混合物施加一个恒定的压力,通过原位聚合制备了聚(苯乙烯-二乙烯基苯)(PSD)型整体柱。在聚合过程中对反应混合物施加一定的压力,使制备的整体柱表面光滑无凹痕现象,并且使柱子的两头平整不凹陷,有利于提高柱效。本文对整体柱的孔结构及其对蛋白质的分离性能进行了研究。实验结果表明,整体柱内部含有大量类似渠道的大孔,孔径为2μm~3μm,在流速为5ml/min时,背压为7MPa。而且流速对色谱分离效率的影响小,流速从1ml/min增大到3ml/min时,牛血清白蛋白和溶菌酶这两种蛋白质的总分离效能指标K1的值基本保持不变,保持在3.35左右,说明可以通过提高流速实现蛋白质的快速分离。 相似文献
83.
C. D. Eisenbach A. Göldel M. Terskan-Reinold U. S. Schubert 《Colloid and polymer science》1998,276(9):780-785
Transmission electron microscopy (TEM) studies on bipyridine (bpy) containing block copolymer systems showed the formation
of nanoscopic polymer–ion complexes through complexation with copper(I) ions which segregated to highly ordered columnar domains
of mesoscopic dimensions. The domains, i.e. stacks of [(bpy)2Cu(I)] complex moieties could be visualized by complementary TEM techniques. First, electron energy loss spectra (EELS) showed
the absorption edges of copper and nitrogen, which are specific for the bipyridine copper complexes. The element spectroscopic
imaging (ESI) technique allowed the imaging of the net copper and net nitrogen distribution, and the coinciding pictures exhibited
a microphase separated system in the case of a 3-block copolymer with complexed end segments. High resolution elastic bright
field images showed interference lines with a line to line distance of about 8 A which could be related to the Cu–Cu distance
in staggered Cu(I)–bipyridine complexes.
Received: 6 August 1997 Accepted: 28 April 1998 相似文献
84.
85.
Reported here is an analytical method enabling the stereochemical resolution of a new antianginal compound possessing two stereogenic centers, leading to four stereoisomers. Only one of these isomers is currently under development as a novel antianginal agent and consequently, the other three isomers are considered as unwanted chiral impurities. Therefore, an enantioselective method is required in order to check its enantiomeric purity. This paper presents a method exploiting the high efficiency of capillary electrophoresis and the complexing properties of cyclodextrins to achieve the separation of the four stereoisomers of this weakly basic compound (pKa = 7.4). For this purpose, the combination of a neutral cyclodextrin, hydroxypropyl-gamma-cyclodextrin (HP-gamma-CD), and an anionic cyclodextrin, carboxymethyl-beta-cyclodextrin (CM-beta-CD), was added to the separation buffer running in an uncoated silica capillary. After selection of the suitable cyclodextrin system, satisfactorily separation conditions were as follows: 30 mM phosphate buffer (pH 6.4) containing 10 mM of HP-gamma-CD and 10 mM of CM-beta-CD, running voltage +30 kV. The resulting run time and resolutions were respectively about 17 min and between 1.95 and 2.84. Linearity curves (0.993 < r2 < 0.998) are also shown. 相似文献
86.
茶汤及河水中铬的形态分析 总被引:8,自引:0,他引:8
本文采用717型强碱性阴离子交换树脂、活性炭分离富集与偶氮胂Ⅲ光度法结合,研究了铬形态的分离及测定,提出了铬的形态分析方法,有此法测定了茶汤及河水中铬的总量,悬浮态.溶解态、无机态、有机态、Cr(Ⅲ)和Cr(Ⅵ)。茶汤中铬主要以有机态存在,而河水中铬则主要以悬浮态存在。 相似文献
87.
88.
Summary Several -cyclodextrin (CD)-bonded stationary phases for high performance liquid chromatography (HPLC) were prepared, based on silica beads coated with a poly(alkylamine), [poly(ethyleneimine)(PEI)]. In order to obtain stationary phases with a high content of CD and maximum accessibility of the CD cavity, the functionalization was carried out after the coating, using the mono-tosyl derivative of CD as the intermediate. The ability of these supports to separate ortho, meta and para isomers of some disubstituted benzene derivatives was examined. The contribution of the amino groups of the polymer and of the CD cavity to the separation process is discussed. The resolution is mainly based on the difference in the stability of the complexes of the various isomers with CD. The influence of the amount of CD on the height of the theoretical plate is also studied. 相似文献
89.
In this paper,p-tricyanovinyl-N,N-dialkylanilines were synthesized as model compounds and through their spectroscopic behavior,the photo-induced electron transfer,charge separation were discussed and the aggregation in DMSO-H_2O system was investigated. 相似文献
90.
The percolation transition of geometric clusters in the three-dimensional, simple cubic, nearest neighbor Ising lattice gas model is investigated in the temperature and concentration region inside the coexistence curve. We consider quenching experiments, where the system starts from an initially completely random configuration (corresponding to equilibrium at infinite temperature), letting the system evolve at the considered temperature according to the Kawasaki spinexchange dynamics. Analyzing the distributionn
l(t) of clusters of sizel at timet, we find that after a time of the order of about 100 Monte Carlo steps per site a percolation transition occurs at a concentration distinctly lower than the percolation concentration of the initial random state. This dynamic percolation transition is analyzed with finite-size scaling methods. While at zero temperature, where the system settles down at a frozen-in cluster distribution and further phase separation stops, the critical exponents associated with this percolation transition are consistent with the universality class of random percolation, the critical behavior of the transient time-dependent percolation occurring at nonzero temperature possibly belongs to a different, new universality class. 相似文献