1
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Grabe B, Hiller W. Online coupling of liquid chromatography and two-dimensional diffusion ordered spectroscopy for the analysis of oligostyrenes. J Chromatogr A 2024; 1719:464750. [PMID: 38412606 DOI: 10.1016/j.chroma.2024.464750] [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: 11/16/2023] [Revised: 02/01/2024] [Accepted: 02/15/2024] [Indexed: 02/29/2024]
Abstract
The aim of this study was to introduce a powerful coupling of Liquid Adsorption Chromatography (LAC) and Diffusion-Ordered Spectroscopy (DOSY) for comprehensive structure analysis. This new hyphenation approach facilitated the simultaneous separation of a polymer mixture and the determination of molar masses within a single 3D experiment. The online coupling of High-Performance Liquid Chromatography (HPLC) and two-dimensional DOSY-NMR will be called 3D-LAC-NMR-DOSY experiment. Our methodology enabled the chromatographic separation of analytes based on their chemical heterogeneity, and provided accurate molar masses of the analytes through 2D-DOSY. This new method was demonstrated on a polystyrene oligomer mixture. In this case, the oligostyrenes could be separated with LAC according to their tacticity and chain length in protonated acetonitrile as eluent and DOSY measurements provided the molar masses of each oligomer. In order to show the power of the 3D-LAC-NMR-DOSY method, the comparison to 2D-DOSY, 3D-DOSY and LAC-NMR was separately evaluated. Furthermore, the recently published solvent-independent molar mass calibration of diffusion coefficients was also successfully applied in our LAC-DOSY studies for molar mass predictions of the oligomers in acetonitrile. The predicted molar masses were in good agreement with the LAC-DOSY measurements and were verified by calibrations of diffusion coefficients and mass spectrometry. Finally, this pioneering 3D technique offers a powerful new tool for advancing structure analysis and enhancing our understanding of complex systems such as oligostyrenes.
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Affiliation(s)
- Bastian Grabe
- Faculty of Chemistry and Chemical Biology, TU Dortmund University, Otto-Hahn-Straße 4a, Dortmund 44227, Germany
| | - Wolf Hiller
- Faculty of Chemistry and Chemical Biology, TU Dortmund University, Otto-Hahn-Straße 4a, Dortmund 44227, Germany.
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2
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Critical conditions for liquid chromatography of statistical polyolefins: Evaluation of diene distribution in EPDM terpolymers. Anal Chim Acta 2023; 1246:340856. [PMID: 36764768 DOI: 10.1016/j.aca.2023.340856] [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: 11/23/2022] [Revised: 01/16/2023] [Accepted: 01/17/2023] [Indexed: 01/21/2023]
Abstract
Liquid chromatography at critical conditions is of interest as it may unravel molecular information on macromolecular structures not accessible by any other analytical techniques. Yet so far, such conditions have never been experimentally established for copolymers, where a particular need for such information exists. Toward this goal, critical conditions for statistical ethylene propylene copolymers were identified. In the first approach the composition of the binary mobile phase was varied at a constant temperature, and secondly by modulating the adsorption-desorption temperature at constant mobile phase composition. Solvents for both methods were identified by using a novel approach that combines structure retention relationships with Hansen Solubility Parameters. As a result, for the first time, the heterogeneity of an ethylene propylene diene terpolymer sample with regard to the pendant double bond of the diene could be determined. The novel chromatographic approach was validated by measuring the composition of fractions taken over the chromatographic run offline by nuclear magnetic resonance. In summary, this work gave the first experimental evidence for the existence of critical conditions for polyolefin random copolymers, as postulated by Brun. This novel chromatographic approach holds immense potential to engineer complex polymers towards future applications by making use of the now-accessible molecular information.
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3
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Losacco GL, Cohen RD, DaSilva JO, Haidar Ahmad IA, Sherer EC, Mangion I, Regalado EL. Deuterated Modifiers in Sub/Supercritical Fluid Chromatography for Streamlined NMR Structure Elucidation. Anal Chem 2022; 94:12176-12184. [PMID: 36001377 DOI: 10.1021/acs.analchem.2c02623] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Isolation and chemical characterization of target components in fast-paced pharmaceutical laboratories can often be challenging, especially when dealing with mixtures of closely related, possibly unstable species. Traditionally, this process involves intense labor and manual intervention including chromatographic method development and optimization, fraction collection, and drying processes prior to NMR analyses for unambiguous structure elucidation. To circumvent these challenges, a foundational framework for the proper utilization of supercritical carbon dioxide (scCO2) and deuterated modifiers (CD3OD) in sub/supercritical fluid chromatography (SFC) is herein introduced. This facilitates a streamlined multicomponent isolation with minimized protic residues, further enabling immediate NMR analysis. In addition to bypassing tedious drying processes and minimizing analyte degradation, this approach (complementary to traditional reversed-phase liquid chromatography, RPLC) delivers highly efficient separations and automated fraction collection using readily available analytical/midscale SFC instrumentation. A series of diverse analytes across a wide spectrum of chemical properties (acid, basic, and neutral), combined with different stationary-phase columns in SFC are investigated using both a protic organic modifier (CH3OH) and its deuterated counterpart (CD3OD). The power of this framework is demonstrated with pharmaceutically relevant applications in the context of target characterization and analysis of complex multicomponent reaction mixtures from modern synthetic chemistry, demonstrating high isolation yields while reducing both the environmental footprint and manual intervention. This workflow enables unambiguous fast-paced structure elucidation on the analytical scale, providing results that are comparable to traditional, but time-consuming, RPLC purification approaches.
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Affiliation(s)
- Gioacchino Luca Losacco
- Analytical Research and Development, MRL, Merck & Co., Inc., 126 E. Lincoln Avenue, Rahway, New Jersey 07065, United States
| | - Ryan D Cohen
- Analytical Research and Development, MRL, Merck & Co., Inc., 126 E. Lincoln Avenue, Rahway, New Jersey 07065, United States
| | - Jimmy O DaSilva
- Analytical Research and Development, MRL, Merck & Co., Inc., 126 E. Lincoln Avenue, Rahway, New Jersey 07065, United States
| | - Imad A Haidar Ahmad
- Analytical Research and Development, MRL, Merck & Co., Inc., 126 E. Lincoln Avenue, Rahway, New Jersey 07065, United States
| | - Edward C Sherer
- Analytical Research and Development, MRL, Merck & Co., Inc., 126 E. Lincoln Avenue, Rahway, New Jersey 07065, United States
| | - Ian Mangion
- Analytical Research and Development, MRL, Merck & Co., Inc., 126 E. Lincoln Avenue, Rahway, New Jersey 07065, United States
| | - Erik L Regalado
- Analytical Research and Development, MRL, Merck & Co., Inc., 126 E. Lincoln Avenue, Rahway, New Jersey 07065, United States
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4
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Ahmad IAH, Losacco GL, Shchurik V, Wang X, Cohen RD, Herron AN, Aiken S, Fiorito D, Wang H, Reibarkh M, Nowak T, Makarov AA, Stoll DR, Guillarme D, Mangion I, Aggarwal VK, Yu JQ, Regalado EL. Trapping-Enrichment Multi-dimensional Liquid Chromatography with On-Line Deuterated Solvent Exchange for Streamlined Structure Elucidation at the Microgram Scale. Angew Chem Int Ed Engl 2022; 61:e202117655. [PMID: 35139257 DOI: 10.1002/anie.202117655] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Indexed: 11/10/2022]
Abstract
At the forefront of chemistry and biology research, development timelines are fast-paced and large quantities of pure targets are rarely available. Herein, we introduce a new framework, which is built upon an automated, online trapping-enrichment multi-dimensional liquid chromatography platform (TE-Dt-mDLC) that enables: 1) highly efficient separation of complex mixtures in a first dimension (1 D-UV); 2) automated peak trapping-enrichment and buffer removal achieved through a sequence of H2 O and D2 O washes using an independent pump setup; and 3) a second dimension separation (2 D-UV-MS) with fully deuterated mobile phases and fraction collection to minimize protic residues for immediate NMR analysis while bypassing tedious drying processes and minimizing analyte degradation. Diverse examples of target isolation and characterization from organic synthesis and natural product chemistry laboratories are illustrated, demonstrating recoveries above 90 % using as little as a few micrograms of material.
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Affiliation(s)
- Imad A Haidar Ahmad
- Analytical Research & Development, MRL, Merck & Co., Inc., Rahway, NJ 07065, USA
| | | | - Vladimir Shchurik
- Analytical Research & Development, MRL, Merck & Co., Inc., Rahway, NJ 07065, USA
| | - Xiao Wang
- Analytical Research & Development, MRL, Merck & Co., Inc., Rahway, NJ 07065, USA
| | - Ryan D Cohen
- Analytical Research & Development, MRL, Merck & Co., Inc., Rahway, NJ 07065, USA
| | - Alastair N Herron
- Department of Chemistry, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Sheenagh Aiken
- School of Chemistry, University of Bristol, Bristol, BS8 1TS, UK
| | - Daniele Fiorito
- School of Chemistry, University of Bristol, Bristol, BS8 1TS, UK
| | - Heather Wang
- Analytical Research & Development, MRL, Merck & Co., Inc., Rahway, NJ 07065, USA
| | - Mikhail Reibarkh
- Analytical Research & Development, MRL, Merck & Co., Inc., Rahway, NJ 07065, USA
| | - Timothy Nowak
- Analytical Research & Development, MRL, Merck & Co., Inc., Rahway, NJ 07065, USA
| | - Alexey A Makarov
- Analytical Research & Development, MRL, Merck & Co., Inc., Rahway, NJ 07065, USA
| | - Dwight R Stoll
- Department of Chemistry, Gustavus Adolphus College, Saint Peter, MN 56082, USA
| | - Davy Guillarme
- School of Pharmaceutical Sciences, University of Geneva, CMU, Rue Michel-Servet 1, 1211, Geneva 4, Switzerland.,Institute of Pharmaceutical Sciences of Western Switzerland, University of Geneva, CMU, Rue Michel-Servet 1, 1211, Geneva 4, Switzerland
| | - Ian Mangion
- Analytical Research & Development, MRL, Merck & Co., Inc., Rahway, NJ 07065, USA
| | | | - Jin-Quan Yu
- Department of Chemistry, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Erik L Regalado
- Analytical Research & Development, MRL, Merck & Co., Inc., Rahway, NJ 07065, USA
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5
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Ahmad IAH, Losacco GL, Shchurik V, Wang X, Cohen RD, Herron AN, Aiken S, Fiorito D, Wang H, Reibarkh M, Nowak T, Makarov AA, Stoll DR, Guillarme D, Mangion I, Aggarwal VK, Yu J, Regalado EL. Trapping‐Enrichment Multi‐dimensional Liquid Chromatography with On‐Line Deuterated Solvent Exchange for Streamlined Structure Elucidation at the Microgram Scale. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202117655] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
| | | | - Vladimir Shchurik
- Analytical Research & Development, MRL, Merck & Co., Inc. Rahway NJ 07065 USA
| | - Xiao Wang
- Analytical Research & Development, MRL, Merck & Co., Inc. Rahway NJ 07065 USA
| | - Ryan D. Cohen
- Analytical Research & Development, MRL, Merck & Co., Inc. Rahway NJ 07065 USA
| | - Alastair N. Herron
- Department of Chemistry The Scripps Research Institute La Jolla CA 92037 USA
| | - Sheenagh Aiken
- School of Chemistry University of Bristol Bristol BS8 1TS UK
| | - Daniele Fiorito
- School of Chemistry University of Bristol Bristol BS8 1TS UK
| | - Heather Wang
- Analytical Research & Development, MRL, Merck & Co., Inc. Rahway NJ 07065 USA
| | - Mikhail Reibarkh
- Analytical Research & Development, MRL, Merck & Co., Inc. Rahway NJ 07065 USA
| | - Timothy Nowak
- Analytical Research & Development, MRL, Merck & Co., Inc. Rahway NJ 07065 USA
| | - Alexey A. Makarov
- Analytical Research & Development, MRL, Merck & Co., Inc. Rahway NJ 07065 USA
| | - Dwight R. Stoll
- Department of Chemistry Gustavus Adolphus College Saint Peter MN 56082 USA
| | - Davy Guillarme
- School of Pharmaceutical Sciences University of Geneva, CMU Rue Michel-Servet 1 1211 Geneva 4 Switzerland
- Institute of Pharmaceutical Sciences of Western Switzerland University of Geneva, CMU Rue Michel-Servet 1 1211 Geneva 4 Switzerland
| | - Ian Mangion
- Analytical Research & Development, MRL, Merck & Co., Inc. Rahway NJ 07065 USA
| | | | - Jin‐Quan Yu
- Department of Chemistry The Scripps Research Institute La Jolla CA 92037 USA
| | - Erik L. Regalado
- Analytical Research & Development, MRL, Merck & Co., Inc. Rahway NJ 07065 USA
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6
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Singh SM, Furman R, Singh RK, Balakrishnan G, Chennamsetty N, Tao L, Li Z. Size exclusion chromatography for the characterization and quality control of biologics. J LIQ CHROMATOGR R T 2021. [DOI: 10.1080/10826076.2021.1979582] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Affiliation(s)
- Surinder M. Singh
- Analytical Development and Attribute Sciences, New Brunswick, NJ, USA
| | - Ran Furman
- Analytical Development and Attribute Sciences, New Brunswick, NJ, USA
| | - Rajesh K. Singh
- Analytical Development and Attribute Sciences, New Brunswick, NJ, USA
| | | | | | - Li Tao
- Analytical Development and Attribute Sciences, New Brunswick, NJ, USA
| | - Zhengjian Li
- Analytical Development and Attribute Sciences, New Brunswick, NJ, USA
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7
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Uliyanchenko E. Applications of Hyphenated Liquid Chromatography Techniques for Polymer Analysis. Chromatographia 2017. [DOI: 10.1007/s10337-016-3193-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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8
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Hehn M, Sinha P, Pasch H, Hiller W. Onflow liquid chromatography at critical conditions coupled to 1H and 2H nuclear magnetic resonance as powerful tools for the separation of poly(methylmethacrylate) according to isotopic composition. J Chromatogr A 2015; 1387:69-74. [DOI: 10.1016/j.chroma.2015.02.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Revised: 02/02/2015] [Accepted: 02/03/2015] [Indexed: 11/30/2022]
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9
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Beskers TF, Hofe T, Wilhelm M. Development of a chemically sensitive online SEC detector based on FTIR spectroscopy. Polym Chem 2015. [DOI: 10.1039/c4py01043d] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A new FTIR–SEC coupling method provides correlated information about the molecular weight distribution and the chemical composition and has the potential to be applied as a standard SEC detector.
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Affiliation(s)
- Timo F. Beskers
- Institute for Chemical Technology and Polymer Chemistry
- Karlsruhe Institute of Technology (KIT)
- 76131 Karlsruhe
- Germany
- PSS Polymer Standards Service GmbH
| | - Thorsten Hofe
- PSS Polymer Standards Service GmbH
- 55120 Mainz
- Germany
| | - Manfred Wilhelm
- Institute for Chemical Technology and Polymer Chemistry
- Karlsruhe Institute of Technology (KIT)
- 76131 Karlsruhe
- Germany
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10
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Abstract
Theoretical and experimental aspects of multiple detection analysis of polymers are critically revised for size exclusion chromatography (SEC). In particular, different combinations of detectors, the importance of the injected mass and the influence of the tacticity of polymers are evaluated in respect to the accuracy of the weight fractions of the polymer components. It is also shown how overlapping detector responses of the chemical components will affect the accuracy of the weight fractions. The calculation of the weight fractions is performed with equations derived for n different chemical components and detectors by using the slopes and intercepts of the linear response equations. Several detector combinations of dual detection in SEC are evaluated with PS-b-PMMA diblock copolymers to determine the comonomer compositions and for the first time different combinations of triple detections are performed for the determination of the weight fractions of a blend of three homopolymers, respectively. The correct determination of the weight fractions of minor and main components of polymers is strongly affected by the chosen combination of detectors, the injected mass and the intercept of the response calibrations. It is shown how these conditions have to be changed to obtain correct quantifications of the weight fractions according to the experimental setups. The experimental results are approved with online SEC-(1)H/NMR where no response factors are required.
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Affiliation(s)
- Wolf Hiller
- Department of Chemistry and Chemical Biology, TU Dortmund , Otto-Hahn-Straße 6, 44227 Dortmund, Germany
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11
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Lee D, Shan CLP, Meunier DM, Lyons JW, Cong R, deGroot AW. Toward absolute chemical composition distribution measurement of polyolefins by high-temperature liquid chromatography hyphenated with infrared absorbance and light scattering detectors. Anal Chem 2014; 86:8649-56. [PMID: 25117509 DOI: 10.1021/ac501477a] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Chemical composition distribution (CCD) is a fundamental metric for representing molecular structures of copolymers in addition to molecular weight distribution (MWD). Solvent gradient interaction chromatography (SGIC) is commonly used to separate copolymers by chemical composition in order to obtain CCD. The separation of polymer in SGIC is, however, not only affected by chemical composition but also by molecular weight and architecture. The ability to measure composition and MW simultaneously after separation would be beneficial for understanding the impact of different factors and deriving true CCD. In this study, comprehensive two-dimensional chromatography (2D) was coupled with infrared absorbance (IR5) and light scattering (LS) detectors for characterization of ethylene-propylene copolymers. Polymers were first separated by SGIC as the first dimension chromatography (D1). The separated fractions were then characterized by the second dimension (D2) size exclusion chromatography (SEC) with IR5 and LS detectors. The concentrations and compositions of the separated fractions were measured online using the IR5 detector. The MWs of the fractions were measured by the ratio of LS to IR5 signals. A metric was derived from online concentration and composition data to represent CCD breadth. The metric was shown to be independent of separation gradients for an "absolute" measurement of CCD breadth. By combining online composition and MW data, the relationship of MW as a function of chemical composition was obtained. This relationship was qualitatively consistent with the results by SEC coupled to IR5, which measures chemical composition as a function of logMW. The simultaneous measurements of composition and MW give the opportunity to study the SGIC separation mechanism and derive chain architectural characteristics of polymer chains.
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Affiliation(s)
- Dean Lee
- The Dow Chemical Company, Analytical Sciences R&D, 1897 Building, Midland, Michigan 48667, United States
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12
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Hiller W, Sinha P, Hehn M, Pasch H. Online LC-NMR – From an expensive toy to a powerful tool in polymer analysis. Prog Polym Sci 2014. [DOI: 10.1016/j.progpolymsci.2013.10.001] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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13
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Sinha P, Hiller W, Pasch H. HPLC-1
H-NMR Characterization of Polystyrene-block
-Polyisoprene Copolymers: LCCC-1
H-NMR Using a Single Mobile Phase. ACTA ACUST UNITED AC 2014. [DOI: 10.1002/masy.201450305] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Pritish Sinha
- University of Stellenbosch; Department of Chemistry and Polymer Science; Private Bag X1 7602 Matieland South Africa
| | - Wolf Hiller
- Faculty of Chemistry; TU Dortmund; Otto-Hahn-Straβe 6 44227 Dortmund Germany
| | - Harald Pasch
- University of Stellenbosch; Department of Chemistry and Polymer Science; Private Bag X1 7602 Matieland South Africa
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14
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Mekap D, Macko T, Brüll R, Cong R, deGroot W, Parrott A, Yau W. Multiple-Injection Method in High-Temperature Two-Dimensional Liquid Chromatography (2D HT-LC). MACROMOL CHEM PHYS 2014. [DOI: 10.1002/macp.201300649] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Dibyaranjan Mekap
- Fraunhofer Institute for Structural Durability and System Reliability; Division Plastics, Group Material Analytics; Schlossgartenstrasse, 6 64289 Darmstadt Germany
| | - Tibor Macko
- Fraunhofer Institute for Structural Durability and System Reliability; Division Plastics, Group Material Analytics; Schlossgartenstrasse, 6 64289 Darmstadt Germany
| | - Robert Brüll
- Fraunhofer Institute for Structural Durability and System Reliability; Division Plastics, Group Material Analytics; Schlossgartenstrasse, 6 64289 Darmstadt Germany
| | - Rongjuan Cong
- Performance Plastics Characterization and Testing Group; The Dow Chemical Company; 2301, Brazosport Blvd. Freeport TX 77541 USA
| | - Willem deGroot
- Performance Plastics Characterization and Testing Group; The Dow Chemical Company; 2301, Brazosport Blvd. Freeport TX 77541 USA
| | - Albert Parrott
- Performance Plastics Characterization and Testing Group; The Dow Chemical Company; 2301, Brazosport Blvd. Freeport TX 77541 USA
| | - Wallace Yau
- Performance Plastics Characterization and Testing Group; The Dow Chemical Company; 2301, Brazosport Blvd. Freeport TX 77541 USA
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15
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Hehn M, Wagner T, Hiller W. Direct Quantification of Molar Masses of Copolymers by Online Liquid Chromatography under Critical Conditions–Nuclear Magnetic Resonance and Size Exclusion Chromatography–Nuclear Magnetic Resonance. Anal Chem 2013; 86:490-7. [DOI: 10.1021/ac402396r] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Mathias Hehn
- TU
Dortmund, Department of Chemistry and Chemical Biology, Otto-Hahn-Straße 6, 44227 Dortmund, Germany
| | - Thomas Wagner
- Max-Planck-Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Wolf Hiller
- TU
Dortmund, Department of Chemistry and Chemical Biology, Otto-Hahn-Straße 6, 44227 Dortmund, Germany
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16
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Šišková A, Macová E, Corradini D, Berek D. Liquid chromatography of synthetic polymers under critical conditions of enthalpic interactions 4: Sample recovery. J Sep Sci 2013; 36:2979-85. [DOI: 10.1002/jssc.201300545] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Revised: 07/04/2013] [Accepted: 07/04/2013] [Indexed: 11/05/2022]
Affiliation(s)
- Alena Šišková
- Polymer Institute; Slovak Academy of Sciences; Bratislava Slovakia
| | - Eva Macová
- Polymer Institute; Slovak Academy of Sciences; Bratislava Slovakia
| | - Danilo Corradini
- Institute of Chemical Methodologies; National Research Council; Rome Italy
| | - Dušan Berek
- Polymer Institute; Slovak Academy of Sciences; Bratislava Slovakia
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17
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Striegel AM. There’s plenty of gloom at the bottom: the many challenges of accurate quantitation in size-based oligomeric separations. Anal Bioanal Chem 2013; 405:8959-67. [DOI: 10.1007/s00216-013-7198-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Revised: 06/21/2013] [Accepted: 07/01/2013] [Indexed: 11/30/2022]
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18
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Hiller W, van Aswegen W, Hehn M, Pasch H. Online ThFFF–NMR: A Novel Tool for Molar Mass and Chemical Composition Analysis of Complex Macromolecules. Macromolecules 2013. [DOI: 10.1021/ma400350y] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Wolf Hiller
- Faculty of Chemistry, TU Dortmund, Otto-Hahn-Strasse 6, 44227 Dortmund, Germany
| | - Werner van Aswegen
- Department of Chemistry and
Polymer Science, University of Stellenbosch, Private Bag X1, 7602 Matieland, South Africa
| | - Mathias Hehn
- Faculty of Chemistry, TU Dortmund, Otto-Hahn-Strasse 6, 44227 Dortmund, Germany
| | - Harald Pasch
- Department of Chemistry and
Polymer Science, University of Stellenbosch, Private Bag X1, 7602 Matieland, South Africa
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19
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