1
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Gong X, Chen W, Zhang K, Li T, Song Q. Serially coupled column liquid chromatography: An alternative separation tool. J Chromatogr A 2023; 1706:464278. [PMID: 37572536 DOI: 10.1016/j.chroma.2023.464278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 07/20/2023] [Accepted: 08/02/2023] [Indexed: 08/14/2023]
Abstract
Despite the rapid development of liquid chromatography (LC) in recent decades, it remains a challenge to achieve the desired chromatographic separation of complex matrices using a single column. Multi-column LC techniques, particularly serially coupled column LC (SCC-LC), have emerged as a promising solution to overcome this challenge. While more attention has been focused on heart-cutting or comprehensive two-dimensional LC, reviews specifically focusing on SCC-LC, which offers advantages in terms of precision and facile instrumentation, are scarce. Here, our concerns are devoted to the progress summary regarding the instrumentation and applications of SCC-LC. Emphasis is placed on column selection aiming to enlarge peak capacity, selectivity, or both through the optimization of combination types (e.g. RPLC-RPLC, -RPLC-HILIC, and achiral-chiral LC), connection devices (e.g. zero dead volume connector, tubing, and T-type connector), elution program (i.e. isocratic or gradient) and detectors (e.g. mass spectrometer, ultraviolet detector, and fluorescence detector). The application of SCC-LC in pharmaceutical, biological, environmental, and food fields is also reviewed, and future perspectives and potential directions for SCC-LC are discussed. We envision that the review can give meaningful information to analytical scientists when facing heavy chromatographic separation tasks for complicated matrices.
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Affiliation(s)
- Xingcheng Gong
- School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing 102488, China
| | - Wei Chen
- School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing 102488, China
| | - Ke Zhang
- School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing 102488, China
| | - Ting Li
- School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing 102488, China
| | - Qingqing Song
- School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing 102488, China.
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2
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Zhong Z, Chu Z, Dong Z, Zhang W, Zhang L. The separation characteristics and performance evaluation of the silica-based poly(pentabromostyrene) stationary phase in capillary electrochromatography. ANALYTICAL METHODS : ADVANCING METHODS AND APPLICATIONS 2021; 13:5764-5771. [PMID: 34816827 DOI: 10.1039/d1ay01594j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
A mixed-mode capillary column packed with silica-based poly(pentabromostyrene) particles (denoted as SiO2@pPBS) was prepared and applied to capillary electrochromatography (CEC) separation. With the presence of benzene rings and bromine atoms in polymer chains, the SiO2@pPBS column provides a reversed-phase/hydrophilic mixed-mode retention mechanism owing to hydrophilic, hydrophobic and π-π interactions between the stationary phase and various analytes, including alkylbenzenes, polycyclic aromatic hydrocarbons, nucleosides, phenols and anilines. In CEC mode, the separation behavior of charged solutes is not only related to the interaction with the stationary phase, but also influenced by electrophoretic effects, which may lead to different selectivities compared to high performance liquid chromatography (HPLC). A column efficiency of up to 1.22 × 105 N m-1 was achieved for p-chloroaniline. Besides, the RSDs of retention time of anilines for run to run (n = 5), day to day (n = 5) and column to column (n = 3) were all less than 4.4%. Finally, the SiO2@pPBS capillary column was applied to the separation of coking wastewater with satisfactory results. All the results demonstrated that the SiO2@pPBS capillary packed column with RP/HILIC mixed-mode has great application potential.
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Affiliation(s)
- Zhihua Zhong
- Shanghai Key Laboratory of Functional Materials Chemistry, Department of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237, China.
| | - Zhanying Chu
- Technology Innovation Center of Mass Spectrometry for State Market Regulation, Center for Advanced Measurement Science, National Institute of Metrology, Beijing, 100029, PR China
| | - Ziyi Dong
- Shanghai Key Laboratory of Functional Materials Chemistry, Department of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237, China.
| | - Weibing Zhang
- Shanghai Key Laboratory of Functional Materials Chemistry, Department of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237, China.
| | - Lingyi Zhang
- Shanghai Key Laboratory of Functional Materials Chemistry, Department of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237, China.
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3
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Preparation of Cationic Mixed-Mode Acrylamide-Based Monolithic Stationary Phases for Capillary Electrochromatography. Chromatographia 2018. [DOI: 10.1007/s10337-018-3564-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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4
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Wang J, Ding C, Xiao J, Jia W, Chen Y, Lin X, Xie Z. Quinine-modified polymer monolithic column with reversed-phase /strong anion-exchange mixed-mode for pressurized capillary electrochromatography. Electrophoresis 2018; 39:1504-1511. [DOI: 10.1002/elps.201800003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2018] [Revised: 02/28/2018] [Accepted: 03/13/2018] [Indexed: 11/05/2022]
Affiliation(s)
- Jiabin Wang
- Institute of Food Safety and Environment Monitoring; Fuzhou University; Fuzhou P. R. China
- Institute of Biomedical and Pharmaceutical Technology; Fuzhou University; Fuzhou P. R. China
| | - Changying Ding
- Institute of Food Safety and Environment Monitoring; Fuzhou University; Fuzhou P. R. China
| | - Jianhua Xiao
- Institute of Biomedical and Pharmaceutical Technology; Fuzhou University; Fuzhou P. R. China
| | - Wenchao Jia
- Institute of Food Safety and Environment Monitoring; Fuzhou University; Fuzhou P. R. China
| | - Yongxuan Chen
- Fujian Inspection and Research Institute for product quality; National Center of Processed Foods Quality Supervision and Inspection; Fuzhou P. R. China
| | - Xucong Lin
- Institute of Food Safety and Environment Monitoring; Fuzhou University; Fuzhou P. R. China
| | - Zenghong Xie
- Institute of Food Safety and Environment Monitoring; Fuzhou University; Fuzhou P. R. China
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5
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Zhang K, Liu X. Reprint of “Mixed-mode chromatography in pharmaceutical and biopharmaceutical applications”. J Pharm Biomed Anal 2016; 130:19-34. [DOI: 10.1016/j.jpba.2016.09.013] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Revised: 05/04/2016] [Accepted: 05/05/2016] [Indexed: 01/31/2023]
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6
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Mixed-mode chromatography in pharmaceutical and biopharmaceutical applications. J Pharm Biomed Anal 2016; 128:73-88. [PMID: 27236100 DOI: 10.1016/j.jpba.2016.05.007] [Citation(s) in RCA: 114] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Revised: 05/04/2016] [Accepted: 05/05/2016] [Indexed: 01/19/2023]
Abstract
Mixed-mode chromatography (MMC) is a fast growing area in recent years, thanks to the new generation of mixed-mode stationary phases and better understanding of multimode interactions. MMC has superior applications in the separation of compounds that are not retained or not well resolved by typical reversed-phase LC methods, especially for polar and charged molecules. Due to the multiple retention modes that a single MMC column can offer, often MMC provides additional dimension to a separation method by adjusting the mobile phase conditions. Mixed-mode media is also an effective way to clean up complex sample matrices for purification purposes or for sensitive detection of trace amounts of analytes. In this article, we discuss mixed-mode stationary phases and separation mechanisms and review recent advances in pharmaceutical and biopharmaceutical applications including the analysis and/or purification of counterions, small molecule drugs, impurities, formulation excipients, peptides and proteins.
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Combination of two different stationary phases for on-line pre-concentration and separation of basic drugs by using nano-liquid chromatography. J Chromatogr A 2013; 1285:118-23. [DOI: 10.1016/j.chroma.2013.02.035] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2012] [Revised: 02/06/2013] [Accepted: 02/09/2013] [Indexed: 11/20/2022]
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8
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Lin X, Jia W, Feng S, Lin J, Xie Z. A polymer monolith for hydrophilic and dynamically surfactant-modified reversed-phase capillary electrochromatography. RSC Adv 2013. [DOI: 10.1039/c3ra43377c] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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9
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Aydoğan C, Denizli A. Preparation and electrochromatographic characterization of methacrylate-based weak cation exchange columns for capillary electrochromatography. Analyst 2013; 138:2118-25. [DOI: 10.1039/c3an36377e] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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10
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Wang Y, Deng QL, Fang GZ, Pan MF, Yu Y, Wang S. A novel ionic liquid monolithic column and its separation properties in capillary electrochromatography. Anal Chim Acta 2012; 712:1-8. [DOI: 10.1016/j.aca.2011.10.023] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Revised: 09/29/2011] [Accepted: 10/11/2011] [Indexed: 11/30/2022]
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11
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Yang Y, Geng X. Mixed-mode chromatography and its applications to biopolymers. J Chromatogr A 2011; 1218:8813-25. [DOI: 10.1016/j.chroma.2011.10.009] [Citation(s) in RCA: 118] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2011] [Revised: 10/06/2011] [Accepted: 10/06/2011] [Indexed: 10/16/2022]
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12
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Choodum A, Smith NW, Thavarungkul P, Kanatharana P. Fluorinated monolithic column for CEC. J Sep Sci 2011; 34:2264-70. [DOI: 10.1002/jssc.201000873] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2010] [Revised: 01/18/2011] [Accepted: 01/20/2011] [Indexed: 11/10/2022]
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13
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Wang X, Ding K, Yang C, Lin X, Lü H, Wu X, Xie Z. Sulfoalkylbetaine-based monolithic column with mixed-mode of hydrophilic interaction and strong anion-exchange stationary phase for capillary electrochromatography. Electrophoresis 2010; 31:2997-3005. [PMID: 20715128 DOI: 10.1002/elps.201000264] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
A novel monolithic stationary phase with mixed mode of hydrophilic and strong anion exchange (SAX) interactions based on in situ copolymerization of pentaerythritol triacrylate (PETA), N,N-dimethyl-N-methacryloxyethyl N-(3-sulfopropyl) ammonium betaine (DMMSA) and a selected quaternary amine acrylic monomer was designed as a multifunctional separation column for CEC. Although the zwitterionic functionalities of DMMSA and hydroxy groups of PETA on the surface of the monolithic stationary phase functioned as the hydrophilic interaction (HI) sites, the quaternary amine acrylic monomer was introduced to control the magnitude of the EOF and provide the SAX sites at the same time. Three different quaternary amine acrylic monomers were tested to achieve maximum EOF velocity and highest plate count. The fabrication of the zwitterionic monolith (designated as HI and SAX stationary phase) was carried out when [2-(acryloyloxy)ethyl]trimethylammonium methylsulfate was used as the quaternary amine acrylic monomer. The separation mechanism of the monolithic column was discussed in detail. For charged analytes, a mixed mode of HI and SAX was observed by studying the influence of mobile phase pH and salt concentration on their retentions on the poly(PETA-co-DMMSA-co-[2-(acryloyloxy)ethyl]trimethylammonium methylsulfate) monolithic column. The optimized monolith showed good separation performance for a range of polar analytes including nucleotides, nucleic acid bases and nucleosides, phenols, estrogens and small peptides. The column efficiencies greater than 192 000 theoretical plates/m for estriol and 135 000 theoretical plates/m for charged cytidine were obtained.
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Affiliation(s)
- Xiaochun Wang
- Institute of Food Safety and Environmental Monitoring, Fuzhou University, Fuzhou, P. R. China
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14
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Chen JL, Lin YC. The role of methacrylate polymerized as porous-layered and nanoparticle-bound phases for open-tubular capillary electrochromatography: Substitution of a charged monomer for a bulk monomer. Electrophoresis 2010; 31:3949-58. [DOI: 10.1002/elps.201000436] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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15
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YUAN R, WANG Y, DING G. Enantiomeric Separation by Capillary Electrochromatography on a Sulfated Poly .BETA.-Cyclodextrin Modified Silica-based Monolith. ANAL SCI 2010; 26:943-7. [DOI: 10.2116/analsci.26.943] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Ruijuan YUAN
- School of Chinese Pharmacy, Beijing University of Chinese Medicine
| | - Yan WANG
- School of Pharmaceutical Science & Technology, Tianjin University
| | - Guosheng DING
- School of Pharmaceutical Science & Technology, Tianjin University
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16
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Ye F, Wang S, Zhao S. Preparation and characterization of mixed-mode monolithic silica column for capillary electrochromatography. J Chromatogr A 2009; 1216:8845-50. [DOI: 10.1016/j.chroma.2009.10.071] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2009] [Revised: 10/16/2009] [Accepted: 10/23/2009] [Indexed: 11/27/2022]
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17
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Preparation of a mixed-mode hydrophilic interaction/anion-exchange polymeric monolithic stationary phase for capillary liquid chromatography of polar analytes. J Chromatogr A 2008; 1216:801-6. [PMID: 19108844 DOI: 10.1016/j.chroma.2008.11.099] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2008] [Revised: 11/23/2008] [Accepted: 11/26/2008] [Indexed: 11/23/2022]
Abstract
A novel cationic hydrophilic interaction monolithic stationary phase based on the copolymerization of 2-(methacryloyloxy)ethyltrimethylammonium methyl sulfate (META) and pentaerythritol triacrylate (PETA) in a binary porogenic solvent consisting of cyclohexanol/ethylene glycol was designed for performing capillary liquid chromatography. While META functioned as both the ion-exchange sites and polar ligand provider, the PETA, a trivinyl monomer, was introduced as cross-linker. The monolithic stationary phases with different properties were easily prepared by adjusting the amount of META in the polymerization solution as well as the composition of the porogenic solvent. The hydrophilicity of the monolith increased with increasing content of META in the polymerization mixture. A typical hydrophilic interaction chromatography mechanism was observed when the content of acetonitrile in the mobile phase was higher than 20%. The poly(META-co-PETA) monolith showed very good selectivity for neutral, basic and acidic polar analytes. For polar-charged analytes, both hydrophilic interaction and electrostatic interaction contributed to their retention. Peak tailing of basic compounds was avoided and the efficient separation of benzoic acid derivatives was obtained.
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18
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Jiang Z, Smith NW, Ferguson PD, Taylor MR. Mixed-mode reversed-phase and ion-exchange monolithic columns for micro-HPLC. J Sep Sci 2008; 31:2774-83. [PMID: 18666170 DOI: 10.1002/jssc.200800124] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
This paper describes the fabrication of RP/ion-exchange mixed-mode monolithic materials for capillary LC. Following deactivation of the capillary surface with 3-(trimethoxysilyl)propyl methacrylate (gamma-MAPS), monoliths were formed by copolymerisation of pentaerythritol diacrylate monostearate (PEDAS), 2-sulphoethyl methacrylate (SEMA) with/without ethylene glycol dimethacrylate (EDMA) within 100 microm id capillaries. In order to investigate the porous properties of the monoliths prepared in our laboratory, mercury intrusion porosimetry, SEM and micro-HPLC were used to measure the monolithic structures. The monolithic columns prepared without EDMA showed bad mechanical stability at high pressure, which is undesirable for micro-HPLC applications. However, it was observed that the small amount (5% w/w) of EDMA clearly improved the mechanical stability of the monoliths. In order to evaluate their application for micro-HPLC, a range of neutral, acidic and basic compounds was separated with these capillaries and satisfactory separations were obtained. In order to further investigate the separation mechanism of these monolithic columns, comparative studies were carried out on the poly(PEDAS-co-SEMA) monolithic column and two other monoliths, poly(PEDAS) and poly(PEDAS-co-2-(methacryloyloxy)ethyl-trimethylammonium methylsulphate (METAM)). As expected, different selectivities were observed for the separation of basic compounds on all three monolithic columns using the same separation conditions. The mobile phase pH also showed clear influence on the retention time of basic compounds. This could be explained by ion-exchange interaction between positively charged analytes and the negatively charged sulphate group.
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Affiliation(s)
- Zhengjin Jiang
- Pharmaceutical Sciences Research Division, King's College London, London, UK
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19
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Ruohua Z, Wenting X. Novel beta-cyclodextrin modified organic polymeric monolithic substrate for solid phase extraction-room temperature phosphorescence. Analyst 2008; 133:1722-8. [PMID: 19082075 DOI: 10.1039/b804123g] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
An organic polymeric monolithic disk was prepared by situ polymerization of glycidyl methacrylate (GMA) and ethylene dimethacrylate (EDMA) in a binary porogenic solvent consisting 1-propanol and 1,4-butanediol, then modified by a reaction with beta-cyclodextrin (beta-CD). The beta-CD modified disk can be used as a solid substrate and solid phase extraction (SPE) membrane for solid phase extraction-room temperature phosphorescence (SPE-RTP). The room temperature phosphorescence (RTP) behaviors of 14 organic compounds on the beta-CD modified disk were examined. The results indicated that phenanthrene, 7,8-benzoquinoline, carbazole, fluorene, 3-indoleacetic acid and 1-naphthylacetic acid can emit strong RTP, and the limits of detection (LOD) were found to be 6.5 x 10(-10)-3.0 x 10(-9) mol mL(-1). Used as solid phase extraction membrane, the modified disk could selectively enrich compounds with three rings such as phenanthrene, 7,8-benzoquinoline, carbazole and fluorene. After solid phase extraction, LODs of four compounds were decreased to 4.0 x 10(-12)-6.4 x 10(-11) mol mL(-1). The method was applied to the determination of fluorene and phenanthrene in biosamples with satisfactory results.
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Affiliation(s)
- Zhu Ruohua
- Department of Chemistry, Capital Normal University, Beijing, China.
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20
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Wu R, Hu L, Wang F, Ye M, Zou H. Recent development of monolithic stationary phases with emphasis on microscale chromatographic separation. J Chromatogr A 2008; 1184:369-92. [DOI: 10.1016/j.chroma.2007.09.022] [Citation(s) in RCA: 232] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2007] [Revised: 09/06/2007] [Accepted: 09/11/2007] [Indexed: 12/28/2022]
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21
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Wang J, Lü H, Lin X, Xie Z. Monolithic column with double mixed-modes of hydrophilic interaction/ cation-exchange and reverse-phase/ cation-exchange stationary phase for pressurized capillary electrochromatography. Electrophoresis 2008; 29:928-35. [DOI: 10.1002/elps.200700600] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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22
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Lü H, Wang J, Wang X, Wu X, Lin X, Xie Z. Single-step preparation and characterization of polymeric monolith for pressurized capillary electrochromatography of typical homologs. J Sep Sci 2007; 30:2993-9. [PMID: 17880031 DOI: 10.1002/jssc.200700220] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
A monolithic stationary phase was prepared in a single step by in situ copolymerization of iso-butyl methacrylate (IBMA), ethylene dimethacrylate (EDMA), and N,N-dimethylallylamine (DMAA) in a binary porogenic solvent consisting of N,N-dimethylformamide (DMF) and 1,4-butanediol. As the frame structures of monoliths, the amino groups are linked to support the EOF necessary for driving the mobile phase through the monolithic capillary, while the hydrophobic groups are introduced to provide the nonpolar sites for the chromatographic retention. To evaluate the column performance, separations of typical kinds of neutral or charged homologs, such as alkylbenzenes, phenols (including isomeric compounds of hydroquinone, resorcin, and catechol), and anilines (including isomeric compounds of o-phenylenediamine and 1,4-phenylenediamine), were performed, respectively on the prepared column under the mode of pressurized pCEC. Effects of the buffer pH and the mobile phase composition on the linear velocity of mobile phase and the retention factors of these compounds were investigated. It was found that the retention mechanism of charged solutes could be attributed to a mixed mode of hydrophobic interaction and electrophoresis, while an RP chromatographic behavior on the monolithic stationary phases was exhibited for neutral solutes. Especially, basic compounds such as anilines were well separated on the monolithic columns in the "counterdirectional mode," which effectively eliminated the electrostatic adsorption of basic analytes on the charged surface of the stationary phases.
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Affiliation(s)
- Haixia Lü
- College of Materials Science and Engineering, Fuzhou University, Fuzhou, Fujian, China
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23
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Yuan R, Ding G, Guo Y, Liu D, Bao JJ. Wide-bore monolithic column for electrochromatography. Electrophoresis 2007; 28:1674-80. [PMID: 17480039 DOI: 10.1002/elps.200600541] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A new wide-bore electrophoresis (WE) system adopting an inner cooling device was set up to perform electrochromatography. In this system, a quartz tube of 1.2 mm inner diameter was used as the separation channel. The Joule heat generated during electrophoresis was removed timely through the outer surface of the quartz tube and a cooling capillary inserted into the quartz tube. A proper coolant passed through the cooling capillary to further improve the cooling efficiency. In the primary research, a polyacrylamide monolithic column was successfully prepared in this quartz tube. Then it was evaluated in the electrochromatographic mode. An electric field strength as high as 625 V/cm can be applied to this system without obvious deviation of the current from the linear curve of the Ohm plot. Sample volume as high as 1 microL was injected into the WE system and reasonable efficiency was obtained for separation of the test compounds.
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Affiliation(s)
- Ruijuan Yuan
- School of Pharmaceutical Science and Technology, Tianjin University, Tianjin, P. R. China
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24
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Freitag R, Hilbrig F. Theory and practical understanding of the migration behavior of proteins and peptides in CE and related techniques. Electrophoresis 2007; 28:2125-44. [PMID: 17557365 DOI: 10.1002/elps.200600792] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
CEC is defined as an analytical method, where the analytes are separated on a chromatographic column in the presence of an applied voltage. The separation of charged analytes in CEC is complex, since chromatographic interaction, electroosmosis and electrophoresis contribute to the experimentally observed behavior. The putative contribution of effects such as surface electrodiffusion has been suggested. A sound theoretical treatment incorporating all effects is currently not available. The question of whether the different effects contribute in an independent or an interdependent manner is still under discussion. In this contribution, the state-of-the-art in the theoretical description of the individual contributions as well as models for the retention behavior and in particular possible dimensionless 'retention factors' is discussed, together with the experimental database for the separation of charged analytes, in particular proteins and peptides, by CEC and related techniques.
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Affiliation(s)
- Ruth Freitag
- Process Biotechnology, University of Bayreuth, Bayreuth, Germany.
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25
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Barceló-Barrachina E, Moyano E, Puignou L, Galceran MT. CEC separation of heterocyclic amines using methacrylate monolithic columns. Electrophoresis 2007; 28:1704-13. [PMID: 17465421 DOI: 10.1002/elps.200600356] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Two methacrylate-based monolithic columns, one with a negatively charged group (sulfonic group) and another with a new monomer N,N-dimethylamino ethyl acrylate (DMAEA), were prepared and tested for the separation of basic compounds by CEC. This new monolithic stationary phase was prepared by the in situ polymerization of DMAEA with butyl methacrylate and ethylene dimethacrylate, using a ternary porogenic solvent consisting of water, 1-propanol and 1,4-butanediol. The performance of this column was evaluated by means of the analysis of a family of heterocyclic amines. Separation conditions such as pH, amount of organic modifier, ionic strength and elution mode (normal or counterdirectional flow) were studied. At the optimal running electrolyte composition, and using the counterdirectional mode, symmetrical electrochromatographic peaks were obtained, with the number of theoretical plates up to 30,000 and a good resolution between closely related peaks. The 2-acrylamido-2-methyl-1-propane-sulfonic acid column was used for CEC-MS, taking advantage of the compatibility of its elution mode (normal flow) with the MS coupling.
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Wieder W, Bisjak CP, Huck CW, Bakry R, Bonn GK. Monolithic poly(glycidyl methacrylate-co-divinylbenzene) capillary columns functionalized to strong anion exchangers for nucleotide and oligonucleotide separation. J Sep Sci 2007; 29:2478-84. [PMID: 17154128 DOI: 10.1002/jssc.200600146] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
In the present work, poly(glycidyl methacrylate-co-divinylbenzene) monoliths were synthesized and further derivatized to obtain strong anion exchange supports. Capillary monoliths (65 x 0.2 mm id) were prepared in situ by copolymerization of glycidyl methacrylate and divinylbenzene, employing 1-decanol and tetrahydrofuran as porogens. The free epoxy groups were derivatized in a two step synthesis to obtain quaternary ammonium functionalities. On testing the pressure stability of the synthesized monolith, a highly linear dependence between flow rate and pressure drop was obtained, indicating the high stability of the material even at high flow rates. The morphology of the copolymer was investigated by scanning electron microscopy. Mercury intrusion porosimetry showed a narrow pore size distribution, having a maximum at 439 nm. On recording a van Deemter plot the number of theoretical plates per meter was found to be 59324. The produced strong anion exchange monoliths turned out to be highly suitable for the separation of nucleotides and oligonucleotides.
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Affiliation(s)
- Wolfgang Wieder
- Institute of Analytical Chemistry and Radiochemistry, Leopold-Franzens University, Innsbruck, Austria
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Huang YF, Huang CC, Hu CC, Chang HT. Capillary electrophoresis-based separation techniques for the analysis of proteins. Electrophoresis 2006; 27:3503-22. [PMID: 16927348 DOI: 10.1002/elps.200600100] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
CE offers the advantages of high speed, great efficiency, as well as the requirement of minimum amounts of sample and buffer for the analysis of proteins. In this review, we summarize the CE-based techniques coupled with absorption, LIF, and MS detection systems for the analysis of proteins mostly within the past 5 years. The basic principle of each technique and its advantages and disadvantages for protein analysis are discussed in brief. Advanced CE techniques, including on-column concentration techniques and high-efficiency multidimensional separation techniques, for high-throughput protein profiling of complex biological samples and/or of single cells are emphasized. Although the developed techniques provide improved peak capacity, they have not become practical tools for proteomics, mainly because of poor reproducibility, low-sample lading capacity, and low throughput due to ineffective interfaces between two separation dimensions and that between separation and MS systems. In order to identify the complexities and dynamics of the proteomes expressed by cells, tissues, or organisms, techniques providing improved analytical sensitivity, throughput, and dynamic ranges are still demanded.
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Affiliation(s)
- Yu-Fen Huang
- Department of Chemistry, National Taiwan University, Taipei, Taiwan
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Ding G, Da Z, Yuan R, Bao JJ. Reversed-phase and weak anion-exchange mixed-mode silica-based monolithic column for capillary electrochromatography. Electrophoresis 2006; 27:3363-72. [PMID: 16944466 DOI: 10.1002/elps.200500931] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
A silica-based CEC monolithic column with mixed modes of RP and weak anion-exchange (WAX) was successfully prepared by using the sol-gel technique at mild temperature. The synthesizing procedure was optimized by changing the ratios of tetraethoxysilane (TEOS), aminopropyltriethoxysilane (APTES), and octyltriethoxysilane (C(8)-TEOS) in the mixture. While serving as WAX group, the amino group dominated the charge on the surface of the capillary column and generated an EOF from cathode to anode at low pH. At pH above 7.5, a cathodic EOF was observed due to the full ionization of silanol group and the suppression in the ionization of amino group. The morphology of monolithic columns was examined by SEM, and the performance of column was evaluated in detail by separating different kinds of compounds. As expected, the monolithic column exhibited RP chromatographic behavior for neutral solutes. Fast and efficient separation of six aromatic acids was obtained using acidic mobile phase with column efficiency up to 160,000 plates/m. Symmetrical peaks can be obtained for aromatic amines because positively charged amino groups on the surface can effectively minimize the adsorption of positively charged analytes to the stationary phase.
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Affiliation(s)
- Guosheng Ding
- School of Pharmaceutical Sciences and Technologies, Tianjin University, Tianjin, China
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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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Adu JK, Lau SS, Watson DG, Euerby MR, Skellern GG, Tettey JNA. Capillary electrochromatography of therapeutic peptides on mixed-mode butylmethacrylate monoliths. Electrophoresis 2005; 26:3445-51. [PMID: 16110461 DOI: 10.1002/elps.200500108] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
In this study, a porous mixed-mode n-alkyl methacrylate-based monolith has been used in the separation of therapeutic peptides. While the sulfonic acid (SCX) moiety derived from 2-acrylamido-2-methyl-1-propanesulfonic acid supports the generation of a stable electroosmotic flow (EOF) at both acidic and basic pH values, the butyl ligands provide the nonpolar sites for chromatographic resolution. The performance of the monolith was evaluated regarding the influence of pH on chromatographic resolution of peptides. The suitability of the butylmethacrylate/SCX monolith for the analysis of therapeutic peptides containing basic centres, for example arginine, at moderately high pH 9.5 and the stability to repeat injections of a mixture of peptides was demonstrated. Separations with efficiencies as high as 5.0 x 10(5) plates/m were obtained and the migration behaviour of the peptides at both low (2.8) and high (9.5) pH values could be rationalised based on their charge, molecular mass/shape and relative hydrophobicities.
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Affiliation(s)
- Joseph K Adu
- Department of Pharmaceutical Sciences, University of Strathclyde, Glasgow, UK
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Svec F. Recent developments in the field of monolithic stationary phases for capillary electrochromatography. J Sep Sci 2005; 28:729-45. [PMID: 15940819 DOI: 10.1002/jssc.200400086] [Citation(s) in RCA: 196] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
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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Affiliation(s)
- Frantisek Svec
- Department of Chemistry, University of California, Berkeley, CA 94720-1460, USA.
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Xie C, Hu J, Xiao H, Su X, Dong J, Tian R, He Z, Zou H. Electrochromatographic evaluation of a silica monolith capillary column for separation of basic pharmaceuticals. Electrophoresis 2005; 26:790-797. [PMID: 15714568 DOI: 10.1002/elps.200410174] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
A silica-based monolithic capillary column was prepared via a sol-gel process. The continuous skeleton and large through-pore structure were characterized by scanning electron microscopy (SEM). The native silica monolith has been successfully employed in the electrochromatographic separation of beta-blockers and alkaloids extracted from traditional Chinese medicines (TCMs). Column efficiencies greater than 250 000 plates/m for capillary electrochromatography (CEC) separation of basic compounds were obtained. It was observed that retention of basic pharmaceuticals on the silica monolith was mainly contributed by a cation-exchange mechanism. Other retention mechanisms including reversed-phase and normal-phase mechanisms and electrophoresis of basic compounds also played a role in separation. A comparison of the differences between CEC and capillary zone electrophoresis (CZE) separation was also discussed.
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Affiliation(s)
- Chuanhui Xie
- National Chromatographic R & A Center, Dalian Institute of Chemical Physics, The Chinese Academy of Sciences, Dalian, China
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