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1.
Li W Zhang W Zhao Q Li Y Ma C Chen L Yin Y 《Analytical and bioanalytical chemistry》2004,378(5):1364-1368
The enantioseparation of seven novel chiral transition metal tetrahedral clusters has been achieved for the first time on cellulose derivatized with tris(3,5-dimethylphenylcarbamate) (CDMPC) as chiral stationary phase (CSP) and hexane containing different alcohols as modifiers as mobile phases. The effect of mobile-phase composition on enantioselectivity was studied, and the effect of structural variation of the solutes on their enantioseparation was also investigated. It was found that both the metal in the tetrahedral core and the ligand coordinated to the atom in the tetrahedral core had significant effects on the chromatographic behavior of the analytes. 相似文献
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W. Lee 《Chromatographia》2000,53(3-4):156-158
Summary The liquid-chromatographic separation of the enantiomers of pyrethroic acids and their esters has been investigated on a polysaccharide-derived
chiral stationary phase (CSP), Chiralpak AS. Good separation of the enantiomers of underivatized pyrethroic acids was achieved
on the column, and the enantiomers of pyrethroic acid methyl and ethyl ester derivatives were also resolved. 相似文献
4.
Summary The chiral separation of eight racemic compounds has been investigated on a cellulose tris(3,5-dimethylphenylcarbamate) chiral
column under reversed-phase conditions. The discrimination mechanism under reversed-phase conditions is discussed. Addition
of acid to the mobile phase is necessary for resolution of acidic racemic compounds. The presence of ion-pair reagent in the
mobile phase is a key factor in the resolution of basic racemic compounds. Retention of the racemates is also affected by
addition of acid or salt. The anion in buffer not only interacts with the racemete, but also with the polysaccharide derivative
on the silica gel surface. 相似文献
5.
A direct liquid chromatographic enantioselective separation of a set of β-blocker enantiomers on the new immobilized and conventional coated amylose tris-(3,5-dimethylphenylcarbamate) chiral stationary phases (Chiralpak IA and Chiralpak AD, respectively) was studied using methanol as mobile phase and ethanolamine as an organic modifier (100:0.1, v/v). The separation, retention and elution order of the enantiomers on both columns under the same conditions were compared. The effect of the immobilization of the amylose tris-(3,5-dimethylphenylcarbamate) chiral stationary phase on silica (Chiralpak IA) on the chiral recognition ability was noted when compared to the coated phase (Chiralpak AD) which possesses a higher resolving power than the immobilized one (Chiralpak IA). A few racemates, which were not or poorly resolved on the immobilized Chiralpak IA were most efficiently resolved on the coated Chiralpak AD. However, the immobilized phase withstand solvents like dichloromethane when used as an eluent or as a dissolving agent for the analyte. The versatility of the immobilized Chiralpak IA in monitoring reactions performed in dichloromethane using direct analysis techniques without further purification, workup or removal of dichloromethane was studied on a representative example consisting of the lipase-catalyzed irreversible transesterification of a β-blocker using either vinylacetate or isopropenyl acetate as acyl donor in dichloromethane as organic solvent. 相似文献
6.
The liquid Chromatographic resolution of the racemic cardiovascular drugs naftopidil and bufuralol to their corresponding enantiomers was achieved on cellulose tris-(3,5-dimethylphenyl carbamate) chiral stationary phase known as Chiralcel OD. The chiral recognition mechanism(s) involved between the chiral stationary phase and these drugs, which include hydrogen bonding, intercalative interactions, and steric interactions, among other factors, were discussed. 相似文献
7.
Summary The high-performance liquid chromatographic resolution of the enantiomers of tebuconazole, a new anti-fungal agent with one
chiral center, and the enantiomers of some impurities in technical tebuconazole, has been studied on a chiral stationary phase
prepared by coating aminopropylated silica gel with celluloseris(3,5-dimethylphenylcarbamate). The effects of solute structure and the amount of the organic mobile-phase modifier, 2-propanol,
on retention and resolution were studied. Under optimum conditions excellent enantiomer separations were achieved for tebuconazole
and its impurities. As far as we are aware this is the only liquid chromatographic system enabling discrimination of the enantiomers
of all of the racemates discussed in this paper. 相似文献
8.
以纤维素-三(3,5-二甲苯基氨基甲酸酯)为手性固定相(Chiralcel OD-H)在高效液相色谱上拆分了氨鲁米特对映体。通过测定氨鲁米特在正己烷/乙醇和正己烷/异丙醇中的溶解度,优选了对样品溶解度大的流动相体系,并考察了流动相添加剂乙醇胺对拆分效果的影响。在此基础上进一步研究了流动相中乙醇含量、柱温和进样量对分离因子、分离度、不对称因子和理论板数的影响,从而确定了最佳的拆分条件:固定相为Chiralcel OD-H,流动相为正己烷/乙醇/乙醇胺(体积比为30:70:0.1),柱温25℃。本文所得结果可为工业放大提供基础数据。 相似文献
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Summary Flavanones ofArachis hypogaea, Hemizonia increscens, Eriodictyon glutinosum andThymus vulgaris extracts have been stereospecifically analysed by gradient elution on a column of cellulose triacetate supported on silica gel diol. The stereochemistry of naringenin, eriodictyol and homoeriodictyol was in favour of the 2S-configurated flavanones. 相似文献
11.
Polysiloxane-encapsulated stationary phase for reversed-phase high-performance liquid chromatography
Summary Silica beads of 6-μm average diameter were silanized with methylvinyldiethoxysilane and then subjected to encapsulation with
poly(methylvinylsiloxane). The resulting product is a new stationary phase for reversed-phase high performance liquid chromatography
(RP-HPLC) which has superior ability for the separation of polar, non-polar and basic compounds. The chromatographic peaks
are symmetric. Its stability has been studied; after continuous use for three months the carbon content and chromatographic
behaviour of the phase were unchanged. on to the silica surface to given an uniform organic film. Material prepared in this
way has both good chromatographic behaviour and superior selectivity. Because contact of the silica matrix with the mobile
phase is avoided, the alkali-resisting ability of the stationary phase is increased. The non-specific adsorption of alkaline
solutes on to the silica surface is also avoided because of the complete coverage of surface silanol groups. Reports of stationary
phases encapsulated with polystyrene [6], polybutadiene [I] and octadecylsiloxane polymers have recently appeared in the literature
[3].
In this paper we report the encapsulation of poly-(methylvinylsiloxane) (analogous to the phase SE-31 often used in GC) on
to a silica matrix previously modified with methylvinyldiethoxysilane. The resulting phase has superior performance in reversed-phase
HPLC. 相似文献
12.
Summary A computer-assisted method is described for optimization of multi-component, mobile phase selection for separating enantiomers of four pesticides in normal-phase HPLC. The method is based on the triangle, solvent-selection concept using a statistical scanning method. The optimization of the separation over the experimental region is based on a special polynomial estimation from seven experimental runs, and resolution (Rs) is used as the selection criterion. Excellent agreement was obtained between predicted and experimental data. 相似文献
13.
Summary Direct separations of the enantiomers of cetirizine and related compounds have been achieved by reversed-phase HPLC on the
Chiralcel OD-R, a polysaccharide-derived chiral stationary phase; the mobile phase was usually perchlorate solution supplemented
with acetonitrile. Resolution of the enantiomers of cetirizine and related compounds was good. The effect of the acetonitrile
content of the mobile phase was investigated, and the effect of the structure of the chiral compounds on their behavior on
the Chiralcel OD-R column is discussed. 相似文献
14.
T. Benincori R. Cirilli R. Ferretti F. La Torre O. Piccolo L. Zanitti 《Chromatographia》2002,55(1-2):25-31
Summary Resolution of the enantiomers of new racemic diphosphines, which are very useful ligands for stereoselective catalysts, and
of the corresponding phosphine oxides has been investigated by high-performance liquid chromatography (HPLC) on four different
chiral stationary phases (CSP)—Chiralpak AD, Whelk-01, and Supelcosil naphthylurea and phenylurea columns. The mobile phases
were optimized to achieve separation of the enantiomers. α andR
S values ranged from 1.05 to 5.17 and from 0.37 to 6.57, respectively, for the Chiralpak AD and (R,R)-Whelk-01 columns. For the Supelcosil LC-(R)-phenylurea and Supelcosil LC-(S)-naphthylurea columns α values ranged from 1.05 to 1.62 andR
S from 0.35 to 3.61. 相似文献
15.
键合型纤维素类手性固定相高效液相色谱法拆分对映异构体 总被引:3,自引:0,他引:3
制备了一种键合型纤维素-三苯基氨基甲酸酯手性固定相。在正相色谱条件下,拆分了九种结构不同的外消旋对映体,实验发现,在流动相中添加四氢呋喃有利于手性化合物拆分,而衍生化官能团可参与手性识别过程,在反相色谱条件下,此固定相同样具有手性拆分能力。研究结果表明,随着流动相中乙腈浓度的增加,对映体的保留值明显减小,但对映异构体的选择性却变化不大。在流动相中使用低pH值,能有效抑制酸性化合物的解离,从而显著增强其手性识别能力;对于中性化合物,流动相中pH对手性分离影响不大。 相似文献
16.
Guo-Sheng Yang Lan Zhou Du Wei Gao-Lan Li P. Parrilla vazquez A. Garrido Frenich 《Chromatographia》2002,56(3-4):143-145
Summary The enantiomers of eightO,O-dialkyl-2-benzyloxycarbonylaminoarylmethyl phosphonates have been directly separated on a tris(3,5-dimethylphenylcarbamate)
cellulose column. The results are very different from those obtained by separation on anN-(3,5-dinitrobenzoyl)leucine (DNBleu) column. The effect of mobile phase composition and column temperature on retention and
enantioselectivity were investigated. The effect on chiral separation of the length of, and steric hindrance by, alkoxyl groups
of the phosphonate ester and of the nature of the substitutentsp-Cl andp-H on the benzene ring attached to the chiral carbon atom are also discussed. 相似文献
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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
19.
Roberto Cirilli Stefano Alcaro Rossella Fioravanti Daniela Secci Stefano Fiore Francesco La Torre Francesco Ortuso 《Journal of chromatography. A》2009,1216(22):4673-4678
The cellulose tris(4-methylbenzoate) chiral stationary phase (CSP) (commercially known as Chiralcel OJ-H) exhibited an extremely high enantioselectivity when used in the HPLC resolution of N-thiocarbamoyl-3-(4′-prenyloxy)-phenyl-5-phenyl-4,5-dihydro-(1H) pyrazole (Compound 1), in both normal-phase and polar organic conditions. Using n-hexane–ethanol (80:20, v/v) as a mobile phase, an enantioseparation factor value of 138.5 was found. In order to modulate the elution time of the longer retained enantiomer, a simple HPLC procedure was developed. The optimized analytical protocol was based on the stopped flow technique and did not involve any change in mobile phase composition. The stronger interaction energy of the (S) enantiomer compared to that of the (R) enantiomer was mainly attributed to the formation of a hydrogen bonding between the amino group of the thiocarbamoyl moiety and the carbonyl oxygen of the CSP. 相似文献
20.
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