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Klimek-Turek A, Misiołek B, Dzido TH. Comparison of the Retention and Separation Selectivity of Aromatic Hydrocarbons with Polar Groups in RP-HPLC Systems with Different Stationary Phases and Eluents. Molecules 2020; 25:molecules25215070. [PMID: 33139630 PMCID: PMC7663032 DOI: 10.3390/molecules25215070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 10/21/2020] [Accepted: 10/28/2020] [Indexed: 11/07/2022] Open
Abstract
In this manuscript, the retention of aromatic hydrocarbons with polar groups has been compared for systems with various nonpolar columns of the types from C3 to C18 and different mobile phases composed of methanol, acetonitrile, or tetrahydrofuran as modifiers. The selectivity separation of the solutes in systems with different adsorbents, when one eluent modifier is swapped by another, has been explained, taking into account molecular interactions of the solutes with components of the stationary phase region (i.e., extracted modifier depending on the chain length of the stationary phase).
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Affiliation(s)
- Anna Klimek-Turek
- Department of Physical Chemistry, Medical University of Lublin, Chodźki 4a, 20-093 Lublin, Poland; (B.M.); (T.H.D.)
- Correspondence: ; Tel.: +48-81448-7206
| | - Beata Misiołek
- Department of Physical Chemistry, Medical University of Lublin, Chodźki 4a, 20-093 Lublin, Poland; (B.M.); (T.H.D.)
- Department for Variations and Renewals of Medicinal Products, The Office for Registration of Medicinal Products, Medical Devices and Biocidal Products, Al. Jerozolimskie 181C, 02-222 Warsaw, Poland
| | - Tadeusz H. Dzido
- Department of Physical Chemistry, Medical University of Lublin, Chodźki 4a, 20-093 Lublin, Poland; (B.M.); (T.H.D.)
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2
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Saha S, Walia S, Sharma K, Banerjee K. Suitability of stationary phase for LC analysis of biomolecules. Crit Rev Food Sci Nutr 2019; 60:2856-2873. [PMID: 31621391 DOI: 10.1080/10408398.2019.1665494] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Biologically active compounds such as carotenoids/isoprenoids, vitamins, steroids, saponins, sugars, long chain fatty acids, and amino acids play a very important role in coordinating functions in living organisms. Determination of those substances is indispensable in advanced biological sciences. Engineered stationary phase in LC for the analysis of biomolecules has become easier with the development of chromatographic science. In general, C18 column is being used for routine analysis but specific columns are being used for specific molecule. Monolithic columns are found to have higher efficiency than normal column. Among recent introduction, triacontyl stationary phases, designed for the separation of carotenoid isomers, are widely used for the estimation of carotenoids. In comparison to conventional C18 phases, C30 phases exhibited superior shape selectivity for the separation of isomers of carotenoids. It is also found useful for better elution and analysis of tocopherols, vitamin K, sterols, and fatty acids. Vitamin K, E, and their isomers are also successfully resoluted and analyzed by using C30 column. Amino bonded phase column is specifically used for better elution of sugars, whereas phenyl columns are suitable for the separation and analysis of curcuminoids and taxol. Like triacontyl stationary phase, pentafluorophenyl columns are also used for the separation and analysis of carotenoids. Similarly, HILIC column are best suited for sugar analysis. All the stationary phases are made possible to resolute and analyze the target biomolecules better, which are the future of liquid chromatography. The present article focuses on the differential interaction between stationary phase and target biomolecules. The applicability of these stationary phases are reported in different matrices.
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Affiliation(s)
- Supradip Saha
- Division of Agricultural Chemicals, ICAR-Indian Agricultural Research Institute, New Delhi, India
| | - Suresh Walia
- Division of Agricultural Chemicals, ICAR-Indian Agricultural Research Institute, New Delhi, India
| | - Khushbu Sharma
- Division of Agricultural Chemicals, ICAR-Indian Agricultural Research Institute, New Delhi, India
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3
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Douša M, Doubský J. Separation of structurally related primary aliphatic amines using hydrophilic interaction chromatography with fluorescence detection after postcolumn derivatization with o-phthaldialdehyde/mercaptoethanol. J Sep Sci 2018; 40:4689-4699. [PMID: 29057598 DOI: 10.1002/jssc.201701005] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Revised: 10/09/2017] [Accepted: 10/09/2017] [Indexed: 11/09/2022]
Abstract
The retention behavior of primary aliphatic amines (homologous series of aliphatic alkyl amines and cycloalkyl amines) and positional isomers of alkylamines in the hydrophilic interaction chromatography mode was studied. The study was carried out on a TSKgel Amide-80 column followed by postcolumn derivatization with fluorescence detection to describe the retention mechanism of tested compounds. The effect of chromatographic conditions including column temperature, acetonitrile content in the mobile phase, mobile phase pH (ranging from 3.5 to 6.8), and salt concentration in the mobile phase was investigated. The final mobile phase consisted of acetonitrile and solution of 20 mM potassium formate pH 3.5 in ratio 80:20 v/v. The analyses were carried out at mobile phase flow rate of 1.0 mL/min and the column temperature of 20°C. The developed method was fully validated in terms of linearity, sensitivity (limit of detection and limit of quantification), accuracy, and precision according to International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use guidelines. The proposed new methods were proved to be highly sensitive, simple, and rapid, and were successfully applied to the determinations of isopropylamine, cyclohexylamine, and cyclopropylamine in relevant active pharmaceutical ingredients.
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Affiliation(s)
- Michal Douša
- Zentiva, k.s. Praha, a Sanofi Company, Prague, Czech Republic
| | - Jan Doubský
- Zentiva, k.s. Praha, a Sanofi Company, Prague, Czech Republic
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4
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Flieger J, Trębacz H, Pizoń M, Kowalska A, Szczęsna A, Plech T. High-performance liquid chromatography thermodynamic study of new potential antiepileptic compounds on a cholesterol column using isocratic elution with methanol/water and acetonitrile/water eluent systems. J Sep Sci 2017; 40:4176-4190. [DOI: 10.1002/jssc.201700748] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Revised: 08/25/2017] [Accepted: 08/25/2017] [Indexed: 11/09/2022]
Affiliation(s)
- Jolanta Flieger
- Department of Analytical Chemistry; Medical University of Lublin; Lublin Poland
| | - Hanna Trębacz
- Chair and Department of Biophysics; Medical University of Lublin; Lublin Poland
| | - Magdalena Pizoń
- Department of Analytical Chemistry; Medical University of Lublin; Lublin Poland
| | - Anna Kowalska
- Department of Analytical Chemistry; Medical University of Lublin; Lublin Poland
| | - Agnieszka Szczęsna
- Chair and Department of Biophysics; Medical University of Lublin; Lublin Poland
| | - Tomasz Plech
- Department of Pharmacology; Medical University of Lublin; Lublin Poland
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5
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Turcsi E, Nagy V, Deli J. Study on the elution order of carotenoids on endcapped C18 and C30 reverse silica stationary phases. A review of the database. J Food Compost Anal 2016. [DOI: 10.1016/j.jfca.2016.01.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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6
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Shirinian M, Kfoury Y, Dassouki Z, El-Hajj H, Bazarbachi A. Tax-1 and Tax-2 similarities and differences: focus on post-translational modifications and NF-κB activation. Front Microbiol 2013; 4:231. [PMID: 23966989 PMCID: PMC3744011 DOI: 10.3389/fmicb.2013.00231] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Accepted: 07/29/2013] [Indexed: 11/13/2022] Open
Abstract
Although human T cell leukemia virus type 1 and 2 (HTLV-1 and HTLV-2) share similar genetic organization, they have major differences in their pathogenesis and disease manifestation. HTLV-1 is capable of transforming T lymphocytes in infected patients resulting in adult T cell leukemia/lymphoma whereas HTLV-2 is not clearly associated with lymphoproliferative diseases. Numerous studies have provided accumulating evidence on the involvement of the viral transactivators Tax-1 versus Tax-2 in T cell transformation. Tax-1 is a potent transcriptional activator of both viral and cellular genes. Tax-1 post-translational modifications and specifically ubiquitylation and SUMOylation have been implicated in nuclear factor-kappaB (NF-κB) activation and may contribute to its transformation capacity. Although Tax-2 has similar protein structure compared to Tax-1, the two proteins display differences both in their protein–protein interaction and activation of signal transduction pathways. Recent studies on Tax-2 have suggested ubiquitylation and SUMOylation independent mechanisms of NF-κB activation. In this present review, structural and functional differences between Tax-1 and Tax-2 will be summarized. Specifically, we will address their subcellular localization, nuclear trafficking and their effect on cellular regulatory proteins. A special attention will be given to Tax-1/Tax-2 post-translational modification such as ubiquitylation, SUMOylation, phosphorylation, acetylation, NF-κB activation, and protein–protein interactions involved in oncogenecity both in vivo and in vitro.
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Affiliation(s)
- Margret Shirinian
- Department of Internal Medicine, Faculty of Medicine, American University of Beirut Beirut, Lebanon
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7
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Tasaki Y, Okada T. Control of Ice Chromatographic Retention Mechanism by Changing Temperature and Dopant Concentration. Anal Chem 2011; 83:9593-9. [DOI: 10.1021/ac202378m] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- Yuiko Tasaki
- Department of Chemistry, Tokyo Institute of Technology, Meguro-ku, Tokyo 152-8551, Japan
| | - Tetsuo Okada
- Department of Chemistry, Tokyo Institute of Technology, Meguro-ku, Tokyo 152-8551, Japan
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Zhang Y, Carr PW. Novel ultra stable silica-based stationary phases for reversed phase liquid chromatography--study of a hydrophobically assisted weak acid cation exchange phase. J Chromatogr A 2011; 1218:763-77. [PMID: 21227426 PMCID: PMC3027354 DOI: 10.1016/j.chroma.2010.11.009] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2010] [Revised: 10/31/2010] [Accepted: 11/08/2010] [Indexed: 10/18/2022]
Abstract
A mixed-mode reversed-phase/weak cation exchange (RP/WCX) phase has been developed by introducing a small amount of carboxylate functionality into a hydrophobic hyper-crosslinked (HC) platform. This silica-based HC platform was designed to form an extensive polystyrene network completely confined to the particle's surface. The fully connected polymer network prevents the loss of bonded phase, which leads to superior hydrolytic stability of the new phase when compared to conventional silica-based phases. Compared to previously introduced HC phases the added carboxylic groups impart a new weak cation exchange selectivity to the base hydrophobic HC platform. The phase thus prepared shows a mixed-mode retention mechanism, allowing for both neutral organic compounds and bases of a wide polarity range to be simultaneously separated on the same phase under the same conditions. In addition, the new phase offers the flexibility that gradients in organic modifier, pH or ionic competitors can be used to affect the separation of a wide range of solutes. Moreover, the inherent weak acid cation exchange groups allow formic and acetic acid buffers to be used as eluents thereby avoiding the mass spectrometric ionization suppression problems concomitant to the use of non-volatile additives such as strong amine modifiers (e.g. triethylamine) or salts (e.g. NaCl) to elute basic solutes from the strong cation exchange phase which was previously developed in this lab. The use of the new phase for achieving strong retention of rather hydrophilic neurotransmitters and drugs of abuse without the need for ion pairing agents is demonstrated.
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Affiliation(s)
- Yu Zhang
- University of Minnesota, 207 Pleasant St. SE, Minneapolis, MN 55455, USA
| | - Peter W. Carr
- University of Minnesota, 207 Pleasant St. SE, Minneapolis, MN 55455, USA
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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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10
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Xin-Du G, Fred E R. An Integrated Theory of Adsorption and Partition Mechanism and Each Contribution to Solute Retention in Reversed Phase Liquid Chromatography. CHINESE J CHEM 2010. [DOI: 10.1002/cjoc.20030210319] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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11
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TASAKI Y, OKADA T. Adsorption-Partition Switching of Retention Mechanism in Ice Chromatography with NaCl-doped Water-Ice. ANAL SCI 2009; 25:177-81. [DOI: 10.2116/analsci.25.177] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Yuiko TASAKI
- Department of Chemistry, Tokyo Institute of Technology
| | - Tetsuo OKADA
- Department of Chemistry, Tokyo Institute of Technology
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12
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Heinisch S, Rocca JL. Sense and nonsense of high-temperature liquid chromatography. J Chromatogr A 2009; 1216:642-58. [DOI: 10.1016/j.chroma.2008.11.079] [Citation(s) in RCA: 136] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2008] [Revised: 11/13/2008] [Accepted: 11/20/2008] [Indexed: 10/21/2022]
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13
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Rafferty JL, Siepmann J, Schure MR. Influence of bonded-phase coverage in reversed-phase liquid chromatography via molecular simulation. J Chromatogr A 2008; 1204:11-9. [DOI: 10.1016/j.chroma.2008.07.037] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2008] [Revised: 06/24/2008] [Accepted: 07/04/2008] [Indexed: 10/21/2022]
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14
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Synthesis, characterization, and high-performance liquid chromatographic evaluation of C14 stationary phases containing branched and unbranched alkyl groups. Anal Bioanal Chem 2008; 391:2627-33. [DOI: 10.1007/s00216-008-2183-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2008] [Revised: 05/08/2008] [Accepted: 05/13/2008] [Indexed: 10/22/2022]
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15
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16
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Chen Z, Nakayama T, Nakagama T, Uchiyama K, Hobo T. Thermodynamic Approaches to Intermolecular Interaction and Retention Behavior in Liquid Chromatography. J LIQ CHROMATOGR R T 2007. [DOI: 10.1081/jlc-120025047] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- Zilin Chen
- a Department of Applied Chemistry, Graduate School of Engineering , Tokyo Metropolitan University , Hachioji, Tokyo , Japan
- b Biosensing Research Group, Ubiquitous Interface Laboratory , NTT Microsystem Integration Laboratories , 3‐1 Wakamiya, Morinosato, Atsugi, Kanagawa , 243‐0198 , Japan
| | - Takashi Nakayama
- a Department of Applied Chemistry, Graduate School of Engineering , Tokyo Metropolitan University , Hachioji, Tokyo , Japan
| | - Tatsuro Nakagama
- a Department of Applied Chemistry, Graduate School of Engineering , Tokyo Metropolitan University , Hachioji, Tokyo , Japan
| | - Katsumi Uchiyama
- a Department of Applied Chemistry, Graduate School of Engineering , Tokyo Metropolitan University , Hachioji, Tokyo , Japan
| | - Toshiyuki Hobo
- a Department of Applied Chemistry, Graduate School of Engineering , Tokyo Metropolitan University , Hachioji, Tokyo , Japan
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17
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Lukulay PH, McGuffin VL. Experimental and Computer Simulation Studies of Solute-Solute Interactions in Liquid Chromatography. J LIQ CHROMATOGR R T 2006. [DOI: 10.1080/10826079608017140] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Patrick H. Lukulay
- a Department of Chemistry , Michigan State University East Lansing , Michigan, 48824, USA
| | - Victoria L. McGuffin
- a Department of Chemistry , Michigan State University East Lansing , Michigan, 48824, USA
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18
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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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19
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Djordjevic NM, Fowler PWJ, Houdiere F, Lerch G. Retention of Neutral Solutes in Capillary Electrochromatography. J LIQ CHROMATOGR R T 2006. [DOI: 10.1080/10826079808006621] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- N. M. Djordjevic
- a Novartis Pharma, Ltd , Pharma Discovery, Bldg , 503/1106, Basle, CH-4002, Switzerland
| | - P. W. J. Fowler
- a Novartis Pharma, Ltd , Pharma Discovery, Bldg , 503/1106, Basle, CH-4002, Switzerland
| | - F. Houdiere
- a Novartis Pharma, Ltd , Pharma Discovery, Bldg , 503/1106, Basle, CH-4002, Switzerland
| | - G. Lerch
- a Novartis Pharma, Ltd , Pharma Discovery, Bldg , 503/1106, Basle, CH-4002, Switzerland
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20
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Liao Z, Orendorff CJ, Sander LC, Pemberton JE. Structure−Function Relationships in High-Density Docosylsilane Bonded Stationary Phases by Raman Spectroscopy and Comparison to Octadecylsilane Bonded Stationary Phases. Anal Chem 2006; 78:5813-22. [PMID: 16906728 DOI: 10.1021/ac060385p] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Raman spectroscopy is used to investigate the effects of temperature, surface coverage, polymerization method (surface or solution polymerized), and nature of the alkylsilane precursor on alkyl chain conformational order in a series of high-density docosylsilane (C22) stationary phases at surface coverages ranging from 3.61 to 6.97 mumol/m(2). The results of this study contribute to an enhanced understanding of the shape-selective retention characteristics of these phases at a molecular level. Conformational order is evaluated using the intensity ratio of the antisymmetric and symmetric nu(CH2) modes as well as the frequency at which these modes are observed. Alkyl chain order is shown to be dependent on surface coverage, alkyl chain length, and polymerization method. In general, alkyl chain order increases with surface coverage. Temperature-induced changes are observed between 250 and 350 K for the three phases with surface coverages between 3.61 and 4.89 mumol/m(2). These changes occur over a broad range of temperatures characteristic of two-dimensional systems, but in general adhere to the behavior predicted for a simple first-order transition. This change is not believed to be an abrupt cooperative disassociation characteristic of a phase transition in a bulk phase, but instead is thought to involve significant changes in conformational order in segments of the surface-tethered molecules, mostly those segments at the outer edge of the alkylsilane. In contrast to the changes observed in coverages below 5 mumol/m(2), a first-order change is not observed for the stationary phase with coverage of 6.97 mumol/m(2). A molecular picture of the temperature-induced disorder is proposed with disorder originating at the distal carbon and propagating only a short distance toward the proximal carbon. A comparison is made between these C22 stationary phases and similar high-density octadecylsilane (C18) bonded phases.
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Affiliation(s)
- Zhaohui Liao
- Department of Chemistry, University of Arizona, 1306 East University Boulevard, Tucson, Arizona 85721, USA
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21
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Meyer C, Pascui O, Reichert D, Sander LC, Wise SA, Albert K. Conformational temperature dependence of a poly(ethylene-co-acrylic acid) stationary phase investigated by nuclear magnetic resonance spectroscopy and liquid chromatography. J Sep Sci 2006; 29:820-8. [PMID: 16830494 DOI: 10.1002/jssc.200500376] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
A polymer-based RP sorbent was prepared by immobilizing a poly(ethylene-co-acrylic acid) copolymer with an acid mass fraction of 5% on silica by using a 3-glycidoxypropyl linkage. 13C cross-polarization/magic angle spinning NMR spectroscopy of the sorbent, either in the dry state or suspended in the mobile phase, showed an increase in mobility at elevated temperatures. Alkyl chain segments with gauche conformations were more mobile than chain segments with trans conformations. The strength of the 13C-1H dipolar couplings in the alkyl chains was measured using the constant time dipolar and chemical shift pulse sequence, revealing less molecular motion for the trans conformation. Non-linear van't Hoff plots were observed for separations of shape-constrained solutes (such as geometric beta-carotene isomers and polycyclic aromatic hydrocarbons). At higher temperatures, the retention behavior was similar to that of monomeric C18 sorbents, whereas at ambient and lower temperatures, enhanced shape-selective properties were exhibited similar to those of polymeric C30 sorbents.
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Affiliation(s)
- Christoph Meyer
- Institute of Organic Chemistry, University of Tuebingen, Tuebingen, Germany
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22
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Sander LC, Lippa KA, Wise SA. Order and disorder in alkyl stationary phases. Anal Bioanal Chem 2005; 382:646-68. [PMID: 15827723 DOI: 10.1007/s00216-005-3127-2] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2004] [Revised: 01/21/2005] [Accepted: 01/24/2005] [Indexed: 11/28/2022]
Abstract
Covalently modified surfaces represent a unique state of matter that is not well described by liquid or solid phase models. The chemical bond in tethered alkanes imparts order to the surface in the form of anisotropic properties that are evident in chromatographic and spectroscopic studies. An understanding of the structure, conformation, and organization of alkyl-modified surfaces is requisite to the design of improved materials and the optimal utilization of existing materials. In recent years, the study of alkyl-modified surfaces has benefited from advances in modern analytical instrumentation. Aspects of alkyl chain conformation and motion have been investigated through the use of nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, fluorescence spectroscopy, and neutron scattering studies. Chromatography provides complementary evidence of alkyl chain organization through interactions with solute probes. Computational simulations offer insights into the structure of covalently modified surfaces that may not be apparent through empirical observation. This manuscript reviews progress achieved in the study of the architecture of alkyl-modified surfaces.
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Affiliation(s)
- Lane C Sander
- Chemical Science and Technology Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899-8392, USA.
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23
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Howerton SB, McGuffin VL. Thermodynamic and Kinetic Characterization of Polycyclic Aromatic Hydrocarbons in Reversed-Phase Liquid Chromatography. Anal Chem 2003; 75:3539-48. [PMID: 14570208 DOI: 10.1021/ac020718s] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The retention of six polycyclic aromatic hydrocarbons (PAHs) was characterized by reversed-phase liquid chromatography. The PAHs were detected by laser-induced fluorescence at four points along an optically transparent capillary column. The profiles were characterized in space and time using an exponentially modified Gaussian equation. The resulting parameters were used to calculate the retention factors, as well as the concomitant changes in molar enthalpy and molar volume, for each PAH on monomeric (2.7 micromol/m2) and polymeric (5.4 micromol/m2) octadecylsilica. The changes in molar enthalpy become more exothermic as ring number increases and as annelation structure becomes less condensed. The changes in molar volume become more negative as ring number increases for the planar PAHs, but are positive for the nonplanar solutes. In addition, the rate constants, as well as the concomitant activation enthalpy and activation volume, are calculated for the first time. The kinetic data demonstrate that many of the PAHs exhibit very fast transitions between the mobile and stationary phases. The transition state is very high in energy, and the activation enthalpies and volumes become greater as ring number increases and as annelation structure becomes less condensed. The changes in thermodynamic and kinetic behavior are much more pronounced for the polymeric phase than for the monomeric phase.
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Affiliation(s)
- Samuel B Howerton
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824-1322, USA
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24
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Skrdla P, Robertson R. Investigation of alcohol dehydration by a cobalt(II) sulfate-promoted γ-alumina catalyst inside a gas chromatograph injection port. ACTA ACUST UNITED AC 2003. [DOI: 10.1016/s1381-1169(02)00529-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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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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26
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Ducey MW, Orendorff CJ, Pemberton JE, Sander LC. Structure-function relationships in high-density octadecylsilane stationary phases by Raman spectroscopy. 1. Effects of temperature, surface coverage, and preparation procedure. Anal Chem 2002; 74:5576-84. [PMID: 12433091 DOI: 10.1021/ac0203488] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Raman spectroscopy is used to examine the effects of temperature, surface coverage, nature of the alkylsilane precursor (octadecyltrichlorosilane, methyloctadecyldichlorosilane, or dimethyloctadecylchlorosilane), and surface grafting method (surface or solution polymerized) on alkyl chain conformational order in a series of high-density octadecylsilane stationary phases ranging in surface coverage from 3.09 to 6.45 micromol/m2. Conformational order is assessed using the intensity ratio of the antisymmetric and symmetric v(CH2) modes as well as the frequency at which these Raman bands are observed. Conformational order increases with surface coverage. Temperature-induced surface phase changes are observed between 258 and 343 K for this homologous series of stationary phases that are demonstrated to adhere to the Clapeyron equation for a simple first-order transition. Phase changes are discussed in terms of variation of the molar enthalpy, molar entropy, and molar volume of the stationary phase, all of which depend on surface coverage. For the limited range of systems investigated, a correlation between stationary-phase preparation (surface versus solution polymerized and nature of the silane precursor) and extent of alkyl chain order is not clearly observed.Instead, akyl chain order is largely dependent on bonding density. A molecular picture of temperature-induced disorder in octadecylsilane stationary phases is proposed, with disorder originating at the distal carbon and propagating toward the proximal carbon.
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Affiliation(s)
- Michael W Ducey
- Department of Chemistry, University of Arizona, Tucson 85721, USA
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27
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Krouskop PE, McGuffin VL. Stochastic simulation of the partition mechanism with a heterogeneous surface phase. J Chromatogr A 2002; 959:49-64. [PMID: 12141561 DOI: 10.1016/s0021-9673(02)00427-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
A three-dimensional stochastic model of chromatography has been used to determine the effect of multiple sites on the partition mechanism. The effect of additional sites on mass transfer rates, zone profiles, and their statistical moments are investigated as a function of the partition coefficient, diffusion coefficient, and interfacial barrier to mass transfer. These studies have demonstrated that changes in the partition coefficient alone are not sufficient to alter the system response from that of a single site. Changes in the diffusion coefficient and the barrier to mass transfer do cause changes in the response compared to that of a single site. The zone profiles produced by the systems become more asymmetric as the difference between the diffusion coefficients or the barriers to mass transfer increases. The site with the slower mass transfer rate plays the dominant role in the total system response.
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Affiliation(s)
- Peter E Krouskop
- Department of Chemistry, Michigan State University, East Lansing 48824, USA
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28
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Ko J, Chilenski J, Rodgers T, Ford JC. Modeling the effect of solvation on solute retention in reversed-phase liquid chromatography. J Chromatogr A 2001; 913:15-22. [PMID: 11355808 DOI: 10.1016/s0021-9673(01)00606-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The retention of a homologous series of alkylbenzenes was determined on octyl and octadecyl reversed-phase columns in several polar organic liquids. Free energies of transfer were calculated by the SM5.0R classical solvation model for each organic liquid tested and for several alkanes. The relationships between the measured retention factors and the calculated free energies of transfer were then investigated. Although the natural logarithms of the retention factor and the calculated free energies of transfer were linearly correlated, the obtained free energies of transfer of the solutes did not completely explain the retention behavior of the solutes. Nonetheless, even in these pure organic liquids, the energetics of RPLC retention behaved very similarly to those of partitioning.
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Affiliation(s)
- J Ko
- Department of Chemistry, Indiana University of Pennsylvania, 15705, USA
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29
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Ranatunga RP, Carr PW. A study of the enthalpy and entropy contributions of the stationary phase in reversed-phase liquid chromatography. Anal Chem 2000; 72:5679-92. [PMID: 11101249 DOI: 10.1021/ac000368e] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The goal of this study was to elucidate the roles played by the stationary and mobile phases in retention in reversed-phase liquid chromatography (RPLC) in terms of their individual enthalpic and entropic contribution to the Gibbs free energy of retention. The experimental approach involved measuring standard enthalpies of transfer of alkylbenzenes from typical mobile phases used in RPLC (methanol/water and acetonitrile/water mixtures), as well as from n-hexadecane (a simple analogue of the stationary phase) to the gas phase, using high-precision headspace gas chromatography. By combining the measured enthalpies with independently measured free energies of transfer, the entropies of transfer were obtained. This allowed us to examine more fully the contribution that each phase makes to the overall retention. It was found that the standard enthalpy of retention in RPLC (i.e., solute transfer from the mobile phase to the stationary phase) is favorable, due to the large and favorable stationary-phase contribution, which actually overcomes an unfavorable mobile-phase contribution to the enthalpy of retention. Further, the net free energy of retention is favorable due to the favorable enthalpic contribution to retention, which arises from the net interactions in the stationary phase. Entropic contributions to retention are not controlling. Therefore, to a great extent, retention is due to enthalpically dominated lipophilic interaction of nonpolar solutes with the stationary phase and not from solvophobic processes in the mobile phase. Further, our enthalpy data support a "partition-like" mechanism of retention rather than an "adsorption-like" mechanism. These results indicate that the stationary phase plays a very significant role in the overall retention process. Our conclusions are in direct contrast to the solvophobic model that has been used extensively to interpret retention in RPLC.
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Affiliation(s)
- R P Ranatunga
- Department of Chemistry, University of Minnesota, Minneapolis 55455, USA
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30
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Doyle CA, Vickers TJ, Mann CK, Dorsey JG. Characterization of C18-bonded liquid chromatographic stationary phases by Raman spectroscopy: the effect of temperature. J Chromatogr A 2000; 877:41-59. [PMID: 10845788 DOI: 10.1016/s0021-9673(00)00174-6] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
This study represents the first time that both the mobile phase composition and the temperature are simultaneously controlled to examine silica-bonded octadecylsilyl (C18) ligands spectroscopically at typical liquid chromatographic (LC) mobile phase flow-rates and back-pressures. Raman spectroscopy is used to characterize the behavior of the C18 bonded ligands equilibrated at temperatures from 45 to 2 degrees C in neat, single-component, mobile phase solvents including: water, acetonitrile, methanol, and chloroform. In addition, the effect of stationary phase ligand bonding density is examined by using two different monomeric reversed-phase liquid chromatographic (RPLC) stationary phases, a 2.34 and a 3.52 micromol m(-2) Microporasil C18 stationary phase, under identical conditions. The direct, on-column, spectroscopic analysis used in this study allows direct evaluation of the temperature-dependent behavior of the bonded C18 ligands. The temperature-dependent ordering of the stationary phase ligands is examined to determine if the ligands undergo a phase transition from a less-ordered "liquid-like" state at higher temperatures to a more-ordered "solid-like" state at lower temperatures. A discrete phase transition was not observed, but rather a continual ordering as temperature was lowered.
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Affiliation(s)
- C A Doyle
- Department of Chemistry, University of Cincinnati, OH 45221-0172, USA
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31
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Chowdhury MA, Ihara H, Sagawa T, Hirayama C. Retention versatility of silica-supported comb-shaped crystalline and non-crystalline phases in high-performance liquid chromatography. J Chromatogr A 2000; 877:71-85. [PMID: 10845790 DOI: 10.1016/s0021-9673(00)00187-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Silica-supported comb-shaped polymer (Sil-ODA18) provided a specific selectivity towards aromatic and non-aromatic solutes. Selectivity of Sil-ODA18 and ODS (polymeric and monomeric) columns towards polycyclic aromatic hydrocarbons and geometric isomers have been discussed in respect of molecular shapes and sizes. The retention versatility of this phase arises from the orientation change on transition from the ordered crystalline to the less ordered non-crystalline state. Selectivity in the crystalline and non-crystalline regions of Sil-ODA18 is similar to that of polymeric and monomeric ODS phases, respectively. Sil-ODA18 column also exhibited the characteristic temperature dependency of liquid-crystalline phases, i.e., an increase in retention with increasing temperature on transition from crystalline to isotropic state.
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Affiliation(s)
- M A Chowdhury
- Graduate School of Science & Technology, Kumamoto University, Japan.
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32
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Mao Y, Carr PW. Adjusting selectivity in liquid chromatography by use of the thermally tuned tandem column concept. Anal Chem 2000; 72:110-8. [PMID: 10655642 DOI: 10.1021/ac990638x] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In this study, we propose the novel "thermally tuned tandem column (T3C)" concept for the optimization of selectivity in LC by continuous adjustment of the stationary phase. Two columns with distinctly different chromatographic selectivities (e.g., polybutadiene- and carbon-coated zirconia) are serially coupled and independently temperature-controlled. Selectivity is "tuned" by adjusting the individual temperatures of the two columns. The effect of changing column temperature is quite analogous to changing the relative column lengths, thereby altering the relative and absolute contribution each column makes to the overall retention time in T3C. The distinct selectivity differences between polybutadiene- and carbon-coated zirconia as well as the extraordinary thermal stability of zirconia-based phases (thermally stable to 200 degrees C) allow us to tune the overall chromatographic selectivity over a very substantial range. We have developed a simplified useful model, which characterizes retention and selectivity for the T3C system as a function of the two column temperatures. The model is in good agreement with the experimental results. We also describe a simple computer-assisted optimization strategy based on the window diagram method, which facilitates the optimization of the T3C system with only four or five initial runs.
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Affiliation(s)
- Y Mao
- Department of Chemistry, University of Minnesota, Minneapolis 55455, USA
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33
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34
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Ma M, Cantwell FF. Chain Unfolding in an ODS-Bonded Phase Caused by the Sorbed Tetra-n-butylammonium Ion. Anal Chem 1999; 71:1879-84. [DOI: 10.1021/ac981215i] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Minhui Ma
- Department of Chemistry, University of Alberta Edmonton, Alberta, Canada T6G 2G2
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35
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Pursch M, Sander LC, Egelhaaf HJ, Raitza M, Wise SA, Oelkrug D, Albert K. Architecture and Dynamics of C22 Bonded Interphases. J Am Chem Soc 1999. [DOI: 10.1021/ja983046p] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Matthias Pursch
- Contribution from the Institut für Organische Chemie der Universität Tübingen, Auf der Morgenstelle 18, and Institut für Physikalische und Theoretische Chemie der Universität Tübingen, Auf der Morgenstelle 8, D-72076 Tübingen, Germany, and National Institute of Standards and Technology (NIST), Gaithersburg, Maryland 20899
| | - Lane C. Sander
- Contribution from the Institut für Organische Chemie der Universität Tübingen, Auf der Morgenstelle 18, and Institut für Physikalische und Theoretische Chemie der Universität Tübingen, Auf der Morgenstelle 8, D-72076 Tübingen, Germany, and National Institute of Standards and Technology (NIST), Gaithersburg, Maryland 20899
| | - Hans-J. Egelhaaf
- Contribution from the Institut für Organische Chemie der Universität Tübingen, Auf der Morgenstelle 18, and Institut für Physikalische und Theoretische Chemie der Universität Tübingen, Auf der Morgenstelle 8, D-72076 Tübingen, Germany, and National Institute of Standards and Technology (NIST), Gaithersburg, Maryland 20899
| | - Martin Raitza
- Contribution from the Institut für Organische Chemie der Universität Tübingen, Auf der Morgenstelle 18, and Institut für Physikalische und Theoretische Chemie der Universität Tübingen, Auf der Morgenstelle 8, D-72076 Tübingen, Germany, and National Institute of Standards and Technology (NIST), Gaithersburg, Maryland 20899
| | - Stephen A. Wise
- Contribution from the Institut für Organische Chemie der Universität Tübingen, Auf der Morgenstelle 18, and Institut für Physikalische und Theoretische Chemie der Universität Tübingen, Auf der Morgenstelle 8, D-72076 Tübingen, Germany, and National Institute of Standards and Technology (NIST), Gaithersburg, Maryland 20899
| | - Dieter Oelkrug
- Contribution from the Institut für Organische Chemie der Universität Tübingen, Auf der Morgenstelle 18, and Institut für Physikalische und Theoretische Chemie der Universität Tübingen, Auf der Morgenstelle 8, D-72076 Tübingen, Germany, and National Institute of Standards and Technology (NIST), Gaithersburg, Maryland 20899
| | - Klaus Albert
- Contribution from the Institut für Organische Chemie der Universität Tübingen, Auf der Morgenstelle 18, and Institut für Physikalische und Theoretische Chemie der Universität Tübingen, Auf der Morgenstelle 8, D-72076 Tübingen, Germany, and National Institute of Standards and Technology (NIST), Gaithersburg, Maryland 20899
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36
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Ho M, Pemberton JE. Alkyl Chain Conformation of Octadecylsilane Stationary Phases by Raman Spectroscopy. 1. Temperature Dependence. Anal Chem 1998; 70:4915-20. [DOI: 10.1021/ac980471s] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Mankit Ho
- Department of Chemistry, University of Arizona, Tucson, Arizona 85721
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37
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Kirkland JJ, Adams JB, van Straten MA, Claessens HA. Bidentate Silane Stationary Phases for Reversed-Phase High-Performance Liquid Chromatography. Anal Chem 1998. [DOI: 10.1021/ac971380i] [Citation(s) in RCA: 104] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- J. J. Kirkland
- Little Falls Analytical Division, Hewlett-Packard Company, Newport Site, 538 First State Boulevard, Newport, Delaware 19804
| | - J. B. Adams
- Adams Research, 759 Morris Road, Hockessin, Delaware, 19707
| | - M. A. van Straten
- Department of Chemistry, Eindhoven University of Technology, 5600 MB, Eindhoven, The Netherlands
| | - H. A. Claessens
- Department of Chemistry, Eindhoven University of Technology, 5600 MB, Eindhoven, The Netherlands
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38
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Pursch M, Brindle R, Ellwanger A, Sander LC, Bell CM, Händel H, Albert K. Stationary interphases with extended alkyl chains: a comparative study on chain order by solid-state NMR spectroscopy. SOLID STATE NUCLEAR MAGNETIC RESONANCE 1997; 9:191-201. [PMID: 9477449 DOI: 10.1016/s0926-2040(97)00058-1] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Stationary interphases with long n-alkyl chains (n = 18, 22, 30, 34) have been examined by solid-state NMR spectroscopy. The determination of the silane functionality and the degree of cross-linking of silane ligands on the silica surface was performed by 29Si CP/MAS NMR spectroscopy. High-speed 1H MAS and 13C CP/MAS NMR spectroscopy were utilized to assess alkyl chain order and mobility of the different bonded phases. For this purpose, 1H NMR line widths and 13C chemical shifts have been evaluated. It is shown that stationary phase order and rigidity increase with alkyl chain length. In addition, the temperature-dependent trans/gauche conformational change occurs at higher temperatures for a polymeric C34 phase compared with a C30 sorbent. This behaviour is discussed in the context of previously reported chromatographic (HPLC) shape selectivity differences.
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Affiliation(s)
- M Pursch
- Institut für Organische Chemie der Universität Tübingen, Germany
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39
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Lukulay PH, McGuffin VL. Parametric Modulation in Liquid Chromatography: Multivariate Optimization of Mobile Phase Composition and Temperature. Anal Chem 1997; 69:2963-71. [DOI: 10.1021/ac9612281] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Patrick H. Lukulay
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824-1322
| | - Victoria L. McGuffin
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824-1322
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40
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McGuffin VL, Chen SH. Molar enthalpy and molar volume of methylene and benzene homologues in reversed-phase liquid chromatography. J Chromatogr A 1997; 762:35-46. [PMID: 9098963 DOI: 10.1016/s0021-9673(96)00958-2] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
In this study, thermodynamic properties are measured for methylene and benzene homologues in reversed-phase liquid chromatography using octadecylsilica stationary phases and methanol mobile phase. The change in molar enthalpy (delta H degree) is determined from graphs of the logarithm of the capacity factor versus the inverse temperature (15 to 60 degrees C), whereas the change in molar volume (delta V degrees) is determined from graphs of the logarithm of the capacity factor versus pressure (830 to 5000 p.s.i.). For octadecylsilica phases with low bonding density (2.7 mumol m-2), delta H degree and delta V degree are small and are relatively unaffected by temperature and pressure. These thermodynamic parameters are linearly related to the homologue number for the methylene homologues, but not for the benzene homologues. For the ethylene group, delta delta H degree and delta delta V degree are in the order of -0.41 kcal mol-1 and -1.0 cm3 mol-1, respectively, at 30 degrees C. As the bonding density increases (5.4 mumol m-2), the molar volume and molar enthalpy decrease in a significant and nonlinear manner with the homologue number. Moreover, these thermodynamic parameters are markedly affected by temperature and pressure. For the ethylene group, delta delta H degree and delta delta V degree are in the order of -3.65 kcal mol-1 and -14.1 cm3 mol-1, respectively, at 30 degrees C. The theoretical and practical implications of these measurements are discussed with respect to the retention mechanism in reversed-phase liquid chromatography.
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Affiliation(s)
- V L McGuffin
- Department of Chemistry, Michigan State University, East Lansing 48824, USA
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41
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Dorsey JG, Cooper WT, Siles BA, Foley JP, Barth HG. Liquid Chromatography: Theory and Methodology. Anal Chem 1996. [DOI: 10.1021/a19600202] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- John G. Dorsey
- Department of Chemistry, Florida State University, Tallahassee, Florida 32306-3006
| | - William T. Cooper
- Department of Chemistry, Florida State University, Tallahassee, Florida 32306-3006
| | - Barbara A. Siles
- Department of Chemistry, College of William and Mary, Williamsburg, Virginia 23187-8795
| | - Joe P. Foley
- Department of Chemistry, Villanova University, Villanova, Pennsylvania 19085-1699
| | - Howard G. Barth
- Central Research and Development Department, E. I. du Pont de Nemours & Company, P. O. Box 80228, Experimental Station, Wilmington, Delaware 19880
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42
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Morel D, Soleiman S, Serpinet J. Gas chromatographic and differential scanning calorimetric studies of new bonded silicas in connection with transition phenomena. Chromatographia 1996. [DOI: 10.1007/bf02272138] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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43
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Pursch M, Strohschein S, Händel H, Albert K. Temperature-Dependent Behavior of C30 Interphases. A Solid-State NMR and LC−NMR Study. Anal Chem 1996. [DOI: 10.1021/ac950761y] [Citation(s) in RCA: 121] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Matthias Pursch
- Institut für Organische Chemie, Auf der Morgenstelle 18, D-72076 Tübingen, Germany
| | - Sabine Strohschein
- Institut für Organische Chemie, Auf der Morgenstelle 18, D-72076 Tübingen, Germany
| | - Heidrun Händel
- Institut für Organische Chemie, Auf der Morgenstelle 18, D-72076 Tübingen, Germany
| | - Klaus Albert
- Institut für Organische Chemie, Auf der Morgenstelle 18, D-72076 Tübingen, Germany
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44
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Siles BA, Halsall HB, Dorsey JG. Retention and selectivity of flavanones on homopolypeptide-bonded stationary phases in both normal- and reversed-phase liquid chromatography. J Chromatogr A 1995; 704:289-305. [PMID: 7670627 DOI: 10.1016/0021-9673(95)00269-s] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Three linear polymers of repeating amino acid units, or homopolypeptides, have been individually covalently bonded to microparticulate silica and evaluated for liquid chromatographic separations. The retention and selectivity of seven flavanones were investigated on these stationary phases and a structurally similar, commercially available reference stationary phase, Chiraspher. All three of the homopolypeptide stationary phases retain solutes in the normal-phase mode. The aromatic-containing homopolypeptide stationary phases also retain solutes in the reversed-phase mode. Selectivity values for the flavanones were higher in the normal-phase mode; chiral selectivity was observed for the amphiphilic homopolypeptide stationary phase in the reversed-phase mode. The retention mechanism of each stationary phase is suggested based on the chemical nature and conformation of the corresponding homopolypeptide ligand.
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Affiliation(s)
- B A Siles
- Department of Chemistry, University of Cincinnati, OH 45221-0172, USA
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