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Shameli SM, Glawdel T, Fernand VE, Ren CL. Micellar affinity gradient focusing in a microfluidic chip with integrated bilinear temperature gradients. Electrophoresis 2012; 33:2703-10. [PMID: 22965715 DOI: 10.1002/elps.201200283] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Micellar affinity gradient focusing (MAGF) is a microfluidic counterflow gradient focusing technique that combines the favorable features of MEKC and temperature gradient focusing. MAGF separates analytes on the basis of a combination of electrophoretic mobility and partitioning with the micellar phase. A temperature gradient is produced along the separation channel containing an analyte/micellar system to create a gradient in interaction strength (retention factor) between the analytes and micelles. Combined with a bulk counterflow, species concentrate at a unique point where their total velocity sums to zero. MAGF can be used in scanning mode by varying the bulk flow so that a large number of analytes can be sequentially focused and passed by a single detection point. In this work, we develop a bilinear temperature gradient along the separation channel that improves separation performance over the conventional linear designs. The temperature profile along the channel consists of a very sharp gradient used to preconcentrate the sample followed by a shallow gradient that increases resolution. We fabricated a hybrid PDMS/glass microfluidic chip with integrated micro heaters that generate the bilinear profile. Performance is characterized by separating several different samples including fluorescent dyes using SDS surfactant and pI markers using both SDS and poly-SUS surfactants as the micellar phase. The new design shows a nearly two times improvement in peak capacity and resolution in comparison to the standard linear temperature gradient.
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Affiliation(s)
- Seyed Mostafa Shameli
- Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo, Ontario, Canada
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2
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Purcaro G, Moret S, Bučar-Miklavčič M, Conte LS. Ultra-high performance liquid chromatographic method for the determination of polycyclic aromatic hydrocarbons in a passive environmental sampler. J Sep Sci 2012; 35:922-8. [DOI: 10.1002/jssc.201100922] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Giorgia Purcaro
- Dipartimento di Scienze degli Alimenti; Università di Udine; Udine Italy
| | - Sabrina Moret
- Dipartimento di Scienze degli Alimenti; Università di Udine; Udine Italy
| | | | - Lanfranco S. Conte
- Dipartimento di Scienze degli Alimenti; Università di Udine; Udine Italy
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3
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Puangpila C, Petsom A, Nhujak T. Theoretical models of separation selectivity for charged compounds in micellar electrokinetic chromatography. Electrophoresis 2010; 32:203-9. [DOI: 10.1002/elps.201000405] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2010] [Revised: 10/18/2010] [Accepted: 10/18/2010] [Indexed: 11/05/2022]
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4
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Maerzke KA, Siepmann JI. Effects of an Applied Electric Field on the Vapor−Liquid Equilibria of Water, Methanol, and Dimethyl Ether. J Phys Chem B 2010; 114:4261-70. [DOI: 10.1021/jp9101477] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Katie A. Maerzke
- Departments of Chemistry and of Chemical Engineering and Materials Science, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455
| | - J. Ilja Siepmann
- Departments of Chemistry and of Chemical Engineering and Materials Science, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455
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5
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Abstract
Recent research and development efforts concerning polymeric pseudostationary phases (PSPs) for electrokinetic chromatography are reviewed. The introduction of new materials, characterization of structural effects on performance and selectivity, applications, and the use of polymeric PSPs with mass spectrometric detection are considered. Very interesting results concerning the effects of polymer structure have been reported. Significant developments have also been reported in the development of novel applications of polymeric PSPs, particularly for sample preconcentration using micellar affinity gradient focusing. The use of mass spectrometric detection with electrokinetic chromatography has seen significant development, and recent reports indicate that this is a robust and sensitive approach.
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Affiliation(s)
- Christopher P Palmer
- Australian Centre for Research, on Separation Science (ACROSS), School of Chemistry, University of Tasmania, Hobart, Tasmania, Australia.
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Schappler J, Guillarme D, Rudaz S, Veuthey JL. Microemulsion electrokinetic chromatography hyphenated to atmospheric pressure photoionization mass spectrometry. Electrophoresis 2008; 29:11-9. [DOI: 10.1002/elps.200700647] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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7
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Aoki T, Harada M, Okada T. Characterization of bromide ions in charge-stacked zwitterionic micellar systems. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2007; 23:8820-6. [PMID: 17628088 DOI: 10.1021/la701145q] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
A novel zwitterionic surfactant, N-dodecyl-N,N,N',N'-tetra-methyl-ethylene-di-ammonio-propane-sulfonate bromide (DEPB), has been synthesized, and Br(-) involved in the micellar system has been characterized by potentiometry, NMR, and X-ray absorption fine structure (XAFS). Although the dissociation degree of Br(-) from the micelle evaluated by potentiometry almost agrees with that determined by NMR, the former is significantly smaller than the latter over the entire range of concentrations of DEPB. This is explained by assuming that the bromide ions in the micellar system have several different peripheral structures. XAFS has given significant insight into the hydration structures of Br(-) involved in the system. Some of the bromide ions partitioned into the micelle are dehydrated and are directly bound by the ammonium groups in the DEP molecules. However, some of the bromide ions are still completely hydrated even when they are partitioned into the micelles. The average hydration number of the bromide ions directly bound by the ammonium groups was determined to be approximately 3.3. The partial dehydration of Br(-) is possibly facilitated by the characteristic hydration circumstances provided by the charge-stacked structure of the surfactant and by the resulting thick palisade layer of the DEP micelle.
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Affiliation(s)
- Takeshi Aoki
- Department of Chemistry, Tokyo Institute of Technology, Meguro-ku, Tokyo 152-8551, Japan
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8
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Abstract
This paper reviews recent methodological and instrumental advances in MEKC. Improvements in sensitivity arising from the use of on-line sample concentration (sweeping, stacking, and combination of both protocols) and derivatization (in-capillary reactions and coupling with flow-injection systems) and improvements in resolution obtained by changing the composition of the BGE (e.g., with organic modifiers, ionic liquids, nonionic and zwitterionic surfactants, mixed micelles, and vesicles) or using coated capillaries are discussed in detail. In addition, MS and LIF spectroscopy are examined in relation to their advantages and restrictions as applied to MEKC analysis. Some thoughts on potential future directions are also expressed.
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Affiliation(s)
- Manuel Silva
- Department of Analytical Chemistry, University of Cordoba, Cordoba, Spain.
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9
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Shihabi ZK, Hinsdale ME. Serum iohexol analysis by micellar electrokinetic capillary chromatography. Electrophoresis 2006; 27:2458-63. [PMID: 16718641 DOI: 10.1002/elps.200500667] [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: 01/08/2023]
Abstract
A simple and rapid ( approximately 4 min) method for the measurement of iohexol in serum for assessing the glomerular filtration rate is described. It is based on direct serum injection on the capillary by MEKC. The method is linear between 8 and 260 mg/L, with an RSD of peak height of 2.9%. Several simple steps have contributed to an improved daily precision, such as choosing a high pH buffer, increasing the SDS concentration, frequent standardization, and eliminating any sample pretreatment.
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Affiliation(s)
- Zak K Shihabi
- Department of Pathology, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA.
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de Villiers A, Lestremau F, Szucs R, Gélébart S, David F, Sandra P. Evaluation of ultra performance liquid chromatography. J Chromatogr A 2006; 1127:60-9. [PMID: 16797562 DOI: 10.1016/j.chroma.2006.05.071] [Citation(s) in RCA: 198] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2006] [Revised: 05/18/2006] [Accepted: 05/24/2006] [Indexed: 11/18/2022]
Abstract
A practical evaluation of the possibilities and limitations of ultra performance liquid chromatography (UPLC) is presented. Acquity BEH columns packed with 1.7 microm particles are evaluated by means of van Deemter and Knox plots. The columns are characterised by high optimal velocities (3.7 mm/s) and low plate heights (4.4 microm). Minimum plate heights of 2d(p) were, however, not reached and reasons are presented and discussed. Furthermore, the use of 1.7 microm particles at 1000 bar is compared, from a theoretical viewpoint, to conventional LC (3.5 and 5 microm particles at 400 bar) in terms of analysis speed and practical maximum efficiency. Experimental data are used to construct kinetic- or "Poppe-plots", which facilitate investigation of the effect of pressure and particle size on speed and efficiency. It is found that UPLC conditions hold advantages in terms of speed of analysis, for required theoretical plate counts up to approximately 80,000.
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Affiliation(s)
- André de Villiers
- Pfizer Analytical Research Centre, Ghent University, Krijgslaan 281 S4-bis, B-9000 Ghent, Belgium
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Kasicka V. Recent developments in capillary electrophoresis and capillary electrochromatography of peptides. Electrophoresis 2006; 27:142-75. [PMID: 16307429 DOI: 10.1002/elps.200500527] [Citation(s) in RCA: 133] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The article gives a comprehensive review on the recent developments in the applications of high-performance capillary electromigration methods, zone electrophoresis, isotachophoresis, isoelectric focusing, affinity electrophoresis, electrokinetic chromatography, and electrochromatography, to analysis, preparation, and physicochemical characterization of peptides. The article presents new approaches to the theoretical description and experimental verification of electromigration behavior of peptides, covers the methodological aspects of capillary electroseparations of peptides, such as rational selection of separation conditions, sample preparation, suppression of peptide adsorption, new developments in individual separation modes, and new designs of detection systems. Several types of applications of capillary electromigration methods to peptide analysis are presented: conventional qualitative and quantitative analysis, purity control, determination in biomatrices, monitoring of chemical and enzymatical reactions and physical changes, amino acid and sequence analysis, and peptide mapping of proteins. Some examples of micropreparative peptide separations are given and capabilities of capillary electromigration techniques to provide important physicochemical characteristics of peptides are demonstrated.
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Affiliation(s)
- Václav Kasicka
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Prague, Czech Republic.
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Schiffer D, Welsch T. Approach to quasi stationary electrokinetic chromatography. J Chromatogr A 2005; 1070:179-84. [PMID: 15861802 DOI: 10.1016/j.chroma.2005.02.054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
A partial filling (PF) electrokinetic chromatography (EKC) system in combination with the application of weak counter pressures was built up by the combination of an UV-active polymeric dye, Poly R-478, used as additive in the separation buffer (SB) zone and an UV-permeable borate background buffer (BB). The electroosmotic flows of the buffers were equalized by matching their ionic strengths to achieve best efficiency. The influence of the pressure for the injection of the separation buffer and the effect of the counter pressure on the breakthrough of the separation buffer zone was investigated. The quasi stationary state of the separation buffer zone was evaluated by recording breakthrough curves. Based on these data the counter pressure was manipulated so that the separation buffer zone became quasi stationary and a large interference-free migration time window results. The system was optimized using a mixture of amino/nitroaromatics as test compounds.
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Affiliation(s)
- Daniela Schiffer
- University of Ulm, Department of Analytical and Environmental Chemistry, Albert-Einstein-Allee 11, D-89081 Ulm, Germany
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13
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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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Pappas TJ, Gayton-Ely M, Holland LA. Recent advances in micellar electrokinetic chromatography. Electrophoresis 2005; 26:719-734. [PMID: 15714572 DOI: 10.1002/elps.200410191] [Citation(s) in RCA: 69] [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 contains nearly 200 reference citations, and covers advances in electrokinetic capillary chromatography based on micelles, including stabilized micelle complexes, polymeric and mixed micelles from 2003-2004. Detection strategies, analyte determinations, and applications in micellar electrokinetic capillary chromatography (MEKC) are discussed. Information regarding methods of analyte concentration, analyte specific analyses, and nonstandard micelles has been summarized in tabular form to provide a means of rapid access to information pertinent to the reader.
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Affiliation(s)
- Theron J Pappas
- Department of Chemistry, West Virginia University, Morgantown, WV 26506, USA
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McCarney JP, Loflin RD, Rauk E, Yusa SI, Palmer CP. Conformational effects on the performance and selectivity of a polymeric pseudostationary phase in electrokinetic chromatography. Electrophoresis 2005; 26:841-848. [PMID: 15714565 DOI: 10.1002/elps.200410196] [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: 11/12/2022]
Abstract
The effect of the conformation of a polymeric pseudostationary phase on performance and selectivity in electrokinetic chromatography was studied using an amphiphilic pH-responsive polymer that forms compact intramolecular aggregates (unimer micelles) at low pH and a more open conformation at high pH. The change in conformation was found to affect the electrophoretic mobility, retention, selectivity, and separation efficiency. The low-pH conformer has higher electrophoretic mobility and greater affinity for most solutes. The unimer micelle conformation was also found to provide a solvation environment more like that of micelles and other amphiphilic self-associative polymers studied previously. It was not possible to fully characterize the effect of conformation on efficiency, but very hydrophobic solutes with long alkyl chains appeared to migrate with better efficiency when the unimer micelle conformation was employed. The results imply that polymers with a carefully optimized lipophilic-hydrophilic balance that allow self-association will perform better as pseudostationary phases. In addition, the results show that electrokinetic chromatography is a useful method for determining the changes in solvation environment provided by stimuli-responsive polymers with changes in the conditions.
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