Polymer-based Stationary Phase Research Articles

Synthesis and evaluation of ginsenosides imprinted polymer-based chromatographic stationary phase.

Molecular imprinting technique has aroused great interest in preparing novel stationary phases, and the resulting materials named molecularly imprinted polymers coated silica packing materials exhibit good performance in separating diverse analytes based on their good characteristics (including high selectivity, simple synthesis, and good chemical stability). To date, mono-template is commonly used in synthesizing molecularly imprinted polymers-based stationary phases. The resulting materials always own the disadvantages of low column efficiency and restricted analytes, and the price of ginsenosides with high purity was very high. In this study, to overcome the weaknesses of molecularly imprinted polymers-based stationary phases mentioned above, the multi-templates (total saponins of folium ginseng) strategy was used to prepare ginsenosides imprinted polymer-based stationary phase. The resulting ginsenosides imprinted polymer-coated silica stationary phase has a good spherical shape and suitable pore structures. Additionally, the total saponins of folium ginseng were cheaper than other kinds of ginsenosides. Moreover, the ginsenosides imprinted polymer-coated silica stationary phase packed column performed well in separation of ginsenosides, nucleosides, and sulfonamides. The ginsenosides imprinted polymer-coated silica stationary phase possesses good reproducibility, repeatability, and stability for seven days. Therefore, a multi-templates strategy for synthesizing the ginsenosides imprinted polymer-coated silica stationary phase is considered in the future. This article is protected by copyright. All rights reserved.

Preparation and chromatographic evaluation of a polymer-based stationary phase for weak anion-exchange/hydrophilic interaction

a weak cationic exchange/hydrophilic interaction mixed-mode stationary phase (Sil-PolyCOOH) for high performance liquid chromatography was prepared by bonding polyethylene maleic anhydride to the surface of amino silica gel via a nucleophilic substitution reaction, followed by hydrolysis of the residual maleic anhydride. The new stationary phase material was characterized by solid-state13C nuclear magnetic resonance analysis and ζ-potential measurements. The chromatographic performance and retention mechanism of this stationary phase were evaluated using nucleosides and nucleic bases as probes. The effects of mobile phase composition, ion strength, and pH on the retention factor were investigated. The results show that the retention mechanism of the stationary phase involves both hydrophilic distribution interaction and multiple forces between the host and guests. The stationary phase also showed good separation performance for saccharides, diquat, and paraquat. These results show that the stationary phase has a good application prospect in the separation of polar compounds.

Retention Behavior of Polycyclic Aromatic Compounds in a Novel Polymer-Based Stationary Phase Liquid Chromatography

Retention Behavior of Polycyclic Aromatic Compounds in a Novel Polymer-Based Stationary Phase Liquid Chromatography

Phosphatidylcholine covalently linked to a methacrylate-based monolith as a biomimetic stationary phase for capillary liquid chromatography

In this study a strategy to immobilize phospholipids onto a polymer-based stationary phase is described. Methacrylate-based monoliths in capillary format (150×0.1mm) were modified by soybean phosphatidylcholine through 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide coupling to obtain stationary phases suitable to mimic cell surface membranes. The covalent coupling reaction involves the phosphate group in phospholipids; therefore, the described methodology is suitable for all types of phospholipids.Immobilization of soy bean phosphatidylcholine on the monolith was confirmed by attenuated total reflectance Fourier transform infrared spectroscopy and gas chromatography-mass spectrometry of the fatty alcohol profile, generated upon reductive cleavage of the fatty acyl side chains of the phospholipid on the monolith surface with lithium aluminium hydride.The prepared stationary phases were evaluated through studies on the retention of low-molar mass model analytes including neutral, acidic, and basic compounds. Liquid chromatographic studies confirmed predominant hydrophobic interactions between the analytes and the synthesized stationary phase; however, electrostatic interactions contributed to the retention as well. The synthesized columns showed high stability even with fully aqueous mobile phases such as Dulbecco's phosphate-buffered saline solution.

Preparation of a novel weak cation exchange/hydrophobic interaction chromatography dual-function polymer-based stationary phase for protein separation using "thiol-ene click chemistry".

A novel dual-function mixed-mode stationary phase based on poly(glycidyl methacrylate-co-ethylene dimethacrylate) microspheres was synthesized by thiol-ene click chemistry and characterized by infrared spectroscopy and elemental analysis. The new system displays both hydrophobic interaction chromatography (HIC) character in a high salt concentration mobile phase, and weak cation exchange (WCX) chromatography character in a low salt concentration mobile phase. It can be used to separate proteins in both ion-exchange chromatography (IEC) mode and HIC mode. The resolution and selectivity of the stationary phase were evaluated in both HIC mode and IEC mode using protein standards. In comparison with the conventional WCX and HIC columns, the results were satisfactory and acceptable. Protein mass and bioactivity recoveries of more than 96% can be achieved in both HIC mode and IEC mode using this column. The results indicate that the novel dual-function mixed-mode column in many cases can replace the use of two individual WCX and HIC columns. In addition, the effects on protein separation of different ligand structures in the dual-function stationary phase and the pH of the mobile phase used were also investigated in detail. The results show that electrostatic interaction of the ligand with proteins must match the hydrophobicity of the ligand, which is an important factor to prepare the dual-function stationary phase. On the basis of this dual-function mixed-mode chromatography column, a new two-dimensional liquid chromatography technology with a single column system was also developed in this study, and was used to renature and purify recombinant human interferon-γ from inclusion bodies. The mass recovery, purity, and specific bioactivity obtained for the purified recombinant human interferon-γ were 87.2%, 92.4%, and 2.8 × 10(7) IU/mg, respectively, in IEC mode, and 83.4%, 95.2%, and 4.3 × 10(7) IU/mg, respectively, in HIC mode. The results indicate that the dual-function mixed-mode stationary phase prepared in this study may aid in the development of new two-dimensional liquid chromatography technology with a single column for intensive proteomic studies, and it may also find applications in recombinant protein drug production since it can save column costs and simplify the biotechnological processes.

Chiral Separation of Amlodipine and its Enantiomer on a Molecularly Imprinted Polymer-Based Stationary Phase

A new chiral stationary phase for amlodipine (3-ethyl 5-methyl-2 -[(-2-(aminoethoxymethyl)-4-(2-chlorophenyl)-1,4-dihydro-6-methyl-3,5-pyridinedicarboxylate) based on a molecularly imprinted polymer has been prepared by radiation polymerization method and used for chromatographic separation of the chiral enantiomers. The effects on the separation of mobile phase and flow rate were investigated, and the optimum conditions for HPLC were shown to be: mobile phase, chloroform; flow rate, 0.3 ml min-1; at room temperature. The results has shown that the amlodipine-imprinted polymer was capable of recognizing the enantiomeric difference between the template and its R-enantiomer, whereas the non-imprinted and thermal polymerization polymer have no chiral recognition ability for the enantiomers.

Chiral Separation of Nateglinide and its L Enantiomer on a Molecularly Imprinted Polymer-Based Stationary Phase

A new chiral stationary phase for nateglinide (N-(trans-4-isopropylcyclohexylcarbonyl)-D-phenylalanine) based on a molecularly imprinted polymer has been prepared by non-covalent imprinting. For chromatographic analysis the effects on the separation of mobile phase composition, flow rate, and temperature were investigated, and the optimum conditions for HPLC were shown to be: mobile phase, acetonitrile; flow rate, 0.5 mL min−1; temperature, 25 °C. It was shown that the nateglinide-imprinted polymer was capable of recognizing the enantiomeric difference between nateglinide and its L enantiomer, whereas the non-imprinted polymer had no such ability. Scatchard analysis was used to investigate the binding characteristics of the nateglinide-imprinted stationary phase; this indicated that two classes of binding site were present in the imprinted polymer. The equilibrium dissociation constant (K D) and the apparent maximum number (Q max) of high- and low-affinity binding sites were 3.7 × 10−4 mol L−1 and 11.38 μmol g−1, and 1.81 × 10−3 mol L−1 and 27.73 μmol g−1, respectively.

Preparation and characterization of polymer-based stationary phase modified with Thiacalix[4]arene

チアカリックスアレーンを導入した充填剤を調製し，液体クロマトグラフィーを用いて評価を行った．チアカリックスアレーンは4つ以上のp-アルキルフェノールを硫黄で架橋した環状化合物である．本研究では二段階膨潤重合法で調製した均一径ポリマー粒子の表面にカルボニル基を導入し，そこへスペーサーを結合させたチアカリックスアレーンを修飾した．評価にはアルキルベンゼンとキシレン，クレゾール，ベンゼンジオールの各位置異性体，そしてカテコール骨格を持つカテコールアミンを用いた．各位置異性体との比較により，チアカリックスアレーンを導入した充填剤は，カテコールに対し，逆相条件下でより疎水性の大きなo-キシレンよりも大きな保持を示した．カテコールアミンに対してもカテコール同様，選択的な保持を示した．このことからチアカリックスアレーンを導入した充填剤は近接して水酸基をもつ化合物の分離に有用であることが示唆された．

Monodisperse polymer‐based stationary phase for carbohydrate analysis by reduced‐diameter column anion‐exchange chromatography with pulsed amperometric detector

AbstractA monodisperse polymer‐based anion exchanger was synthesized through a two‐step swelling and polymerization method for the analysis of unmodified carbohydrates by reduced‐diameter column liquid chromatography with a pulsed amperometric detector. Separation characteristics were studied for several different classes of carbohydrates, including sugar phosphates. © 2001 John Wiley & Sons, Inc. J Micro Sep 13: 8–12, 2001

Molecularly imprinted uniform-sized polymer-based stationary phase for naproxen: Comparison of molecular recognition ability of the molecularly imprinted polymers prepared by thermal and redox polymerization techniques

A molecularly imprinted uniform-sized polymer-based stationary phase for ( S)-naproxen has been prepared by a multi-step swelling and thermal or redox polymerization method using 4-vinylpyridine and ethylenedimethacrylate as a host functional monomer and cross-linker, respectively. The obtained molecularly imprinted polymers were evaluated using aqueous-rich mobile phases. The molecularly imprinted polymer materials could separate naproxen enantiomers. Further, the materials showed high selectivity for naproxen and moderate selectivity for other 2-arylpropionic acid derivatives. On the other hand, the molecularly imprinted polymer materials showed little selectivity for other acidic compounds, and basic and neutral compounds. With regard to comparison of the molecularly imprinted polymers prepared by thermal and redox polymerization techniques, the latter materials gave higher retentivity and enantioselectivity than the former materials, while the former materials gave higher column efficiency than the latter materials. Thus, naproxen enantiomers were resolved much better on the molecularly imprinted polymer material prepared by a thermal polymerization method.

Molecularly Imprinted Uniform-Sized Polymer-Based Stationary Phase for Naproxen

Abstract A molecularly imprinted uniform-sized polymer-based stationary phase for (S)-naproxen has been prepared using 4-vinylpyridine and ethylenedimethacrylate as a host functional monomer and cross-linker, respectively. The imprinted polymer material could separate naproxen enantiomers with separation factor of 1.74. Further, the materials showed high selectivity for naproxen and moderate selectivity for other 2-arylpropionic acid derivatives. On the other hand, the imprinted polymer material showed little selectivity for other acidic, basic and neutral compounds.

Molecularly imprinted uniform-size polymer-based stationary phase for high-performance liquid chromatography structural contribution of cross-linked polymer network on specific molecular recognition

Non-covalently molecularly imprinted, uniform-size, polymer-based, stationary phases were prepared by a two-step swelling technique using isomers of diaminonaphthalene or a chiral amide derived from ( S)- α-methylbenzylamine as the template molecule. Methacrylic acid worked as an effective host molecule for diaminonaphthalene templates, however, an imprinted, cross-linked, polymer-based, stationary phase without such a relatively strong host functionality unexpectedly showed moderate molecular recognition, which suggested that the cross-linked polymer network could memorize the shape of a template. In chiral separation of amide derivatives, a cross-linked polymer network also memorized the shape of a chiral template, resulting in chiral resolution. In addition, a chiral cross-linking agent having similar functionality to the chiral amide template could enhance molecular recognition drastically. Further studies suggested that this enhancement in chiral recognition was due to a favorable structural interaction within the specific recognition sites.

Uniform-size Macroporous Polymer-based Stationary Phase for HPLC Prepared through Molecular Imprinting Technique

Abstract Uniform-size macroporous polymer-based stationary phase was prepared through molecular imprinting technique. Although the stationary phase was prepared by polymerization in an aqueous medium, template molecule was effectively imprinted onto the uniform-size macroporous polymer particles. The ability of chromatographic recognition toward the template molecule on the stationary phase was almost identical to that of the previously reported rod-type separation media1) with larger capacity factor.

The Separation and Indirect Visible Detection of Rare Earth Metal Cations on a Dye-Coated Stationary Phase

Abstract The separation and indirect visible detection of rare earth metal cations on a dye-coated stationary phase was studied. Phenol Red, which is typically used for pH titrations, was used as an ion-interaction reagent in this study and is composed of a hydrophobic group and a fixed charge site. The mobile phase variables that were found to affect metal cation retention and resolution are: concentration of dye, concentration of organic modifier, mobile-phase pH, type and concentration of ligand, and ionic strength. A polymer-based stationary phase was used in this study and detection of the metal cations was accomplished by indirect visible detection at 490 nm.

Direct resolution of organic acid enantiomers on a novel polymer-based stationary phase

A chiral packing for high-performance liquid chromatography was obtained by copolymerization of urea with formaldehyde in the presence of an optically active amino acid derivative. Spherical particles with a mean bead size of 6 μm were evaluated as stationary phases with respect to their chemical stability and chromatographic performance. Electrostatic interactions govern the overall kinetics of the retention in the chromatographic process, so that ion pairing seems to be responsible for the chiral recognition. Increasing the column temperature improves the chromatographic pattern considerably, and the resolution and peak shape are similar to those in the usual high-performance liquid chromatographic separations. The support is easy to pack and yields good column lifetimes. Its application to the resolution of some organic acid racemates is illustrated.

Separation of soy lecithin using gel permeation chromatography

Gel permeation chromatography was applied to develop a broad relative molecular mass profile of soy lecithin. A non-aqueous mobile phase and an organic polymer-based stationary phase were found to be necessary in order to achieve interpretable chromatographic elution. Calibration of the column was performed using polystyrene standards. A broad peak was observed at a relative molecular mass of ca. 8000 in the two soy lecithin lots studied. This peak disappeared at sufficiently low concentrations of soy lecithin injected. The results suggested that this peak was due to the formation of reverse micelles or non-covalent aggregates of the phospholipid components and not to polymeric or protein-like high relative molecular mass component(s). No other high molecular mass (> 2000) components were detected under the conditions used.