THE SEPARATIONS OF ENANTIOMERS OF α—SUBSTITUTED-(2—PYRIDYL)—METHYLAMINES ON A CHIRASIL-VAL CAPILLARY COLUMN

Enantiomers of a-substituted-(2-pyridyl)-methylarfdnes uere separated on SC -7 gas chromatograph with a 20m×0.25mm Chirasil-Val capIlary column,Carrier gas was nitro- gen or hydrogen.The resolution factors(ri.s) were 1.02 to 1.06.Enantiomers of pyridyl anines were separated to and near to base line.

Thin-Layer Chromatographic Separation of Amino Acid Enantiomers using Ligand Exchange

Silica gel thin-layer plates covered with L-arginine and copper acetate were used for the separation of amino acid enantiomers, The chromatographic selectivity and the effects of plate different preparation methods, sample molecular structure and solvent compositions on resolution performance were also discussed.

Direct Enantiomer Separation of 2-PhenylcyclopropanecarboxylateEsters on Cyclodextrin Derivatives Stationary Phases in GC

Direct enantiomeric separation of all four optical isomers of 2-phenylcyclopropane carboxylate ester was first achieved on each of the three different beta-cyciodextrin chiral stationary phases (CSPs) in GC. Using these CSPs, enantiomeric excess of the products of enantioselective cyclopropanation can be determined directly, conveniently and fast.

The Enantiomer Separations of Allethrone and Propargyllone Using Two Long Chain Acylated b-Cyclodextrin Derivatives as CGC Capillary Stationary Phases

Using two b-cyclodextrin derivatives (CDs) with long chain of acyl groups as chiral stationary phases (CSPs) of capillary gas chromatography (CGC), the enantiomers of racemic allethrone and propargyllone were well resolved after derived with acetyl chloride. The enantiomer excess values (e.e.%) of 1S-allethrone and 1S-propargyllone were also determined successfully using these CDs.

Investigation on chiral capillary columns and their application in separation of enantiomers

Six chiral diamide stationary phases (CSPs), namely N-(3-carbobenzoxypropionyl)-L- Val-tert-butylamide (CSP-1), N-undecenoyl-L-Val-S-α-phenylethylamide (CSP-2), N-undecenoyl-L- Val-R-α-phenylethylamide (CSP-3), OV-225-L-Val-tert-butylamide (CSP-4), XE-60-L-Val-tert- butylamide (CSP-5) and polycyanoethyl vinyl siloxane-L-Val-tert-butylamide (CSP-6), were inves- tigated and CSP-6 was crosslinked within narrow bore (70 μm) fused silica capillary columns. The separation of amino acid enantiomers on this narrow bore column by gas chromatography (GC) is illustrated.

A crosslinked chiral stationary phase for the separation of enantiomers by gas and supercritical fluid chromatography

Crosslinking experin(?)tnts for the chiral stationary phase OV-225-L-Val-t-butylamide within both fused silica and glass capillary columns have been carried out.Amino acid enantiomers were separated on crosslinked columns by、both GC and SFC methods.In SFC,the α values of amino acid enantiomers are independent of the density of the mobile phase,and they are hig her than those obtained by GC for the tested enantiomers with the same column due to the lower column tempera- ture used in SFC.

Preparation of Silica-Based Superfi cially Porous Silica and its Application in Enantiomer Separations: a Review

Chromatographic substrate material,as a carrier of chromatographic stationary phases,plays a vital role in defining its chromatographic characteristics,including column efficiency,stability,peak capacity and so on.In recent years,superficially porous silica(SPS)was widely valued for its excellent performance in improving the column efficiency due to its special structural properties,which was considered as a real substitute for fully porous SiO_(2)(FPS)and had been used to develop a new generation of highly efficient stationary phase.To help researchers better understand the SPS and further promote its application and development in the field of chromatography,the rapid separation mechanism,preparation method and its applications in the rapid separation and analysis of enantiomers were systematically introduced,and the development prospects of SPS were also prospected in this paper.

Enantiomer Separation of α-Dimethyl Dicarboxylate Biphenyl and Related Biphenyl Compounds by Normal Phase HPLC on Polysaccharide Based Chiral Stationary Phases

Cellulose tris(4-methylphenylcarbamate), amylosetris(3,5-di-methylphenylcarbamate) and amylose tris (phenylcarbamate) were prepared by the methodreported by Okamoto and were coated onto an aminopropylated mesoporous spherical silica gel. Thesefinal products were used as chiral stationary phases of high performance liquid chromatography forthe eighteen structurally related biphenyl compounds. The resolution was made using normal-phasemethodology with a mobile phase consisting of n-hexane-alcohol (ethanol, 1-propanol, 2-pro-panol or1-butanol). The effects of various aliphatic alcohols in the mobile phase were studied. Thestructural features of the solutes that influence then- k′ were discussed. A dominant effect oftrifluoroacetic acid on chiral separation of acidic solutes was noted.

Enantiomeric Separation of Epinephrine and Salbutamol by Micellar Electrokinetic Chromatography Using β-Cyclodextrin as Chiral Additive

Enantiomeric separations of epinephrine and salbutamol, by means of micellar electrokinetic chromatography (MEKC) employing β-cyclodextrin as chiral additive in ammonium chloride-ammonia solution were investigated. In this system, the analytes migrated with the micellar phase towards the anode and were detected by electrochem- istry using gold microelectrode at +0.65 V vs. SCE. The success of the chiral separations is strongly dependent on the concentration of β-CD and SDS, and the optimal concentration is 8 mmol?L-1 and 15 mmol?L-1 respectively. The effects of detection potential, pH value of electrolyte and applied voltage were discussed also. Using the pro- posed method, baseline separation of the enantiomers could be accomplished in 6 min. Further, an attempt was made to elucidate the plausible mechanism of the chiral recognition.

Direct chiral high performance liquid chromatography separation of O-ethyl O-phenyl N - isopropylphosphoroamidothioates

The enantiomers of thirty-nine O-ethyl O-phenyl N-isopropyl phosphoroamidothioates have been separated by high performance liquid chromatography on a Pirkle model chiral stationary phase using ten mobile phase. Chromatographic data are presented for the separation of these organic phosphorus enantiomers on the chiral phase. The influences of molecular structures and compositions of mobile phases have been described.