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Yang Y, Wang J, Liu R, Quan K, Chen J, Liu X, Qiu H. Grafting of Tetraphenylethylene on Silica Surface, Characterizations, and Their Chromatographic Performance as Reversed-Phase Stationary Phases. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:14400-14408. [PMID: 36350796 DOI: 10.1021/acs.langmuir.2c02709] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Surface modification is an effective way to functionalize the materials so as to get some special properties. Tetraphenylethylene (TPE) has been widely investigated as a well-known reagent which has the nature of aggregation-induced emission (AIE), but has never been reported in the liquid chromatography stationary phase. In this work, TPE-grafted silica (Sil-TPE) was obtained successfully using the derivative of 1-(4-hydroxyphenyl)-1,2,2-triphenylethylene as a ligand, and then characterized by elemental analysis, Fourier transform infrared spectra, thermogravimetric analysis, and so forth. Laser scanning confocal microscopy images reflected the AIE phenomenon of grafted TPE because the internal vibration and rotation of TPE molecules were restrained in the confined silica space. The contact angle test showed superhydrophobic properties of Sil-TPE. In order to understand thoroughly the mechanism of chromatographic performance and retention behavior for Sil-TPE, Tanaka test mixture, alkylbenzenes, polycyclic aromatic hydrocarbons (PAHs), and phenols were separated. This reveals that Sil-TPE has strong aromaticity and certain shape selectivity, especially, has excellent separation performance for PAHs and phenols. The thermodynamic properties and repeatability of Sil-TPE were further studied, which showed the stability of Sil-TPE. This work shows that TPE can be successfully grafted on silica surface and it has the potential to be a new kind of promising stationary phases in the future.
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Affiliation(s)
- Yali Yang
- Key Laboratory of Bioelectrochemistry & Environmental Analysis of Gansu Province, College of Chemistry & Chemical Engineering, Northwest Normal University, Lanzhou730070, China
- CAS Key Laboratory of Chemistry of Northwestern Plant Resources and Key Laboratory for Natural Medicine of Gansu Province, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou730000, China
| | - Juanjuan Wang
- CAS Key Laboratory of Chemistry of Northwestern Plant Resources and Key Laboratory for Natural Medicine of Gansu Province, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou730000, China
| | - Ruirui Liu
- Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources; Key Laboratory of Salt Lake Resources Chemistry of Qinghai Province; Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining810008, China
| | - Kaijun Quan
- CAS Key Laboratory of Chemistry of Northwestern Plant Resources and Key Laboratory for Natural Medicine of Gansu Province, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou730000, China
| | - Jia Chen
- CAS Key Laboratory of Chemistry of Northwestern Plant Resources and Key Laboratory for Natural Medicine of Gansu Province, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou730000, China
| | - Xiuhui Liu
- Key Laboratory of Bioelectrochemistry & Environmental Analysis of Gansu Province, College of Chemistry & Chemical Engineering, Northwest Normal University, Lanzhou730070, China
| | - Hongdeng Qiu
- CAS Key Laboratory of Chemistry of Northwestern Plant Resources and Key Laboratory for Natural Medicine of Gansu Province, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou730000, China
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2
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Žuvela P, Skoczylas M, Jay Liu J, Ba Czek T, Kaliszan R, Wong MW, Buszewski B, Héberger K. Column Characterization and Selection Systems in Reversed-Phase High-Performance Liquid Chromatography. Chem Rev 2019; 119:3674-3729. [PMID: 30604951 DOI: 10.1021/acs.chemrev.8b00246] [Citation(s) in RCA: 143] [Impact Index Per Article: 28.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Reversed-phase high-performance liquid chromatography (RP-HPLC) is the most popular chromatographic mode, accounting for more than 90% of all separations. HPLC itself owes its immense popularity to it being relatively simple and inexpensive, with the equipment being reliable and easy to operate. Due to extensive automation, it can be run virtually unattended with multiple samples at various separation conditions, even by relatively low-skilled personnel. Currently, there are >600 RP-HPLC columns available to end users for purchase, some of which exhibit very large differences in selectivity and production quality. Often, two similar RP-HPLC columns are not equally suitable for the requisite separation, and to date, there is no universal RP-HPLC column covering a variety of analytes. This forces analytical laboratories to keep a multitude of diverse columns. Therefore, column selection is a crucial segment of RP-HPLC method development, especially since sample complexity is constantly increasing. Rationally choosing an appropriate column is complicated. In addition to the differences in the primary intermolecular interactions with analytes of the dispersive (London) type, individual columns can also exhibit a unique character owing to specific polar, hydrogen bond, and electron pair donor-acceptor interactions. They can also vary depending on the type of packing, amount and type of residual silanols, "end-capping", bonding density of ligands, and pore size, among others. Consequently, the chromatographic performance of RP-HPLC systems is often considerably altered depending on the selected column. Although a wide spectrum of knowledge is available on this important subject, there is still a lack of a comprehensive review for an objective comparison and/or selection of chromatographic columns. We aim for this review to be a comprehensive, authoritative, critical, and easily readable monograph of the most relevant publications regarding column selection and characterization in RP-HPLC covering the past four decades. Future perspectives, which involve the integration of state-of-the-art molecular simulations (molecular dynamics or Monte Carlo) with minimal experiments, aimed at nearly "experiment-free" column selection methodology, are proposed.
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Affiliation(s)
- Petar Žuvela
- Department of Chemistry , National University of Singapore , Singapore 117543 , Singapore
| | - Magdalena Skoczylas
- Department of Environmental Chemistry and Bioanalytics, Center for Modern Interdisciplinary Technologies , Nicolaus Copernicus University , Wileńska 4 , 87-100 Toruń , Poland
| | - J Jay Liu
- Department of Chemical Engineering , Pukyong National University , 365 Sinseon-ro , Nam-gu, 48-513 Busan , Korea
| | | | | | - Ming Wah Wong
- Department of Chemistry , National University of Singapore , Singapore 117543 , Singapore
| | - Bogusław Buszewski
- Department of Environmental Chemistry and Bioanalytics, Center for Modern Interdisciplinary Technologies , Nicolaus Copernicus University , Wileńska 4 , 87-100 Toruń , Poland
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3
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DeJaco RF, Elyassi B, Dorneles de Mello M, Mittal N, Tsapatsis M, Siepmann JI. Understanding the unique sorption of alkane-α, ω-diols in silicalite-1. J Chem Phys 2018; 149:072331. [DOI: 10.1063/1.5026937] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Robert F. DeJaco
- Department of Chemical Engineering and Materials Science, University of Minnesota, 412 Washington Avenue SE, Minneapolis, Minnesota 55455-0132, USA
- Department of Chemistry and Chemical Theory Center, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455-0431, USA
| | - Bahman Elyassi
- Department of Chemical Engineering and Materials Science, University of Minnesota, 412 Washington Avenue SE, Minneapolis, Minnesota 55455-0132, USA
| | - Matheus Dorneles de Mello
- Department of Chemical Engineering and Materials Science, University of Minnesota, 412 Washington Avenue SE, Minneapolis, Minnesota 55455-0132, USA
| | - Nitish Mittal
- Department of Chemical Engineering and Materials Science, University of Minnesota, 412 Washington Avenue SE, Minneapolis, Minnesota 55455-0132, USA
| | - Michael Tsapatsis
- Department of Chemical Engineering and Materials Science, University of Minnesota, 412 Washington Avenue SE, Minneapolis, Minnesota 55455-0132, USA
| | - J. Ilja Siepmann
- Department of Chemical Engineering and Materials Science, University of Minnesota, 412 Washington Avenue SE, Minneapolis, Minnesota 55455-0132, USA
- Department of Chemistry and Chemical Theory Center, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455-0431, USA
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4
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The inclusion complexation of daidzein with β-cyclodextrin and 2,6-dimethyl-β-cyclodextrin: a theoretical and experimental study. MONATSHEFTE FUR CHEMIE 2018. [DOI: 10.1007/s00706-018-2209-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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5
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Sykora D, Vozka J, Tesarova E. Chromatographic methods enabling the characterization of stationary phases and retention prediction in high-performance liquid chromatography and supercritical fluid chromatography. J Sep Sci 2015; 39:115-31. [DOI: 10.1002/jssc.201501023] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Revised: 10/08/2015] [Accepted: 10/08/2015] [Indexed: 11/11/2022]
Affiliation(s)
- David Sykora
- Department of Analytical Chemistry; University of Chemistry and Technology; Prague Czech Republic
| | - Jiri Vozka
- Department of Analytical Chemistry; University of Chemistry and Technology; Prague Czech Republic
- Department of Physical and Macromolecular Chemistry, Faculty of Science; Charles University in Prague; Prague Czech Republic
| | - Eva Tesarova
- Department of Physical and Macromolecular Chemistry, Faculty of Science; Charles University in Prague; Prague Czech Republic
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6
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Gagliardi LG, Tascon M, Castells CB. Effect of temperature on acid–base equilibria in separation techniques. A review. Anal Chim Acta 2015; 889:35-57. [DOI: 10.1016/j.aca.2015.05.053] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2014] [Revised: 05/16/2015] [Accepted: 05/22/2015] [Indexed: 10/23/2022]
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7
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Bartó E, Prauda I, Kilár F, Kiss I, Felinger A. Retention behavior of resorcinarene-based cavitands on C8and C18stationary phases. J Sep Sci 2015; 38:2975-82. [DOI: 10.1002/jssc.201500153] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Revised: 06/05/2015] [Accepted: 06/11/2015] [Indexed: 11/09/2022]
Affiliation(s)
- Endre Bartó
- Department of Analytical and Environmental Chemistry and Szentágothai Research Center; University of Pécs; Pécs Hungary
| | - Ibolya Prauda
- Department of Analytical and Environmental Chemistry and Szentágothai Research Center; University of Pécs; Pécs Hungary
| | - Ferenc Kilár
- Department of Analytical and Environmental Chemistry and Szentágothai Research Center; University of Pécs; Pécs Hungary
- Institute of Bioanalysis; University of Pécs; Pécs Hungary
| | - Ibolya Kiss
- Department of Analytical and Environmental Chemistry and Szentágothai Research Center; University of Pécs; Pécs Hungary
| | - Attila Felinger
- Department of Analytical and Environmental Chemistry and Szentágothai Research Center; University of Pécs; Pécs Hungary
- MTA-PTE Molecular Interactions in Separation Science Research Group; Hungary
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8
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Medium-property relationships and compensation effect in the adsorption of heteroaromatic compounds from aqueous acetonitrile solutions. Russ Chem Bull 2015. [DOI: 10.1007/s11172-014-0787-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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9
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Characterization and classification of stationary phases in HPLC and SFC – a review. Anal Chim Acta 2015; 886:1-15. [DOI: 10.1016/j.aca.2015.04.009] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Revised: 04/03/2015] [Accepted: 04/05/2015] [Indexed: 11/18/2022]
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10
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Cavazzini A, Marchetti N, Guzzinati R, Pasti L, Ciogli A, Gasparrini F, Laganà A. Understanding Mixed-Mode Retention Mechanisms in Liquid Chromatography with Hydrophobic Stationary Phases. Anal Chem 2014; 86:4919-26. [DOI: 10.1021/ac500248b] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- Alberto Cavazzini
- Department
of Chemistry and Pharmaceutical Sciences, University of Ferrara, via L. Borsari, 46, 44121 Ferrara, Italy
| | - Nicola Marchetti
- Department
of Chemistry and Pharmaceutical Sciences, University of Ferrara, via L. Borsari, 46, 44121 Ferrara, Italy
| | - Roberta Guzzinati
- Department
of Chemistry and Pharmaceutical Sciences, University of Ferrara, via L. Borsari, 46, 44121 Ferrara, Italy
| | - Luisa Pasti
- Department
of Chemistry and Pharmaceutical Sciences, University of Ferrara, via L. Borsari, 46, 44121 Ferrara, Italy
| | - Alessia Ciogli
- Dipartimento
di Chimica e Tecnologia del Farmaco, University “La Sapienza”, 00185 Rome, Italy
| | - Francesco Gasparrini
- Dipartimento
di Chimica e Tecnologia del Farmaco, University “La Sapienza”, 00185 Rome, Italy
| | - Aldo Laganà
- Department
of Chemistry, University of Rome, “La Sapienza”, Piazzale
Aldo Moro 5, 00185 Rome, Italy
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11
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Roy S, Covert PA, FitzGerald WR, Hore DK. Biomolecular Structure at Solid–Liquid Interfaces As Revealed by Nonlinear Optical Spectroscopy. Chem Rev 2014; 114:8388-415. [DOI: 10.1021/cr400418b] [Citation(s) in RCA: 93] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- Sandra Roy
- Department
of Chemistry, University of Victoria, Victoria, British Columbia, V8W 3V6 Canada
| | - Paul A. Covert
- Department
of Chemistry, University of Victoria, Victoria, British Columbia, V8W 3V6 Canada
| | - William R. FitzGerald
- Department
of Chemistry, University of Victoria, Victoria, British Columbia, V8W 3V6 Canada
| | - Dennis K. Hore
- Department
of Chemistry, University of Victoria, Victoria, British Columbia, V8W 3V6 Canada
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12
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Jandera P, Vyňuchalová K, Nečilová K. Combined effects of mobile phase composition and temperature on the retention of phenolic antioxidants on an octylsilica polydentate column. J Chromatogr A 2013; 1317:49-58. [DOI: 10.1016/j.chroma.2013.08.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2013] [Revised: 07/29/2013] [Accepted: 08/02/2013] [Indexed: 10/26/2022]
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13
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Lindsey RK, Rafferty JL, Eggimann BL, Siepmann JI, Schure MR. Molecular simulation studies of reversed-phase liquid chromatography. J Chromatogr A 2013; 1287:60-82. [PMID: 23489490 DOI: 10.1016/j.chroma.2013.02.040] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Revised: 02/10/2013] [Accepted: 02/11/2013] [Indexed: 11/28/2022]
Abstract
Over the past 20 years, molecular simulation methods have been applied to the modeling of reversed-phase liquid chromatography (RPLC). The purpose of these simulations was to provide a molecular-level understanding of: (i) the structure and dynamics of the bonded phase and its interface with the mobile phase, (ii) the interactions of analytes with the bonded phase, and (iii) the retention mechanism for different analytes. However, the investigation of chromatographic systems poses significant challenges for simulations with respect to the accuracy of the molecular mechanics force fields and the efficiency of the sampling algorithms. This review discusses a number of aspects concerning molecular simulation studies of RPLC systems including the historical development of the subject, the background needed to understand the two prevalent techniques, molecular dynamics (MD) and Monte Carlo (MC) methods, and the wealth of insight provided by these simulations. Examples from the literature employing MD approaches and from the authors' laboratory using MC methods are discussed. The former can provide information on chain dynamics and transport properties, whereas the latter techniques are uniquely suited for the investigation of phase and sorption equilibria that underly RPLC retention, and both can be used to elucidate the bonded-chain conformations and solvent distributions.
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Affiliation(s)
- Rebecca K Lindsey
- Department of Chemistry and Chemical Theory Center, University of Minnesota, 207 Pleasant Street SE, Minneapolis, MN 55455-0431, USA
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14
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The use of methyl-β-cyclodextrin to solubilize cholesterol prior to coating onto a C18 stationary phase. J Chromatogr A 2012; 1266:69-75. [PMID: 23107117 DOI: 10.1016/j.chroma.2012.10.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2012] [Revised: 10/05/2012] [Accepted: 10/08/2012] [Indexed: 11/21/2022]
Abstract
The use of methyl-β-cyclodextrin (MBCD) as a mobile phase additive in reversed-phase liquid chromatography is explored, with the primary goal of using MBCD to solubilize cholesterol in reversed-phase mobile phases for cholesterol-coating of C18 stationary phases. MBCD is shown to increase the solubility of cholesterol in typical reversed-phase mobile phases, especially when the stoichiometric ratio of MBCD to cholesterol exceeds 2:1. Additional equivalents of MBCD further increase solubility, or allow for weaker solvents to be used. The use of weaker solvents allows for larger coating levels of cholesterol onto a C18 stationary phase than are possible without the use of MBCD. Stationary phases coated with cholesterol using MBCD as a co-additive have different selectivity than uncoated phases, especially with regards to phenyl and shape selectivity. Further, the use of MBCD as a mobile phase additive for the elution of cholesterol is examined. It is seen via van't Hoff analysis that the reduction in retention of cholesterol when MBCD is added to the mobile phase is enthalpically driven.
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15
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Quast AD, Curtis AD, Horn BA, Goates SR, Patterson JE. Role of Nonresonant Sum-Frequency Generation in the Investigation of Model Liquid Chromatography Systems. Anal Chem 2012; 84:1862-70. [DOI: 10.1021/ac2032035] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Arthur D. Quast
- Department of Chemistry and
Biochemistry, Brigham Young University,
Provo, Utah 84602, United States
| | - Alexander D. Curtis
- Department of Chemistry and
Biochemistry, Brigham Young University,
Provo, Utah 84602, United States
| | - Brent A. Horn
- Department of Criminal Justice, Weber State University, Ogden, Utah 84408, United States
| | - Steven R. Goates
- Department of Chemistry and
Biochemistry, Brigham Young University,
Provo, Utah 84602, United States
| | - James E. Patterson
- Department of Chemistry and
Biochemistry, Brigham Young University,
Provo, Utah 84602, United States
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16
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Rafferty JL, Siepmann JI, Schure MR. Molecular simulations of retention in chromatographic systems: use of biased Monte Carlo techniques to access multiple time and length scales. Top Curr Chem (Cham) 2012; 307:181-200. [PMID: 21898207 DOI: 10.1007/128_2011_210] [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: 05/31/2023]
Abstract
The use of configurational-bias Monte Carlo simulations in the Gibbs ensemble allows for the sampling of phenomena that occur on vastly different time and length scales. In this review, applications of this simulation approach to probe retention in gas and reversed-phase liquid chromatographic systems are discussed. These simulations provide an unprecedented view of the retention processes at the molecular-level and show excellent agreement with experimental retention data.
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Affiliation(s)
- Jake L Rafferty
- Department of Chemistry and Chemical Theory Center, University of Minnesota, 207 Pleasant Street SE, Minneapolis, MN 55455-0431, USA
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17
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Erdemir S, Yilmaz M. Evaluation of the Chromatographic Performance of di-and tri-amide Calix[4]arene Derivatives Bonded Silica Stationary Phases. JOURNAL OF MACROMOLECULAR SCIENCE PART A-PURE AND APPLIED CHEMISTRY 2012. [DOI: 10.1080/10601325.2012.728462] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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18
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Agrafiotou P, Ràfols C, Castells C, Bosch E, Rosés M. Simultaneous effect of pH, temperature and mobile phase composition in the chromatographic retention of ionizable compounds. J Chromatogr A 2011; 1218:4995-5009. [DOI: 10.1016/j.chroma.2010.12.119] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2010] [Revised: 12/27/2010] [Accepted: 12/30/2010] [Indexed: 10/18/2022]
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19
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Rafferty JL, Siepmann JI, Schure MR. Mobile phase effects in reversed-phase liquid chromatography: A comparison of acetonitrile/water and methanol/water solvents as studied by molecular simulation. J Chromatogr A 2011; 1218:2203-13. [DOI: 10.1016/j.chroma.2011.02.012] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2010] [Revised: 01/28/2011] [Accepted: 02/05/2011] [Indexed: 11/16/2022]
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20
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Galaon T, Mihailciuc C, Medvedovici A, David V. THE INFLUENCE OF MOBILE-PHASE FLOW-RATE IN RP-LC ON THERMODYNAMIC PARAMETERS STUDIED FOR POLAR COMPOUNDS. J LIQ CHROMATOGR R T 2011. [DOI: 10.1080/10826076.2011.556974] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- Toma Galaon
- a Bioanalytical Laboratory, S.C. LaborMed Pharma S.A. , Bucharest, Romania
| | - Constantin Mihailciuc
- b Department of Chemical Physics , University of Bucharest, Faculty of Chemistry , Bucharest, Romania
| | - Andrei Medvedovici
- a Bioanalytical Laboratory, S.C. LaborMed Pharma S.A. , Bucharest, Romania
- c Department of Analytical Chemistry , University of Bucharest, Faculty of Chemistry , Bucharest, Romania
| | - Victor David
- c Department of Analytical Chemistry , University of Bucharest, Faculty of Chemistry , Bucharest, Romania
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21
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Ogden PB, Coym JW. Retention mechanism of a cholesterol-coated C18 stationary phase: van't Hoff and Linear Solvation Energy Relationships (LSER) approaches. J Chromatogr A 2011; 1218:2936-43. [PMID: 21457990 DOI: 10.1016/j.chroma.2011.03.018] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2010] [Revised: 02/18/2011] [Accepted: 03/09/2011] [Indexed: 11/15/2022]
Abstract
This study examines the effect of temperature on the dynamic cholesterol coating of a C18 stationary phase and the effect of this coating on the retention mechanism. In general, an increase in temperature results in a decrease in the mass of cholesterol coated on the stationary phase. Typically, an increase in temperature from 25°C to 55°C results in a nearly 60% reduction in the mass of cholesterol loaded. The inclusion of temperature, along with loading solvent composition and cholesterol concentration in the loading solvent, allows for loading a targeted amount of cholesterol on the stationary phase over an order-of-magnitude range. In addition to loading studies, the retention mechanism of small non-ionizable solutes was examined on cholesterol-coated stationary phases. A van't Hoff analysis was performed to assess retention thermodynamics, while a LSER approach was used to examine retention mechanism. With 50/50 water/organic mobile phases, the addition of cholesterol results in an increase in the entropic contribution to retention, with a decrease in the enthalpic contribution. The opposite trend is seen with 40/60 water/organic mobile phases. LSER system constants are also affected by a cholesterol coating on the stationary phase, with some changing to favor elution and others changing to favor retention.
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Affiliation(s)
- Phillip B Ogden
- Department of Chemistry, University of South Alabama, Mobile, AL 36688-0002, USA
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22
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Borówko M, Sokołowski S, Staszewski T. A density functional approach to retention in chromatography with chemically bonded phases. J Chromatogr A 2011; 1218:711-20. [DOI: 10.1016/j.chroma.2010.12.029] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2010] [Revised: 12/06/2010] [Accepted: 12/07/2010] [Indexed: 10/18/2022]
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23
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Kwietniewski L. THE EFFECT OF THE CHAIN LENGTH OF BONDED PHASE ON RETENTION OF AROMATIC SOLUTES IN RP LC WITH PURE WATER AS MOBILE PHASE. J LIQ CHROMATOGR R T 2010. [DOI: 10.1080/10826076.2010.503744] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- L. Kwietniewski
- a Faculty of Mathematics and Natural Science, Institute of Biotechnology, Chair of Bioanomaterials, John Paul II Catholic University of Lublin , Lublin, Poland
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24
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Thermodynamic and kinetic characterization of a bridged-ethylene hybrid C18 stationary phase. J Chromatogr A 2010; 1217:6241-9. [DOI: 10.1016/j.chroma.2010.08.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2010] [Revised: 08/02/2010] [Accepted: 08/06/2010] [Indexed: 11/18/2022]
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25
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Hupp AM, McGuffin VL. COMPARISON OF THEORETICAL METHODS FOR EXTRACTING RETENTION FACTORS AND RATE CONSTANTS IN LIQUID CHROMATOGRAPHY. J LIQ CHROMATOGR R T 2010. [DOI: 10.1080/10826076.2010.503785] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Amber M. Hupp
- a Department of Chemistry , Michigan State University , East Lansing, Michigan, USA
| | - Victoria L. McGuffin
- a Department of Chemistry , Michigan State University , East Lansing, Michigan, USA
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26
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Jandera P, Krupczyńska K, Vyňuchalová K, Buszewski B. Combined effects of mobile phase composition and temperature on the retention of homologous and polar test compounds on polydentate C8 column. J Chromatogr A 2010; 1217:6052-60. [DOI: 10.1016/j.chroma.2010.07.019] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2010] [Revised: 07/01/2010] [Accepted: 07/11/2010] [Indexed: 10/19/2022]
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27
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Coym JW. Evaluation of ternary mobile phases for reversed-phase liquid chromatography: Effect of composition on retention mechanism. J Chromatogr A 2010; 1217:5957-64. [DOI: 10.1016/j.chroma.2010.07.056] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2010] [Revised: 07/01/2010] [Accepted: 07/22/2010] [Indexed: 10/19/2022]
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28
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Retention mechanisms in subcritical water reversed-phase chromatography. J Chromatogr A 2009; 1216:5106-11. [DOI: 10.1016/j.chroma.2009.04.068] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2009] [Revised: 04/13/2009] [Accepted: 04/22/2009] [Indexed: 11/17/2022]
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29
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Coym JW. Comparison of retention on traditional alkyl, polar endcapped, and polar embedded group stationary phases. J Sep Sci 2008; 31:1712-8. [DOI: 10.1002/jssc.200700483] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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30
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Gagliardi LG, Castells CB, Ràfols C, Rosés M, Bosch E. Effect of temperature on the chromatographic retention of ionizable compounds. III. Modeling retention of pharmaceuticals as a function of eluent pH and column temperature in RPLC. J Sep Sci 2008; 31:969-80. [DOI: 10.1002/jssc.200700491] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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31
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David V, Medvedovici A. Structure‐Retention Correlation in Liquid Chromatography for Pharmaceutical Applications. J LIQ CHROMATOGR R T 2007. [DOI: 10.1080/10826070701191052] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Victor David
- a Department of Analytical Chemistry , University of Bucharest , Bucharest , Romania
| | - Andrei Medvedovici
- a Department of Analytical Chemistry , University of Bucharest , Bucharest , Romania
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32
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Vailaya A. Fundamentals of Reversed Phase Chromatography: Thermodynamic and Exothermodynamic Treatment. J LIQ CHROMATOGR R T 2007. [DOI: 10.1081/jlc-200052969] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- Anant Vailaya
- a Merck Research Laboratories , Rahway, New Jersey, USA
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33
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Zhang L, Rafferty JL, Siepmann JI, Chen B, Schure MR. Chain conformation and solvent partitioning in reversed-phase liquid chromatography: Monte Carlo simulations for various water/methanol concentrations. J Chromatogr A 2006; 1126:219-31. [PMID: 16820151 DOI: 10.1016/j.chroma.2006.06.003] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2006] [Revised: 05/24/2006] [Accepted: 06/01/2006] [Indexed: 11/25/2022]
Abstract
Many structural models for the stationary phase in reversed-phase liquid chromatography (RPLC) systems have been suggested from thermodynamic and spectroscopic measurements and theoretical considerations. To provide a molecular picture of chain conformation and solvent partitioning in a typical RPLC system, a particle-based Monte Carlo simulation study is undertaken for a dimethyl octadecyl (C(18)) bonded stationary phase on a model siliceous substrate in contact with mobile phases having different methanol/water concentrations. Following upon previous simulations for gas-liquid chromatography and liquid-liquid phase equilibria, the simulations are conducted using the configurational-bias Monte Carlo method in the Gibbs ensemble and the transferable potentials for phase equilibria force field. The simulations are performed for a chain surface density of 2.9 micromol/m(2), which is a typical bonded-phase coverage for mono-functional alkyl silanes. The solvent concentrations used here are pure water, approximately 33 and 67% mole fraction of methanol and pure methanol. The simulations show that the chain conformation depends only weakly on the solvent composition. Most chains are conformationally disordered and tilt away from the substrate normal. The interfacial width increases with increasing methanol content and, for mixtures, the solvent shows an enhancement of the methanol concentration in a 10 Angstrom region outside the Gibbs dividing surface. Residual surface silanol groups are found to provide hydrogen bonding sites that lead to the formation of substrate bound water and methanol clusters, including bridging clusters that penetrate from the solvent/chain interfacial region all the way to the silica surface.
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Affiliation(s)
- Ling Zhang
- Department of Chemistry, University of Minnesota, 207 Pleasant Street SE, Minneapolis, MN 55455-0431, USA
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34
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Wu N, Gauthier DR, Dovletoglou A, Yehl PM. Mechanistic Studies of the Separation of an HIV Protease Inhibitor from Its Piperazine Diastereomer by Reversed Phase High Performance Liquid Chromatography. J LIQ CHROMATOGR R T 2006. [DOI: 10.1081/jlc-120025594] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- N. Wu
- a Department of Analytical Research , Merck Research Laboratories , Building RY818‐B215, P.O. Box 2000, Rahway, New Jersey, 07065, USA
| | - D. R. Gauthier
- a Department of Analytical Research , Merck Research Laboratories , Building RY818‐B215, P.O. Box 2000, Rahway, New Jersey, 07065, USA
| | - A. Dovletoglou
- a Department of Analytical Research , Merck Research Laboratories , Building RY818‐B215, P.O. Box 2000, Rahway, New Jersey, 07065, USA
| | - P. M. Yehl
- a Department of Analytical Research , Merck Research Laboratories , Building RY818‐B215, P.O. Box 2000, Rahway, New Jersey, 07065, USA
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35
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Vitha M, Carr PW. The chemical interpretation and practice of linear solvation energy relationships in chromatography. J Chromatogr A 2006; 1126:143-94. [PMID: 16889784 DOI: 10.1016/j.chroma.2006.06.074] [Citation(s) in RCA: 389] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2006] [Revised: 06/09/2006] [Accepted: 06/19/2006] [Indexed: 11/30/2022]
Abstract
This review focuses on the use of linear solvation energy relationships (LSERs) to understand the types and relative strength of the chemical interactions that control retention and selectivity in the various modes of chromatography ranging from gas chromatography to reversed phase and micellar electrokinetic capillary chromatography. The most recent, widely accepted symbolic representation of the LSER model, as proposed by Abraham, is given by the equation: SP=c + eE + sS + aA + bB + vV, in which, SP can be any free energy related property. In chromatography, SP is most often taken as logk' where k' is the retention factor. The letters E, S, A, B, and V denote solute dependent input parameters that come from scales related to a solute's polarizability, dipolarity (with some contribution from polarizability), hydrogen bond donating ability, hydrogen bond accepting ability, and molecular size, respectively. The e-, s-, a-, b-, and v-coefficients and the constant, c, are determined via multiparameter linear least squares regression analysis of a data set comprised of solutes with known E, S, A, B, and V values and which span a reasonably wide range in interaction abilities. Thus, LSERs are designed to probe the type and relative importance of the interactions that govern solute retention. In this review, we include a synopsis of the various solvent and solute scales in common use in chromatography. More importantly, we emphasize the development and physico-chemical basis of - and thus meaning of - the solute parameters. After establishing the meaning of the parameters, we discuss their use in LSERs as applied to understanding the intermolecular interactions governing various gas-liquid and liquid-liquid phase equilibria. The gas-liquid partition process is modeled as the sum of an endoergic cavity formation/solvent reorganization process and exoergic solute-solvent attractive forces, whereas the partitioning of a solute between two solvents is thermodynamically equivalent to the difference in two gas/liquid solution processes. We end with a set of recommendations and advisories for conducting LSER studies, stressing the proper chemical and statistical application of the methodology. We intend that these recommendations serve as a guide for future studies involving the execution, statistical evaluation, and chemical interpretation of LSERs.
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Affiliation(s)
- Mark Vitha
- Drake University, Department of Chemistry, 2507 University Avenue, Des Moines, IA 50311, USA
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36
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Jandera P, Novotná K. Characterization of High‐Pressure Liquid Chromatography Columns using Chromatographic Methods. ANAL LETT 2006. [DOI: 10.1080/00032710600773424] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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37
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Limsavarn L, Dorsey JG. Influence of stationary phase solvation on shape selectivity and retention in reversed-phase liquid chromatography. J Chromatogr A 2006; 1102:143-53. [PMID: 16289120 DOI: 10.1016/j.chroma.2005.10.035] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2003] [Revised: 09/28/2005] [Accepted: 10/17/2005] [Indexed: 11/22/2022]
Abstract
In the past few decades, shape selectivity has drawn a great deal of attention from chromatographers. The chemistry and characteristics of bonded stationary phases such as phase type, length of bonded phase, surface coverage, and silica surface material have an effect on the shape selectivity of the columns. Although the effects of bonded phase shape selectivity are relatively well understood, one remaining question is the effect of intercalated solvent on shape selectivity. The intercalation of organic modifier and water molecules into the stationary phase is believed to introduce more rigidity into bonded alkyl chains in RPLC. The use of gas chromatography (GC) opens a new dimension to approach this question. C18 columns 4 cm in length were prepared in our laboratory and used in both LC and GC experiments. Shape selectivity and thermodynamic constants for the transfer of a solute from the mobile phase to the stationary phase have been determined as a function of monomeric octadecyl stationary phase bonding densities over the range of 1.44-3.43 micromol/m2 and a polymeric phase (nominal surface coverage 4.77 micromol/m2). Comparing LC and GC experiments, we observed: (a) similar relationships between shape and phenyl selectivities with monomerically bonded C18 phase densities; (b) different correlation of thermodynamic quantities (DeltaH degrees , DeltaS degrees , and DeltaG degrees ) versus bonded phase densities. The effects of high temperature and residual silanol groups are sources of difficulty in elucidation of the intercalated mobile phase role in selectivity and retention for GC measurements.
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Affiliation(s)
- Luxsana Limsavarn
- Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand
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38
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Trathnigg B, Veronik M. A thermodynamic study of retention of poly(ethylene glycol)s in liquid adsorption chromatography on reversed phases. J Chromatogr A 2005; 1091:110-7. [PMID: 16395799 DOI: 10.1016/j.chroma.2005.07.076] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The retention behaviour of poly(ethylene glycol)s (PEGs) on various reversed phase columns has been studied in liquid interaction chromatography at different temperatures. Similar separations could be achieved in different mobile phases. In methanol-water practically no temperature dependence was observed, while in acetone-water retention decreased with increasing temperature. From the van't Hoff plots the thermodynamic parameters were calculated, which showed, that retention is driven by enthalpy in methanol-water, while in acetone-water the driving force is entropy.
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Affiliation(s)
- Bernd Trathnigg
- Institute of Chemistry, Karl-Franzens-University, Heinrichstrasse 28, A-8010 Graz, Austria.
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39
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Gagliardi LG, Castells CB, Ràfols C, Rosés M, Bosch E. Effect of temperature on the chromatographic retention of ionizable compounds. J Chromatogr A 2005; 1077:159-69. [PMID: 16001552 DOI: 10.1016/j.chroma.2005.04.070] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The retentive behavior of weak acids and bases in reversed-phase liquid chromatography (RPLC) upon changes in column temperature has been theoretically and experimentally studied. The study focuses on examining the temperature dependence of the retention of various solutes at eluent pH close to their corresponding pKa values, and on the indirect role exerted by the buffer ionization equilibria on retention and selectivity. Retention factors of several ionizable compounds in a typical octadecylsilica column and using buffer solutions dissolved in 30% (v/v) acetonitrile as eluent at five temperatures in the range from 25 to 50 degrees C were carefully measured. Six buffer solutions were prepared from judiciously chosen conjugated pairs of different chemical nature. Their pKa values in this acetonitrile-water composition and within the range of 15-50 degrees C were determined potentiometrically. These compounds exhibit very different standard ionization enthalpies within this temperature range. Thus, whenever they are used to control mobile phase pH, the column temperature determines their final pH. Predictive equations of retention that take into account the temperature effect on both the transfer and the ionization processes are evaluated. This study demonstrates the significant role that the selected buffer would have on retention and selectivity in RPLC at temperatures higher than 25 degrees C, particularly for solutes that coelute.
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Affiliation(s)
- Leonardo G Gagliardi
- Departament de Química Analítica, Facultat de Química, Universitat de Barcelona, Barcelona, Spain
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40
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Trathnigg B, Fraydl S, Veronik M. Thermodynamic study of retention in liquid exclusion–adsorption chromatography. J Chromatogr A 2004; 1038:43-52. [PMID: 15233520 DOI: 10.1016/j.chroma.2004.03.029] [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: 11/29/2022]
Abstract
The retention behaviour of fatty alcohol ethoxylates and fatty acid methyl ester ethoxylates on various reversed-phase columns in acetone-water has been studied in the regime of liquid exclusion-adsorption chromatography at different temperatures. Straight lines were obtained in the van't Hoff plots. The entropy and enthalpy changes were found to be negative (at least in the range of lower oligomers) and showed a dependence of the number of oxyethylene units. For higher oligomers, both entropy and enthalpy changes approach a constant value. This can be explained by the existence of a rather thick layer of organic solvent close to the surface of the stationary phase.
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Affiliation(s)
- Bernd Trathnigg
- Institute of Chemistry, Karl-Franzens-University, Heinrichstrasse 28, A-8010 Graz, Austria.
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41
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Abstract
The potentiality of capillary gas chromatography (GC) as a means for research on solubility phenomena is focused. Basic thermodynamic information can be obtained in a simple and direct way from this technique relying on few parameters with their associated errors tightly controlled. An unexplored field of solvation phenomenology inaccessible to other techniques is revealed by the accuracy of capillary GC, provided that relevant chromatographic variables are utilized and an adequate treatment of the experimental information performed. The present article reviews different approaches for the attainment of basic thermodynamic information through capillary GC. Some traditional concepts on the treatment of chromatographic data for physicochemical measurement are questioned. Applications of the technique to research on solubility phenomena are depicted.
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Affiliation(s)
- Francisco Rex González
- Div. Química Analítica, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, 47 y 115, 1900 La Plata, Argentina.
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42
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Wick CD, Siepmann JI, Schure MR. Simulation Studies on the Effects of Mobile-Phase Modification on Partitioning in Liquid Chromatography. Anal Chem 2004; 76:2886-92. [PMID: 15144201 DOI: 10.1021/ac0352225] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Various driving forces have been suggested to explain retention and selectivity in reversed-phase liquid chromatography (RPLC). To provide molecular-level information on the retention mechanism in RPLC, configurational-bias Monte Carlo simulations in the Gibbs ensemble were carried out for model systems consisting of three phases: an n-hexadecane retentive phase, a mobile phase with varying water-methanol composition, and a helium vapor phase as reference state. Liquid n-hexadecane functions as a model of a hydrophobic stationary phase, and a wealth of experimental data exists for this system. Gibbs free energies for solute transfers from gas to retentive phase, from gas to mobile phase, and from mobile to retentive phase were determined for a series of short linear alkanes and primary alcohols. Although the magnitude of the incremental Gibbs free energy of transfer for a methylene segment is always larger for the gas- to retentive-phase transfer than the gas- to mobile-phase transfer, it is found that the partitioning of alkanes and alkyl tail groups is mostly affected by the changes in the aqueous mobile phase that occur when methanol modifiers are added. In contrast, the partitioning of the alcohol headgroup is sensitive to changes in both the n-hexadecane and the mobile phases. In particular, it is found that hydrogen-bonded aggregates of methanol are present in the n-hexadecane phase for higher methanol concentrations in the mobile phase. These aggregates strongly increase alcohol partitioning into the retentive phase. The simulation data clearly demonstrate that due to modification of the retentive-phase hydrocarbons by solvent components, neither the solvophobic theory of RPLC, advocated by Horvath and co-workers, nor the lipophilic theory of RPLC, advocated by Carr and co-workers, can adequately describe the separation mechanism of the hexadecane model system of a retentive phase studied here nor the more complex situation present in actual RPLC systems.
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Affiliation(s)
- Collin D Wick
- Department of Chemistry and of Chemical Engineering and Materials Science, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455-0431, USA
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43
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Howerton SB, McGuffin VL. Thermodynamics and kinetics of solute transfer in reversed-phase liquid chromatography. J Chromatogr A 2004; 1030:3-12. [PMID: 15043247 DOI: 10.1016/j.chroma.2003.08.111] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
A series of four-ring polycyclic aromatic hydrocarbons (PAHs) with varying annelation structure was studied by reversed-phase liquid chromatography. Using a polymeric octadecylsilica stationary phase over a temperature range from 273 to 303 K and an average pressure range from 585 to 3585 psi (1 psi = 6894.76 Pa), the thermodynamic and kinetic aspects of the retention mechanism were examined. Thermodynamic behavior was characterized by the retention factor, together with the associated changes in molar enthalpy and molar volume, whereas kinetic behavior was characterized by the rate constants, together with the associated activation enthalpies and activation volumes. The data indicate that pyrene, with a more condensed annelation structure, exhibits smaller changes in molar enthalpy and molar volume (delta Hsm = -4.4 kcal/mol, delta Vsm = -1.9 ml/mol; 1 cal = 4.184J) than PAHs with a more linear structure such as chrysene (delta Hsm = -8.2 kcal/mol, delta Vsm = - 11.7 ml/mol). The kinetic data indicate that pyrene undergoes faster rates of transport than chrysene (k(ms) = 313 and 14 s(-1), respectively), but the non-planar benzo[c]phenanthrene undergoes the fastest transport (k(ms) = 330 s(-1)). The activation enthalpies and activation volumes are similarly affected by the annelation structure. It is noteworthy that deviations from the exponentially modified Gaussian (EMG) model are observed for some PAH zone profiles at the lowest temperature, which suggests a possible change in retention mechanism. In order to characterize these deviations, the non-linear chromatography (NLC) model and a new bi-exponentially modified Gaussian (E2MG) model were examined. The regression results indicate that neither the NLC nor E2MG model offer significant improvements in the statistical quality of fit or provide a better description of the observed retention behavior.
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Affiliation(s)
- Samuel B Howerton
- Department of Chemistry, College of Natural Science, Michigan State University East Lansing, MI 48824-1322, USA
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44
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Abstract
The linear relation ln k' = Bn + ln A between the retention factor k' in liquid adsorption chromatography (LAC) and the number of repeat units n within a homologous series of oligomers is called Martin's rule. This empirical relation was supported by the retention behavior of the homologous series of different classes of oligomers but had no theoretical justification. In this paper, it is demonstrated that Martin's rule is a consequence of the general theory of liquid chromatography and the molecular sense of coefficients B and A is clarified: B is the Gibbs energy of the repeat unit of the long polymer chain adsorbed at the wall surface, and A is a combination different parameters which characterize the column and the adsorption correlation length H. The theory predicts the deviations from the linear dependence under conditions of weak adsorption between repeat units and stationary phase when H is close to radius of gyration Rg. Experimental data for retention volumes and selectivity of poly(ethylene glycol)s are given for normal and reversed-phase LAC on different columns in acetone-water and methanol-water as mobile phases. These data show excellent agreement between the theory and experiments. It is shown that Martin's rule holds under special conditions, which are theoretically defined by the relation H > Rg/1.5.
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Affiliation(s)
- Alexander Skvortsov
- Chemical-Pharmaceutical Academy, Prof. Popova 14, 197376 St. Petersburg, Russia
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45
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Chester TL, Coym JW. Effect of phase ratio on van't Hoff analysis in reversed-phase liquid chromatography, and phase-ratio-independent estimation of transfer enthalpy. J Chromatogr A 2003; 1003:101-11. [PMID: 12899299 DOI: 10.1016/s0021-9673(03)00846-x] [Citation(s) in RCA: 153] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
In analysis of the thermodynamics of the transfer of a solute from the mobile phase to the stationary phase in reversed-phase liquid chromatography, it is nearly always assumed that the phase ratio is constant. This type of analysis is typically performed by applying a form of the van't Hoff equation, which relates the retention factor to temperature via the enthalpy and entropy of transfer. When non-linear van't Hoff plots are observed, it is often assumed that the enthalpy and entropy of transfer change with temperature. However, when the possibility of a change in the phase ratio is considered, it becomes apparent that non-linear van't Hoff behavior may or may not be due to changes in enthalpy or entropy. In this work, we present mathematical evidence that phase ratio changes, if they occur, can cause deviations from linearity in a van't Hoff plot. We also show that the phase ratio influence can be eliminated by considering the molecular difference between two solutes instead of the solutes themselves. The resulting selectivity van't Hoff plots may be linear, even when the van't Hoff plots of the two solutes are non-linear. In such cases, temperature-dependent phase ratio changes, and not necessarily changes in the transfer enthalpy, may be responsible for the curved van't Hoff plots of the individual solutes. In addition, we present chromatographic evidence that different solutes may "see" different thermodynamic phase ratios. It is clear that the concept of a phase ratio in reversed-phase chromatography is not nearly as well defined as a phase ratio in a bulk system like a liquid-liquid extraction.
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Affiliation(s)
- Thomas L Chester
- The Procter and Gamble Company, Miami Valley Laboratories, P.O. Box 538707, Cincinnati, OH 45253-8707, USA.
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46
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Observations on the effect of temperature on performance and stability of anion exchange columns in ion chromatography. Chromatographia 2003. [DOI: 10.1007/bf02492544] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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47
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McGuffin VL, Lee C. Thermodynamics and kinetics of solute transfer in reversed-phase liquid chromatography. J Chromatogr A 2003; 987:3-15. [PMID: 12613792 DOI: 10.1016/s0021-9673(02)01455-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
In this study, the thermodynamic and kinetic behavior of a homologous series of fatty acids is examined using a polymeric octadecylsilica stationary phase and a methanol mobile phase. The zone profiles are evaluated as the temperature is varied from 20 to 60 degrees C and the average pressure from 400 to 4570 p.s.i. (1 p.s.i.=6894.76 Pa). The rate constant for solute transfer from mobile to stationary phase (k(ms)) appears to be relatively constant with carbon number. In contrast, the rate constant from stationary to mobile phase (k(sm)) decreases logarithmically with increasing carbon number. This suggests that the mass transport processes become progressively slower, owing to the smaller diffusion coefficients of the larger solutes in the stationary phase. The activation energy decreases slightly in the mobile phase and increases slightly in the stationary phase with increasing carbon number. The activation energy in the stationary phase ranges from 41.6 to 55.9 kcal/mol, while the thermodynamic change in internal energy ranges from -9.8 to -29.0 kcal/mol for C10 to C22, respectively (1 cal=4.184 J). The activation volume increases with increasing carbon number in both the mobile and stationary phase. The activation volume in the stationary phase ranges from 31.7 to 211 cm3/mol, while the thermodynamic change in molar volume ranges from -27.1 to -104 cm3/mol for C10 to C22, respectively. These large changes in activation energy and volume suggest that the solutes do not enter and leave the stationary phase in a single step, but in a stepwise or progressive manner.
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Affiliation(s)
- Victoria L McGuffin
- Department of Chemistry, 320 Chemistry Building, Michigan State University, East Lansing, MI 48824-1322, USA.
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48
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Price GJ, Shillcock IM. Inverse gas chromatographic measurement of solubility parameters in liquid crystalline systems. J Chromatogr A 2002; 964:199-204. [PMID: 12198848 DOI: 10.1016/s0021-9673(02)00651-9] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Inverse gas chromatography, (IGC), has been used to measure interaction parameters in two low-molar-mass liquid crystals and a polymer substituted with the same mesogenic group. Solubility parameters have been calculated. The IGC method is shown to be applicable to this class of compounds and to give meaningful values over a range of temperatures.
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Affiliation(s)
- Gareth J Price
- Department of Chemistry, University of Bath, Bath BA2 7AY, UK.
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49
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Sander LC, Wise SA. The influence of column temperature on selectivity in reversed-phase liquid chromatography for shape-constrained solutes. J Sep Sci 2001. [DOI: 10.1002/1615-9314(20011201)24:12<910::aid-jssc910>3.0.co;2-a] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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50
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Wick CD, Siepmann JI, Schure MR. Simulation Studies of Retention in Isotropic or Oriented Liquid n-Octadecane. J Phys Chem B 2001. [DOI: 10.1021/jp012300o] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Collin D. Wick
- Departments of Chemistry and of Chemical Engineering and Materials Science, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455-0431, and Theoretical Separations Science Laboratory, Rohm and Haas Company, 727 Norristown Road, Spring House, Pennsylvania 19477
| | - J. Ilja Siepmann
- Departments of Chemistry and of Chemical Engineering and Materials Science, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455-0431, and Theoretical Separations Science Laboratory, Rohm and Haas Company, 727 Norristown Road, Spring House, Pennsylvania 19477
| | - Mark R. Schure
- Departments of Chemistry and of Chemical Engineering and Materials Science, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455-0431, and Theoretical Separations Science Laboratory, Rohm and Haas Company, 727 Norristown Road, Spring House, Pennsylvania 19477
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