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31.
Summary Three -Cyclodextrin derivatives (-CDs) were synthesized by substituting the 2,6-OH groups of -CD with allyl groups and the 3-OH groups with three different acyl groups (valeryl, heptanonyl, octanoyl). The chromatographic properties of these -CDs as stationary phases for capillary gas chromatography (CGC) were studied. The test results showed that the three -CDs possessed good coating properties and that the capillary columns coated with them exhibited high column efficiency. These -CDs can separate not only the disubstituted benzene isomers but also some racemic compounds. 相似文献
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By reacting platinum with alkali metals (A = K, Rb, Cs) a new family of binary alkali metal platinides has been synthesized and characterized by chemical analysis, X‐ray powder diffraction, thermal analysis (DTA and DSC), and magnetic measurements. All three compounds exhibit similar XRD‐patterns with strong reflections that can be indexed on the basis of a rhombohedral crystal system (KxPt: a = 2.6462(1), c = 17.123(1); RbxPt: a = 2.6415(1) Å, c = 17.871(1) Å; CsxPt: a = 2.6505(1) Å, c = 18.536(1) Å; x < ½. The a lattice constant is independent on the alkali metal used and of value close to the Pt–Pt distance in NaPt2 (2.645Å). The c parameter increases monotonically with the growing atomic radius of the alkali metal. The average structure of the alloys consists of cubic close packed layers of platinum atoms with layers of disordered alkali metals in between. For all compounds besides the strong reflections small satellites are observed which cannot be indexed together with the rhombohedral peaks in any rational 3‐dimensional lattice. However, these satellites can be indexed as incommensurate modulations within the ab plane (found propagation vectors k = (0.1011, 0.2506, 0) for CsxPt, and k = (0.0168, 0.2785, 0) for RbxPt). 相似文献
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J. S. Bradshaw N. W. Adams R. S. Johnson B. J. Tarbet C. M. Schregenberger M. A. Pulsipher M. B. Andrus K. E. Markides M. L. Lee 《Journal of separation science》1985,8(10):678-683
Contemporary methods for the synthesis of alkyl- and arylsubstituted polysiloxane stationary phases are reviewed. A new, moderately polar phase containing the 3-(4-methoxyphenyl)-propyl group is reported. 相似文献
37.
本文叙述氨基酸及其对映体的全氟酰基烷基脂(O-异丙基、-异丁基、-正丁基;N(O,S)-三氟乙酰基,TFA、-七氟丁酰基,HFB)在Chirasil-Val上的洗脱特性。随烷基取代增大,保留时间增加;用HFB代替TFA,对映体的分离因子降低。此外,DL-氨基酸与另丁醇衍生,生成的对映及非对映衍生物在Chirasil-Val上可拆分成四个色谱峰。 相似文献
38.
本文用新方法合成了Cr(bza)_3,改进了其mer-、fac-异构体的分离方法;增大了Cr(acac)_3的化学拆分量(1.5g)。试制了DBT(二苯甲酰-d-酒石酸)吸附型手性固定相(CSP),并成功地用于色谱拆分标题配合物的对映体,mer-[Cr(bza)_3]的部分拆分是首次发现的,其他配合物的拆分结果均优于文献方法。根据mer-[Cr(bza)_3)拆分流出液前、后组分的CD光谱,指定了其对映体绝对构型。还讨论了DBT吸附型CSP的拆分效能和色谱特性。 相似文献
39.
Summary The chromatographic performance of newly developed dicyanobiphenyl polysiloxane stationary phases were evaluated and compared
with the performance of other polar stationary phases, including the previously reported monocyanobiphenyl polysiloxanes.
Due to the unique combination of polarizable biphenyl and polar cyano functionalities in the side chains of the flexible polysiloxane
backbone, and by virtue of their mild liquid crystalline properties, the new stationary phases provide excellent resolution
of a wide variety of analytes, both polar and nonpolar, in both GC and SFC. They can be easily coated and cross-linked in
open tubular columns, and the resultant columns demonstrate excellent efficiency and performance at temperatures up to 280–300°C.
The new stationary phases exhibit enhanced selectivities for various types of isomeric compounds. 相似文献
40.
Summary Polymerisation of bicontinuous microemulsions yields porous monolithic structures with well defined pore sizes that are potentially
suitable for use as stationary phases for capillary electrochromatography (CEC). A variety of pore sizes can be achieved by
altering the composition of the microemulsion, which typically consists of butyl methacrylate (BMA) and ethylene glycol dimethacrylate
(EGDMA) as the polymerisable oil phase. The aqueous phase consists of water, a surfactant (sodium dodecyl sulphate, SDS) and
a co-surfactant (1-propanol). 2-acrylamido-2-methyl-1-propane sulfonic acid (AMPS) is also added to provide charges along
the polymer backbone to allow electroosmotic flow (EOF) to occur. SEM analysis shows that in-situ polymerisation yields a
monolithic structure with a porous topography. Investigations have shown that these monoliths are easy to prepare, robust
and suitable for the separation of phthalates. They generate higher linear velocities than are achieved using the silica based
HPLC packings normally used for CEC. 相似文献