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1.
B. T. Mathews A. E. Beezer M. J. Snowden M. J. Hardy J. C. Mitchell 《Chromatographia》2000,53(3-4):147-155
Summary The reversed phase chromatographic properties of the [G1]-L-glutamic and ethyl ester-AC-silica (1), [G2]-L-glutamic acid ethyl ester-AC-silica (2) and the [G1]-L-glutamic acidt-butyl ester-AC-silica (3) dendrimer stationary phases were evaluated. Initial studies involved the comparison between these phases with a classic
reversed phase (i.e. ODS1) by the separation of a standard reversed phase test mixture composed of dimethylphthalate, nitrobenzene,
anisole, diphenylamine and fluorene. Separations were achieved with comparable performance to those obtained with the conventional
reversed phase (ODS1). However, it was apparent that the chromatographic selectivity exhibited by the dendrimer stationary
phases was different from that of the ODS1 phase. On a per mole basis, the dendrimers exhibited similar (and sometimes greater)
affinity for these analytes compared with the ODS1 ligand. Subsequent chromatographic experiments were conducted upon the
dendrimer chiral stationary phases using chiral analytes under reversed phase and normal phase conditions. Chiral resolution
was not observed. 相似文献
2.
Summary Substituted β-cyclodextrin chiral stationary phases having different types of phenyl carbamate substituents have been prepared
and evaluated (retention, selectivity, resolution) for the liquid chromatographic separation of several series of enantiomers.
The influence on separations of the degree of substitution and the structure of the substituent are discussed. Different mechanisms
are suggested to explain separations in normal mode conditions. 相似文献
3.
Summary Five methoxytetrahydronaphthalene derivatives, new agonist and antagonist ligands for melatonin receptors, were resolved into
their diastereomers by analytical HPLC methods using derivatized amylose, chiral stationary phases. Separation was by using
normal phase methodology with a mobile phase ofn-hexane-alcohol (ethanol or 2-propanol) and a silica-based amylose tris-(S)-1-phenylethylcarbamate (Chiralpak AS), or tris-3,5-dimethylphenylcarbamate (Chiralpak AD). The effects of structural variation
in the solutes were noted. Baseline separation was easily obtained in many cases. 相似文献
4.
Analytical HPLC methods using derivatized cellulose chiral stationary phases were developed for the direct enantioseparation of substituted [1-(imidazo-1-yl)-1-phenylmethyl)]-benzothiazolinone and benzoxazolinone derivatives with one chiral center. Those analogues of fadrozole constitute new potent nonsteroidal inhibitors of aromatase (P450 arom). The separations were made using normal phase methodology with a mobile phase consisting of n-hexane-alcohol (ethanol, 1-propanol, or 2-propanol) in various proportions, and a silica-based cellulose tris-3,5-dimethylphenylcarbamate (Chiralcel OD-H), or tris-methylbenzoate (Chiralcel OJ). The effects of concentration of various aliphatic alcohols in the mobile phase were studied. A better separation was achieved on cellulose carbamate phase compared with the cellulose ester phase. The effects of structural features of the solutes along with the temperature of the column on the discrimination between the enantiomers were examined. Baseline separation (Rs > 1.5) was easily obtained in many cases. 相似文献
5.
I. W. Wainer P. Jadaud G. R. Schombaum S. V. Kadodkar M. P. Henry 《Chromatographia》1988,25(10):903-907
Summary A new HPLC stationary phase was synthesized by the covalent immobilization of -chymotrypsin on silica. This increased the stability of the enzyme, without decreasing its activity. The initial chromatographic studies show that this phase can be used for chiral separations of enantiomeric solutes. The stereochemical resolutions of amino acids and amino acid derivatives are reported. 相似文献
6.
E. Tobler M. Lämmerhofer W. R. Oberleitner N. M. Maier W. Lindner 《Chromatographia》2000,51(1-2):65-70
Summary An enantioselective liquid-solid batch extraction method is described for the screening of novel chiral stationary phases
(CSPs) during optimization studies of chiral selectors derived form a common lead structure. Extraction enantioselectivity
(α) values can be calculated from the enantiomeric excess ee-values of the selectand, which are measured in the liquid phase
by enantioselective HPLC. Extraction α-values have been correlated with chromatographic α-values. The influence was studied
of several experimental parameters of the assay (pHa, buffer concentration, temperature, selector/selectand and phase ratio) on the enantiomeric excess (ee) values of the selectands and the enantioselectivity of the CSPs, respectively. The derived statistically significant model
has then been implemented to predict chromatographic α-values of novel CSPs. For example, an ee of 89.3% for DNB-Leu as selectand
could be achieved in batch extraction for a novel synthesized but mechanistically similarly-acting CSP derived form quinine.
This corresponds to a calculated extraction α-value of 17.7. Based on this αextraction a chromatographic α-value of 28.8 was predicted by the linear correlation model; the experimental HPLC α-value of 31.7 was
in good agreement and demonstrated the validity of the proposed screening method. The method is particularly helpful in SO
optimization studies. 相似文献
7.
Summary The employment of three chiral stationary phases (CSPs) obtained by derivatizing γ-mercaptopropyl-silanized silica gel with
quinine, quinidine and N-methyl-quinium iodide, for the separation of organic racemates, is presented. They are quite useful
in the resolution of alkylarylcarbinols, binaphthyl derivatives, amides and other substances of pharmaceutical interest. 相似文献
8.
Three polysaccharide-based chiral stationary phases, Sepapak® 1, Sepapak® 2 and Sepapak® 3 have been evaluated in the present work for the stereoisomer separation of a group of 12 flavonoids including flavanones (flavanone, 4′-methoxyflavanone, 6-methoxyflavanone, 7-methoxyflavanone, 2′-hydroxyflavanone, 4′-hydroxyflavanone, 6-hydroxyflavanone, 7-hydroxyflavanone, hesperetin, naringenin) and flavanone glycosides (hesperidin, naringin) by nano-liquid chromatography (nano-LC). The behaviour of these chiral stationary phases (CSPs) towards the selected compounds was studied in capillary columns (100 μm internal diameter (i.d.)) packed with the above mentioned CSPs using polar organic, reversed and normal elution modes. The influence of nature and composition of the mobile phase in terms of concentration and type of organic modifier, buffer type and water content (reversed phase elution mode) on the enantioresolution (Rs), retention factor (k) and enantioselectivity (α) was evaluated. Sepapak® 3 showed the best chromatographic results in terms of enantioresolution, enantioselectivity and short analysis time, employing a polar organic phase mode. A mixture of methanol/isopropanol (20/80, v/v) as mobile phase enabled the chiral separation of eight flavanones with enantioresolution factor (Rs) in the range 1.15–4.18. The same analytes were also resolved employing reversed and normal phase modes with mixtures of methanol/water and hexane/ethanol at different ratios as mobile phases, respectively. Loss in resolution for some compounds, broaden peaks and longer analysis times were observed with these last two chromatographic elution modes. 相似文献
9.
Three chiral stationary phases, obtained by grafting silica gel with (-)-trans-1,2-cyclohexanediamine, were studied for the resolution of α-amino acids by ligand-exchange chromatography. The packings were prepared by bonding the chiral ligand to silica gel via different hydrocarbon spacers. Separation of the optical isomers was accomplished by eluents containing a constant concentration of copper(II) acetate (0.05mM). The elution sequence of amino acids was found to be dependent on the grafting reaction selected to prepare the chiral packings. 相似文献
10.
Veronika R. Meyer 《Chromatographia》1987,24(1):639-645
Summary In preparative column liquid chromatography, it is necessary to work with conditions of mass overload to obtain high throughput
per unit time. The influence of sample mass and of eluent composition on the separation of R,S-1-(1-naphthylethyl)propylamide
on chiral 3,5-dinitrobenzoylphenylglycine-silica (Pirkle type stationary phase) was investigated. At a sample load of 200μg
of racemate per gram of stationary phase, the column becomes overloaded. At higher sample loads the peaks become triangular;
therefore the first peak is always pure up to loads of 10mg g−1, although resolution is low. The purity of the second peak depends on sample mass, but not on the strength (polarity) of
the mobile phase. This is due to the effect that peak width, as well as resolution, decrease as the polarity of the eluent
increases. In certain cases the polarimeter, used as a detector, can give more information on peak purity than the UV detector. 相似文献
11.
Summary L-N-(3,5-dimethoxyoxybenzoyl)isoleucine, ionically bonded to γ-aminopropyl silica, has been tested as a chiral stationary
phase for the separation of racemates by HPLC. The phase shows good selectivity towards different types of racemates and in
particular for those having an electron-poor aromatic group in their molecule. The separation of benzoin racemate can be achieved
on the developed chiral phase with an α value of 1.10. 相似文献
12.
Summary Native and derivatized β-cyclodextrins such as chiral stationary phases (CSP) were used for the simultaneous enantiomeric
separation of four methylenedioxylated amphetamines (MDA, MDMA, MDEA and MBDB) by liquid chromatography. Fluorimetric detection
was used in order to enhance sensitivity and selectivity. The mobile phase was, optimised by studying the influence of pH,
triethylamine concentration, organic solvent type, column temperature and flow rate of the mobile phase. This method was validated
by determining linearity, precision, accuracy, limits of detection and quantification, and was applied to the stereoselective
analysis of illicit tablets (23 samples) and of human whole blood samples (spiked samples and two post-mortem cases). Whereas
no significant deviation from a racemic ratio was observed in the tablets contents, the analysis of blood samples showed an
enantioselective metabolism of MDMA. 相似文献
13.
Enantiomeric resolution of some imidazole antifungal agents on chiralpak WH chiral stationary phase using HPLC 总被引:1,自引:0,他引:1
Summary The enantiomeric resolution of (±)-econazole, (±)-miconazole and (±)-sulconazole was achieved on a Chiralpak WH column. The
mobile phase used was hexane-2-propanol-diethylamine (400:99:1,v/v/v). The flow rates of the mobile phase used were 0.50 and 1.00 mL min−1. The values of α of the resolved enantiomers of econazole, miconazole and sulconazole were in the range of 1.68 to 1.23 while
the values of Rs varied from 2.42 to 1.10. The resolution of these antifungal agents on Chiralpak WH column is governed by
ligand exchange mechanism. Hydrophobic interactions also play an important role for the enantiomeric resoltuion of antifungal
agents on the reported CSP. 相似文献
14.
Summary The preparation and properties of chiral bonded phases with amino acid groups are described. These phases were used in non-polar
eluents and in aqueous systems in the presence of Cu2+ ions in the ligand-exchange mode. The optimization of chiral resolution is demonstrated for both cases. With non-polar eluents
similarity between bonded groups and solutes is required. The elution could be accelerated by non-protonic moderators.
Ligand-exchange separation is influenced by the copper content of the eluent and the stationary phase, the organic moderator
concentration, the pH and ionic strength of the buffer and by the temperature. Structural requirements of both the bonded
groups and of the solutes for chiral separation are discussed. 相似文献
15.
Roberto Dallocchio Barbara Sechi Alessandro Dessì Bezhan Chankvetadze Sergio Cossu Victor Mamane Robin Weiss Patrick Pale Paola Peluso 《Electrophoresis》2021,42(17-18):1853-1863
2’-(4-Pyridyl)- and 2’-(4-hydroxyphenyl)-TCIBPs (TCIBP = 3,3’,5,5’-tetrachloro-2-iodo-4,4’-bipyridyl) are chiral compounds that showed interesting inhibition activity against transthyretin fibrillation in vitro. We became interested in their enantioseparation since we noticed that the M-stereoisomer is more effective than the P-enantiomer. Based thereon, we recently reported the enantioseparation of 2’-substituted TCIBP derivatives with amylose-based chiral columns. Following this study, herein we describe the comparative enantioseparation of both 2’-(4-pyridyl)- and 2’-(4-hydroxyphenyl)-TCIBPs on four cellulose phenylcarbamate-based chiral columns aiming to explore the effect of the polymer backbone, as well as the nature and position of substituents on the side groups on the enantioseparability of these compounds. In the frame of this project, the impact of subtle variations of analyte and polysaccharide structures, and mobile phase (MP) polarity on retention and selectivity was evaluated. The effect of temperature on retention and selectivity was also considered, and overall thermodynamic parameters associated with the analyte adsorption onto the CSP surface were derived from van ’t Hoff plots. Interesting cases of enantiomer elution order (EEO) reversal were observed. In particular, the EEO was shown to be dependent on polysaccharide backbone, the elution sequence of the two analytes being P-M and M-P on cellulose and amylose tris(3,5-dimethylphenylcarbamate), respectively. In this regard, a theoretical investigation based on molecular dynamics (MD) simulations was performed by using amylose and cellulose tris(3,5-dimethylphenylcarbamate) nonamers as virtual models of the polysaccharide-based selectors. This exploration at the molecular level shed light on the origin of the enantiodiscrimination processes. 相似文献
16.
Rupak Raja Syed Dilshad Alam Vikas Srisath Arvind Kumar Jain Zeid A. ALOthman Abdallah A. A. Mohammed Mohammad Ataul Islam Tahir Bhatt Imran Ali 《Journal of separation science》2022,45(4):804-811
A comparative study of chiral separation of pantoprazole and rabeprazole is carried out using supercritical fluid chromatography and high-performance liquid chromatography. The columns used were Chiralpak IA and Chiralpak IE. The best mobile phase in supercritical fluid chromatography was carbon dioxide-0.2% triethylamine in methanol (60:40) and 0.1% triethylamine in n-hexane-ethanol (50:50) in high-performance liquid chromatography. For supercritical fluid chromatography, values of the retention factor of pantoprazole enantiomers were 3.97 and 4.88. These values for rabeprazole enantiomers were 6.10 and 7.52. The values of separation and resolution factor for pantoprazole and rabeprazole were 1.23 and 1.23 and 2.20 and 3.36, respectively. Similarly, for high-performance liquid chromatography, the values of retention factor for enantiomers of pantoprazole were 4.02 and 7.32. These values for rabeprazole enantiomers were 5.32 and 7.88, respectively. The values of separation and resolution factor for pantoprazole and rabeprazole were 1.82 and 1.48 and 9.22 and 6.58, respectively. A comparison was carried out, which confirmed supercritical fluid chromatography as the best method due to its fastness, eco-friendly, and inexpensiveness. The reported methods are effective, efficient, and reproducible and may be used to separate and identify pantoprazole and rabeprazole in any unknown samples. 相似文献
17.
E. Domenici C. Bertucci P. Salvadori G. Félix I. Cahagne S. Motellier I. W. Wainer 《Chromatographia》1990,29(3-4):170-176
Summary A new HPLC stationary phase was synthesized by thein situ covalent immobilization of human serum albumin (HSA). The protein was immobilized on a commerically available diol column which had been activated with 1,1-carbonyldiimidazole. Initial chromatographic studies show that this phase can be used for chiral separations of enantiomeric solutes and that these separations may reflectin vitro binding to the HSA. The effects of mobile phase composition and temperature on the stereochemical resolutions are reported. 相似文献
18.
19.
Ciogli A D'Acquarica I Gasparrini F Molinaro C Rompietti R Simone P Villani C Zappia G 《Journal of separation science》2010,33(19):3022-3032
Two hybrid polyacrylamide chiral stationary phases (CSPs) for HPLC have been synthesized by a new surface-initiated photo-induced radical polymerization approach of enantiopure N,N'-diacryloyl derivatives of (1R,2R)-diaminocyclohexane (CSP1) and (1R,2R)-diphenylethylenediamine (CSP2). This system is based on the activation of mesoporous silica microparticles by chemically bonded trichloroacetyl groups and dimanganese decacarbonyl as catalyst. UV irradiation was performed using a lab-made quartz photochemical reactor, ad hoc designed for the photo-induced polymerization process on the surface of microparticles. The two phases were evaluated and compared as chromatographic supports for the enantioselective HPLC of model chiral compounds. Their physico-chemical properties and chromatographic performances were also evaluated in comparison with those exhibited by the homologue CSPs obtained by the grafting-from thermal-induced process (CSP3 and CSP4). The new photopolymerization approach yielded higher grafting density than the thermal-induced one, especially in the case of the less reactive monomer (the diacryloyl derivative of (1R,2R)-diphenylethylenediamine), good chromatographic efficiency and a broad application field under normal phase and polar organic mode conditions. 相似文献
20.
高效液相色谱手性固定相法拆分阿折地平对映体 总被引:2,自引:0,他引:2
建立了阿折地平对映体的高效液相色谱拆分方法。采用Chiralpak AD-H (250 mm×4.6 mm, 5.0 μm, Daicel公司)手性色谱柱在正相条件下直接拆分阿折地平对映体,考察了固定相种类、流动相组成及柱温等对阿折地平对映体分离的影响。确定了最佳的拆分条件: 流动相为正己烷-异丙醇(90:10, v/v),流速为0.8 mL/min,检测波长为254 nm;柱温为20 ℃;在此条件下阿折地平对映体的分离度为3.3。该法简单快速,重现性好。 相似文献