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Staffan Nilsson - One of the best experts on this subject based on the ideXlab platform.
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hydrophobic interaction Capillary Electrochromatography of protein mutants use of lipid based liquid crystalline nanoparticles as pseudostationary phase
Analytical Chemistry, 2009Co-Authors: Christian Nilsson, Kristian Becker, Ian Harwigsson, Leif Bulow, Staffan Birnbaum, Staffan NilssonAbstract:Nanoparticle-based hydrophobic interaction-Capillary Electrochromatography was utilized for separation of proteins with similar mass-to-charge ratio at neutral pH without organic modifier. Lipid-based liquid crystalline nanoparticles were prepared and used as pseudostationary phase, benefiting from their high biocompatibility, ease of preparation, and suspension stability at high concentrations. Use of laser-induced fluorescence enabled detection at high nanoparticle concentrations. Green fluorescent protein (GFP) and mutants of GFP harboring single or double amino acid substitutions with the same charge were separated in the described system but not in conventional Capillary electrophoresis. Separation was achieved by increasing the salt concentration to promote hydrophobic interactions by shielding of the repulsive electrostatic interactions. In addition, the method was adapted to a Capillary with an effective length of 6.7 cm, enabling fast separations and future applications on chip.
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monoclonal behavior of molecularly imprinted polymer nanoparticles in Capillary Electrochromatography
Analytical Chemistry, 2008Co-Authors: F Priegocapote, Sadia Shakil, Shahab A Shamsi, Staffan NilssonAbstract:A new approach based on miniemulsion polymerization is demonstrated for synthesis of molecularly imprinted nanoparticles (MIP-NP; 30-150 nm) with "monoclonal" binding behavior. The performance of the MIP nanoparticles is characterized with partial filling Capillary Electrochromatography, for the analysis of rac-propranolol, where (S)-propranolol is used as a template. In contrast to previous HPLC and CEC methods based on the use of MIPs, there is no apparent tailing for the enantiomer peaks, and baseline separation with 25 000-60 000 plate number is achieved. These effects are attributed to reduction of the MIP site heterogeneity by means of peripheral location of the core cross-linked NP and to MIP-binding sites with the same ordered radial orientation. This new MIP approach is based on the substitution of the functional monomers with a surfactant monomer, sodium N-undecenoyl glycinate (SUG) for improved inclusion in the MIP-NP structure and to the use of a miniemulsion in the MIP-NP synthesis. The feasibility of working primarily with aqueous electrolytes (10 mM phosphate with a 20% acetonitrile at pH 7) is attributable to the micellar character of the MIP-NPs, provided by the inclusion of the SUG monomers in the structure. To our knowledge this is the first example of "monoclonal" MIP-NPs incorporated in CEC separations of drug enantiomers.
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molecularly imprinted polymer formats for Capillary Electrochromatography
Journal of Chromatography B, 2004Co-Authors: Jakob Nilsson, Peter Spegel, Staffan NilssonAbstract:The research aimed towards the adaptation of molecularly imprinted polymers (MIPs) to the Capillary format and the use of these highly selective matrices for Capillary Electrochromatography (CEC) is reviewed in this article. The MIP is prepared by incorporation of a template molecule into a polymerization protocol. After polymerization and extraction of the template from the resulting polymer a highly selective material with recognition cavities complementary to the template in size, shape and chemical functionality is obtained. MIPs have been used as recognition elements in several different analytical techniques. In combination with CEC a novel separation system with a unique selectivity towards a predetermined target (the template) is achieved. The merge of molecular imprinting technology (MIT) and CEC have introduced several interesting polymer formats, due to the adaptation of the MIP to the miniaturized Capillary format. The polymer formats can be classified according to their preparation protocols and appearance into three conceptually different categories, i.e. the monolith, the coating and the nanoparticles. The preparation protocols, characteristics and applications of these formats will be discussed.
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Molecular imprint-based stationary phases for Capillary Electrochromatography
Journal of Chromatography A, 1998Co-Authors: Leif Schweitz, Lars I Andersson, Staffan NilssonAbstract:The combination of Capillary Electrochromatography, which provides a high degree of separation efficiency and short separation times, with molecular imprinting, which provides a means for preparing stationary phases of predetermined selectivity, is discussed in this review. Polymerisation around a templating ligand, using monomers that are selected for their ability to participate in non-covalent interactions, constitute the key step of molecular imprinting. Imprints possessing a permanent memory for the imprint species are formed, enabling the resultant polymer selectively to rebind the imprint molecule from a mixture of closely related compounds. Levels of binding affinity and selectivity typical of antibodies are achievable in the best cases. Several studies have focused on imprinted polymers being used as chiral stationary phases in liquid chromatography (LC) where the enantioselectivity of a given polymer is predetermined by the enantiomeric form of the templating ligand. The use of imprinted LC columns, however, is hampered by their poor chromatographic performance, evidenced by peak broadening and tailing. Being a more efficient chromatography technique, the use of Capillary Electrochromatography greatly improves the performance of imprinted polymer-based separations. The most successful approach utilises Capillary columns filled with a monolithic, superporous imprinted polymer obtained by an in situ photo-initiated polymerisation process. This technique enables imprint-based separation systems to be operational within 3 h from the start of Capillary preparation. Enantiomer separations with baseline resolution have been carried out in less than 2 min. Other approaches to Capillary Electrochromatography (CEC) and Capillary electrophoresis (CE) involve immobilisation of imprinted polymer particles inside capillaries using a polyacrylamide gel, the use of imprinted particles as a chiral mobile phase additive and the use of an imprinted polymer prepared by a dispersion polymerisation process.
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Capillary Electrochromatography with molecular imprint based selectivity for enantiomer separation of local anaesthetics
Journal of Chromatography A, 1997Co-Authors: Leif Schweitz, Lars I Andersson, Staffan NilssonAbstract:Abstract Preparation of stationary phases of predetermined selectivity for use in Capillary Electrochromatography by molecular imprinting was studied. Molecular imprinting of the local anaesthetic (S)-ropivacaine in methacrylate-type polymers was done using an in situ photo-initiated polymerisation process. Such stationary phases could separate the enantiomers of ropivacaine and the enantiomers of the structural analogues mepivacaine and bupivacaine. The influence of several parameters on the ability of the resultant imprinted Capillary column to resolve rac-ropivacaine was investigated. These parameters included the type and amount of functional and cross-linking monomers, the molar ratio of the imprint molecule to the monomers and the type of the porogen. The polymer-based, monolithic Capillary columns could be rendered super-porous by the use of 1–25% isooctane as a porogenic agent. The best resolution was obtained for polymers made using trimethylolpropane trimethacrylate as the cross-linking monomer. The enantiomer separation increased with increasing molar ratio of the functional monomer methacrylic acid to (S)-ropivacaine, however, at the expense of peak broadening. Initial studies on the optimisation of the electrolyte composition showed that the separation increased for electrolytes as the volume ratio of acetonitrile to buffer increased, the temperature raised and the pH became higher.
Xingguo Chen - One of the best experts on this subject based on the ideXlab platform.
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synthesis of novel chiral da td covalent organic framework for open tubular Capillary Electrochromatography enantioseparation
Chemical Communications, 2021Co-Authors: Guoxiu Wang, Hongli Chen, Congjie Pan, Xingguo ChenAbstract:Herein, a novel chiral covalent organic framework, DA-TD COF, with good chemical/thermal stability was synthesized and used as chiral stationary phase for open-tubular Capillary Electrochromatography enantioseparation. The DA-TD COF coated Capillary exhibited excellent enantioseparation efficiency and the separation efficiency did not reveal an obvious decrease over 200 runs. Furthermore, the enantioseparation mechanism was studied.
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separation of small organic molecules using covalent organic frameworks lzu1 as stationary phase by open tubular Capillary Electrochromatography
Journal of Chromatography A, 2016Co-Authors: Xiaoying Niu, Sanyuan Ding, Weifeng Wang, Hongli Chen, Xingguo ChenAbstract:Covalent organic frameworks (COFs) have attracted much attention because of their permanent nanoscale porosity and higher surface area compared to zeolites as well as robustness. COFs have great potential in several fields such as hydrogen storage, gas separation, and catalysis. However, COFs have not yet been applied in Capillary Electrochromatography. Herein, covalent organic frameworks-LZU1 (COF-LZU1) was used as the stationary phase in open-tubular Capillary Electrochromatography for the first time. Compared to the monoliths used in Electrochromatography, the preparation technique of a COF-LZU1-coated Capillary was simple and practical. The baseline separation of model analytes including alkylbenzenes, polyaromatic hydrocarbons, and anilines by the COF-LZU1-coated Capillary was achieved based on the size selectivity of COF-LZU1 porous structure and hydrophobic interactions between the model analytes and organic ligands of COF-LZU1. The load capacity of the COF-LZU1-coated Capillary for naphthalene was 0.6mg/mL. For three consecutive runs, the intraday relative standard deviations (RSDs) were 1.4-2.6% for the migration time and 2.7-8.7% for the peak area. The interday RSDs were 1.3-3.9% for the migration time and 3.7-9.7% for the peak area. The column-to-column reproducibility of migration time was in the range 1.0-3.9%. Moreover, the coated Capillary was used for >300 runs with no changes in the separation efficiency. Thus, COFs have great potential in Capillary Electrochromatography and may provide a new method for chromatographic separation.
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in situ synthesis of homochiral metal organic framework in Capillary column for Capillary Electrochromatography enantioseparation
Journal of Chromatography A, 2015Co-Authors: Congjie Pan, Weifeng Wang, Huige Zhang, Xingguo ChenAbstract:Homochiral metal-organic frameworks (MOFs) are promising as porous stationary phase for open-tubular Capillary Electrochromatography (OT-CEC) enantioseparation owing to their fine-tuned pore sizes and large surface areas. In this work, the homochiral MOF AlaZnCl was successfully coated on the inner wall of fused silica Capillary by an in situ, layer-by-layer self-assembly approach at room temperature. The results of scanning electron microscopy (SEM), X-ray diffraction (XRD), streaming potential (SP) and Fourier-transform infrared spectroscopy (FT-IR) indicated that the homochiral MOF AlaZnCl was successfully coated on the Capillary inner wall. To evaluate the performance of the homochiral MOF AlaZnCl coated Capillary column, the enantioseparation was carried out by using six amine drugs and monoamine neurotransmitters as model analytes and excellent enantioseparation efficiency was achieved. Run-to-run, day-to-day, and column-to-column relative standard deviations (RSDs) were all less than 5%. Moreover, the separation efficiency of the homochiral MOF AlaZnCl coated Capillary column did not decrease obviously over 100 runs.
Jean M J Frechet - One of the best experts on this subject based on the ideXlab platform.
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development and application of polymeric monolithic stationary phases for Capillary Electrochromatography
Journal of Chromatography A, 2004Co-Authors: Emily F Hilder, Frantisek Svec, Jean M J FrechetAbstract:Monolithic columns for Capillary Electrochromatography are receiving quite remarkable attention. This review summarizes results excerpted from numerous papers concerning this rapidly growing area with a focus on monoliths prepared from synthetic polymers. Both the simplicity of the in situ preparation and the large number of readily available chemistries make the monolithic separation media a vital alternative to Capillary columns packed with particulate materials. Therefore, they are now a well-established stationary phase format in the field of Capillary Electrochromatography. A wide variety of synthetic approaches as well as materials used for the preparation of the monolithic stationary phases are presented in detail. The analytical potential of these columns is demonstrated with separations involving various families of compounds and different chromatographic modes.
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design of the monolithic polymers used in Capillary Electrochromatography columns
Journal of Chromatography A, 2000Co-Authors: Frantisek Svec, Eric C Peters, David Sýkora, Jean M J FrechetAbstract:Monolithic columns for Capillary Electrochromatography (CEC) are receiving quite remarkable attention. Both the simplicity of the in situ preparation and the large number of readily available chemistries make the monolithic separation media a vital alternative to Capillary columns packed with particulate materials. This review summarizes the current state-of-the-art in this rapidly growing area of CEC with a focus on monolithic Capillary columns prepared from synthetic polymers. Recent achievements in column technologies for both high-performance liquid chromatography and Capillary electrophoresis are used as the starting point to highlight the influence of these well established analytical methods on the development of monolithic Capillary columns for CEC. The effects of individual variables on the separation properties of monolithic capillaries are discussed in detail. The analytical potential of these columns is demonstrated with separations involving various families of compounds in different chromatographic modes.
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monolithic stationary phases for Capillary Electrochromatography based on synthetic polymers designs and applications
Hrc-journal of High Resolution Chromatography, 2000Co-Authors: Frantisek Svec, Eric C Peters, David Sýkora, Jean M J FrechetAbstract:Monolithic materials have quickly become a well-established stationary phase format in the field of Capillary Electrochromatography (CEC). Both the simplicity of their in situ preparation method and the large variety of readily available chemistries make the monolithic separation media an attractive alternative to Capillary columns packed with particulate materials. This review summarizes the contributions of numerous groups working in this rapidly growing area, with a focus on monolithic Capillary columns prepared from synthetic polymers. Various approaches employed for the preparation of the monoliths are detailed, and where available, the material properties of the resulting monolithic Capillary columns are shown. Their chromatographic performance is demonstrated by numerous separations of different analyte mixtures in variety of modes. Although detailed studies of the effect of polymer properties on the analytical performance of monolithic capillaries remain scarce at this early stage of their development, this review also discusses some important relationships such as the effect of pore size on the separation performance in more detail.
Frantisek Svec - One of the best experts on this subject based on the ideXlab platform.
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recent developments in the field of monolithic stationary phases for Capillary Electrochromatography
Journal of Separation Science, 2005Co-Authors: Frantisek SvecAbstract:This review summarizes the contributions to the rapidly growing area of monolithic columns based on both silica and synthetic polymers for Capillary Electrochromatography and chip Electrochromatography, with a focus on those published during the year 2004. A wide variety of both modified approaches to the "old" monoliths and new monoliths have been reported despite the very short period of time covered. This demonstrates that monolithic stationary phases have become a well-established format in the field of Electrochromatography. The simplicity of their preparation as well as the good control over their porous properties and surface chemistries make the monolithic separation media an attractive alternative to Capillary columns packed with particulate materials.
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development and application of polymeric monolithic stationary phases for Capillary Electrochromatography
Journal of Chromatography A, 2004Co-Authors: Emily F Hilder, Frantisek Svec, Jean M J FrechetAbstract:Monolithic columns for Capillary Electrochromatography are receiving quite remarkable attention. This review summarizes results excerpted from numerous papers concerning this rapidly growing area with a focus on monoliths prepared from synthetic polymers. Both the simplicity of the in situ preparation and the large number of readily available chemistries make the monolithic separation media a vital alternative to Capillary columns packed with particulate materials. Therefore, they are now a well-established stationary phase format in the field of Capillary Electrochromatography. A wide variety of synthetic approaches as well as materials used for the preparation of the monolithic stationary phases are presented in detail. The analytical potential of these columns is demonstrated with separations involving various families of compounds and different chromatographic modes.
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design of the monolithic polymers used in Capillary Electrochromatography columns
Journal of Chromatography A, 2000Co-Authors: Frantisek Svec, Eric C Peters, David Sýkora, Jean M J FrechetAbstract:Monolithic columns for Capillary Electrochromatography (CEC) are receiving quite remarkable attention. Both the simplicity of the in situ preparation and the large number of readily available chemistries make the monolithic separation media a vital alternative to Capillary columns packed with particulate materials. This review summarizes the current state-of-the-art in this rapidly growing area of CEC with a focus on monolithic Capillary columns prepared from synthetic polymers. Recent achievements in column technologies for both high-performance liquid chromatography and Capillary electrophoresis are used as the starting point to highlight the influence of these well established analytical methods on the development of monolithic Capillary columns for CEC. The effects of individual variables on the separation properties of monolithic capillaries are discussed in detail. The analytical potential of these columns is demonstrated with separations involving various families of compounds in different chromatographic modes.
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monolithic stationary phases for Capillary Electrochromatography based on synthetic polymers designs and applications
Hrc-journal of High Resolution Chromatography, 2000Co-Authors: Frantisek Svec, Eric C Peters, David Sýkora, Jean M J FrechetAbstract:Monolithic materials have quickly become a well-established stationary phase format in the field of Capillary Electrochromatography (CEC). Both the simplicity of their in situ preparation method and the large variety of readily available chemistries make the monolithic separation media an attractive alternative to Capillary columns packed with particulate materials. This review summarizes the contributions of numerous groups working in this rapidly growing area, with a focus on monolithic Capillary columns prepared from synthetic polymers. Various approaches employed for the preparation of the monoliths are detailed, and where available, the material properties of the resulting monolithic Capillary columns are shown. Their chromatographic performance is demonstrated by numerous separations of different analyte mixtures in variety of modes. Although detailed studies of the effect of polymer properties on the analytical performance of monolithic capillaries remain scarce at this early stage of their development, this review also discusses some important relationships such as the effect of pore size on the separation performance in more detail.
Jeremy D Glennon - One of the best experts on this subject based on the ideXlab platform.
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gold nanoparticle modified etched capillaries for open tubular Capillary Electrochromatography
Analytical Chemistry, 2005Co-Authors: Li Yang, Elizabeth Guihen, Justin D Holmes, Michael Loughran, Gerard P Osullivan, Jeremy D GlennonAbstract:The use of gold nanoparticles in conjunction with etched Capillary-based open-tubular Capillary Electrochromatography (OTCEC) to improve the efficiency of separation and the selectivity between selected solutes is described. The fused-silica capillaries (50-μm i.d.) were etched with ammonium hydrogen difluoride, followed by prederivatization of the new surface with (3-mercaptopropyl)trimethoxysilane (MPTMS) for the immobilization of dodecanethiol gold nanoparticles, for OTCEC. The Electrochromatography of a “reversed-phase” test mixture and of selected polycylic aromatic hydrocarbons was investigated, and efficient separations and high theoretical plate numbers per meter were obtained. The electroosmotic flow characteristics of the etched gold nanoparticle Capillary, unetched gold nanoparticle Capillary, bare Capillary, and etched bare Capillary were studied by varying the percentage of organic modifier in buffer, buffer pH, and separation voltage. Optical microscopy and scanning electron microscopy were ...
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recent highlights in stationary phase design for open tubular Capillary Electrochromatography
Journal of Chromatography A, 2004Co-Authors: Elizabeth Guihen, Jeremy D GlennonAbstract:This review examines the most recent innovations made to achieve high performance in open-tubular Capillary Electrochromatography (OT-CEC) separations, focusing on the ingenious chemical and physical solutions made to increase the surface area and equip the stationary phase with exploitable selectivity. Among the approaches taken are chemically bonded ligands, etching with chemical bonding, sol-gels, molecularly imprinted polymers, porous layers, physically attached or adsorbed phases, and nanoparticle coatings. Particularly noteworthy are modern developments with macrocyclic receptor ligands, nanoparticles and open channel Electrochromatography on-chip.
