Enantioseparation of propranolol, amlodipine and metoprolol by electrochromatography using an open tubular capillary modified with ß-cyclodextrin and poly(glycidyl methacrylate) nanoparticles.

The inner wall of a capillary was coated with glycidyl methacrylate (GMA) to form tentacle-type coating, and poly(glycidyl methacrylate) nanoparticles (PGMA NPs) were then immobilized on the film. Ethanediamine-ß-cyclodextrin as chiral selector was covalently bonded into the PGMA NPs through the ring-open reaction. The materials were characterized by SEM, TEM and FT-IR. The modified column was applied to the enantioseparation of the racemates of propranolol, amlodipine and metoprolol. Compared to a capillary with a single layer of CD-PGMA (without GMA coating) and to a CD-GMA system (without PGMA nanoparticles), the performance of the capillary is strongly improved. The effects of buffer pH value and applied voltage were optimized. Best resolutions (propranolol: 1.27, metoprolol: 1.01 and amlodipine: 2.93) were obtained when using the PGMA-coated capillary system. The run-to-run, day-to-day and column-to-column reproducibility were tested and found to be highly attractive. The new stationary phase is likely to have a large potential and scope in that it may also be applied to chiral separations of other enantiomers, such as amino acids and biogenic amines. Graphical abstract Schematic presentation of the preparation of a capillary column with glycidyl methacrylate (GMA) coating which was then immobilized with poly(glycidyl methacrylate) nanoparticles and ethanediamine-ß-cyclodextrin. This novel open tubular column was applied to construct capillary electrochromatography system for separation of basic racemic drugs.

A monolithic capillary modified with a copoplymer prepared from the ionic liquid 1-vinyl-3-octylimidazolium bromide and styrene for electrochromatography of alkylbenzenes, polycyclic aromatic hydrocarbons, proteins and amino acids.

A monolithic capillary column was prepared by single-step copolymerization of the ionic liquid 1-vinyl-3-octylimidazolium bromide (VOI) and styrene. The VOI and styrene monomers were introduced to provide multiple interaction sites and increase hydrophobicity and aromaticity of the monolithic column, respectively. The effect of porogen ratio, monomer ratio and reaction temperature on permeability was investigated. The resulting column was characterized by scanning electron microscopy, and the results suggest that the column possesses high porosity and good homogeneity. A relatively strong anodic electroosmotic flow was generated over a wide range of pH values (pH 2.0-10.0), and this facilitates the rapid separation of analytes within 12 min. Alkylbenzenes, polycyclic aromatic hydrocarbons (PAHs), proteins and amino acids were used to evaluate the performance of the monolithic column under capillary electrochromatography mode by UV detection. Mixed-mode retention mechanisms including hydrophobic interaction, π-stacking, ion-exclusion interaction were observed. The monolithic column exhibits high column efficiency (8.72 × 104 plates∙m-1) and satisfying separation capability (the resolution of four alkylbenzenes: 2.54, 2.86 and 4.62, four PAHs: 2.79, 4.83 and 4.77, three proteins: 4.35 and 2.86, two amino acids: 3.34). Graphical abstractSchematic representation of capillary electrochromatography (CEC) systems with ionic liquid and styrene based organic polymer monolithic column for separation of alkylbenzenes, polycyclic aromatic hydrocarbons, proteins and amino acids.

An organic polymer monolith modified with an amino acid ionic liquid and graphene oxide for use in capillary electrochromatography: application to the separation of amino acids, ß-blockers, and nucleotides.

The preparation of an organic polymer monolithic column modified with an amino acid ionic liquid and graphene oxide (AAIL-GO) and its application to capillary electrochromatography (CEC) was described. The AAIL tetramethylammonium-L-arginine was bonded to a monolithic column that was previously modified with graphene oxide by using an hydrochloride/N-hydroxysuccinimide coupling reaction. The morphology of a poly(glycidyl methacrylate-co-ethylene dimethacrylate) monolith was examined by scanning electron microscopy. The incorporation of AAIL and graphene oxide was detected by infrared spectroscopy and elemental analysis. The resulting monolithic column produced a strong and stable electroosmotic flow from the anode to the cathode in the pH range from 3 to 9. Compared with a column modified with AAIL or graphene oxide only, the AAIL-GO-modified column has a better separation ability for amino acids, ß-blockers, and nucleotides (the resolution of three amino acids: 2.231 and 2.036, ß-blockers: 2.779 and 2.470 and nucleotides: 8.345 and 3.321). Molecular modeling was applied to demonstrate the separation mechanism of small molecules which showed a good support for experimental results. Graphical abstract Schematic representation of capillary electrochromatography (CEC) systems with an amino acid ionic liquid-graphene oxide modified organic polymer monolithic column as stationary phases for separation of amino acids, ß-blockers, and nucleotides.