作者: Indurate 時間: 2025-3-21 20:17 作者: enfeeble 時間: 2025-3-22 01:42
Chiral liquid chromatography: past and presentution of enantiomers from a racemate goes to Louis Pasteur who, in 1848, separated manually the non-identical crystals of the enantiomers of sodium ammonium tartrate (Pasteur, 1848). In 1874, Le Bel and Van’t Hoff independently proposed the ‘a(chǎn)symmetric carbon atom’ to account for the chirality of or作者: 使害怕 時間: 2025-3-22 06:26
Chiral derivatizationes. Derivatization of chiral substances is carried out with both chiral and achiral reagents. The latter may serve to block functional groups which may cause excessive band broadening on chiral columns (e.g, amines), or to introduce groups which interact favourably with the chiral stationary phase (作者: photopsia 時間: 2025-3-22 10:56
Chiral ligand exchange chromatographynd ligand introduced to the chromatographic system. Chromatography thus performed is highly selective for the differentiation of chelatable solutes. Stereoselective resolution of isomeric ligands can be achieved if the system ligand is optically active and forms a chiral complex in the presence of a作者: 抒情短詩 時間: 2025-3-22 14:16 作者: 抒情短詩 時間: 2025-3-22 20:42
Immobilized proteins as HPLC chiral stationary phasesal system including the complexation (or binding) of xenobiotic materials. As proteins are chiral polymers, it is not surprising that the binding of small enantiomeric molecules is often stereospecific. This is especially true for the serum proteins α.-acid glycoprotein (AGP) and albumin (SA).作者: FILTH 時間: 2025-3-23 00:01 作者: 不安 時間: 2025-3-23 04:01
Binding to cellulose derivativestive polymers. Like the interaction between an enzyme and its substrate, the polymer can lock on to the different stereochemistries of each enantiomer and provide chiral recognition. Proteins, oligosaccharides and celluloses have had the greatest degree of success, although usually bonded on to sili作者: Commonwealth 時間: 2025-3-23 05:32
Binding to synthetic polymerso mimic and improve upon them. This expected development has taken place, and synthetic polymer chiral stationary phases (CSPs) are amongst the most recent to be made commercially available. As for natural polymers these synthetic polymers must first be immobilized on silica in some way to be of any作者: 禍害隱伏 時間: 2025-3-23 12:52 作者: 勉勵 時間: 2025-3-23 14:32
Choice of chiral LC systemsmost suitable, it would then be most prudent to take a careful look at the literature. Taking a logical approach to what might work and what might not work is highly commendable, but is no substitute for checking what has been shown to work and what has been shown not to work. A literature search sh作者: Gastric 時間: 2025-3-23 21:23 作者: 挑剔小責(zé) 時間: 2025-3-23 23:50
http://image.papertrans.cn/c/image/225953.jpg作者: Obloquy 時間: 2025-3-24 03:17 作者: 異端邪說下 時間: 2025-3-24 09:53 作者: seruting 時間: 2025-3-24 12:06 作者: 輕率看法 時間: 2025-3-24 18:05
Lecture Notes in Computer ScienceThe first step to take in developing an assay in chiral liquid chromatography is self-evident; the question must be asked, ‘Is LC the best technique to use?’ This is especially so since there is a surprising variety of techniques available for the determination of enantiomers, and the number of options is ever-increasing.作者: textile 時間: 2025-3-24 19:51 作者: 襲擊 時間: 2025-3-25 00:06
Ion-pairingIn comparing the use of chiral counter-ions in HPLC eluents for the separation of enantiomeric compounds to other approaches of direct chiral resolution, there are some general features of the ion-pairing technique which should be considered when selecting a method.作者: implore 時間: 2025-3-25 04:22
Consideration of other techniquesThe first step to take in developing an assay in chiral liquid chromatography is self-evident; the question must be asked, ‘Is LC the best technique to use?’ This is especially so since there is a surprising variety of techniques available for the determination of enantiomers, and the number of options is ever-increasing.作者: Vulnerary 時間: 2025-3-25 09:34
OptimizationAs suggested in the previous chapter, the process of method development does not end when enantiomeric resolution is obtained. In almost every case, a further fine-tuning of experimental variables will be necessary, or at least advisable.作者: 滴注 時間: 2025-3-25 11:58 作者: 方便 時間: 2025-3-25 19:28 作者: URN 時間: 2025-3-25 20:09
The Challenge for Public Health,ution of enantiomers from a racemate goes to Louis Pasteur who, in 1848, separated manually the non-identical crystals of the enantiomers of sodium ammonium tartrate (Pasteur, 1848). In 1874, Le Bel and Van’t Hoff independently proposed the ‘a(chǎn)symmetric carbon atom’ to account for the chirality of or作者: Introvert 時間: 2025-3-26 00:33
Overview of formalism and systems,es. Derivatization of chiral substances is carried out with both chiral and achiral reagents. The latter may serve to block functional groups which may cause excessive band broadening on chiral columns (e.g, amines), or to introduce groups which interact favourably with the chiral stationary phase (作者: Petechiae 時間: 2025-3-26 06:50 作者: 等級的上升 時間: 2025-3-26 10:36
The revision in terminological systems,ltipleinteraction bonded phases. This class of CSP has arisen during the past ten years or so, nurtured by an eminently sensible idea: that the greater the number of specific, discrete, simultaneous interactions between chiral solute molecules and a chiral locus on the stationary phase, then the gre作者: amplitude 時間: 2025-3-26 13:05
Terminological reason maintenance,al system including the complexation (or binding) of xenobiotic materials. As proteins are chiral polymers, it is not surprising that the binding of small enantiomeric molecules is often stereospecific. This is especially true for the serum proteins α.-acid glycoprotein (AGP) and albumin (SA).作者: 外貌 時間: 2025-3-26 19:56 作者: 悲觀 時間: 2025-3-26 22:51 作者: MORT 時間: 2025-3-27 01:53
Overview of formalism and systems,o mimic and improve upon them. This expected development has taken place, and synthetic polymer chiral stationary phases (CSPs) are amongst the most recent to be made commercially available. As for natural polymers these synthetic polymers must first be immobilized on silica in some way to be of any作者: APO 時間: 2025-3-27 06:52
Overview of formalism and systems,an those already mentioned in Part 3 of this book. Even for less common direct methods, such as those which have only been used in a research environment, the categorization used in the rest of Part 3 is virtually all-encompassing. However there are some other direct chiral resolution methods about 作者: 粗糙 時間: 2025-3-27 11:11 作者: 倔強不能 時間: 2025-3-27 15:51
Book 1989 or books, discussed in terms of their practical application. Accordingly this book is very much orientated towards the practical aspects of these commercially available and readily accessible chiral LC systems. To this end, it is written for practising chromatographers by a team of practising, expe作者: CHECK 時間: 2025-3-27 21:20 作者: 譏諷 時間: 2025-3-28 01:46
Looking for Some Historical Rootsensional structure due to different arrangements of the bonds in space. In order to interconvert two configurations, it is necessary to break at least one .pair of bonds in the molecule and exchange the positions of the substituents, or to carry out some other high-energy twisting process (see below作者: sundowning 時間: 2025-3-28 04:00
Molecular asymmetryensional structure due to different arrangements of the bonds in space. In order to interconvert two configurations, it is necessary to break at least one .pair of bonds in the molecule and exchange the positions of the substituents, or to carry out some other high-energy twisting process (see below作者: muster 時間: 2025-3-28 09:20
The importance of enantiomer separations scientists for more than a century. The rare instance of a successful separation was often treated either as happenstance or as the success of trial and error. In either event, a systematic approach to the problem was not seen as feasible, except in a few special cases. Clearly, commercial exploitation was unthinkable.作者: Nerve-Block 時間: 2025-3-28 10:59 作者: 綁架 時間: 2025-3-28 17:18
Choice of chiral LC systemsould be carried out for LC enantioseparations, not only of the compound in question but also of other closely related structures. A computer search would be ideal, but for those with no access to such facilities reference to the index of this book would be a more than useful substitute.作者: 創(chuàng)造性 時間: 2025-3-28 21:06 作者: 斷言 時間: 2025-3-29 02:42
Terminological reason maintenance,atographic eluent to effect isomeric separation on an achiral stationary phase, i.e. C. bonded phase. Stereoselective separation of the enantiomeric amino acid pairs results when one of the isomers is differentially retained as the ternary complexes of the metal ion and the chiral ligand.作者: encomiast 時間: 2025-3-29 04:01 作者: 拍翅 時間: 2025-3-29 09:53 作者: 特別容易碎 時間: 2025-3-29 14:11 作者: DNR215 時間: 2025-3-29 16:41
The Problem of Monotonicity and the Skeleton scientists for more than a century. The rare instance of a successful separation was often treated either as happenstance or as the success of trial and error. In either event, a systematic approach to the problem was not seen as feasible, except in a few special cases. Clearly, commercial exploitation was unthinkable.作者: 廚師 時間: 2025-3-29 21:33 作者: Fierce 時間: 2025-3-30 02:47 作者: 熟練 時間: 2025-3-30 07:20
Representation and management of knowledge,re are no hydroxyls on the interior cavity and it is therefore relatively hydrophobic. Each glucose unit contributes five chiral centres to the molecule, and the 2- hydroxyl groups at the entrance of the cavity are orientated in a clockwise direction. This can best be appreciated by studying Figure 8.2 which shows the geometry of .-cyclodextrin.作者: forestry 時間: 2025-3-30 09:48 作者: Defense 時間: 2025-3-30 14:47
Cyclodextrin inclusion complexationre are no hydroxyls on the interior cavity and it is therefore relatively hydrophobic. Each glucose unit contributes five chiral centres to the molecule, and the 2- hydroxyl groups at the entrance of the cavity are orientated in a clockwise direction. This can best be appreciated by studying Figure 8.2 which shows the geometry of .-cyclodextrin.作者: 深淵 時間: 2025-3-30 19:31
Other direct chiral resolution methodsularized in the future, or else they may provide further useful insights into the whole process of chiral recognition. Most of these other methods are in fact only minor variations on the categories discussed already, but there are also some more novel methods of achieving enantiomeric resolution.作者: Neuralgia 時間: 2025-3-31 00:10
