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Ndiripo A, Pornwilard MM, Pathaweeisariyakul T, Pasch H. Multidimensional chromatographic analysis of carboxylic acid-functionalized polyethylene. Polym Chem 2019. [DOI: 10.1039/c9py01191a] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Carboxy-functionalized polyethylene is comprehensively analysed using a multidimensional fractionation approach based on high-temperature HPLC, two-dimensional liquid chromatography and selective infrared detection.
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Muza UL, Greyling G, Pasch H. Stereocomplexation of Polymers in Micelle Nanoreactors As Studied by Multiple Detection Thermal Field-Flow Fractionation. Anal Chem 2018; 90:13987-13995. [DOI: 10.1021/acs.analchem.8b03590] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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28
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Greyling G, Lederer A, Pasch H. Thermal Field-Flow Fractionation for the Investigation of the Thermoresponsive Nature of Star and Linear Polystyrene. MACROMOL CHEM PHYS 2018. [DOI: 10.1002/macp.201800417] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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29
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Venter P, Muller M, Vestner J, Stander MA, Tredoux AGJ, Pasch H, de Villiers A. Comprehensive Three-Dimensional LC × LC × Ion Mobility Spectrometry Separation Combined with High-Resolution MS for the Analysis of Complex Samples. Anal Chem 2018; 90:11643-11650. [PMID: 30193064 DOI: 10.1021/acs.analchem.8b03234] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Comprehensive two-dimensional liquid chromatography (LC × LC) and ion mobility spectrometry-mass spectrometry (IMS-MS) are increasingly being used to address challenges associated with the analysis of highly complex samples. In this work, we evaluate the potential of the combination of these techniques in the form of a comprehensive three-dimensional LC × LC × IMS separation system. As application, hydrophilic interaction chromatography (HILIC) × reversed phase LC (RP-LC) × IMS-high-resolution MS (HR-MS) was used to analyze a range of phenolic compounds, including hydrolyzable and condensed tannins, flavonoids, and phenolic acids in several natural products. A protocol for the extraction and visualization of the four-dimensional data obtained using this approach was developed. We show that the combination of HILIC, RP-LC, and IMS offers excellent separation of complex phenolic samples in three dimensions. Benefits associated with the incorporation of IMS include improved MS sensitivity and mass-spectral data quality. IMS also provided separation of trimeric procyanidin isomeric species that could not be differentiated by HILIC × RP-LC or HR-MS. On the traveling wave IMS (TWIMS) system used here, both IMS separation performance and the extent of second dimension (2D) undersampling depend on the upper mass scan limit, which might present a limitation for the analysis of larger molecular ions. The performance of the LC × LC × IMS system was characterized in terms of practical peak capacity and separation power, using established theory and taking undersampling and orthogonality into account. An average increase in separation performance by a factor of 13 was found for the samples analyzed here when IMS was incorporated into the HILIC × RP-LC-MS workflow.
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Botha C, Kuntz JF, Moire C, Farcet C, Pfukwa H, Pasch H. Molar Mass Analysis of Hydrophobically Modified Hyaluronic Acid by SEC-MALLS: Facing the Challenges of Amphiphilic Biomacromolecules. MACROMOL CHEM PHYS 2018. [DOI: 10.1002/macp.201800233] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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31
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Muza U, Greyling G, Pasch H. Core microstructure, morphology and chain arrangement of block copolymer self-assemblies as investigated by thermal field-flow fractionation. J Chromatogr A 2018; 1562:87-95. [DOI: 10.1016/j.chroma.2018.05.065] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Revised: 05/22/2018] [Accepted: 05/27/2018] [Indexed: 12/01/2022]
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32
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Ndiripo A, Pasch H. Comprehensive Analysis of Oxidized Waxes by Solvent and Thermal Gradient Interaction Chromatography and Two-Dimensional Liquid Chromatography. Anal Chem 2018; 90:7626-7634. [PMID: 29807432 DOI: 10.1021/acs.analchem.8b01480] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
This report addresses the comprehensive analysis of oxidized/functionalized polyethylene waxes according to chemical composition and molar mass by selective chromatographic methods. For the first time, tailored high-temperature interaction chromatography in solvent gradient (HT-SGIC) and thermal gradient (HT-TGIC) modes are used for the chemical composition separation of these materials. Separation protocols are developed using three model wax samples with different degrees of oxidation. For the chromatographic separations polar silica gel is used as the stationary phase. Solvent gradients of decane and cyclohexanone are used in HT-SGIC at 110 °C to separate the bulk waxes into several heterogeneous fractions according to polarity and the type of functionality. Column temperature and gradient manipulation are shown to influence chromatographic resolution and retention. The HT-SGIC investigations are complemented by HT-TGIC separations where a solvent mixture of decane and cyclohexanone is used as the mobile phase in isocratic mode. It is shown that HT-SGIC and HT-TGIC provide different types of separation, however, both are predominantly based on differences in functionality. To provide comprehensive information on chemical composition (functionality) and molar mass, HT-SGIC and HT-TGIC are coupled to HT-SEC, using ortho-dichlorobenzene as the second dimension mobile phase. Clear differences between oxidized and nonoxidized waxes are detected in HT-2D-LC providing comprehensive information on the molecular heterogeneity of these materials.
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Ndiripo A, Pasch H. A multidimensional fractionation protocol for the oligomer analysis of oxidized waxes. Anal Chim Acta 2018; 1027:137-148. [PMID: 29866263 DOI: 10.1016/j.aca.2018.03.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Revised: 02/28/2018] [Accepted: 03/02/2018] [Indexed: 11/29/2022]
Abstract
Oxidized waxes possess far superior properties as compared to the alkanes they are derived from. The separation of alkane oligomers via gas chromatography (GC) becomes a challenge when polar oxygen-containing functional groups are introduced or when higher molar masses are targeted. In the present study, the separation and analysis of oligomers in oxidized and non-oxidized waxes using different liquid chromatographic techniques are investigated. Oligomers in two oxidized waxes and a non-oxidized wax from which they are derived, are separated using high-temperature solvent gradient interaction chromatography (HT-SGIC) and high-temperature two-dimensional liquid chromatography (HT-2D-LC). Evaporative light scattering detector conditions are tailored to provide the best detection with the solvent system at use. It is shown that oligomers in oxidized and non-oxidized waxes can be separated and identified using the mentioned techniques. It has been found that the ELSD detector response systematically decreases as the oxidation levels of the waxes increase. Coupling of HT-HPLC and high-temperature size exclusion chromatography (HT-SEC) in a comprehensive 2D-LC setup shows a broadening of the molar mass distributions of the lower oligomer fractions as a consequence of the modification indicating changes in the oligomer chain microstructures. A preparative fractionation technique is utilized to collect specific oligomer fractions from the bulk waxes followed by hyphenation to HT-HPLC and other techniques. HPLC is shown to provide more detailed information on the oligomer composition of waxes when coupled to a pre-fractionation technique.
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Ndiripo A, Eselem Bungu PS, Pasch H. Comprehensive branching analysis of polyethylene by combined fractionation and thermal analysis. POLYM INT 2018. [DOI: 10.1002/pi.5547] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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35
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Ndiripo A, Albrecht A, Monrabal B, Wang J, Pasch H. Chemical Composition Fractionation of Olefin Plastomers/Elastomers by Solvent and Thermal Gradient Interaction Chromatography. Macromol Rapid Commun 2018; 39:e1700703. [DOI: 10.1002/marc.201700703] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Revised: 12/04/2017] [Indexed: 11/08/2022]
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36
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Eselem Bungu PS, Pasch H. Branching and molar mass analysis of low density polyethylene using the multiple preparative fractionation concept. Polym Chem 2018. [DOI: 10.1039/c7py02076g] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The multiple preparative fractionation concept provides sample libraries with different degrees of branching and different molar masses that are analyzed regarding the LDPE microstructure.
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Eselem Bungu PS, Pflug K, Pasch H. Combination of preparative and two-dimensional chromatographic fractionation with thermal analysis for the branching analysis of polyethylene. Polym Chem 2018. [DOI: 10.1039/c8py00522b] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Multiple preparative fractionation of LDPE provides molar mass and branching fractions that are analyzed regarding their thermal properties.
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Eselem Bungu PS, Pflug K, Busch M, Pasch H. Comprehensive analysis of novel grafted polyethylenes using multidimensional fractionation methods. Polym Chem 2018. [DOI: 10.1039/c8py01122b] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Noval graft copolymers HDPE-g-LDPE were prepared using a dual reactor setup and characterized regarding molar mass, branching and grafting efficiency using a multidimensional analytical approach.
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Greyling G, Pasch H. Characterization of charged polymer self-assemblies by multidetector thermal field-flow fractionation in aqueous mobile phases. J Chromatogr A 2017; 1532:175-181. [PMID: 29223324 DOI: 10.1016/j.chroma.2017.12.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Revised: 12/04/2017] [Accepted: 12/04/2017] [Indexed: 11/15/2022]
Abstract
Charged block copolymer self-assemblies, such as charged micelles, have attracted much attention as versatile drug delivery systems due to their readily tunable characteristics such as size and surface charge. However, current column-based analytical techniques are not suitable to fractionate and comprehensively characterize charged micelles in terms of size, molar mass, chemical composition and morphology. Multidetector thermal field-flow fractionation (ThFFF) is shown to be a unique characterization platform that can be used to characterize charged micelles in terms of size, molar mass, chemical composition and morphology in aqueous mobile phases with various ionic strengths and pH. This is demonstrated by the characterization of poly(methacrylic acid)-b-poly(methyl methacrylate) self-assemblies in high pH buffers as well as the characterization of cationic poly(2-vinyl pyridine)-b-polystyrene and poly(4-vinyl pyridine)-b-polystyrene self-assemblies in low pH buffers. Moreover, it is shown that ThFFF is capable of separating charged micelles according to the corona composition. These investigations prove convincingly that ThFFF is broadly applicable to the comprehensive characterization of amphiphilic self-assemblies even when aqueous mobile phases are used.
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Liu Y, Phiri MJ, Ndiripo A, Pasch H. Chemical composition separation of a propylene–ethylene random copolymer by high temperature solvent gradient interaction chromatography. J Chromatogr A 2017; 1522:23-29. [DOI: 10.1016/j.chroma.2017.09.042] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Revised: 06/04/2017] [Accepted: 09/19/2017] [Indexed: 11/30/2022]
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41
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Greyling G, Pasch H. Fractionation of poly(methacrylic acid) and poly(vinyl pyridine) in aqueous and organic mobile phases by multidetector thermal field-flow fractionation. J Chromatogr A 2017; 1512:115-123. [PMID: 28716356 DOI: 10.1016/j.chroma.2017.07.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Revised: 07/04/2017] [Accepted: 07/05/2017] [Indexed: 11/26/2022]
Abstract
Multidetector thermal field-flow fractionation (ThFFF) is shown to be a versatile characterisation platform that can be used to characterise hydrophilic polymers in a variety of organic and aqueous solutions with various ionic strengths. It is demonstrated that ThFFF fractionates isotactic and syndiotactic poly(methacrylic acid) (PMAA) as well as poly(2-vinyl pyridine) (P2VP) and poly(4-vinyl pyridine) (P4VP) according to microstructure in organic solvents and that the ionic strength of the mobile phase has no influence on the retention behaviour of the polymers. With regard to aqueous solutions, it is shown that, despite the weak retention, isotactic and syndiotactic PMAA show different retention behaviours which can qualitatively be attributed to microstructure. Additionally, it is shown that the ionic strength of the mobile phase has a significant influence on the thermal diffusion of polyelectrolytes in aqueous solutions and that the addition of an electrolyte is essential to achieve a microstructure-based separation of P2VP and P4VP in aqueous solutions.
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Muza UL, Greyling G, Pasch H. Characterization of Complex Polymer Self-Assemblies and Large Aggregates by Multidetector Thermal Field-Flow Fractionation. Anal Chem 2017; 89:7216-7224. [DOI: 10.1021/acs.analchem.7b01445] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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43
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Greyling G, Pasch H. Characterisation of block copolymer self-assemblies by thermal field-flow fractionation. POLYM INT 2017. [DOI: 10.1002/pi.5350] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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44
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Greyling G, Pasch H. Multidetector Thermal Field-Flow Fractionation for the Characterization of Vinyl Polymers in Binary Solvent Systems. Macromolecules 2017. [DOI: 10.1021/acs.macromol.6b02314] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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45
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Eselem Bungu PS, Pasch H. Comprehensive analysis of branched polyethylene: the multiple preparative fractionation concept. Polym Chem 2017. [DOI: 10.1039/c7py00893g] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A concept for the comprehensive analysis of branched polyethylene is developed where a multiple fractionation protocol is used.
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46
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47
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Makan AC, Williams RP, Pasch H. Field Flow Fractionation for the Size, Molar Mass, and Gel Content Analysis of Emulsion Polymers for Water-Based Coatings. MACROMOL CHEM PHYS 2016. [DOI: 10.1002/macp.201600208] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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48
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Makan AC, Spallek MJ, du Toit M, Klein T, Pasch H. Advanced analysis of polymer emulsions: Particle size and particle size distribution by field-flow fractionation and dynamic light scattering. J Chromatogr A 2016; 1442:94-106. [DOI: 10.1016/j.chroma.2016.03.013] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Revised: 02/19/2016] [Accepted: 03/06/2016] [Indexed: 12/01/2022]
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49
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Greyling G, Pasch H. Multidetector Thermal Field-Flow Fractionation: A Unique Tool for Monitoring the Structure and Dynamics of Block Copolymer Micelles. Macromolecules 2016. [DOI: 10.1021/acs.macromol.5b02634] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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50
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Phiri MJ, Pasch H. Exploring the Compositional Heterogeneity of Vis-Broken Impact Poly(propylene) Copolymers by Advanced Fractionation Methods. MACROMOL CHEM PHYS 2016. [DOI: 10.1002/macp.201500470] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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