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Kościelniak P. White calibration methods based on gradient techniques as a modern approach to quantitative flow analysis. Trends Analyt Chem 2022. [DOI: 10.1016/j.trac.2022.116758] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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2
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Baeza-Baeza JJ, Bernabé-Zafón V, Herrero-Martínez JM, Simó-Alfonso EF. Study of elution behaviour with gradient voltage in CEC using methacrylate monolithic columns. Electrophoresis 2010; 31:1003-10. [PMID: 20309914 DOI: 10.1002/elps.200900353] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
A theoretical study on the retention behaviour and chromatographic performance of neutral solutes using a lauryl methacrylate-based monolithic column under voltage gradient mode in CEC was carried out. Through a flexible mathematical function based on a modified Gaussian model, the peak shape of compounds was firstly fitted under constant and gradient voltage. Using the peak shape parameters and retention time, the estimation of global chromatographic performance, efficiency and peak capacity under several voltage conditions was performed. The influence of voltage gradient on the separation efficiency is discussed and simple equations are presented to calculate retention and peak widths under voltage gradient conditions. A comparison in terms of chromatographic performance of a test mixture of neutral solutes under constant and gradient voltage modes was also carried out. The experiments carried out under gradient voltage showed better efficiencies (172,000 plates/m) and lower peak widths than those obtained under constant voltage (52,000 plates/m).
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Affiliation(s)
- Juan José Baeza-Baeza
- Department of Analytical Chemistry, Faculty of Chemistry, University of Valencia, Valencia, Spain
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3
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Study of peak shape and efficiency in butyl acrylate-based monolithic columns for capillary electrochromatography. J Chromatogr A 2009; 1216:6831-7. [DOI: 10.1016/j.chroma.2009.08.016] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2009] [Revised: 06/09/2009] [Accepted: 08/07/2009] [Indexed: 11/18/2022]
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4
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Svec F. CEC: selected developments that caught my eye since the year 2000. Electrophoresis 2009; 30 Suppl 1:S68-82. [PMID: 19517503 DOI: 10.1002/elps.200900062] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
During the last decade, a number of new developments have emerged in the field of CEC. This paper focuses only on monolithic columns prepared from synthetic polymers. Monolithic columns have become a well-established format of stationary phases for CEC immediately after their inception in the mid-1990s. They are readily prepared in situ from liquid precursors. Also, the control over both porous properties and surface chemistries is easy to achieve. These advantages make the monolithic separation media an attractive alternative to capillary columns packed with particulate materials. Since the number of papers concerned with just this single topic of polymer-based monolithic CEC columns is large, this overview describes only those approaches this author found interesting.
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Affiliation(s)
- Frantisek Svec
- The Molecular Foundry, E. O. Lawrence Berkeley National Laboratory, Berkeley, CA 94720-8197, USA.
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5
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Poole CF, Poole SK. Foundations of retention in partition chromatography. J Chromatogr A 2009; 1216:1530-50. [PMID: 19013576 DOI: 10.1016/j.chroma.2008.10.092] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2008] [Revised: 10/22/2008] [Accepted: 10/28/2008] [Indexed: 10/21/2022]
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6
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Kitagawa S. Enhancement in Separation Efficiency by Control in Electric Field on Pressurized-Flow Driven Capillary Electrochromatography. BUNSEKI KAGAKU 2008. [DOI: 10.2116/bunsekikagaku.57.937] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Shinya Kitagawa
- Materials Science and Engineering, Graduate School of Engineering, Nagoya Institute of Technology
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SAKAI T, NAKAGAWA H, KITAGAWA S, OHTANI H. Dual-Gradient Capillary Electrochromatography by Varying the Mobile Phase Composition and Applied Voltage. ANAL SCI 2008; 24:735-8. [DOI: 10.2116/analsci.24.735] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Tomoharu SAKAI
- Department of Materials Science and Engineering, Graduate School of Engineering, Nagoya Institute of Technology
| | - Hiroyuki NAKAGAWA
- Department of Materials Science and Engineering, Graduate School of Engineering, Nagoya Institute of Technology
| | - Shinya KITAGAWA
- Department of Materials Science and Engineering, Graduate School of Engineering, Nagoya Institute of Technology
| | - Hajime OHTANI
- Department of Materials Science and Engineering, Graduate School of Engineering, Nagoya Institute of Technology
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8
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Debowski JK. SELECTED APPLICATIONS OF CAPILLARY ELECTROCHROMATOGRAPHY IN THE PHARMACEUTICAL INDUSTRY: TO BUY OR NOT TO BUY? J LIQ CHROMATOGR R T 2007. [DOI: 10.1081/jlc-120013988] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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9
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Belenkii BG. Monolithic stationary phases: Yesterday, today, and tomorrow. RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY 2006. [DOI: 10.1134/s1068162006040029] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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10
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Oda T, Kitagawa S, Ohtani H. Development of dual gradient column in liquid chromatography. J Chromatogr A 2006; 1105:154-8. [PMID: 16185701 DOI: 10.1016/j.chroma.2005.09.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2005] [Revised: 08/30/2005] [Accepted: 09/07/2005] [Indexed: 11/16/2022]
Abstract
The dual gradient column, in which both the chemical property of the stationary phase and the flow velocity in the mobile phase are heterogeneous longitudinally along the column, is developed to obtain the mobile phase gradient-like elution in an isocratic condition. Here, the step-wise dual gradient columns were prepared by connecting an inlet column (I.D. 50 microm, packed with ODS) serially to an outlet column (I.D. 100-200 microm, packed with the mixture of ODS and C1 [9:1]). The retention behavior of alkylbenzenes was able to be controlled in the dual gradient column depending on the variation in the flow velocity. Moreover, the change in retention behavior induced by the flow velocity variation for the dual gradient columns was quite different from that by the variation in organic modifier content of the mobile phase in isocratic elution for a single gradient column and can induce the similar effect with an ordinary gradient elution in a mobile phase composition.
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Affiliation(s)
- Toyoharu Oda
- Department of Materials Science and Engineering, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso, Showa, Nagoya 466-8555, Japan
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11
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Ohyama K, Wada M, Kishikawa N, Ohba Y, Nakashima K, Kuroda N. Stepwise gradient of buffer concentration for capillary electrochromatography of peptides on sulfonated naphthalimido-modified silyl silica gel. J Chromatogr A 2005; 1064:255-9. [PMID: 15739894 DOI: 10.1016/j.chroma.2004.12.052] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The advantage of using a stepwise gradient of buffer concentration in CEC was demonstrated with the mixed-mode stationary phase, 3-(4-sulfo-1,8-naphthalimido)propyl-modified silyl silica gel (SNAIP). Before the application of a stepwise gradient, the effect of buffer concentration on the separations of six peptides and tryptic digests was investigated. Bubble formation caused by Joule heating at currents up to 95 microA was successfully suppressed by using SNAIP column even without pressurization, which contributed to a stepwise gradient of buffer concentration. Utilizing the stepwise gradient improved and shortened the separation of six peptides as compared to the separation under an isocratic elution.
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Affiliation(s)
- Kaname Ohyama
- Graduate School of Biomedical Sciences, Course of Pharmaceutical Sciences, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki 852-8521, Japan
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Abstract
This review discusses the development of capillary electrochromatography (CEC) coupled to mass spectrometric (MS) detection over the last few years. Major topics addressed are instrumental setups employed and applications of this technology published in the recent literature. The instrumental section includes a discussion of the most commonly used interfaces for the hyphenation of CEC and MS as well as ionization techniques. Applications reviewed in this paper come from a variety of different fields such as the analysis of biomolecules like proteins, peptides, amino acids or carbohydrates, chiral separations or the analysis of pharmaceutical an their metabolites in a series of matrices.
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Affiliation(s)
- Christian W Klampfl
- Institute of Analytical Chemistry, Johannes-Kepler-University, Altenbergerstrasse 69, A-4040 Linz, Austria.
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Pucci V, Raggi MA, Svec F, Fréchet JMJ. Monolithic columns with a gradient of functionalities prepared via photoinitiated grafting for separations using capillary electrochromatography. J Sep Sci 2004; 27:779-88. [PMID: 15354555 DOI: 10.1002/jssc.200401828] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Stationary phases for capillary electrochromatography with a longitudinal gradient of functionalities have been prepared via photoinitiated grafting of polymer chains onto the pore surface of a porous polymer monolith. In order to achieve the desired retention and electroosmotic flow, the hydrophobic poly(butyl methacrylate-co-ethylene dimethacrylate) monolith with optimized porous properties was grafted with a layer of ionizable polymer, poly(2-acrylamido-2-methyl-1-propanesulfonic acid). A moving shutter and a neutral density filter were used to control the dose of UV light received at different locations along the monolith in order to create the longitudinal gradient of functionalities. Formation of the desired gradients was confirmed using electron probe microanalysis of different locations along the column. The preparation technique significantly affects performance in the CEC mode as demonstrated on the separations of a model mixture using columns both with homogeneous distribution of grafts and with a gradient of functionality. Columns grafted with the gradient of functionalities were found superior to those functionalized uniformly. A comparison of the performance of the gradient column with another containing evenly distributed functionalities showed the performance benefits of the "gradient" column.
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Affiliation(s)
- Vincenzo Pucci
- Material Sciences Division, E.O. Lawrence Berkeley National Laboratory, Berkeley, CA 97420-8139, USA
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Barceló-Barrachina E, Moyano E, Galceran MT. State-of-the-art of the hyphenation of capillary electrochromatography with mass spectrometry. Electrophoresis 2004; 25:1927-1948. [PMID: 15237393 DOI: 10.1002/elps.200305908] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The high separation efficiency and loading capacity of capillary electrochromatography (CEC) make it an attractive separation mode for coupling with mass spectrometry (MS), which has the ability to unambiguously identify analytes with high selectivity and sensitivity. We present an overview of recent advances on both instrumentation and separation columns employed in CEC-MS systems. In particular, the main characteristics of the stationary phases, as well as the configurations of the column outlet that are related with the coupling arrangements of the MS ionization sources, are reported. At present, packed columns and conventional electrospray ionization (ESI) sources are mainly employed in CEC-MS. Nevertheless, the use of monolithic capillary columns and nanoelectrospray sources has the potential for wide acceptance in the next future. Moreover, the main features of several mass analyzers including ion trap, quadrupole, time-of-flight, magnetic sector, and Fourier transform-ion cyclotron resonance are examined. Finally, current applications of this technology, mainly in the pharmaceutical field and proteomics, are reviewed.
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Affiliation(s)
| | - Encarnación Moyano
- Department of Analytical Chemistry of the University of Barcelona, Barcelona, Spain
| | - M Teresa Galceran
- Department of Analytical Chemistry of the University of Barcelona, Barcelona, Spain
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Ohyama K, Shirasawa Y, Wada M, Kishikawa N, Ohba Y, Nakashima K, Kuroda N. Investigation of the novel mixed-mode stationary phase for capillary electrochromatography. J Chromatogr A 2004; 1042:189-95. [PMID: 15296405 DOI: 10.1016/j.chroma.2004.05.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
A novel packing material, 3-(4-sulfo-1,8-naphthalimido)propyl-modified silyl silica gel (SNAIP), was prepared for the use as a stationary phase of capillary electrochromatography (CEC). The sulfonic acid groups on SNAIP stationary phase contributed to the generation of electroosmotic flow (EOF) at low pH and served as a strong cation-exchanger. In CEC with SNAIP, a mixed-mode separation was predicted, comprising hydrophobic and electrostatic interactions as well as electrophoretic migration process. In order to understand the retention mechanism on SNAIP, effects of buffer pH, concentration, and mobile phase composition on EOF mobility and the retention factors of barbiturates and benzodiazepines were systematically investigated. Moreover, the retention behavior of barbiturates on SNAIP was investigated and compared with those on octadecyl silica (ODS), phenyl-bonded silica, and 3-(1,8-naphthalimido)propyl-modified silyl silica gel to confirm the presence of pi-pi interaction on its retention mechanism. It was observed that a column efficiency was more than 85,000 N/m for retained compounds and the relative standard deviations for the retention times of EOF marker, thiourea, and five barbiturates were below 2.5% (n = 4). Under an applied voltage of 20 kV and a mobile phase consisted of 5 mM phosphate (pH 3.8) and 40% methanol, the baseline separation of five barbiturates was achieved within 3 min.
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Affiliation(s)
- Kaname Ohyama
- Department of Analytical Chemistry, Graduate School of Biomedical Sciences, Course of Pharmaceutical Sciences, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki 852-8521, Japan
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Nakashima R, Kitagawa S, Yoshida T, Tsuda T. Study of flow rate in pressurized gradient capillary electrochromatography using splitter and separation of peptides using an Amide stationary phase. J Chromatogr A 2004; 1044:305-9. [PMID: 15354452 DOI: 10.1016/j.chroma.2004.03.081] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
A pressurized gradient capillary electrochromatograph using a splitter was constructed. The variation in flow rate during gradient elution was investigated and separations of peptides using an Amide stationary phase were demonstrated. The flow rate, which is one of the important factors to control chromatographic behavior, was increased during the gradient elution, and the mismatching of mobile phase between the column and the resistance tubing derived three variation patterns in the flow rate. The electrophoretic migration in electrochromatography could enhance in separation of peptides. The separated peak number of tryptic digest of bovine serum albumin was increased from 30 to 40 by the application of +5 kV.
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Affiliation(s)
- Rie Nakashima
- Department of Materials Science and Engineering, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso, Showa, Nagoya 466-8555, Japan
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Jiskra J, Claessens HA, Cramers CA. Stationary and mobile phases in capillary electrochromatography (CEC). J Sep Sci 2003. [DOI: 10.1002/jssc.200301305] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Abstract
A microprocessor controlled gradient elution system suitable for capillary electrochromatography has been developed and tested. It is based on a liquid handling device described previously which is capable of liquid transport with both low and high fluid dispersion. The low dispersion region formed by stainless steel needle 250 microm I.D. serves for sample injection, while the high dispersion region, created by steep extension of tube diameter, is used for continuous mobile phase gradient generation. A homologous series of seven alkylphenones was electrochromatographically separated on a monolithic polyacrylic column under gradient conditions. An S-shaped acetonitrile gradient (30-70%) was applied. A high reproducibility of retention times (RSD about 0.1%) was obtained, indicating accuracy of automated gradient operations.
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Affiliation(s)
- Vladislav Kahle
- Institute of Analytical Chemistry, Academy of Sciences of the Czech Republic, Veveri 97, 61142 Brno, Czech Republic.
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Zhang L, Zhang W, Ping G, Zhang Y, Kettrup A. Characteristics of electroosmotic flow and migration of neutral solutes under stepwise gradient elution of capillary electrochromatography. Electrophoresis 2002; 23:2417-23. [PMID: 12210197 DOI: 10.1002/1522-2683(200208)23:15<2417::aid-elps2417>3.0.co;2-e] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
A theoretical study on the velocity of electroosmotic flow (EOF) and the retention times of neutral solutes under multiple-step gradient of capillary electrochromatography (CEC) was carried out, focusing on that with three kinds of mobile phases. Through the model computations, the detaining time of the second kind of mobile phase in the column was proved to play an important role in affecting EOF. The variation speed of EOF was shown to be determined by the differences among dead times in different steps. In addition, the prediction of the retention times of 13 aromatic compounds under gradient mode was performed with the deduced equations. A relative error below 3.3% between the calculated and experimental values was obtained, which demonstrated the rationality of the theoretical deduction. Our study could not only improve the comprehension of stepwise gradient elution, but also be of significance for the further optimization of separation conditions in the analysis of complex samples.
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Affiliation(s)
- Lihua Zhang
- Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, PR China
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Ye M, Zou H, Wu R, Fu H, Lei Z. Modeling and optimization for separation of ionic solutes in pressurized flow capillary electrochromatography. J Sep Sci 2002. [DOI: 10.1002/1615-9314(20020501)25:7<416::aid-jssc416>3.0.co;2-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Jiang T, Jiskra J, Claessens HA, Cramers CA. Preparation and characterization of monolithic polymer columns for capillary electrochromatography. J Chromatogr A 2001; 923:215-27. [PMID: 11510544 DOI: 10.1016/s0021-9673(01)00982-7] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
A series of micro-monolithic columns with different porosities were prepared for capillary electrochromatography (CEC) by in-situ copolymerization of butyl methacrylate, ethylene glycol dimethacrylate, and 2-acrylamido-2-methyl-1-propane-sulfonic acid in the presence of a porogen in fused-silica capillaries of 100 microm I.D. Different column porosities were obtained by changing the ratios of monomers to porogenic solvents. Columns were investigated and evaluated under both pressure-driven (high-performance liquid chromatography, HPLC) and electro-driven (capillary electrochromatography, CEC) conditions. Each column exhibited different efficiency and dependency on flow velocity under electro-driven conditions. Abnormally broad peaks for some relatively bulky molecules were observed. Possible explanations are discussed. The differences in column efficiency and retention behavior between the two eluent-driven modes were studied in detail. In addition, other column properties, such as morphology, porosity, stability and reproducibility, were extensively tested.
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Affiliation(s)
- T Jiang
- Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, The Netherlands
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Medina JC, Alonso MC, Barcelo D, Lee ML. Simple gradient system For capillary electrochromatography. ACTA ACUST UNITED AC 2001. [DOI: 10.1002/mcs.10018] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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