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Zhou Y, Ramirez A, Yuill EM, Wang Q. Mechanistic studies to understand peak tailing due to sulfinic acid- and carboxylic acid-silanophilic interactions in reversed-phase liquid chromatography. J Chromatogr A 2024; 1721:464819. [PMID: 38537485 DOI: 10.1016/j.chroma.2024.464819] [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: 01/08/2024] [Revised: 03/13/2024] [Accepted: 03/14/2024] [Indexed: 04/13/2024]
Abstract
Silanophilic interactions are a primary contributor to peak tailing of acidic pharmaceutical compounds, thus a thorough understanding is especially important for reversed-phase liquid chromatography (RPLC) method development. Herein, a sulfinic acid compound that exhibited severe peak tailing in RPLC with acidic mobile phases was carefully studied. Results indicated that the neutral protonated form of the sulfinic acid is involved in the strong interaction that leads to peak tailing, but that tailing can be mitigated with a blocking effect achieved through use of acetic acid modifier in the mobile phase. Peak tailing was also observed with other structurally-similar sulfinic acids and carboxylic acids but was, in general, less severe with the latter. The Hydrophobic Subtraction Model (HSM) was applied to six commercial C18 columns that exhibited different tailing behaviors for the sulfinic acid compound in attempts to identify key sites of interaction within the stationary phase. A combination of heated acid column wash experiments and density functional theory (DFT) calculations indicate that the differential interactions of the acids with vicinal silanol pairs in the stationary phase play a major role in peak tailing.
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Affiliation(s)
- Yiyang Zhou
- Chemical Process Development, Bristol Myers Squibb Company, 1 Squibb Drive, New Brunswick, NJ 08903, USA.
| | - Antonio Ramirez
- Chemical Process Development, Bristol Myers Squibb Company, 1 Squibb Drive, New Brunswick, NJ 08903, USA
| | - Elizabeth M Yuill
- Chemical Process Development, Bristol Myers Squibb Company, 1 Squibb Drive, New Brunswick, NJ 08903, USA
| | - Qinggang Wang
- Chemical Process Development, Bristol Myers Squibb Company, 1 Squibb Drive, New Brunswick, NJ 08903, USA
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2
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Wang X, Jiao Q, Wang C, Jin R, Zhou Y, Shi S, Huang Z, Li M, Qin X, Chen S, Dai Y. Establishment of Holistic Quality Control Methods for Nelumbinis Folium Containing Alkaloids and Flavonoids with Simple HPLC Conditions. J Chromatogr Sci 2022; 60:871-879. [PMID: 34965584 DOI: 10.1093/chromsci/bmab138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 10/27/2021] [Accepted: 11/21/2021] [Indexed: 11/14/2022]
Abstract
In this study, a positive charged C18 column was used to explore its performance in analysis of herbal medicines containing alkaloids and flavonoids with Nelumbinis Folium (NF) as an example. A chromatographic fingerprint analysis method was established by high performance liquid chromatography-diode array detector with commonly used 0.1% formic acid as mobile phase additive and this method could simultaneously detect both alkaloids and flavonoids with good peak shape. It is noted that the HPLC conditions were directly applied in the HPLC-ESI-Orbitrap-MS/MS analysis, and 12 common peaks were identified. In the quantification method of nuciferine, compared with common C18 column, good performance was observed, including sharp and symmetric peak shape of nuciferine, and no obvious retention time shift in chromatogram. The fingerprint method and quantification method of nuciferine and quercetin-3-O-glucuronic acid could be readily utilized as quality control methods for NF and its related preparations.
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Affiliation(s)
- Xueyuan Wang
- Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, 16 Nanxiao Street, Dongzhimen Nei, Beijing 100700, China
- Modern Research Center for Traditional Chinese Medicine, Shanxi University, 92 Wu Cheng Road, Xiaodian District, Taiyuan 030006, China
| | - Qishu Jiao
- Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, 16 Nanxiao Street, Dongzhimen Nei, Beijing 100700, China
| | - Chaoran Wang
- Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, China
| | - Runa Jin
- Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, 16 Nanxiao Street, Dongzhimen Nei, Beijing 100700, China
| | - Yanyan Zhou
- Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, 16 Nanxiao Street, Dongzhimen Nei, Beijing 100700, China
| | - Shougang Shi
- Sunflower Pharmaceutical Group Longzhong Co., Ltd, 85 Dengcheng Avenue, High-tech Zone, Xiangyang 441003, China
| | - Zhengjun Huang
- Sunflower Pharmaceutical Group Longzhong Co., Ltd, 85 Dengcheng Avenue, High-tech Zone, Xiangyang 441003, China
| | - Mingqian Li
- Cancer Institute of Integrated Traditional Chinese and Western Medicine, Zhejiang Academy of Traditional Chinese Medicine, Tongde Hospital of Zhejiang Province, 234 Gucui Road, Hangzhou, Zhejiang 310012, China
| | - Xuemei Qin
- Modern Research Center for Traditional Chinese Medicine, Shanxi University, 92 Wu Cheng Road, Xiaodian District, Taiyuan 030006, China
| | - Shilin Chen
- Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, 16 Nanxiao Street, Dongzhimen Nei, Beijing 100700, China
| | - Yuntao Dai
- Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, 16 Nanxiao Street, Dongzhimen Nei, Beijing 100700, China
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Sobczak Ł, Kołodziej D, Goryński K. Modifying current thin-film microextraction (TFME) solutions for analyzing prohibited substances: Evaluating new coatings using liquid chromatography. J Pharm Anal 2022; 12:470-480. [PMID: 35811627 PMCID: PMC9257446 DOI: 10.1016/j.jpha.2021.12.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 12/30/2021] [Accepted: 12/31/2021] [Indexed: 11/01/2022] Open
Abstract
For identifying and quantifying prohibited substances, solid-phase microextraction (SPME) continues to arouse interest as a sample preparation method. However, the practical implementation of this method in routine laboratory testing is currently hindered by the limited number of coatings compatible with the ubiquitous high-performance liquid chromatography (HPLC) systems. Only octadecyl (C18) and polydimethylsiloxane/divinylbenzene ligands are currently marketed for this purpose. To address this situation, the present study evaluated 12 HPLC-compatible coatings, including several chemistries not currently used in this application. The stationary phases of SPME devices in the geometry of thin film-coated blades were prepared by applying silica particles bonded with various functional ligands (C18, octyl, phenyl-hexyl, 3-cyanopropyl, benzenesulfonic acid, and selected combinations of these), as well as unbonded silica, to a metal support. Most of these chemistries have not been previously used as microextraction coatings. The 48 most commonly misused substances were selected to assess the extraction efficacy of each coating, and eight desorption solvent compositions were used to optimize the desorption conditions. All samples were analyzed using an HPLC system coupled with triple quadrupole tandem mass spectrometry. This evaluation enables selection of the best-performing coatings for quantifying prohibited substances and investigates the relationship between extraction efficacy and the physicochemical characteristics of the analytes. Ultimately, using the most suitable coatings is essential for trace-level analysis of chemically diverse prohibited substances. 12 HPLC-compatible TFME coatings were evaluated for extraction of small molecules. 8 desorption solvent compositions were used to optimize the desorption conditions. 48 prohibited substances (drugs of abuse and doping agents) were used as analytes. A mixed coating comprising octyl/3-cyanopropyl (50/50) provided the best results.
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Zhang P, Carlin S, Lotti C, Mattivi F, Vrhovsek U. On sample preparation methods for fermented beverage VOCs profiling by GCxGC-TOFMS. Metabolomics 2020; 16:102. [PMID: 32949264 PMCID: PMC7502039 DOI: 10.1007/s11306-020-01718-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Accepted: 08/26/2020] [Indexed: 11/23/2022]
Abstract
INTRODUCTION Aromas and tastes have crucial influences on the quality of fermented beverages. The determination of aromatic compounds requires global non-targeted profiling of the volatile organic compounds (VOCs) in the beverages. However, experimental VOC profiling result depends on the chosen VOC collection method. OBJECTIVES This study aims to observe the impact of using different sample preparation techniques [dynamic headspace (DHS), vortex-assisted liquid-liquid microextraction (VALLME), multiple stir bar sorptive extraction (mSBSE), solid phase extraction (SPE), and solid phase micro-extraction (SPME)] to figure out the most suitable sample preparation protocol for profiling the VOCs from fermented beverages. METHODS Five common sample preparation methods were studied with beer, cider, red wine, and white wine samples. After the sample preparation, collected VOCs were analyzed by two-dimensional gas chromatography coupled with time of flight mass spectrometry (GCxGC-TOFMS). RESULTS GCxGC oven parameters can be optimized with the Box-Behnken surface response model and response measure on peak dispersion. Due to the unavoidable column and detector saturation during metabolomic analysis, errors may happen during mass spectrum construction. Profiling results obtained with different sample preparation methods show considerable variance. Common findings occupy a small fraction of total annotated VOCs. For known fermentative aromas, best coverage can be reached by using SPME together with SPE for beer, and VALLME for wine and cider. CONCLUSIONS GCxGC-TOFMS is a promising tool for non-targeted profiling on VOCs from fermented beverages. However, a proper data processing protocol is lacking for metabolomic analysis. Each sample preparation method has a specific profiling spectrum on VOC profiling. The coverage of the VOC metabolome can be improved by combining complementary methods.
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Affiliation(s)
- Penghan Zhang
- Metabolomic Unit, Food Quality and Nutrition Department, Research and Innovation Center, Edmund Mach Foundation, Via E. Mach 1, 38010, San Michele all'Adige, Italy
- Department of Cellular Computational and Integrative Biology (CIBIO), University of Trento, Via Sommarive 9, 38123, Povo, Trento, Italy
| | - Silvia Carlin
- Metabolomic Unit, Food Quality and Nutrition Department, Research and Innovation Center, Edmund Mach Foundation, Via E. Mach 1, 38010, San Michele all'Adige, Italy
| | - Cesare Lotti
- Metabolomic Unit, Food Quality and Nutrition Department, Research and Innovation Center, Edmund Mach Foundation, Via E. Mach 1, 38010, San Michele all'Adige, Italy
| | - Fulvio Mattivi
- Metabolomic Unit, Food Quality and Nutrition Department, Research and Innovation Center, Edmund Mach Foundation, Via E. Mach 1, 38010, San Michele all'Adige, Italy
- Department of Cellular Computational and Integrative Biology (CIBIO), University of Trento, Via Sommarive 9, 38123, Povo, Trento, Italy
| | - Urska Vrhovsek
- Metabolomic Unit, Food Quality and Nutrition Department, Research and Innovation Center, Edmund Mach Foundation, Via E. Mach 1, 38010, San Michele all'Adige, Italy.
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Evaluation of the solvation parameter model as a quantitative structure-retention relationship model for gas and liquid chromatography. J Chromatogr A 2020; 1626:461308. [DOI: 10.1016/j.chroma.2020.461308] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2020] [Revised: 06/02/2020] [Accepted: 06/03/2020] [Indexed: 12/14/2022]
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6
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Vanderlinden K, Desmet G, Bell DS, Broeckhoven K. Detailed efficiency analysis of columns with a different packing quality and confirmation via total pore blocking. J Chromatogr A 2018; 1581-1582:55-62. [PMID: 30446265 DOI: 10.1016/j.chroma.2018.10.052] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Revised: 10/26/2018] [Accepted: 10/29/2018] [Indexed: 11/16/2022]
Abstract
We report on a systematic study involving columns with a clearly different efficiency (4 distinct quality groups) obtained by packing the columns that were C18 bonded and endcapped with a different carbon loading. Using B-term analysis (via peak parking) and theoretical models to estimate the magnitude of the Cm- and Cs-term contributions, it could be concluded that the difference in efficiency among the groups was entirely due to a difference in eddy dispersion. As such, the columns provided an ideal testing ground to verify how well the total pore blocking (TPB)-method can be used to probe differences in packing heterogeneity. In agreement with earlier literature observations, it turns out the TPB-method is much more sensitive to packing heterogeneities than the eddy dispersion (Heddy)-contribution measured under open-pore conditions via B- and C- term subtraction. Typically, differences in Heddy on the order of 0.1-0.5μm translate into a difference on the order of 0.5-2μm in the TPB mode. This confirms the TPB as a powerful technique to make very sensitive measurements of the homogeneity of packed beds.
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Affiliation(s)
- Kim Vanderlinden
- Vrije Universiteit Brussel, Department of Chemical Engineering, Pleinlaan 2, 1050 Brussels, Belgium
| | - Gert Desmet
- Vrije Universiteit Brussel, Department of Chemical Engineering, Pleinlaan 2, 1050 Brussels, Belgium
| | - David S Bell
- MilliporeSigma/Supelco, 595 North Harrison Road, Bellefonte, PA 16823, USA
| | - Ken Broeckhoven
- Vrije Universiteit Brussel, Department of Chemical Engineering, Pleinlaan 2, 1050 Brussels, Belgium.
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7
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Wu C, Liang Y, Zhu X, Zhao Q, Fang F, Zhang X, Liang Z, Zhang L, Zhang Y. Macro-mesoporous organosilica monoliths with bridged-ethylene and terminal-vinyl: High-density click functionalization for chromatographic separation. Anal Chim Acta 2018; 1038:198-205. [PMID: 30278903 DOI: 10.1016/j.aca.2018.07.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2018] [Revised: 06/20/2018] [Accepted: 07/02/2018] [Indexed: 11/24/2022]
Abstract
A novel kind of macro-mesoporous organosilica monolith, with not only bridged-ethylene groups incorporated into the skeleton but also terminal-vinyl groups protruded from the pore-wall, was prepared so that high-loaded double bonds were achieved. Via highly efficient "thiol-ene" click reaction of such high-loaded double bonds, the surface coverage of C18 groups on monolith could be 5.54 μmol m-2, significantly larger than that of the reported separation materials, beneficial to improvement of separation resolution, especially for peptide separation. The separation performance was evaluated using alkylbenzenes and standard peptides. Furthermore, the tryptic digests of complex sample was successfully analyzed. Because of high separation resolution of our prepared hybrid monolith, the peak capacity for 6-h gradient was achieved as 482. Coupling to LTQ Orbitrap Velos Mass Spectrometry, 22523 tryptic peptides from 4423 proteins were identified from the HeLa cells, more than that using the other long-gradient separation by the same system reported, showing great promising of such monolith for large-scale in-depth proteomic analysis.
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Affiliation(s)
- Ci Wu
- CAS Key Lab of Separation Sciences for Analytical Chemistry, National Chromatographic Research and Analysis Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China; Inspection and Quarantine Technical Center of Dalian Entry-Exit Inspection and Quarantine Bureau, Dalian, 116100, China
| | - Yu Liang
- CAS Key Lab of Separation Sciences for Analytical Chemistry, National Chromatographic Research and Analysis Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China
| | - Xudong Zhu
- CAS Key Lab of Separation Sciences for Analytical Chemistry, National Chromatographic Research and Analysis Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China
| | - Qun Zhao
- CAS Key Lab of Separation Sciences for Analytical Chemistry, National Chromatographic Research and Analysis Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China
| | - Fei Fang
- CAS Key Lab of Separation Sciences for Analytical Chemistry, National Chromatographic Research and Analysis Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China
| | - Xiaodan Zhang
- CAS Key Lab of Separation Sciences for Analytical Chemistry, National Chromatographic Research and Analysis Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China
| | - Zhen Liang
- CAS Key Lab of Separation Sciences for Analytical Chemistry, National Chromatographic Research and Analysis Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China
| | - Lihua Zhang
- CAS Key Lab of Separation Sciences for Analytical Chemistry, National Chromatographic Research and Analysis Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China.
| | - Yukui Zhang
- CAS Key Lab of Separation Sciences for Analytical Chemistry, National Chromatographic Research and Analysis Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China
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8
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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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9
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Gritti F. Impact of straight, unconnected, radially-oriented, and tapered mesopores on column efficiency: A theoretical investigation. J Chromatogr A 2017; 1485:70-81. [DOI: 10.1016/j.chroma.2017.01.030] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2016] [Revised: 01/09/2017] [Accepted: 01/11/2017] [Indexed: 11/25/2022]
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10
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Bian W, Li Q. Comparative study of the thermodynamics and extrathermodynamics on the conformational transformation and adsorption of bovine serum albumin. J LIQ CHROMATOGR R T 2017. [DOI: 10.1080/10826076.2017.1282870] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Wenhai Bian
- College of Chemistry and Materials Science, Northwest University, Xi’an, China
| | - Qian Li
- College of Life Science, Northwest University, Xi’an, China
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11
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Blind column selection protocol for two-dimensional high performance liquid chromatography. Talanta 2016; 154:85-91. [DOI: 10.1016/j.talanta.2016.03.056] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Revised: 03/15/2016] [Accepted: 03/16/2016] [Indexed: 11/22/2022]
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12
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Andrade-Eiroa A, Canle M, Leroy-Cancellieri V, Cerdà V. Solid-phase extraction of organic compounds: A critical review (Part I). Trends Analyt Chem 2016. [DOI: 10.1016/j.trac.2015.08.015] [Citation(s) in RCA: 265] [Impact Index Per Article: 33.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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13
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Caiali E, David V, Aboul-Enein HY, Moldoveanu SC. Evaluation of the phase ratio for three C18 high performance liquid chromatographic columns. J Chromatogr A 2016; 1435:85-91. [PMID: 26818239 DOI: 10.1016/j.chroma.2016.01.043] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Revised: 01/12/2016] [Accepted: 01/14/2016] [Indexed: 11/29/2022]
Abstract
For a chromatographic column, phase ratio Φ is defined as the ratio between the volume of the stationary phase Vst and the void volume of the column V0, and it is an important parameter characterizing the HPLC process. Although apparently simple, the evaluation of Φ presents difficulties because there is no sharp boundary between the mobile phase and the stationary phase. In addition, the boundary depends not only on the nature of the stationary phase, but also on the composition of the mobile phase. In spite of its importance, phase ratio is seldom reported for commercially available HPLC columns and the data typically provided by the vendors about the columns do not provide key information that would allow the calculation of Φ based on Vst and V0 values. A different procedure for the evaluation of Φ is based on the following formula: log k'j=a log Kow,j+log Φ, where k'j is the retention factor for a compound j that must be a hydrocarbon, Kow,j is the octanol/water partition coefficient, and a is a proportionality constant. Present study describes the experimental evaluation of Φ based on the measurement of k'j for the compounds in the homologous series between benzene and butylbenzene for three C18 columns: Gemini C18, Luna C18 both with 5 μm particles, and a Chromolith Performance RP-18. The evaluation was performed for two mobile phase systems at different proportions of methanol/water and acetonitrile/water. The octanol/water partition coefficients were obtained from the literature. The results obtained in the study provide further support for the new procedure for the evaluation of phase ratio.
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Affiliation(s)
- Edvin Caiali
- University of Bucharest, Faculty of Chemistry, Department of Analytical Chemistry, Bucharest, Romania
| | - Victor David
- University of Bucharest, Faculty of Chemistry, Department of Analytical Chemistry, Bucharest, Romania
| | - Hassan Y Aboul-Enein
- National Research Centre, Pharmaceutical and Drug Industries Research Division, Pharmaceutical and Medicinal Chemistry Department, Cairo, Egypt
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14
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Wu C, Liang Y, Yang K, Min Y, Liang Z, Zhang L, Zhang Y. Clickable Periodic Mesoporous Organosilica Monolith for Highly Efficient Capillary Chromatographic Separation. Anal Chem 2016; 88:1521-5. [DOI: 10.1021/acs.analchem.5b04641] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Ci Wu
- Key
Lab of Separation Sciences for Analytical Chemistry, National Chromatographic
Research and Analysis Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China
- University of the Chinese Academy of Sciences, Beijing, 100049, China
| | - Yu Liang
- Key
Lab of Separation Sciences for Analytical Chemistry, National Chromatographic
Research and Analysis Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China
| | - Kaiguang Yang
- Key
Lab of Separation Sciences for Analytical Chemistry, National Chromatographic
Research and Analysis Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China
| | - Yi Min
- Key
Lab of Separation Sciences for Analytical Chemistry, National Chromatographic
Research and Analysis Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China
- University of the Chinese Academy of Sciences, Beijing, 100049, China
| | - Zhen Liang
- Key
Lab of Separation Sciences for Analytical Chemistry, National Chromatographic
Research and Analysis Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China
| | - Lihua Zhang
- Key
Lab of Separation Sciences for Analytical Chemistry, National Chromatographic
Research and Analysis Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China
| | - Yukui Zhang
- Key
Lab of Separation Sciences for Analytical Chemistry, National Chromatographic
Research and Analysis Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China
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15
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Sykora D, Vozka J, Tesarova E. Chromatographic methods enabling the characterization of stationary phases and retention prediction in high-performance liquid chromatography and supercritical fluid chromatography. J Sep Sci 2015; 39:115-31. [DOI: 10.1002/jssc.201501023] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Revised: 10/08/2015] [Accepted: 10/08/2015] [Indexed: 11/11/2022]
Affiliation(s)
- David Sykora
- Department of Analytical Chemistry; University of Chemistry and Technology; Prague Czech Republic
| | - Jiri Vozka
- Department of Analytical Chemistry; University of Chemistry and Technology; Prague Czech Republic
- Department of Physical and Macromolecular Chemistry, Faculty of Science; Charles University in Prague; Prague Czech Republic
| | - Eva Tesarova
- Department of Physical and Macromolecular Chemistry, Faculty of Science; Charles University in Prague; Prague Czech Republic
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16
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Gritti F. Determination of the solvent density profiles across mesopores of silica-C18 bonded phases in contact with acetonitrile/water mixtures: A semi-empirical approach. J Chromatogr A 2015; 1410:90-8. [DOI: 10.1016/j.chroma.2015.07.073] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Revised: 07/13/2015] [Accepted: 07/18/2015] [Indexed: 11/29/2022]
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17
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New environmentally friendly MSPD solid support based on golden mussel shell: characterization and application for extraction of organic contaminants from mussel tissue. Anal Bioanal Chem 2015; 407:4805-14. [DOI: 10.1007/s00216-015-8686-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2015] [Revised: 03/26/2015] [Accepted: 04/08/2015] [Indexed: 11/26/2022]
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18
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Moldoveanu S, David V. Estimation of the phase ratio in reversed-phase high-performance liquid chromatography. J Chromatogr A 2015; 1381:194-201. [DOI: 10.1016/j.chroma.2015.01.034] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Revised: 01/12/2015] [Accepted: 01/13/2015] [Indexed: 10/24/2022]
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19
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Gritti F, Guiochon G. Separation of peptides and intact proteins by electrostatic repulsion reversed phase liquid chromatography. J Chromatogr A 2014; 1374:112-121. [PMID: 25488252 DOI: 10.1016/j.chroma.2014.11.036] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Revised: 11/13/2014] [Accepted: 11/14/2014] [Indexed: 11/30/2022]
Abstract
A new brand of BEH-C18 hybrid particles chemically bonded to a leash carrying an amine group permits the implementation of electrostatic repulsive interactions chromatography. Using columns packed with this material, the influence of the concentration of positive charges bonded to the BEH-C18 surface on the overloaded band profiles of a few positively charged peptides and proteins was investigated in the gradient elution mode. Three columns packed with endcapped BEH-C18 particles bonded with three different surface-charge densities (LOW, MEDIUM and HIGH) were used and compared with those provided by a column packed with non-doped, endcapped BEH-C18 particles. The surface concentrations of fixed charges in the LOW, MEDIUM and HIGH columns were estimated at 0.029, 0.050, and 0.064μmol/m(2), for example, about two orders of magnitude smaller than the surface density of bonded C18 chains (2.1μmol/m(2)). Three different mobile phase additives (0.1% v/v of trifluoro-acetic, phosphoric, and formic acid) were used to optimize the purification levels of proteins under different loading conditions. The weak ion-pairing ions (formate and phosphate) generate smaller retention but broader, more fronting band profiles than those eluted with a stronger ion-pairing ion (trifluoroactate). This effect is worse in the presence of fixed charges at the surface of the BEH-C18 particles. This was explained by an enhanced anti-Langmuirian adsorption behavior of the charged proteins in the presence of fixed surface charges. As the protein concentration increases in the bulk, so does the internal ionic strength, the electrostatic repulsive interactions weaken, and retention increases. Band fronting is mostly eliminated by replacing weak ion-pairing acids with TFA with which the adsorption isotherm remains weakly langmuirian. Faster but still complete gradient separation of insulin and myoglobin were achieved with the HIGH column than with the reference neutral column, despite a measurable loss in selectivity.
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Affiliation(s)
- Fabrice Gritti
- Department of Chemistry, University of Tennessee, Knoxville, TN 37996-1600, USA.
| | - Georges Guiochon
- Department of Chemistry, University of Tennessee, Knoxville, TN 37996-1600, USA.
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20
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Band broadening along gradient reversed phase columns: A potential gain in resolution factor. J Chromatogr A 2014; 1342:24-9. [DOI: 10.1016/j.chroma.2014.03.025] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2014] [Revised: 03/07/2014] [Accepted: 03/10/2014] [Indexed: 11/23/2022]
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21
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Vajda P, Felinger A. Multilayer adsorption on fractal surfaces. J Chromatogr A 2014; 1324:121-7. [DOI: 10.1016/j.chroma.2013.11.028] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Revised: 11/11/2013] [Accepted: 11/12/2013] [Indexed: 10/26/2022]
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22
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Undin T, Samuelsson J, Törncrona A, Fornstedt T. Evaluation of a combined linear-nonlinear approach for column characterization using modern alkaline-stable columns as model. J Sep Sci 2013; 36:1753-61. [DOI: 10.1002/jssc.201201132] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2012] [Revised: 02/25/2013] [Accepted: 03/18/2013] [Indexed: 11/09/2022]
Affiliation(s)
- Torgny Undin
- Department of Chemistry - BMC, Uppsala University; Uppsala; Sweden
| | - Jörgen Samuelsson
- Department of Engineering and Chemical Sciences; Karlstad University; Karlstad; Sweden
| | | | - Torgny Fornstedt
- Department of Engineering and Chemical Sciences; Karlstad University; Karlstad; Sweden
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23
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Overloading study of basic compounds with a positively charged C18 column in liquid chromatography. J Chromatogr A 2013; 1281:60-6. [PMID: 23411141 DOI: 10.1016/j.chroma.2013.01.074] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2012] [Revised: 12/30/2012] [Accepted: 01/17/2013] [Indexed: 11/23/2022]
Abstract
While tailing and overloading of basic compounds remain problematic on most RP columns, a new kind of positively charged RP column named XCharge C18 was found to be superior good for the separation of alkaloids in our practical use. In this work, the surface charge property of the XCharge C18 column was evaluated by the retention of NO(3)(-) under different pH values and buffer concentrations. A considerable and pH-dependent positive charge was confirmed on the column. Then overloading behaviors of bases were systematically studied using amitriptyline as a basic probe. Good peak shapes (Tf<1.5) and extra high loadability with a C(0.5) of about 30,000 mg/L were observed on the column, with commonly used 0.1% formic acid as mobile phase additive. However, increasing the ionic strength of buffer with phosphates led to tailing peaks at high sample amount and sharp decline in loadability (C(0.5) of 2000-3000 mg/L), although it brought higher column efficiency at low sample amount. Higher pH also induced worse performance and lower loadability. The overall results demonstrated the importance of an appropriate level of ionic repulsion for the XCharge C18 column to achieve the good performance for bases, which could be explained by the multiple-site adsorption theory as ionic repulsion would shield the solute from occupying high-energy sites deeper in C18 layer.
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Yeman H, Nicholson T, Matyska MT, Pesek JJ, Albert K. Simulation of the chromatographic separation process in HPLC employing suspended-state NMR spectroscopy - comparison of interaction behavior for monomeric and hydride-modified C18stationary phases. J Sep Sci 2012. [DOI: 10.1002/jssc.201200729] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Helen Yeman
- Institute of Organic Chemistry; University of Tübingen; Tübingen Germany
| | - Tim Nicholson
- Institute of Organic Chemistry; University of Tübingen; Tübingen Germany
| | - Maria T. Matyska
- Department of Chemistry; San Jose State University; San Jose CA USA
| | - Joseph J. Pesek
- Department of Chemistry; San Jose State University; San Jose CA USA
| | - Klaus Albert
- Institute of Organic Chemistry; University of Tübingen; Tübingen Germany
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25
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Excess adsorption of binary aqueous organic mixtures on various reversed-phase packing materials. J Chromatogr A 2012; 1240:104-12. [DOI: 10.1016/j.chroma.2012.03.087] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2012] [Revised: 03/25/2012] [Accepted: 03/26/2012] [Indexed: 11/24/2022]
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26
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27
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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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28
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Vajda P, Bocian S, Buszewski B, Felinger A. Influence of the solvation process on solute adsorption in reversed phase liquid chromatography. J Chromatogr A 2011; 1218:1954-65. [PMID: 21109248 DOI: 10.1016/j.chroma.2010.10.108] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2010] [Revised: 10/20/2010] [Accepted: 10/26/2010] [Indexed: 10/18/2022]
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29
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Guiochon G, Gritti F. Shell particles, trials, tribulations and triumphs. J Chromatogr A 2011; 1218:1915-38. [DOI: 10.1016/j.chroma.2011.01.080] [Citation(s) in RCA: 273] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2010] [Revised: 01/23/2011] [Accepted: 01/25/2011] [Indexed: 11/25/2022]
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30
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Buszewski B, Bocian S, Rychlicki G. Investigation of silanol activity on the modified silica surfaces using microcalorimetric measurements. J Sep Sci 2011; 34:773-9. [DOI: 10.1002/jssc.201000736] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2010] [Revised: 12/22/2010] [Accepted: 01/22/2011] [Indexed: 11/11/2022]
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31
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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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32
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33
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Vajda P, Bocian S, Buszewski B, Felinger A. Examination of the surface heterogeneity of reversed-phase packing materials with solvent adsorption. J Sep Sci 2010; 33:3644-54. [DOI: 10.1002/jssc.201000341] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2010] [Revised: 06/29/2010] [Accepted: 09/01/2010] [Indexed: 11/08/2022]
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34
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Cyano bonded silica monolith—Development of an in situ modification method for analytical scale columns. J Chromatogr A 2010; 1217:6085-91. [DOI: 10.1016/j.chroma.2010.07.052] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2010] [Revised: 07/15/2010] [Accepted: 07/17/2010] [Indexed: 11/21/2022]
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35
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Lesellier E. Extension of the C18 stationary phase knowledge by using the carotenoid test. J Sep Sci 2010; 33:3097-105. [DOI: 10.1002/jssc.201000239] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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36
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Stevenson PG, Soliven A, Dennis GR, Gritti F, Guiochon G, Shalliker RA. π-Selective stationary phases: (III) Influence of the propyl phenyl ligand density on the aromatic and methylene selectivity of aromatic compounds in reversed phase liquid chromatography. J Chromatogr A 2010; 1217:5377-83. [DOI: 10.1016/j.chroma.2010.05.029] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2010] [Revised: 05/14/2010] [Accepted: 05/19/2010] [Indexed: 12/01/2022]
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37
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Buszewski B, Bocian S, Nowaczyk A. Modeling solvation on the chemically modified silica surfaces. J Sep Sci 2010; 33:2060-8. [DOI: 10.1002/jssc.201000101] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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38
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Zhang L, Zhao G, Sun Y. Effects of Ligand Density on Hydrophobic Charge Induction Chromatography: Molecular Dynamics Simulation. J Phys Chem B 2010; 114:2203-11. [DOI: 10.1021/jp903852c] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Lin Zhang
- Department of Biochemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
| | - Guofeng Zhao
- Department of Biochemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
| | - Yan Sun
- Department of Biochemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
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39
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Gritti F, Guiochon G. Mass transfer kinetic mechanism in monolithic columns and application to the characterization of new research monolithic samples with different average pore sizes. J Chromatogr A 2009; 1216:4752-67. [DOI: 10.1016/j.chroma.2009.04.034] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2009] [Revised: 04/09/2009] [Accepted: 04/10/2009] [Indexed: 10/20/2022]
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40
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Andrzejewska A, Gritti F, Guiochon G. Investigation of the adsorption mechanism of a peptide in reversed phase liquid chromatography, from pH controlled and uncontrolled solutions. J Chromatogr A 2009; 1216:3992-4004. [DOI: 10.1016/j.chroma.2009.03.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2008] [Revised: 03/02/2009] [Accepted: 03/06/2009] [Indexed: 10/21/2022]
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41
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Borówko M, Rżysko W, Sokołowski S, Staszewski T. Density Functional Approach to Adsorption and Retention of Spherical Molecules on Surfaces Modified with End-Grafted Polymers. J Phys Chem B 2009; 113:4763-70. [DOI: 10.1021/jp811143n] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- M. Borówko
- Department for the Modeling of Physico-Chemical Processes, Maria Curie-Skłodowska University, 20-031 Lublin, Poland
| | - W. Rżysko
- 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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42
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BIAN L, WANG X, YANG X, LIU L, CHEN C. Thermodynamics and Extra-thermodynamics of Bacillus subtilis α-Amylase in Some Chromatographic Systems. CHINESE J CHEM 2009. [DOI: 10.1002/cjoc.200990087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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43
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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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44
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Rafferty JL, Siepmann JI, Schure MR. Influence of bonded-phase coverage in reversed-phase liquid chromatography via molecular simulation. J Chromatogr A 2008; 1204:20-7. [DOI: 10.1016/j.chroma.2008.07.038] [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: 11/16/2022]
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45
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Comparison between the loading capacities of columns packed with partially and totally porous fine particles. J Chromatogr A 2007; 1176:107-22. [DOI: 10.1016/j.chroma.2007.10.076] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2007] [Revised: 10/19/2007] [Accepted: 10/24/2007] [Indexed: 11/18/2022]
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46
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Tarafder A, Aumann L, Müller-Späth T, Morbidelli M. Improvement of an overloaded, multi-component, solvent gradient bioseparation through multiobjective optimization. J Chromatogr A 2007; 1167:42-53. [PMID: 17765250 DOI: 10.1016/j.chroma.2007.07.086] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2007] [Revised: 07/25/2007] [Accepted: 07/27/2007] [Indexed: 10/23/2022]
Abstract
Solvent gradient chromatography is quite often used in analytical studies for decreasing the analysis time of samples having components with widely different retention behaviour. Several studies, both theoretical and experimental, have been reported on the optimization of gradient profiles in improving analytical separation performance, suggesting various linear and non-linear gradients. In preparative chromatography, on the other hand, though solvent gradient is being increasingly used (especially in bioseparation) to improve the product yield and productivity, there is a dearth of literature and clearer understanding of the effect(s) of modifier gradients on the separation performance. For this, the gradients used in applications are of relatively simple profiles like step or linear gradients, obtained through hand optimization based on experience and intuition. Significant improvements, however, can be expected using the state-of-the art modelling of chromatographic processes and optimization routines running on widely available hi-speed desktop computers. In this work we are reporting such an optimization procedure to improve the purification of an industrial multi-component mixture, containing 65.8% of Calcitonin as the main product, in an overloaded reversed-phase column. The work comprises both theoretical simulations and their experimental validation using multilinear gradients as optimization variable. The study produced interesting insights for modifier gradient design, like using peak deformation of the target peptide to increase yield and productivity, and improved our understanding of the effect of modifier gradients in non-linear separations.
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Affiliation(s)
- Abhijit Tarafder
- Institute for Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zurich, 8093 Zurich, Switzerland
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47
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Gritti F, Kazakevich YV, Guiochon G. Effect of the surface coverage of endcapped C18-silica on the excess adsorption isotherms of commonly used organic solvents from water in reversed phase liquid chromatography. J Chromatogr A 2007; 1169:111-24. [PMID: 17875311 DOI: 10.1016/j.chroma.2007.08.071] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2007] [Revised: 08/27/2007] [Accepted: 08/30/2007] [Indexed: 11/22/2022]
Abstract
The excess adsorption isotherms of methanol, ethanol, 2-propanol, acetonitrile, and tetrahydrofuran from water were measured on five different silica-based packing materials by the minor disturbance method. These materials were prepared with the same lot of 5-microm particles (average pore size 90 A), all endcapped with trimethylchlorosilane (TMS), and bonded to octadecyl chains with different surface coverages (0, 0.42, 1.01, 2.03, and 3.15 micromol/m2). The relative adsorption of one eluent by respect to a second one informs on the heterogeneity of the material (alkyl-bonded and bare silica regions) and on the accessibility of the unreacted silanol groups to the mobile phase. It is shown that the total surface area of the adsorbent decreases with increasing degree of surface coverage with octadecyl chains and that the relative surface area of the regions occupied by accessible silanol groups to the regions occupied by alkyl-bonded groups decreases. For the five columns, an average of 10% of the adsorbent surface area is covered of bare silica accessible to the liquid phase, with a minimum of 5% with tetrahydrofuran and a maximum of 12% with ethanol or 2-propanol. Increasing the surface coverage by the C18 chains causes a significant increase of the attraction potential of the hydrophobic surface toward the organic solvent. This result is confirmed by the increase of the number of adsorbate monolayers with increasing bonding density of the octadecyl chains. This number is twice larger for the 315C18 column than for the C1 column.
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Affiliation(s)
- Fabrice Gritti
- Department of Chemistry, University of Tennessee, Knoxville, TN 37996-1600, USA
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48
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Rafferty JL, Zhang L, Siepmann JI, Schure MR. Retention Mechanism in Reversed-Phase Liquid Chromatography: A Molecular Perspective. Anal Chem 2007; 79:6551-8. [PMID: 17668929 DOI: 10.1021/ac0705115] [Citation(s) in RCA: 114] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A detailed, molecular-level understanding of the retention mechanism in reversed-phase liquid chromatography (RPLC) has eluded analytical chemists for decades. Through validated, particle-based Monte Carlo simulations of a model RPLC system consisting of dimethyloctadecylsilanes at a coverage of 2.9 micro mol/m2 on an explicit silica substrate with unprotected residual silanols in contact with a water/methanol mobile phase, we show that the molecular-level retention processes for nonpolar and polar analytes, such as alkanes and alcohols, are much more complex than what has been previously deduced from thermodynamic and theoretical arguments. In contrast to some previous assumptions, the simulations indicate that both partitioning and adsorption play a key role in the separation process and that the stationary phase in RPLC behaves substantially different from a bulk hydrocarbon phase. The retention of nonpolar methylene segments is dominated by lipophilic interactions with the retentive phase, while solvophilic interactions are more important for the retention of the polar hydroxyl group.
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Affiliation(s)
- Jake L Rafferty
- Department of Chemistry and of Chemical Engineering, University of Minnesota, Minneapolis, MN 55455-0431, USA
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49
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Glenn KM, Lucy CA, Haddad PR. Ion chromatography on a latex-coated silica monolith column. J Chromatogr A 2007; 1155:8-14. [PMID: 17306813 DOI: 10.1016/j.chroma.2007.01.098] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2006] [Revised: 01/24/2007] [Accepted: 01/26/2007] [Indexed: 11/15/2022]
Abstract
A silica monolith column (Merck Chromolith, 100 mm x 4.6 mm) has been coated with Dionex AS9-SC latex nanoparticles to convert the column into an anion-exchange stationary phase. For comparison purposes, a reversed-phase silica monolith was also converted into an anion-exchange column by coating with the cationic surfactant didodecyldimethylammonium bromide (DDAB). Separations of common inorganic anions were carried out using 7.5 or 5.0 mM 4-hydroxybenzoic acid at pH 7.0 along with suppressed conductivity detection. Direct comparisons were then made between the two columns in terms of selectivity, efficiency and stability. The latex-coated column was on average 50% more efficient than the DDAB-coated column. A 10% decrease in retention times was observed on the DDAB column over 11 h of continuous eluent flow, while the latex coating exhibited <1% change in retention even after 2.5 months of periodic use.
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Affiliation(s)
- Karen M Glenn
- Department of Chemistry, University of Alberta, Gunning/Lemieux Chemistry Centre, Edmonton, AB, Canada T6G 2G2
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50
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Gritti F, Guiochon G. Limits of the numerical estimation of the adsorption energy distribution from adsorption isotherm data using the expectation-maximization method. J Chromatogr A 2007; 1144:208-20. [PMID: 17275011 DOI: 10.1016/j.chroma.2007.01.057] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2006] [Revised: 01/09/2007] [Accepted: 01/12/2007] [Indexed: 11/18/2022]
Abstract
The limits of the use of the expectation-maximization (EM) method for the study of the heterogeneity of adsorbent surfaces were tested by calculating the adsorption energy distribution of systems having known degrees of heterogeneity. Connecting on-line two different columns allows the simulation of a heterogeneous system. The two columns used were endcapped, C(18)-bonded silica used as stationary phases and having different degrees of C(18) chain coverages (0.42 and 2.03 micromol/m(2)). The adsorption constants of phenol measured by frontal analysis (FA) are significantly different on these two columns. On each column, the adsorption behavior was best accounted for by a bi-Langmuir isotherm model, corresponding to a heterogeneous surface with a bimodal energy distribution. The difference between the adsorption energies on the weak adsorption sites of the two columns is 1.5 kJ/mol. The energy difference of their high energy sites is 2.2 kJ/mol. The EM method can readily distinguish between adsorption sites having energies that differ by more than 5 kJ/mol after more than 10 million iterations, but it cannot distinguish between adsorption sites for which this energy difference is less than 2 kJ/mol, even after 100 million iterations. For highly heterogeneous systems, (e.g., those with more than three different types of adsorption sites), the EM program does not converge necessarily towards the actual energy distribution function but toward a simpler one, having fewer adsorption sites that are almost equally spaced in the energy space. This failure of the EM program is related to the fact that, despite the excellent precision of the FA measurements (<1%), any series of adsorption data can be represented by several distinct AEDs. Thus, the degree of heterogeneity of RPLC adsorbents determined with the EM method might often be minimized, resulting in erroneous values of the isotherm parameters.
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Affiliation(s)
- Fabrice Gritti
- Department of Chemistry, University of Tennessee, Knoxville, TN 37996-1600, USA
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