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Tallarek U, Trebel N, Frerichs D, Steinhoff A, Höltzel A. Organic-solvent ditch overlap in reversed-phase liquid chromatography: A molecular dynamics simulation study in cylindrical 6-12 nm-diameter pores. J Chromatogr A 2024; 1726:464960. [PMID: 38718695 DOI: 10.1016/j.chroma.2024.464960] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2024] [Revised: 04/28/2024] [Accepted: 04/30/2024] [Indexed: 05/23/2024]
Abstract
Mass transport through the mesopore space of a reversed-phase liquid chromatography (RPLC) column depends on the properties of the chromatographic interface, particularly on the extent of the organic-solvent ditch that favors the analyte surface diffusivity. Through molecular dynamics simulations in cylindrical RPLC mesopore models with pore diameters between 6 and 12 nm we systematically trace the evolution of organic-solvent ditch overlap due to spatial confinement in the mesopore space of RPLC columns for small-molecule separations. Each pore model of a silica-based, endcapped, C18-stationary phase is equilibrated with two mobile phases of comparable elution strength, namely 70/30 (v/v) water/acetonitrile and 60/40 (v/v) water/methanol, to consider the influence of the mobile-phase composition on the onset of organic-solvent ditch overlap. The simulations show that, as the pore diameter decreases from 9 to 6 nm, the bonded-phase density extends and compacts towards the pore center, which leads to increased accumulation of organic-solvent excess and thus enhanced organic-solvent diffusivity in the ditch. Because the acetonitrile ditch is more pronounced than the methanol ditch, acetonitrile ditch overlap sets in at less severe spatial confinement than methanol ditch overlap. The pore-averaged methanol and acetonitrile diffusivities are considerably raised by ditch overlap in the 6 nm-diameter pore, but also benefit from the ditch (without overlap) in the 7 to 12 nm-diameter pores, whereby local and pore-averaged effects are generally larger for acetonitrile than methanol.
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Affiliation(s)
- Ulrich Tallarek
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse 4, Marburg 35032, Germany.
| | - Nicole Trebel
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse 4, Marburg 35032, Germany
| | - Daniel Frerichs
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse 4, Marburg 35032, Germany
| | - Andreas Steinhoff
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse 4, Marburg 35032, Germany
| | - Alexandra Höltzel
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse 4, Marburg 35032, Germany
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2
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Steinhoff A, Höltzel A, Tallarek U. The Solvation Shell of Small Solutes in Aqueous-Organic Solvent Mixtures and Its Implications for Reversed-Phase Liquid Chromatography. J Phys Chem B 2023; 127:10052-10066. [PMID: 37943096 DOI: 10.1021/acs.jpcb.3c05492] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2023]
Abstract
Reversed-phase liquid chromatography (RPLC) operates with water-organic solvent (W-OS) mobile phases where preferential solvation (PS) of solutes is likely. To investigate the relevance of the solute solvation shell in the mobile phase for RPLC retention, we combine data from molecular dynamics simulations of small, neutral solutes (six analytes and two dead time markers) in W-methanol (MeOH) and W-acetonitrile (ACN) mixtures with corresponding retention data obtained on an RPLC column over a wide range of W/OS ratios. Data derived from Kirkwood-Buff integrals show PS by the OS for analytes vs low or negative PS for dead time markers. W-ACN mixtures generate a higher amount of PS than W-MeOH mixtures, which contributes to the higher eluent strength of ACN in RPLC. Difference spatial distribution functions reveal anisotropic solvation shells with OS excess at hydrocarbon elements and W excess at functional groups, predicting that retention by the hydrophobic stationary phase is favored by hydrocarbon elements and limited by functional groups. Analysis of solute-solvent hydrogen bonds pinpoints the hydrogen-bond requirements toward W as the retention-limiting factor. The relation between the solute solvation shell and retention confirms the importance of W-OS and solute-W hydrogen bonding for RPLC retention.
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Affiliation(s)
- Andreas Steinhoff
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse 4, Marburg 35032, Germany
| | - Alexandra Höltzel
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse 4, Marburg 35032, Germany
| | - Ulrich Tallarek
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse 4, Marburg 35032, Germany
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3
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Scrosati PM, Konermann L. Atomistic Details of Peptide Reversed-Phase Liquid Chromatography from Molecular Dynamics Simulations. Anal Chem 2023; 95:3892-3900. [PMID: 36745777 DOI: 10.1021/acs.analchem.2c05667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Peptide separations by reversed-phase liquid chromatography (RPLC) are an integral part of bottom-up proteomics. These separations typically employ C18 columns with water/acetonitrile gradient elution in the presence of formic acid. Despite the widespread use of such workflows, the exact nature of peptide interactions with the stationary and mobile phases is poorly understood. Here, we employ microsecond molecular dynamics (MD) simulations to uncover details of peptide RPLC. We examined two tryptic peptides, a hydrophobic and a hydrophilic species, in a slit pore lined with C18 chains that were grafted onto SiO2 support. Our simulations explored peptide trapping, followed by desorption and elution. Trapping in an aqueous mobile phase was initiated by C18 contacts with Lys butyl moieties. This was followed by extensive anchoring of nonpolar side chains (Leu/Ile/Val) in the C18 layer. Exposure to water/acetonitrile triggered peptide desorption in a stepwise fashion; charged sites close to the termini were the first to lift off, followed by the other residues. During water/acetonitrile elution, both peptides preferentially resided close to the pore center. The hydrophilic peptide exhibited no contacts with the stationary phase under these conditions. In contrast, the hydrophobic species underwent multiple transient Leu/Ile/Val binding interactions with C18 chains. These nonpolar interactions represent the foundation of differential peptide retention, in agreement with the experimental elution behavior of the two peptides. Extensive peptide/formate ion pairing was observed in water/acetonitrile, particularly at N-terminal sites. Overall, this work uncovers an unprecedented level of RPLC molecular details, paving the way for MD simulations as a future tool for improving retention prediction algorithms and for the design of novel column materials.
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Affiliation(s)
- Pablo M Scrosati
- Department of Chemistry, The University of Western Ontario, London, Ontario, N6A 5B7, Canada
| | - Lars Konermann
- Department of Chemistry, The University of Western Ontario, London, Ontario, N6A 5B7, Canada
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Steinhoff A, Höltzel A, Trebel N, Tallarek U. Mobile-Phase Contributions to Organic-Solvent Excess Adsorption and Surface Diffusion in Reversed-Phase Liquid Chromatography. J Phys Chem B 2022; 126:10554-10568. [PMID: 36469753 DOI: 10.1021/acs.jpcb.2c06871] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Fast transport of retained analytes in reversed-phase liquid chromatography occurs through surface diffusion in the organic-solvent (OS)-enriched interfacial "ditch" region between the hydrophobic stationary phase and the water (W)-OS mobile phase. Through molecular dynamics simulations that recover the OS excess adsorption isotherms of a typical C18-stationary phase for methanol and acetonitrile, we explore the relation between OS properties, OS excess adsorption, and surface diffusion. The emerging molecular-level picture attributes the mobile-phase contribution to surface diffusion to the hydrogen-bond capability and the eluting power of the OS. The higher affinity of methanol for the formation of W-OS hydrogen bonds at the soft, hydrophobic surface presented by the bonded-phase (C18) chains reduces the OS excess and the related viscosity drop in the ditch. The lower eluting power of methanol, however, translates to increased bonded-phase contacts for analytes, which can increase their mobility gain from surface diffusion above the gain observed with acetonitrile.
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Affiliation(s)
- Andreas Steinhoff
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse 4, 35032Marburg, Germany
| | - Alexandra Höltzel
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse 4, 35032Marburg, Germany
| | - Nicole Trebel
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse 4, 35032Marburg, Germany
| | - Ulrich Tallarek
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse 4, 35032Marburg, Germany
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Volume and composition of semi-adsorbed stationary phases in hydrophilic interaction liquid chromatography. Comparison of water adsorption in common stationary phases and eluents. J Chromatogr A 2021; 1656:462543. [PMID: 34571282 DOI: 10.1016/j.chroma.2021.462543] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Revised: 09/02/2021] [Accepted: 09/05/2021] [Indexed: 12/11/2022]
Abstract
Pycnometric and homologous series retention methods are used to determine the volume and mean composition of the water-rich layers partially adsorbed on the surface of several hydrophilic interaction liquid chromatography (HILIC) column fillings with acetonitrile-water and methanol-water as eluents. The findings obtained in this work confirm earlier studies using direct methods for measuring the stationary phase water content performed by Jandera's and Irgum's research groups. Water is preferentially adsorbed on the surface of the HILIC bonded phase in hydroorganic eluents containing more than 40% acetonitrile or 70% methanol, and a gradient of several water-rich transition layers between the polar bonded phase and the poorly polar bulk mobile phase is formed. These layers of reduced mobility act as HILIC stationary phases, retaining polar solutes. The volume of these layers and concentration of adsorbed water is much larger for acetonitrile-water than for methanol-water mobile phases. In hydroorganic eluents with less than 20-30% acetonitrile or 40% methanol the amount of preferentially adsorbed water is very small, and the observed retention behavior is close to the one in reversed-phase liquid chromatography (RPLC). In eluents with intermediate acetonitrile-water or methanol-water compositions a mixed HILIC-RPLC behavior is presented. Comparison of several HILIC columns shows that the highest water enrichment in the HILIC retention region for acetonitrile-water mobile phases is observed for zwitterionic and aminopropyl bonded phases, followed in minor grade for diol and polyvinyl alcohol functionalizations. Pentafluorophenyl bonded phase, usually considered a HILIC column, does not show significant water adsorption, nor HILIC retention.
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Trebel N, Höltzel A, Lutz JK, Tallarek U. Consequences of Cylindrical Pore Geometry for Interfacial Phenomena in Reversed-Phase Liquid Chromatography. J Phys Chem B 2021; 125:11320-11336. [PMID: 34610741 DOI: 10.1021/acs.jpcb.1c06732] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The interfacial phenomena behind analyte separation in a reversed-phase liquid chromatography column take place nearly exclusively inside the silica mesopores. Their cylindrical geometry can be expected to shape the properties of the chromatographic interface with consequences for the analyte density distribution and diffusivity. To investigate this topic through molecular dynamics simulations, we introduce a cylindrical pore inside a slit pore configuration, where the inner curved and outer planar silica surface bear the same bonded phase. The present model replicates an average-sized (9 nm) mesopore in an endcapped C18 column equilibrated with a mobile phase of 70/30 (v/v) water/acetonitrile. Simulations performed for ethylbenzene and acetophenone show that the surface curvature shifts the bonded phase and analyte density toward the pore center, decreases the solvent density in the bonded-phase region, increases the acetonitrile excess in the interfacial region, and considerably enhances the surface diffusivity of both analytes. Overall, the cylindrical pore provides a more hydrophobic environment than the slit pore. Ethylbenzene density is decidedly increased in the cylindrical pore, whereas acetophenone density is nearly equally distributed between the cylindrical and slit pore. The cylindrical pore geometry thus sharpens the discrimination between the apolar and moderately polar analytes while enhancing the mass transport of both.
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Affiliation(s)
- Nicole Trebel
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse 4, 35032 Marburg, Germany
| | - Alexandra Höltzel
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse 4, 35032 Marburg, Germany
| | - Julia K Lutz
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse 4, 35032 Marburg, Germany
| | - Ulrich Tallarek
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse 4, 35032 Marburg, Germany
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7
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Sobańska AW. Emerging or Underestimated Silica-Based Stationary Phases in Liquid Chromatography. Crit Rev Anal Chem 2020; 51:631-655. [PMID: 32482079 DOI: 10.1080/10408347.2020.1760782] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Several newly synthesized or forgotten silica-based stationary phases proposed for liquid chromatography are described, including non-endcapped, short-chain alkyl phases; hydrophilic and polar-endcapped stationary phases; polar-embedded alkyl phases; long-chain alkyl phases. Stationary phases with aromatic, cyanopropyl, diol and aminopropyl functionalities are also reviewed. Stationary phases of particular interest are biomolecular materials - based on immobilized cholesterol, aminoacids, peptides, proteins or lipoproteins. Packing materials involving macrocyclic chemistry (crown ethers; calixarenes; aza-macrocycles; oligo-and polysaccharides including these of marine origin - chitin- or chitosan-based; macrocyclic antibiotics) are discussed. Since many stationary phases developed for one type of applications (e.g. chiral separation) have been found useful in solving other analytical problems (e.g. drug's plasma protein binding ability), it seemed reasonable to discuss particular chemistries behind the stationary phases presented in this review rather than specific types of interactions or chromatographic modes.
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Affiliation(s)
- Anna W Sobańska
- Department of Analytical Chemistry, Faculty of Pharmacy, Medical University of Lodz, Lodz, Poland
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8
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Design and evaluation of polar-embedded stationary phases containing triacontyl group for liquid chromatography. J Chromatogr A 2020; 1621:461035. [DOI: 10.1016/j.chroma.2020.461035] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 03/09/2020] [Accepted: 03/10/2020] [Indexed: 02/06/2023]
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9
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Liu J, Li X, Liu J, Liao X, Liu F, Ren S. Molecular level separation of crude oil/water emulsion on carbon nanotube surface induced by weak interaction: a molecular dynamic simulation study. J DISPER SCI TECHNOL 2019. [DOI: 10.1080/01932691.2019.1645026] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- Juan Liu
- Jiangxi Key Laboratory of Mining Engineering, School of Resources and Environmental Engineering, Jiangxi University of Science and Technology , Ganzhou , P. R. China
- School of Chemical Engineering and Materials, Changzhou Institute of Technology , Changzhou , P. R. China
| | - Xiaocheng Li
- School of Materials and Chemical Engineering, Jiangxi University of Science and Technology , Ganzhou , P. R. China
| | - Jun Liu
- Jiangxi Key Laboratory of Mining Engineering, School of Resources and Environmental Engineering, Jiangxi University of Science and Technology , Ganzhou , P. R. China
| | - Xiaofeng Liao
- Jiangxi Key Laboratory of Mining Engineering, School of Resources and Environmental Engineering, Jiangxi University of Science and Technology , Ganzhou , P. R. China
| | - Fuyan Liu
- School of Chemical Engineering and Materials, Changzhou Institute of Technology , Changzhou , P. R. China
| | - Sili Ren
- Jiangxi Key Laboratory of Mining Engineering, School of Resources and Environmental Engineering, Jiangxi University of Science and Technology , Ganzhou , P. R. China
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10
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Han H, Zhang Y, Lu R, Zhang M. An alternative approach for preparation of amide-embedded stationary phase for reversed-phase liquid chromatography. J Chromatogr A 2019; 1593:24-33. [DOI: 10.1016/j.chroma.2019.01.054] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2018] [Revised: 01/15/2019] [Accepted: 01/19/2019] [Indexed: 11/27/2022]
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11
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Column selection for comprehensive two-dimensional liquid chromatography using the hydrophobic subtraction model. J Chromatogr A 2019; 1589:47-55. [DOI: 10.1016/j.chroma.2018.09.018] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Revised: 09/05/2018] [Accepted: 09/09/2018] [Indexed: 12/15/2022]
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12
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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: 134] [Impact Index Per Article: 26.8] [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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Zhang Y, Li Q, Zhong H, Zhou S, Zhao Y, Zhang M, Han H, Qiu H. Tuning selectivity via electronic interaction: Preparation and systematic evaluation of serial polar-embedded aryl stationary phases bearing large polycyclic aromatic hydrocarbons. Anal Chim Acta 2018; 1036:162-171. [DOI: 10.1016/j.aca.2018.09.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Revised: 08/29/2018] [Accepted: 09/01/2018] [Indexed: 11/26/2022]
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14
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Ferreira CDC, Gama MR, da Silva GS, Almeida WP, Collins CH, Jardim ICSF. Synthesis and evaluation of a pentafluorobenzamide stationary phase for HPLC separations in the reversed phase and hydrophilic interaction modes. J Sep Sci 2018; 41:3855-3862. [DOI: 10.1002/jssc.201800522] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Revised: 07/19/2018] [Accepted: 08/08/2018] [Indexed: 12/19/2022]
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15
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Zhang Y, Li Q, Dai B, Zhou S, Zhang M, Han H, Qiu H. A versatile polar-embedded polyphenyl phase for multimodal separation in liquid chromatography. J Chromatogr A 2018; 1553:81-89. [DOI: 10.1016/j.chroma.2018.04.025] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Revised: 04/07/2018] [Accepted: 04/10/2018] [Indexed: 10/17/2022]
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16
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Prauda I, Bartó E, Felinger A. Influence of pressure on the retention of resorcinarene-based cavitands. J Chromatogr A 2018; 1535:123-128. [DOI: 10.1016/j.chroma.2018.01.021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Revised: 01/07/2018] [Accepted: 01/08/2018] [Indexed: 10/18/2022]
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17
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Bai P, Siepmann JI. Assessment and Optimization of Configurational-Bias Monte Carlo Particle Swap Strategies for Simulations of Water in the Gibbs Ensemble. J Chem Theory Comput 2017; 13:431-440. [DOI: 10.1021/acs.jctc.6b00973] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Peng Bai
- Departments of Chemistry
and of Chemical Engineering and Materials Science and Chemical Theory
Center, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455-0431, United States
| | - J. Ilja Siepmann
- Departments of Chemistry
and of Chemical Engineering and Materials Science and Chemical Theory
Center, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455-0431, United States
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18
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Jin H, Liu Y, Guo Z, Wang J, Zhang X, Wang C, Liang X. Recent development in liquid chromatography stationary phases for separation of Traditional Chinese Medicine components. J Pharm Biomed Anal 2016; 130:336-346. [PMID: 27329167 DOI: 10.1016/j.jpba.2016.06.008] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Revised: 05/25/2016] [Accepted: 06/07/2016] [Indexed: 01/20/2023]
Abstract
Traditional Chinese Medicine (TCM) is an ancient medical practice which has been used to prevent and cure diseases for thousands of years. TCMs are frequently multi-component systems with mainly unidentified constituents. The study of the chemical compositions of TCMs remains a hotspot of research. Different strategies have been developed to manage the significant complexity of TCMs, in an attempt to determine their constituents. Reversed-phase liquid chromatography (RPLC) is still the method of choice for the separation of TCMs, but has many problems related to limited selectivity. Recently, enormous efforts have been concentrated on the development of efficient liquid chromatography (LC) methods for TCMs, based on selective stationary phases. This can improve the resolution and peak capacity considerably. In addition, high-efficiency stationary phases have been applied in the analysis of TCMs since the invention of ultra high-performance liquid chromatography (UHPLC). This review describes the advances in LC methods in TCM research from 2010 to date, and focuses on novel stationary phases. Their potential in the separation of TCMs using relevant applications is also demonstrated.
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Affiliation(s)
- Hongli Jin
- Key Lab of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, People's Republic of China
| | - Yanfang Liu
- Key Lab of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, People's Republic of China.
| | - Zhimou Guo
- Key Lab of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, People's Republic of China
| | - Jixia Wang
- Key Lab of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, People's Republic of China
| | - Xiuli Zhang
- Key Lab of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, People's Republic of China
| | - Chaoran Wang
- Key Lab of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, People's Republic of China
| | - Xinmiao Liang
- Key Lab of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, People's Republic of China.
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Gómara B, Lebrón-Aguilar R, González M, Quintanilla-López J. Insight into the retention processes of phthalate metabolites on different liquid chromatography stationary phases for the development of improved separation methods. J Chromatogr A 2015; 1423:86-95. [DOI: 10.1016/j.chroma.2015.10.069] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Revised: 10/20/2015] [Accepted: 10/22/2015] [Indexed: 12/28/2022]
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20
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Mallik AK, Qiu H, Kuwahara Y, Takafuji M, Ihara H. A remarkable enhancement of selectivity towards versatile analytes by a strategically integrated H-bonding site containing phase. Chem Commun (Camb) 2015; 51:14243-6. [PMID: 26264655 DOI: 10.1039/c5cc04966k] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A double β-alanylated L-glutamide-derived organic phase has been newly designed and synthesized in such a way that integrated H-bonding (interaction) sites make it very suitable for the separation of versatile analytes, including shape-constrained isomers, and nonpolar, polar and basic compounds. The β-alanine residues introduced into two long-chain alkyl group moieties provide ordered polar groups through H-bonding among the amide groups.
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Affiliation(s)
- Abul K Mallik
- Department of Applied Chemistry and Biochemistry, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555, Japan.
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21
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Mallik AK, Qiu H, Oishi T, Kuwahara Y, Takafuji M, Ihara H. Design of C18 Organic Phases with Multiple Embedded Polar Groups for Ultraversatile Applications with Ultrahigh Selectivity. Anal Chem 2015; 87:6614-21. [DOI: 10.1021/acs.analchem.5b00663] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
| | - Hongdeng Qiu
- 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, Lanzhou 730000, China
| | | | - Yutaka Kuwahara
- Kumamoto Institute for Photo-Electro Organics (Phoenics), Kumamoto 862-0901, Japan
| | - Makoto Takafuji
- Kumamoto Institute for Photo-Electro Organics (Phoenics), Kumamoto 862-0901, Japan
| | - Hirotaka Ihara
- Kumamoto Institute for Photo-Electro Organics (Phoenics), Kumamoto 862-0901, Japan
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22
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Contributions to reversed-phase column selectivity. J Chromatogr A 2015; 1395:57-64. [DOI: 10.1016/j.chroma.2015.03.044] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Revised: 03/17/2015] [Accepted: 03/18/2015] [Indexed: 11/23/2022]
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23
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Borówko M, Sokołowski S, Staszewski T. Adsorption on chemically bonded chain layers with embedded active groups. Mol Phys 2014. [DOI: 10.1080/00268976.2014.962636] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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24
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Borges EM. Silica, hybrid silica, hydride silica and non-silica stationary phases for liquid chromatography. J Chromatogr Sci 2014; 53:580-97. [PMID: 25234386 DOI: 10.1093/chromsci/bmu090] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Free silanols on the surface of silica are the "villains", which are responsible for detrimental interactions of those compounds and the stationary phase (i.e., bad peak shape, low efficiency) as well as low thermal and chemical stability. For these reasons, we began this review describing new silica and hybrid silica stationary phases, which have reduced and/or shielded silanols. At present, in liquid chromatography for the majority of analyses, reversed-phase liquid chromatography is the separation mode of choice. However, the needs for increased selectivity and increased retention of hydrophilic bases have substantially increased the interest in hydrophilic interaction chromatography (HILIC). Therefore, stationary phases and this mode of separation are discussed. Then, non-silica stationary phases (i.e., zirconium oxide, titanium oxide, alumina and porous graphitized carbon), which afford increased thermal and chemical stability and also selectivity different from those obtained with silica and hybrid silica, are discussed. In addition, the use of these materials in HILIC is also reviewed.
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Affiliation(s)
- Endler M Borges
- Núcleo Biotecnológico, Universidade do Oeste de Santa Catarina, Rua Paese, 198, Bairro Universitário-Bloco K. Videira, SC CEP 89560-000, Brazil
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25
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Borówko M, Sokołowski S, Staszewski T. Adsorption-induced changes of the structure of the tethered chain layers in a simple fluid. J Chem Phys 2014; 140:234904. [PMID: 24952565 DOI: 10.1063/1.4883336] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
We use density functional theory to study the influence of fluid adsorption on the structure of grafted chain layer. The chains are modeled as freely jointed spheres. The chain segments and spherical molecules of the fluid interact via the Lennard-Jones potential. The fluid molecules are attracted by the substrate. We calculate the excess adsorption isotherms, the average height of tethered chains, and the force acting on selected segments of the chains. The parameters that were varied include the length of grafted chains, the grafting density, the parameters characterizing fluid-chain and fluid-surface interactions, the bulk fluid density, and temperature. We show that depending on the density of the bulk fluid the height of the bonded layer increases, remains constant, or decreases with increasing temperature.
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Affiliation(s)
- M Borówko
- Department for the Modelling of Physico-Chemical Processes, Maria Curie-Skłodowska University, 20-031 Lublin, Poland
| | - S Sokołowski
- Department for the Modelling of Physico-Chemical Processes, Maria Curie-Skłodowska University, 20-031 Lublin, Poland
| | - T Staszewski
- Department for the Modelling of Physico-Chemical Processes, Maria Curie-Skłodowska University, 20-031 Lublin, Poland
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26
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Gritti F, Guiochon G. Comparison between the intra-particle diffusivity in the hydrophilic interaction chromatography and reversed phase liquid chromatography modes. Impact on the column efficiency. J Chromatogr A 2013; 1297:85-95. [DOI: 10.1016/j.chroma.2013.04.055] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2013] [Revised: 04/16/2013] [Accepted: 04/18/2013] [Indexed: 11/26/2022]
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27
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Gritti F, Guiochon G. Effect of the pH and the ionic strength on overloaded band profiles of weak bases onto neutral and charged surface hybrid stationary phases in reversed-phase liquid chromatography. J Chromatogr A 2013; 1282:113-26. [DOI: 10.1016/j.chroma.2013.01.063] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2012] [Revised: 01/10/2013] [Accepted: 01/11/2013] [Indexed: 11/24/2022]
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28
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Gritti F, Guiochon G. Effect of the ionic strength on the adsorption process of an ionic surfactant onto a C18-bonded charged surface hybrid stationary phase at low pH. J Chromatogr A 2013; 1282:46-57. [DOI: 10.1016/j.chroma.2013.01.027] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2012] [Revised: 12/18/2012] [Accepted: 01/06/2013] [Indexed: 12/01/2022]
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29
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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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30
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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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31
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Bai P, Tsapatsis M, Siepmann JI. Multicomponent adsorption of alcohols onto silicalite-1 from aqueous solution: isotherms, structural analysis, and assessment of ideal adsorbed solution theory. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:15566-15576. [PMID: 23050981 DOI: 10.1021/la303247c] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Configurational-bias Monte Carlo (CBMC) simulations in the isobaric-isothermal version of the Gibbs ensemble (GE) were carried out to probe the adsorption from aqueous solutions of methanol and/or ethanol onto silicalite-1. This methodology does require neither specification of the chemical potential nor any reference to activity models based on experimental data. The CBMC-GE methodology can be applied to the complete range of mixture compositions from pure water to pure alcohols and can also be used when multiple solute types are present at high concentration. The simulations demonstrate high selectivities for the alcohols (α(ethanol) > α(methanol)) almost over the entire composition range. The ideal adsorbed solution theory is found to substantially underpredict the amount of sorbed water and leads to very large errors for low alcohol solution concentrations. The simulations indicate that, at lower loadings, the adsorbed alcohol molecules can serve as seeds for water adsorption but, at higher loadings, alcohols displace water molecules from their preferred region.
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Affiliation(s)
- Peng Bai
- Departments of Chemistry, University of Minnesota, Minneapolis, 55455, United States
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32
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Borówko M, Sokołowski S, Staszewski T. Adsorption from Oligomer–Monomer Solutions on the Surfaces Modified with End-Grafted Chains. J Phys Chem B 2012; 116:12842-9. [DOI: 10.1021/jp305624n] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- M. Borówko
- Department for the Modeling
of Physico-Chemical
Processes, Maria Curie-Skłodowska University, 20-031 Lublin, Poland
| | - S. Sokołowski
- Department for the Modeling
of Physico-Chemical
Processes, Maria Curie-Skłodowska University, 20-031 Lublin, Poland
| | - T. Staszewski
- Department for the Modeling
of Physico-Chemical
Processes, Maria Curie-Skłodowska University, 20-031 Lublin, Poland
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33
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Gupta PK, Meuwly M. Dynamics of Water/Methanol Mixtures at Functionalized Chromatographic Interfaces. J Phys Chem B 2012; 116:10951-9. [DOI: 10.1021/jp305351f] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Prashant Kumar Gupta
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, 4056 Basel, Switzerland
| | - Markus Meuwly
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, 4056 Basel, Switzerland
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34
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Qiu H, Mallik AK, Takafuji M, Liu X, Jiang S, Ihara H. A new imidazolium-embedded C18 stationary phase with enhanced performance in reversed-phase liquid chromatography. Anal Chim Acta 2012; 738:95-101. [DOI: 10.1016/j.aca.2012.06.018] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2012] [Revised: 06/09/2012] [Accepted: 06/10/2012] [Indexed: 11/30/2022]
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35
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Borówko M, Sokołowski S, Staszewski T. Adsorption from Binary Solutions on the Polymer-Tethered Surfaces. J Phys Chem B 2012; 116:3115-24. [DOI: 10.1021/jp300114y] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- M. Borówko
- Department for the Modeling
of Physico-Chemical
Processes, Maria Curie-Skłodowska University, 20-031 Lublin, Poland
| | - S. Sokołowski
- Department for the Modeling
of Physico-Chemical
Processes, Maria Curie-Skłodowska University, 20-031 Lublin, Poland
| | - T. Staszewski
- Department for the Modeling
of Physico-Chemical
Processes, Maria Curie-Skłodowska University, 20-031 Lublin, Poland
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36
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Rafferty JL, Siepmann JI, Schure MR. A molecular simulation study of the effects of stationary phase and solute chain length in reversed-phase liquid chromatography. J Chromatogr A 2012; 1223:24-34. [DOI: 10.1016/j.chroma.2011.11.039] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2011] [Revised: 11/17/2011] [Accepted: 11/20/2011] [Indexed: 10/15/2022]
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37
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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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38
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Separation of imidacloprid and its degradation products using reversed phase liquid chromatography with water rich mobile phases. J Chromatogr A 2011; 1218:9221-6. [DOI: 10.1016/j.chroma.2011.10.057] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2011] [Revised: 10/18/2011] [Accepted: 10/21/2011] [Indexed: 11/18/2022]
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39
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Rafferty JL, Siepmann JI, Schure MR. Retention mechanism for polycyclic aromatic hydrocarbons in reversed-phase liquid chromatography with monomeric stationary phases. J Chromatogr A 2011; 1218:9183-93. [DOI: 10.1016/j.chroma.2011.10.043] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2011] [Revised: 10/11/2011] [Accepted: 10/17/2011] [Indexed: 10/15/2022]
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40
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Borówko M, Patrykiejew A, Sokołowski S. Unusual mechanism of capillary condensation in pores modified with chains forming pillars. J Chem Phys 2011; 135:054703. [DOI: 10.1063/1.3617413] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
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41
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Pizio O, Sokołowski S, Sokołowska Z. Phase behavior of binary symmetric mixtures in pillared slit-like pores: A density functional approach. J Chem Phys 2011; 134:214702. [DOI: 10.1063/1.3597773] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
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42
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Ilnytskyi JM, Patsahan T, Sokołowski S. Nanostructures in a binary mixture confined in slit-like pores with walls decorated with tethered polymer brushes in the form of stripes: Dissipative particle dynamics study. J Chem Phys 2011; 134:204903. [DOI: 10.1063/1.3592562] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
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43
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Borówko M, Sokołowski S, Staszewski T. Adsorption of oligomers on the polymer-tethered surfaces. J Colloid Interface Sci 2011; 356:267-76. [DOI: 10.1016/j.jcis.2011.01.023] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2010] [Revised: 01/05/2011] [Accepted: 01/05/2011] [Indexed: 10/18/2022]
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44
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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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45
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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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46
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Protein separation on a polar-copolymerized C8 stationary phase. Anal Bioanal Chem 2010; 399:3415-21. [DOI: 10.1007/s00216-010-4462-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2010] [Revised: 10/21/2010] [Accepted: 11/22/2010] [Indexed: 10/18/2022]
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47
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Characterization and optimization by experimental design of a liquid chromatographic method for the separation of hydroxylated polychlorinated biphenyls on a polar-embedded stationary phase. J Chromatogr A 2010; 1217:7231-41. [DOI: 10.1016/j.chroma.2010.09.032] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2010] [Revised: 09/08/2010] [Accepted: 09/09/2010] [Indexed: 11/19/2022]
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48
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Mitchell CR, Benz NJ, Zhang S. Characterization of stationary phases by a linear solvation energy relationship utilizing supercritical fluid chromatography. J Sep Sci 2010; 33:3060-7. [DOI: 10.1002/jssc.201000371] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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49
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Gritti F, Guiochon G. Comparison between heterogeneous multi-Langmuir and homogeneous electrostatically modified Langmuir models in accounting for the adsorption of small organic ions in reversed-phase liquid chromatography. J Chromatogr A 2010; 1217:5584-94. [DOI: 10.1016/j.chroma.2010.06.046] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2010] [Revised: 06/17/2010] [Accepted: 06/18/2010] [Indexed: 10/19/2022]
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50
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Olariu RI, Vione D, Grinberg N, Arsene C. SAMPLE PREPARATION FOR TRACE ANALYSIS BY CHROMATOGRAPHIC METHODS. J LIQ CHROMATOGR R T 2010. [DOI: 10.1080/10826076.2010.484371] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Romeo-Iulian Olariu
- a Department of Chemistry , Faculty of Chemistry, Laboratory of Analytical Chemistry, “Al. I. Cuza” University of Iasi , Iasi , Romania
| | - Davide Vione
- b Dipartimento di Chimica Analitica , Università di Torino , Torino , Italy
| | - Nelu Grinberg
- c Boehringer Ingelheim Pharmaceuticals Inc. , Ridgefield , Connecticut , USA
| | - Cecilia Arsene
- a Department of Chemistry , Faculty of Chemistry, Laboratory of Analytical Chemistry, “Al. I. Cuza” University of Iasi , Iasi , Romania
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