1
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Ladner Y, Crétier G, Faure K. Fabrication of acrylate monolith using photopolymerization: Effect of light intensity on electrochromatographic performance. J Sep Sci 2012; 35:1940-4. [DOI: 10.1002/jssc.201200165] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
| | | | - Karine Faure
- Université de Lyon; Institut des Sciences Analytiques (UMR 5280 Université Lyon 1 / CNRS); Domaine scientifique de La Doua; Villeurbanne Cedex France
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2
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Puangpila C, Nhujak T, Rassi ZE. Investigation of neutral monolithic capillary columns with varying n-alkyl chain lengths in capillary electrochromatography. Electrophoresis 2012; 33:1431-42. [DOI: 10.1002/elps.201200018] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
| | - Thumnoon Nhujak
- Chromatography and Separation Research Unit; Department of Chemistry; Faculty of Science; Chulalongkorn University; Bangkok; Thailand
| | - Ziad El Rassi
- Department of Chemistry; Oklahoma State University; OKlahoma
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3
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Hybrid monolithic columns with nanoparticles incorporated for capillary electrochromatography. J Chromatogr A 2012; 1239:64-71. [DOI: 10.1016/j.chroma.2012.03.065] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2011] [Revised: 02/24/2012] [Accepted: 03/20/2012] [Indexed: 11/21/2022]
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4
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Karenga S, El Rassi Z. A novel, neutral hydroxylated octadecyl acrylate monolith with fast electroosmotic flow velocity and its application to the separation of various solutes including peptides and proteins in the absence of electrostatic interactions. Electrophoresis 2012; 31:3192-9. [PMID: 22216430 DOI: 10.1002/elps.201000360] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
A neutral hydroxylated octadecyl monolith (ODM-OH) for reversed-phase capillary electrochromatography has been developed. The ODM-OH was prepared by the in situ polymerization of octadecyl acrylate and pentaerythritol triacrylate (PETA) in a ternary porogenic solvent. Pentaerythritol triacrylate possesses a hydroxyl functional group, which imparts the monolith with a hydrophilic group, thus the acronym ODM-OH. The ODM-OH column exhibited cathodal EOF over a wide range of pH and ACN concentration in the mobile phase despite the fact that it was devoid of any fixed charges. This ODM-OH monolith exhibited stronger EOF than its counterpart the ODM made from the in situ polymerization of octadecyl acrylate and trimethylolpropane trimethacrylate. Similar to ODM, it is believed that the EOF was due to the adsorption of ions from the mobile phase onto the surface of the monolith thus imparting the neutral monolithic column the zeta potential necessary to support the EOF. The higher EOF exhibited by ODM-OH was due to the presence of polar OH groups on its surface, which would favor stronger adsorption of ions from the mobile phase. The wide applications of the neutral ODM-OH column were demonstrated in the separation of a wide range of small and large solutes. As a typical result, the ODM-OH was able to separate proteins quite rapidly yielding 200,000 plates/m.
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Affiliation(s)
- Samuel Karenga
- Department of Chemistry, Oklahoma State University, Stillwater, OK 74075, USA
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5
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Cakal C, Ferrance JP, Landers JP, Caglar P. Microchip extraction of catecholamines using a boronic acid functional affinity monolith. Anal Chim Acta 2011; 690:94-100. [DOI: 10.1016/j.aca.2011.02.009] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2010] [Revised: 01/29/2011] [Accepted: 02/02/2011] [Indexed: 11/24/2022]
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6
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Turson M, Zhou M, Jiang P, Dong X. Monolithic poly(ethylhexyl methacrylate-co
-ethylene dimethacrylate) column with restricted access layers prepared via
reversible addition-fragmentation chain transfer polymerization. J Sep Sci 2011; 34:127-34. [DOI: 10.1002/jssc.201000255] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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7
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Karenga S, El Rassi Z. Trends in nonpolar polymer-based monolithic columns for reversed-phase capillary electrochromatography. Electrophoresis 2010; 32:90-104. [PMID: 21171116 DOI: 10.1002/elps.201000490] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2010] [Revised: 09/30/2010] [Accepted: 10/05/2010] [Indexed: 11/11/2022]
Abstract
This review article is concerned with describing the various strategies that have been introduced for the preparation of nonpolar polymer-based monolithic columns for RP-CEC. First, the various traditional ways of generating the EOF that involved the introduction of fixed charges on the surface of the monoliths are reviewed. This is followed by a description of the development of neutral monoliths as the most promising monoliths for the separation of a wide range of neutral and charged species at a relatively moderate to strong EOF in the absence of electrostatic attraction or repulsion.
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Affiliation(s)
- Samuel Karenga
- Department of Chemistry, Oklahoma State University, Stillwater, OK, USA
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8
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Zhang YP, Chen N, Gong WJ, Yang SK. A Simple Method to Prepare Methacrylate-Based Capillary Monolithic Column Using Microwave Irradiation. J CHIN CHEM SOC-TAIP 2010. [DOI: 10.1002/jccs.201000088] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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9
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Lin J, Lin J, Lin X, Wu X, Xie Z. Preparation of a neutral porous monolith and its evaluation in pressurized capillary electrochromatography with neutral and charged solutes. Electrophoresis 2010; 31:1674-80. [DOI: 10.1002/elps.200900669] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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10
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CHOODUM A, THAVARUNGKUL P, KANATHARANA P, SMITH NW. Ecstasy Analysis by Monolithic Materials-Capillary Electrochromatography. ANAL SCI 2009; 25:517-22. [DOI: 10.2116/analsci.25.517] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Aree CHOODUM
- Trace Analysis and Biosensor Research Center, Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Prince of Songkla University
| | - Panote THAVARUNGKUL
- Trace Analysis and Biosensor Research Center, Department of Physics, Faculty of Science, Prince of Songkla University
| | - Proespichaya KANATHARANA
- Trace Analysis and Biosensor Research Center, Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Prince of Songkla University
| | - Norman W. SMITH
- Micro Separations Group, Pharmaceutical Science Research Division, King's College, London
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11
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Fan LQ, Zhang YP, Ye XW, Zhang YJ, Li B, Lee KP. Rapid Preparation of Monolithic Silica Column for Electrophoretic and Chromatographic Separation by Microwave Irradiation. J LIQ CHROMATOGR R T 2008. [DOI: 10.1080/10826070802548606] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
- Li Qun Fan
- a Henan Institute of Science and Technology , Xinxiang, P. R. China
| | - Yu Ping Zhang
- a Henan Institute of Science and Technology , Xinxiang, P. R. China
| | - Xiong Wen Ye
- a Henan Institute of Science and Technology , Xinxiang, P. R. China
| | - Yi Jun Zhang
- a Henan Institute of Science and Technology , Xinxiang, P. R. China
| | - Bo Li
- a Henan Institute of Science and Technology , Xinxiang, P. R. China
| | - Kwang Pill Lee
- b Department of Chemistry , Graduate School, Kyungpook National University , South Korea
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12
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Karenga S, El Rassi Z. Neutral octadecyl monolith for reversed phase capillary electrochromatography of a wide range of solutes. J Sep Sci 2008; 31:2677-85. [PMID: 18693309 DOI: 10.1002/jssc.200800310] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
A neutral octadecyl monolithic (ODM) column for RP capillary electrochromatography (RP-CEC) has been developed. The ODM column was prepared by the in situ polymerization of octadecyl acrylate (ODA) as the monomer and trimethylolpropanetrimethacrylate (TRIM) as the crosslinker, in a ternary porogenic solvent containing cyclohexanol, ethylene glycol, and water. The ODM column exhibited cathodal EOF over a wide range of pH and ACN concentration in the mobile phase despite the fact that it was devoid of any fixed charges. It is believed that the EOF is due to the adsorption of ions from the mobile phase onto the surface of the monolith thus imparting to the neutral ODM column the zeta potential necessary to support the EOF required for mass transport across the monolithic column. Furthermore, the adsorption of mobile phase ions to the neutral monolith modulated solute retention and affected the separation selectivity. The wide applications of the neutral ODM column were demonstrated by its ability to separate a wide range of small and large solutes, both neutral and charged. While the separation of the neutral solutes was based on RP retention mechanism, the charged solutes were separated on the basis of their electrophoretic mobility and hydrophobic interaction with the C18 ligands of the stationary phase. As a typical result, the neutral monolithic column was able to separate peptides quite rapidly with a separation efficiency of nearly 200,000 plates/m, and this efficiency was exploited in tryptic peptide mapping of standard proteins, e. g., lysozyme and cytochrome C, by isocratic elution.
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Affiliation(s)
- Samuel Karenga
- Department of Chemistry, Oklahoma State University, OK 74075, USA
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13
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Cantó‐Mirapeix A, Herrero‐Martínez JM, Mongay‐Fernández C, Simó‐Alfonso EF. Preparation and characterization of hexyl methacrylate monolithic columns for CEC. Electrophoresis 2008; 29:3866-74. [DOI: 10.1002/elps.200800154] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Amparo Cantó‐Mirapeix
- Department of Analytical Chemistry, Faculty of Chemistry, University of Valencia, Valencia, Spain
| | - José M. Herrero‐Martínez
- Department of Analytical Chemistry, Faculty of Chemistry, University of Valencia, Valencia, Spain
| | - Carlos Mongay‐Fernández
- Department of Analytical Chemistry, Faculty of Chemistry, University of Valencia, Valencia, Spain
| | - Ernesto F. Simó‐Alfonso
- Department of Analytical Chemistry, Faculty of Chemistry, University of Valencia, Valencia, Spain
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14
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Urban J, Jandera P. Polymethacrylate monolithic columns for capillary liquid chromatography. J Sep Sci 2008; 31:2521-40. [DOI: 10.1002/jssc.200800182] [Citation(s) in RCA: 112] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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15
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Cantó-Mirapeix A, Herrero-Martínez JM, Benavente D, Mongay-Fernández C, Simó-Alfonso EF. Peroxodisulfate as a chemical initiator for methacrylate-ester monolithic columns for capillary electrochromatography. Electrophoresis 2008; 29:910-8. [PMID: 18213597 DOI: 10.1002/elps.200700458] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Organic monolithic stationary phases for CEC were synthesized in situ in fused-silica capillaries. Polymerization mixtures were composed of butyl methacrylate, ethylene dimethacrylate, and [2-(methacryloyloxy)ethyl]trimethyl ammonium chloride in the presence of a porogenic solvent, using ammonium peroxodisulfate as chemical initiator, and N,N,N',N'-tetramethylethylenediamine to activate the reaction. The influence of the amount of initiator, temperature, and composition of porogenic solvent on the physical and chromatographic properties of monolithic stationary phases has been investigated. A minimum plate height of 14.5 microm was obtained at 18 wt% of 1,4-butanediol in the polymerization mixture. The produced monolithic stationary phases exhibited a good repeatability and batch-to-batch and mixture-to-mixture reproducibility, with RSD values below 5.6% in the electrochromatographic parameters studied. A comparison with columns prepared by thermal initiation with alpha,alpha'-azobisisobutyronitrile (AIBN) was also performed. The most efficient column initiated with peroxodisulfate showed better efficiencies and selectivities than that prepared with AIBN at the same composition mixture.
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Affiliation(s)
- Amparo Cantó-Mirapeix
- Department of Analytical Chemistry, Faculty of Chemistry, University of Valencia, Valencia, Spain
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16
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Characterization of polymer-based monolithic capillary columns by inverse size-exclusion chromatography and mercury-intrusion porosimetry. J Chromatogr A 2008; 1182:161-8. [DOI: 10.1016/j.chroma.2008.01.006] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2007] [Revised: 12/24/2007] [Accepted: 01/04/2008] [Indexed: 11/19/2022]
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17
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Thabano JR, Breadmore MC, Hutchinson JP, Johns C, Haddad PR. Capillary electrophoresis of neurotransmitters using in-line solid-phase extraction and preconcentration using a methacrylate-based weak cation-exchange monolithic stationary phase and a pH step gradient. J Chromatogr A 2007; 1175:117-26. [DOI: 10.1016/j.chroma.2007.09.069] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2007] [Revised: 09/17/2007] [Accepted: 09/25/2007] [Indexed: 10/22/2022]
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18
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Urban J, Moravcová D, Jandera P. A model of flow-through pore formation in methacrylate ester-based monolithic columns. J Sep Sci 2007; 29:1064-73. [PMID: 16830720 DOI: 10.1002/jssc.200500457] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The main factors affecting the porosity of methacrylate-ester based monolithic columns were investigated. We prepared 23 monolithic capillary columns with porosity controlled by varying the proportions of butyl methacrylate and ethylene dimethacrylate monomers and of 1,4-butanediol and 1-propanol as the porogen solvent in the polymerization mixtures by thermally initiated in-situ polymerization in fused-silica capillaries. Using mixture design software, we systematically varied the composition of the polymerisation mixtures to find significant factors affecting flow-through pore formation. Multivariate analysis of the experimental data obtained for the fabricated columns yielded a model for prediction of the flow-through porosity in monolithic beds as a function of the composition of the polymerization mixture used to prepare polymethacrylate monolithic capillary columns. The mean error of prediction was lower than 8% for eight columns prepared independently of the original set of 15 columns used to derive the flow-through model. The flow-through porosity increases with increasing concentration of the binary porogen solvent mixture, the concentration of 1,4-butanediol being the main factor enhancing flow-through pore formation. On the other hand, increasing concentrations of the hydrophobic monomer butyl methacrylate and increasing concentrations of 1-propanol have a negative effect on flow-through pore formation. The capillary columns prepared with a high proportion of flow-through pores and a minimum amount of mesopores can be used for fast gradient separations of both low-molecular weight compounds and biopolymers.
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Affiliation(s)
- Jirí Urban
- Department of Analytical Chemistry, University of Pardubice, Czech Republic
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19
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Urban J, Jandera P, Schoenmakers P. Preparation of monolithic columns with target mesopore-size distribution for potential use in size-exclusion chromatography. J Chromatogr A 2007; 1150:279-89. [PMID: 17049537 DOI: 10.1016/j.chroma.2006.09.065] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2006] [Revised: 09/04/2006] [Accepted: 09/08/2006] [Indexed: 11/19/2022]
Abstract
The main factors affecting the mesopore porosity of methacrylate-ester based monolithic columns were investigated. We prepared 40 monolithic capillary columns with porosity controlled by varying the proportions of butyl methacrylate (BMA) and ethylene dimethacrylate (EDMA) monomers and of 1,4-butanediol (BUT) and 1-propanol (PROP) as the porogen solvent in the polymerisation mixtures by thermally initiated in situ polymerisation in fused-silica capillaries. Using mixture design software, we systematically varied the composition of the polymerisation mixtures to find significant factors affecting mesopore formation. Multivariate analysis of the experimental data obtained for the fabricated columns yielded a model for prediction of the mesopore porosity in monolithic beds as a function of the composition of the polymerisation mixture used to prepare polymethacrylate monolithic capillary columns. The mean absolute deviation of predicted porosities is 0.029 for most of the columns, with only eight columns showing deviations exceeding 0.050. The main factor affecting the mesopore porosity proved to be the combination of the concentration of hydrophobic monomer (BMA) and the concentration of the less-polar solvent, 1-propanol, in the porogen mixture. The proportion of mesopores in the monolithic capillary columns increases with increasing concentration of 1-propanol and with decreasing concentration ratios of the cross-linker (EDMA) to monomer (BMA) and of BUT to PROP porogenic solvents.
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Affiliation(s)
- Jirí Urban
- Department of Analytical Chemistry, University of Pardubice, Czech Republic
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20
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Zhang YP, Fan LQ, Lee KP, Zhang YJ, Choi SH, Gong WJ. Preparation of monolithic capillary columns for capillary electrochromatography by γ-ray irradiation. Mikrochim Acta 2006. [DOI: 10.1007/s00604-006-0694-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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21
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Stulík K, Pacáková V, Suchánková J, Coufal P. Monolithic organic polymeric columns for capillary liquid chromatography and electrochromatography. J Chromatogr B Analyt Technol Biomed Life Sci 2006; 841:79-87. [PMID: 16714153 DOI: 10.1016/j.jchromb.2006.04.016] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2006] [Revised: 04/13/2006] [Accepted: 04/20/2006] [Indexed: 11/30/2022]
Abstract
This review briefly summarizes the present state of the preparation and use of capillary monolithic columns for liquid chromatography (LC) and electrochromatography (EC). Most important approaches to the preparation of monolithic stationary phases based on organic polymers are outlined and the properties of the monoliths obtained are compared with those of classical particulate phases. A few selected applications of monolithic columns are shown to demonstrate the most important advantages of monolithic capillary columns. It is concluded that both the monolithic and particulate capillary columns are important and that judicious choice of the type suitable for a particular application requires careful consideration of the purpose of the separation and the properties of the solutes to be separated. Monolithic columns are substantially younger than packed ones and thus will require further theoretical and experimental study to further improve their preparation and to enable reliable prediction of their properties and applicability; nevertheless, they are very promising for the future.
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Affiliation(s)
- Karel Stulík
- Department of Analytical Chemistry, Charles University, Hlavova 2030, 128 40 Prague 2, Czech Republic
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22
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Jandera P, Urban J, Moravcová D. Polymetacrylate and hybrid interparticle monolithic columns for fast separations of proteins by capillary liquid chromatography. J Chromatogr A 2006; 1109:60-73. [PMID: 16183070 DOI: 10.1016/j.chroma.2005.08.085] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2005] [Revised: 08/22/2005] [Accepted: 08/29/2005] [Indexed: 11/17/2022]
Abstract
Preparation of organic polymer monolithic columns in fused silica capillaries was aimed at fast gradient separation of proteins. For this purpose, polymerization in situ procedure was optimized, using ethylene dimetacrylate and butyl metacrylate monomers with azobisisobutyronitrile as initiator of the polymerization reaction in presence of non-aqueous porogen solvent mixtures composed of 1-propanol and 1,4-butanediol. The separation of proteins in totally monolithic capillary columns was compared with the chromatography on a new type of "hybrid interparticle monolithic" capillary columns, prepared by in situ polymerization in capillary packed with superficially porous spherical beds, 37-50 microm. The "hybrid" columns showed excellent stability and improved hydrodynamic flow properties with respect to the "totally" monolithic capillary columns. The separation selectivity is similar in the two types of columns. The nature of the superficially porous layer (bare silica or bonded C18 ligands) affects the separation selectivity less significantly than the porosity (density) of the monolithic moiety in the interparticle space, controlled by the composition of the polymerization mixture. The retention behaviour of proteins on all prepared columns is consistent with the reversed-phase gradient elution theory.
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Affiliation(s)
- Pavel Jandera
- Department of Analytical Chemistry, Faculty of Chemical Technology, University of Pardubice, Nam. Cs. Legii 565, 532 10 Pardubice, Czech Republic.
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23
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Courtois J, Szumski M, Byström E, Iwasiewicz A, Shchukarev A, Irgum K. A study of surface modification and anchoring techniques used in the preparation of monolithic microcolumns in fused silica capillaries. J Sep Sci 2006; 29:14-24. [PMID: 16485705 DOI: 10.1002/jssc.200500294] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Based on a survey of the literature on pretreatment of fused silica capillaries, 3 etching procedures and 11 silanization protocols based on the vinylic silane 3-((trimethoxysilyl)propyl) methacrylate (gamma-MAPS) were found to be most representative as a means of ensuring attachment of in situ prepared vinylic polymers. These techniques were applied to fused silica capillaries and the success in establishing the intended surface modification was assessed. X-ray photoelectron spectroscopy (XPS) was used to characterize the chemical state of the surface, providing information regarding presence of the reagent bound to the capillary. Wetting angles were measured and correlated with the XPS results. An adherence test was done by photopolymerization of a 2 mm long plug of 1,6-butanediol dimethacrylate in the prepared capillaries and evaluation of its ability to withstand applied hydraulic pressure. SEM was also performed in cases where the plug was released or other irregularities were observed. Finally, the roughness of the etched surface, considered to be of importance, was assessed by atomic force microscopy. Alkaline etching at elevated temperature provided a surface roughness promoting adhesion. The commonly used silanization protocols involving water in the silanization or washing steps gave inadequate surface treatment. The best silanization procedure was based on toluene as a solvent.
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24
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Okanda FM, El Rassi Z. Capillary electrochromatography with monolithic stationary phases. 4. Preparation of neutral stearyl-acrylate monoliths and their evaluation in capillary electrochromatography of neutral and charged small species as well as peptides and proteins. Electrophoresis 2005; 26:1988-95. [PMID: 15841500 DOI: 10.1002/elps.200500073] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
A neutral, nonpolar monolithic capillary column having a relatively strong electroosmotic flow (EOF) yet free of electrostatic interactions with charged solutes was developed for the reversed-phase capillary electrochromatography (RP-CEC) of neutral and charged species including peptides and proteins. The neutral nonpolar monolith is based on the in situ polymerization of pentaerythritol diacrylate monostearate (PEDAS) in a ternary porogenic solvent composed of cyclohexanol, ethylene glycol, and water. PEDAS plays the role of both the cross-linker and the ligand provider, generating a macroporous nonpolar monolith having C17 chains as the chromatographic ligands. Despite the fact that the neutral PEDAS monolith is devoid of fixed charges, the monolithic capillary columns exhibited a relatively strong EOF due to the ability of PEDAS to adsorb sufficient amounts of electrolyte ions from the mobile phase. The adsorbed ions imparted the neutral PEDAS monolith the zeta potential necessary to support the EOF required for mass transport across the monolithic column. The absence of fixed charges on the surface of the neutral PEDAS monolith and in turn the adsorption sites for electrostatic attraction of charged solutes allowed the rapid and efficient separations of proteins and peptides at pH 7.0, with an average plate number of 255,000 and 121,000 plates/m, respectively. To the best of our knowledge, this constitutes the first report on the separation of proteins at neutral pH by RP-CEC using a neutral monolithic column.
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Affiliation(s)
- Fred M Okanda
- Department of Chemistry, Oklahoma State University, Stillwater, OK 74078-3071, USA
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25
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Bedair M, El Rassi Z. Recent advances in polymeric monolithic stationary phases for electrochromatography in capillaries and chips. Electrophoresis 2004; 25:4110-9. [PMID: 15597411 DOI: 10.1002/elps.200406136] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
This review article summarizes the advances made over the last two years in polymeric monoliths for capillary electrochromatography (CEC). It covers the scientific literature in the period extending form the second half of 2002 until the end of first half of 2004. Currently, there is an increasing interest in monolithic stationary phases in CEC as an alternative to particulate packed capillary columns due in major part to the simplicity of the in situ preparation of monolithic stationary phases and the availability of a wide chemistry for surface ligands, which allow for tailoring the chromatographic sorbent needed for solving a given separation problem(s). The various approaches, formats, and chemistries used for the preparation of monolithic stationary phases are described.
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Affiliation(s)
- Mohamed Bedair
- Department of Chemistry, Oklahoma State University, Stillwater, OK 74078-3071, USA
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26
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Hilder EF, Svec F, Fréchet JMJ. Development and application of polymeric monolithic stationary phases for capillary electrochromatography. J Chromatogr A 2004; 1044:3-22. [PMID: 15354426 DOI: 10.1016/j.chroma.2004.04.057] [Citation(s) in RCA: 191] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
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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Affiliation(s)
- Emily F Hilder
- EO Lawrence Berkeley National Laboratory, Materials Sciences Division, Berkeley, CA 94720, USA
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Holdšvendová P, Coufal P, Suchánková J, Tesařová E, Bosáková Z. Methacrylate monolithic columns for capillary liquid chromatography polymerized using ammonium peroxodisulfate as initiator. J Sep Sci 2003. [DOI: 10.1002/jssc.200301564] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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