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Tsui HW, Huang SX, Tseng TH. Heterogenous adsorption mechanisms for describing enantioselective retention in normal-phase liquid chromatography. J Chromatogr A 2023; 1704:464140. [PMID: 37315447 DOI: 10.1016/j.chroma.2023.464140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 06/02/2023] [Accepted: 06/07/2023] [Indexed: 06/16/2023]
Abstract
In this study, the enantioselective retention behaviors of methyl mandelate (MM) and benzoin (B) were investigated using Chiralpak IB as a sorbent and ethanol, 1-propanol, and 1-butanol as solvent modifiers in the normal-phase mode. For both MM and B, similar chiral recognition mechanisms were observed, potentially involving at least two types of chiral adsorption sites. With a retention model describing local retention behaviors, an enantioselectivity model based on a three-site model was proposed to describe the data. Fitted parameters were also used to analyze the contributions of each type of adsorption site to the apparent retention behavior. Combining the local retention model with the three-site model provided a qualitative and quantitative explanation for the correlation between modifier concentration and enantioselectivity. Overall, our results indicated that heterogeneous adsorption mechanisms are a key aspect in understanding enantioselective retention behaviors. Distinct local adsorption sites contribute differently to apparent retention behaviors, with these contributions being influenced by the mobile phase composition to varying degrees. Hence, enantioselectivity changes with variations in modifier concentration.
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Affiliation(s)
- Hung-Wei Tsui
- Department of Chemical Engineering and Biotechnology, National Taipei University of Technology, 1, Sec. 3, Zhongxiao E. Rd., Taipei 10608 Taiwan.
| | - Si-Xian Huang
- Department of Chemical Engineering and Biotechnology, National Taipei University of Technology, 1, Sec. 3, Zhongxiao E. Rd., Taipei 10608 Taiwan
| | - Ting-Hsien Tseng
- Department of Chemical Engineering and Biotechnology, National Taipei University of Technology, 1, Sec. 3, Zhongxiao E. Rd., Taipei 10608 Taiwan
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Tsui HW, Hsieh CH, Zhan CF. Effect of mobile-phase modifiers on the enantioselective retention behavior of methyl mandelate with an amylose 3,5-dimethylphenylcarbamate chiral stationary phase under reversed-phase conditions. J Sep Sci 2023; 46:e2200651. [PMID: 36401614 DOI: 10.1002/jssc.202200651] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 11/15/2022] [Accepted: 11/16/2022] [Indexed: 11/21/2022]
Abstract
In this study, methanol, ethanol, n-propyl alcohol, isopropyl alcohol, acetone, and tert-butanol were used as organic modifiers in reversed-phase mode chiral liquid-chromatography to systematically investigate the effects of mobile phase components on the enantioselective retention behavior of methyl mandelate with immobilized amylose 3,5-dimethylphenylcarbamate-based sorbent called Chiralpak IA. A two-site enantioselective model was used to obtain information on the recognition mechanisms by observing the dependence of the enantioselectivity and retention factor difference on the modifier content. Similar enantioselective retention behaviors were observed for all modifiers, and characteristic modifier concentration points (PL , PM , and PH ) were identified. At modifier concentrations up to PM , the weakened hydrophobic environment resulted in polymer structural relaxation, which changed the recognition mechanisms. By contrast, at concentrations beyond PH , considerably different enantioselectivity behaviors were observed, indicating that the existence of dipole-dipole interaction, which was stronger at higher modifier concentrations, contributed to the retention mechanisms. The concentrations at which these characteristic points occurred were dependent on the carbon number of the modifier molecule. Modifiers with more carbon numbers facilitated the transition in the enantioselective behaviors. These results demonstrated that the proposed method can provide a physically consistent quantitative description of enantioselective retention behavior in reversed-phase mode.
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Affiliation(s)
- Hung-Wei Tsui
- Department of Chemical Engineering and Biotechnology, National Taipei University of Technology, Taipei, Taiwan
| | - Ching-Hung Hsieh
- Department of Chemical Engineering and Biotechnology, National Taipei University of Technology, Taipei, Taiwan
| | - Chao-Fu Zhan
- Department of Chemical Engineering and Biotechnology, National Taipei University of Technology, Taipei, Taiwan
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3
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Retention modeling and adsorption mechanisms in reversed-phase liquid chromatography. J Chromatogr A 2021; 1662:462736. [PMID: 34923304 DOI: 10.1016/j.chroma.2021.462736] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Revised: 12/02/2021] [Accepted: 12/04/2021] [Indexed: 12/22/2022]
Abstract
To interpret the dependence of solute retention behavior on modifier content in reversed-phase liquid chromatography, a theoretical framework, based on the concentration dependence of solvophobic forces imposed on solutes and the competitive adsorptions of solutes and solvent modifiers, was proposed. The generality of the developed model was demonstrated by comparing the model with conventional retention models. The linear dependence of the Gibbs energy change of solute adsorption with respect to the modifier concentration was assumed, and the model was fitted to the experimental results, with good agreement demonstrated between the experimental data and the model. Retention behaviors were inferred to be determined by two key dimensionless groups that represented the reductions in the retention factors resulting from a weakened solvophobic interaction and modifier competitive adsorption. The retention behaviors were successfully deconvoluted for each contribution as a function of the modifier concentration by using the fitted parameters. The effects of both contributions on the retention behaviors were enhanced for the solutes with aromatic groups. The standard Gibbs energy change SLo of benzene adsorption was found to depend linearly on the number of modifier molecules present but independent of modifier identity. For the solutes associated with hydrogen-bonding groups, the degree of reduction in the solvophobic interactions was considerably reduced. Hence, the relative contributions of both mechanisms to solute retention depend greatly on the solute structure. Perturbation method was performed to investigate the modifier adsorption mechanisms. The results show that the standard Gibbs energy change SLo for the first-layer adsorption of modifiers changed linearly with the carbon number of modifier molecule. These results demonstrated that the proposed model can offer a physically consistent quantitative description of retention when solvent composition is varied.
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Tsui HW, Zhang HL, Hsieh CH. Effect of 2-propanol content on solute retention mechanisms determined using amylose tris(3,5-dimethylphenylcarbamate) chiral stationary phase under normal- and reversed-phase conditions. J Chromatogr A 2021; 1650:462226. [PMID: 34087518 DOI: 10.1016/j.chroma.2021.462226] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 04/12/2021] [Accepted: 04/29/2021] [Indexed: 11/29/2022]
Abstract
The electrostatic interactions between chiral solutes and polysaccharide (PS)-based chiral selectors are the key to achieving chiral recognition; however, PS-based sorbents, derivatized of phenyl moieties, can exhibit considerably non-polar characteristics, and they are also useful for the separation of enantiomers in the reversed-phase mode. In this study, an immobilized amylose 3,5-dimethylphenylcarbamate-based sorbent was used to investigate the balance between electrostatic interactions and solvophobic interactions, with complementary effects on solute retention behavior when the isopropanol (IPA) concentration was altered. It was proposed that in both normal- and reversed-phase modes, information on the retention mechanisms could be obtained by observing the curvature of the logarithm of the retention factor versus the logarithm of the IPA concentration, and the slope values of the curves were related to the number of displaced IPA molecules upon solute adsorption. Using the proposed model and the two-site adsorption model, the retention behaviors of pantolactone (PL) enantiomers in both normal- and reversed-phase modes were investigated. The PL-sorbent interactions were classified into four types: electrostatic/enantioselective, electrostatic/nonselective, solvophobic/enantioselective, and solvophobic/nonselective. At IPA concentrations below 50 vol.% in n-hexane, the retention behaviors of PL were dominated by electrostatic/enantioselective sites, whereas at IPA concentrations beyond 50 vol.%, the solvophobic interactions of PL-sorbent were strengthened and mostly nonselective. By contrast, in the reversed-phase mode, a reverse in the enantiomeric elution order of PL was observed at 10 vol.% IPA, and considerably different enantioselectivity behaviors were found below and above 20 vol.%, indicating an abrupt change in the sorbent molecular environment. At IPA concentrations beyond 40 vol.%, the presence of PL-sorbent electrostatic interactions enhanced chiral recognition.
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Affiliation(s)
- Hung-Wei Tsui
- Department of Chemical Engineering and Biotechnology, National Taipei University of Technology, 1, Sec. 3, Zhongxiao E. Rd., Taipei 10608 Taiwan.
| | - Hong-Lin Zhang
- Department of Chemical Engineering and Biotechnology, National Taipei University of Technology, 1, Sec. 3, Zhongxiao E. Rd., Taipei 10608 Taiwan
| | - Ching-Hung Hsieh
- Department of Chemical Engineering and Biotechnology, National Taipei University of Technology, 1, Sec. 3, Zhongxiao E. Rd., Taipei 10608 Taiwan
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Tsui HW, Ye PW, Huang SX. Effect of solvents on the chiral recognition mechanisms of immobilized cellulose-based chiral stationary phase. J Chromatogr A 2020; 1637:461796. [PMID: 33387913 DOI: 10.1016/j.chroma.2020.461796] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Revised: 12/07/2020] [Accepted: 12/08/2020] [Indexed: 02/06/2023]
Abstract
The effect of solvents on the enantioselectivities of four structurally similar chiral solutes with a cellulose derivative-based chiral stationary phase, Chiralpak IB, were studied using acetone (AC), 2-propanol (IPA), and tert-butanol (TBA) separately as polar modifiers. The enantioselectivities α of benzoin and methyl mandelate decrease with an increase in modifier concentration CM, whereas the enantioselectivity of pantolactone increased with increasing AC concentration. These results were attributed to the heterogeneous adsorption mechanisms of enantiomers. To interpret the dependence of enantioselectivity on modifier content, an enantioselectivity model based on a two-site adsorption model was proposed. The dependence of α on CM was inferred to be mainly due to the distinct modulating effects of modifier concentration on the two adsorption sites: the nonselective type-I site and enantioselective type-II site. The model fitted the benzoin data satisfactorily over a wide TBA concentration range. The retention factors as a function of TBA concentration were successfully deconvoluted for each site. With the use of the proposed model, it was inferred that the chiral recognitions of benzoin and methyl mandelate were mainly achieved by the presence of an aromatic group adjacent to the hydroxyl group. When using IPA and TBA separately as modifiers, the presence of an aromatic group adjacent to the ketone group mainly contributed to the nonselective π interactions and enantioselective steric interactions, respectively. These results, along with those of the modifier adsorption isotherms, determined using the perturbation method, as well as the retention behaviors of various achiral solutes, indicate that the molecular recognition mechanism of IB sorbent is highly sensitive to the adsorbate's molecular geometry. The molecular environment of the sorbent can be controlled using different modifiers, leading to distinct adsorption and retention mechanisms.
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Affiliation(s)
- Hung-Wei Tsui
- Department of Chemical Engineering and Biotechnology, National Taipei University of Technology, 1, Sec. 3, Zhongxiao E. Rd., Taipei 10608 Taiwan.
| | - Pei-Wen Ye
- Department of Chemical Engineering and Biotechnology, National Taipei University of Technology, 1, Sec. 3, Zhongxiao E. Rd., Taipei 10608 Taiwan
| | - Si-Xian Huang
- Department of Chemical Engineering and Biotechnology, National Taipei University of Technology, 1, Sec. 3, Zhongxiao E. Rd., Taipei 10608 Taiwan
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Tsui HW, Kuo CH. Retention and Partition Behaviors of Solutes in a Surfactant-Based Mobile Phase at Concentrations Approaching the Critical Micelle Concentration in Liquid Chromatography. Chromatographia 2020. [DOI: 10.1007/s10337-020-03939-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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7
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Tsui HW, Chou PY, Ye PW, Chen SC, Chen YW. Effects of the Sorbent Backbone and Side Chain on Retention Mechanisms Using Immobilized Polysaccharide-Based Stationary Phases in Normal Phase Mode. Chromatographia 2020. [DOI: 10.1007/s10337-020-03898-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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8
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Stepinski DC, Youker AJ, Chemerisov SD, Tkac P, Rotsch DA, Krebs JF, Vandegrift GF. Development of Mo recovery and concentration column processes for production of 99Mo from accelerator-driven irradiation of aqueous uranyl-sulfate solution. SEP SCI TECHNOL 2020. [DOI: 10.1080/01496395.2019.1591448] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
| | - Amanda J. Youker
- Nuclear Engineering Division, Argonne National Laboratory, Illinois, US
| | | | - Peter Tkac
- Nuclear Engineering Division, Argonne National Laboratory, Illinois, US
| | - David A. Rotsch
- Nuclear Engineering Division, Argonne National Laboratory, Illinois, US
| | - John F. Krebs
- Nuclear Engineering Division, Argonne National Laboratory, Illinois, US
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Separation of 4C-Substituted Pyrrolidin-2-One Derivatives on Polysaccharide-Based Coated Chiral Stationary Phases. Chromatographia 2020. [DOI: 10.1007/s10337-020-03862-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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10
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Tsui HW, Cheng KT, Lin AY, Chen SC, Hung YL, Chou PY. Solvent effects on the retention mechanisms of an amylose-based sorbent. J Chromatogr A 2018; 1556:64-72. [DOI: 10.1016/j.chroma.2018.04.065] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Revised: 04/06/2018] [Accepted: 04/26/2018] [Indexed: 11/25/2022]
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11
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Mignot M, Schammé B, Tognetti V, Joubert L, Cardinael P, Peulon-Agasse V. Anthracenyl polar embedded stationary phases with enhanced aromatic selectivity. Part II: A density functional theory study. J Chromatogr A 2017; 1519:91-99. [DOI: 10.1016/j.chroma.2017.08.083] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Revised: 08/28/2017] [Accepted: 08/30/2017] [Indexed: 12/28/2022]
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12
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Effect of solvent composition on the van’t Hoff enthalpic curve using amylose 3,5-dichlorophenylcarbamate–based sorbent. J Chromatogr A 2017; 1515:179-186. [DOI: 10.1016/j.chroma.2017.08.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Revised: 06/19/2017] [Accepted: 08/03/2017] [Indexed: 11/18/2022]
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13
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Hsieh HY, Wu SG, Tsui HW. Retention models and interaction mechanisms of benzene and other aromatic molecules with an amylose-based sorbent. J Chromatogr A 2017; 1494:55-64. [DOI: 10.1016/j.chroma.2017.03.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Revised: 03/01/2017] [Accepted: 03/06/2017] [Indexed: 11/30/2022]
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14
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Stepinski DC, Youker AJ, Krahn EO, Vandegrift GF, Chung PL, Wang NHL. Design of a Fission 99Mo Recovery Process and Implications toward Mo Adsorption Mechanism on Titania and Alumina Sorbents. Ind Eng Chem Res 2017. [DOI: 10.1021/acs.iecr.6b04667] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Dominique C. Stepinski
- Nuclear
Engineering Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439, United States
| | - Amanda J. Youker
- Nuclear
Engineering Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439, United States
| | - Elizabeth O. Krahn
- Nuclear
Engineering Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439, United States
| | - George F. Vandegrift
- Nuclear
Engineering Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439, United States
| | - Pei-Lun Chung
- School
of Chemical Engineering, Purdue University, West Lafayette, Indiana 47907, United States
| | - Nien-Hwa Linda Wang
- School
of Chemical Engineering, Purdue University, West Lafayette, Indiana 47907, United States
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15
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Elucidation of adsorption mechanisms of solvent molecules with distinct functional groups on amylose tris(3,5-dimethylphenylcarbamate)-based sorbent. J Chromatogr A 2016; 1460:123-34. [DOI: 10.1016/j.chroma.2016.07.024] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Revised: 07/07/2016] [Accepted: 07/07/2016] [Indexed: 11/24/2022]
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16
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Tsui HW, Franses EI, Wang NHL. Effect of alcohol aggregation on the retention factors of chiral solutes with an amylose-based sorbent: Modeling and implications for the adsorption mechanism. J Chromatogr A 2014; 1328:52-65. [DOI: 10.1016/j.chroma.2013.12.078] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Revised: 12/11/2013] [Accepted: 12/26/2013] [Indexed: 11/29/2022]
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17
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Ling L, Chung PL, Youker A, Stepinski DC, Vandegrift GF, Wang NHL. Capture chromatography for Mo-99 recovery from uranyl sulfate solutions: Minimum-column-volume design method. J Chromatogr A 2013; 1309:1-14. [DOI: 10.1016/j.chroma.2013.08.023] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Revised: 08/02/2013] [Accepted: 08/05/2013] [Indexed: 11/16/2022]
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18
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Tsui HW, Wang NHL, Franses EI. Chiral Recognition Mechanism of Acyloin-Containing Chiral Solutes by Amylose Tris[(S)-α-methylbenzylcarbamate]. J Phys Chem B 2013; 117:9203-16. [PMID: 23848510 DOI: 10.1021/jp404549t] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Affiliation(s)
- Hung-Wei Tsui
- School of Chemical Engineering, Purdue University, 480 Stadium Mall Drive, West Lafayette,
Indiana 47907-2100, United States
| | - N.-H. Linda Wang
- School of Chemical Engineering, Purdue University, 480 Stadium Mall Drive, West Lafayette,
Indiana 47907-2100, United States
| | - Elias I. Franses
- School of Chemical Engineering, Purdue University, 480 Stadium Mall Drive, West Lafayette,
Indiana 47907-2100, United States
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