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Zientek N, Laurain C, Meyer K, Paul A, Engel D, Guthausen G, Kraume M, Maiwald M. Automated data evaluation and modelling of simultaneous (19) F-(1) H medium-resolution NMR spectra for online reaction monitoring. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2016; 54:513-520. [PMID: 25854892 DOI: 10.1002/mrc.4216] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2014] [Revised: 10/31/2014] [Accepted: 01/19/2015] [Indexed: 06/04/2023]
Abstract
Medium-resolution nuclear magnetic resonance spectroscopy (MR-NMR) currently develops to an important analytical tool for both quality control and process monitoring. In contrast to high-resolution online NMR (HR-NMR), MR-NMR can be operated under rough environmental conditions. A continuous re-circulating stream of reaction mixture from the reaction vessel to the NMR spectrometer enables a non-invasive, volume integrating online analysis of reactants and products. Here, we investigate the esterification of 2,2,2-trifluoroethanol with acetic acid to 2,2,2-trifluoroethyl acetate both by (1) H HR-NMR (500 MHz) and (1) H and (19) F MR-NMR (43 MHz) as a model system. The parallel online measurement is realised by splitting the flow, which allows the adjustment of quantitative and independent flow rates, both in the HR-NMR probe as well as in the MR-NMR probe, in addition to a fast bypass line back to the reactor. One of the fundamental acceptance criteria for online MR-MNR spectroscopy is a robust data treatment and evaluation strategy with the potential for automation. The MR-NMR spectra are treated by an automated baseline and phase correction using the minimum entropy method. The evaluation strategies comprise (i) direct integration, (ii) automated line fitting, (iii) indirect hard modelling (IHM) and (iv) partial least squares regression (PLS-R). To assess the potential of these evaluation strategies for MR-NMR, prediction results are compared with the line fitting data derived from the quantitative HR-NMR spectroscopy. Although, superior results are obtained from both IHM and PLS-R for (1) H MR-NMR, especially the latter demands for elaborate data pretreatment, whereas IHM models needed no previous alignment. Copyright © 2015 John Wiley & Sons, Ltd.
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Affiliation(s)
- Nicolai Zientek
- BAM Federal Institute for Materials Research and Testing, Richard-Willstaetter-Straße 11, 12489, Berlin, Germany
| | - Clément Laurain
- BAM Federal Institute for Materials Research and Testing, Richard-Willstaetter-Straße 11, 12489, Berlin, Germany
- École Nationale Supérieure de Chimie de Lille, Avenue Mendeleiev CS 90108, 59652, Villeneuve D'ascq Cedex, France
| | - Klas Meyer
- BAM Federal Institute for Materials Research and Testing, Richard-Willstaetter-Straße 11, 12489, Berlin, Germany
| | - Andrea Paul
- BAM Federal Institute for Materials Research and Testing, Richard-Willstaetter-Straße 11, 12489, Berlin, Germany
| | - Dirk Engel
- Pro2NMR, Institute of Mechanical Process Engineering and Mechanics and Institute of Biological Interfaces, KIT, Adenauerring 20b, 76131, Karlsruhe, Germany
| | | | - Matthias Kraume
- Department of Chemical Engineering, Technische Universität Berlin, Straße des 17. Juni 136, MA 5-7, 10623, Berlin, Germany
| | - Michael Maiwald
- BAM Federal Institute for Materials Research and Testing, Richard-Willstaetter-Straße 11, 12489, Berlin, Germany
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Zientek N, Laurain C, Meyer K, Kraume M, Guthausen G, Maiwald M. Simultaneous 19F- 1H medium resolution NMR spectroscopy for online reaction monitoring. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2014; 249:53-62. [PMID: 25462947 DOI: 10.1016/j.jmr.2014.10.007] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Revised: 10/03/2014] [Accepted: 10/04/2014] [Indexed: 06/04/2023]
Abstract
Medium resolution nuclear magnetic resonance (MR-NMR) spectroscopy is currently a fast developing field, which has an enormous potential to become an important analytical tool for reaction monitoring, in hyphenated techniques, and for systematic investigations of complex mixtures. The recent developments of innovative MR-NMR spectrometers are therefore remarkable due to their possible applications in quality control, education, and process monitoring. MR-NMR spectroscopy can beneficially be applied for fast, non-invasive, and volume integrating analyses under rough environmental conditions. Within this study, a simple 1/16″ fluorinated ethylene propylene (FEP) tube with an ID of 0.04″ (1.02mm) was used as a flow cell in combination with a 5mm glass Dewar tube inserted into a benchtop MR-NMR spectrometer with a 1H Larmor frequency of 43.32MHz and 40.68MHz for 19F. For the first time, quasi-simultaneous proton and fluorine NMR spectra were recorded with a series of alternating 19F and 1H single scan spectra along the reaction time coordinate of a homogeneously catalysed esterification model reaction containing fluorinated compounds. The results were compared to quantitative NMR spectra from a hyphenated 500MHz online NMR instrument for validation. Automation of handling, pre-processing, and analysis of NMR data becomes increasingly important for process monitoring applications of online NMR spectroscopy and for its technical and practical acceptance. Thus, NMR spectra were automatically baseline corrected and phased using the minimum entropy method. Data analysis schemes were designed such that they are based on simple direct integration or first principle line fitting, with the aim that the analysis directly revealed molar concentrations from the spectra. Finally, the performance of 1/16″ FEP tube set-up with an ID of 1.02mm was characterised regarding the limit of detection (LOQ (1H)=0.335molL-1 and LOQ (19F)=0.130molL-1 for trifluoroethanol in D2O (single scan)) and maximum quantitative flow rates up to 0.3mLmin-1. Thus, a series of single scan 19F and 1H NMR spectra acquired with this simple set-up already presents a valuable basis for quantitative reaction monitoring.
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Affiliation(s)
- Nicolai Zientek
- BAM Federal Institute for Materials Research and Testing, Richard-Willstaetter-Straße 11, 12489 Berlin, Germany
| | - Clément Laurain
- BAM Federal Institute for Materials Research and Testing, Richard-Willstaetter-Straße 11, 12489 Berlin, Germany; École Nationale Supérieure de Chimie de Lille, Avenue Mendeleiev CS 90108, 59652 Villeneuve D'ascq Cedex, France
| | - Klas Meyer
- BAM Federal Institute for Materials Research and Testing, Richard-Willstaetter-Straße 11, 12489 Berlin, Germany
| | - Matthias Kraume
- Department of Chemical Engineering, Technische Universität Berlin, Straße des 17. Juni 136, MA 5-7, 10623 Berlin, Germany
| | - Gisela Guthausen
- Pro(2)NMR, Institute of Mechanical Process Engineering and Mechanics and Institute of Biological Interfaces, KIT, Adenauerring 20 b, 76131 Karlsruhe, Germany
| | - Michael Maiwald
- BAM Federal Institute for Materials Research and Testing, Richard-Willstaetter-Straße 11, 12489 Berlin, Germany.
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Jones CJ, Larive CK. Microcoil NMR Study of the Interactions between Doxepin, β-Cyclodextrin, and Acetate during Capillary Isotachophoresis. Anal Chem 2012; 84:7099-106. [DOI: 10.1021/ac301401p] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Christopher J. Jones
- Department of Chemistry, University of California, Riverside, California 92521,
United States
| | - Cynthia K. Larive
- Department of Chemistry, University of California, Riverside, California 92521,
United States
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Dalitz F, Cudaj M, Maiwald M, Guthausen G. Process and reaction monitoring by low-field NMR spectroscopy. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2012; 60:52-70. [PMID: 22293399 DOI: 10.1016/j.pnmrs.2011.11.003] [Citation(s) in RCA: 131] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2011] [Accepted: 11/29/2011] [Indexed: 05/31/2023]
Affiliation(s)
- Franz Dalitz
- Institute of Mechanical Process Engineering and Mechanics, SRG10-2, KIT, Adenauerring 20 b, 76131 Karlsruhe, Germany
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Jones CJ, Beni S, Limtiaco JFK, Langeslay DJ, Larive CK. Heparin characterization: challenges and solutions. ANNUAL REVIEW OF ANALYTICAL CHEMISTRY (PALO ALTO, CALIF.) 2011; 4:439-465. [PMID: 21469955 DOI: 10.1146/annurev-anchem-061010-113911] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Although heparin is an important and widely prescribed pharmaceutical anticoagulant, its high degree of sequence microheterogeneity and size polydispersity make molecular-level characterization challenging. Unlike nucleic acids and proteins that are biosynthesized through template-driven assembly processes, heparin and the related glycosaminoglycan heparan sulfate are actively remodeled during biosynthesis through a series of enzymatic reactions that lead to variable levels of O- and N-sulfonation and uronic acid epimers. As summarized in this review, heparin sequence information is determined through a bottom-up approach that relies on depolymerization reactions, size- and charge-based separations, and sensitive mass spectrometric and nuclear magnetic resonance experiments to determine the structural identity of component oligosaccharides. The structure-elucidation process, along with its challenges and opportunities for future analytical improvements, is reviewed and illustrated for a heparin-derived hexasaccharide.
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Affiliation(s)
- Christopher J Jones
- Department of Chemistry, University of California, Riverside, California 92521, USA.
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Hooper S, Roach D, Anderson M. Application of a Square-Wave Potential Program for Time-Dependent Amperometric Detection in Capillary Electrophoresis. ELECTROANAL 2008. [DOI: 10.1002/elan.200704077] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Korir AK, Larive CK. On-line NMR detection of microgram quantities of heparin-derived oligosaccharides and their structure elucidation by microcoil NMR. Anal Bioanal Chem 2007; 388:1707-16. [PMID: 17607565 DOI: 10.1007/s00216-007-1400-2] [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: 04/19/2007] [Revised: 05/20/2007] [Accepted: 05/24/2007] [Indexed: 10/23/2022]
Abstract
The isolation and purification of sufficient quantities of heparin-derived oligosaccharides for characterization by NMR is a tedious and time-consuming process. In addition, the structural complexity and microheterogeneity of heparin makes its characterization a challenging task. The improved mass-sensitivity of microcoil NMR probe technology makes this technique well suited for characterization of mass-limited heparin-derived oligosaccharides. Although microcoil probes have poorer concentration sensitivity than conventional NMR probes, this limitation can be overcome by coupling capillary isotachophoresis (cITP) with on-line microcoil NMR detection (cITP-NMR). Strategies to improve the sensitivity of on-line NMR detection through changes in probe design and in the cITP-NMR experimental protocol are discussed. These improvements in sensitivity allow acquisition of cITP-NMR survey spectra facilitating tentative identification of unknown oligosaccharides. Complete structure elucidation for microgram quantities of the purified material can be carried out through acquisition of 2D NMR spectra using a CapNMR microcoil probe.
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Affiliation(s)
- Albert K Korir
- Department of Chemistry, University of California, Riverside, CA 92521, USA.
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Anwar MS, Hilty C, Chu C, Bouchard LS, Pierce KL, Pines A. Spin Coherence Transfer in Chemical Transformations Monitored by Remote Detection NMR. Anal Chem 2007; 79:2806-11. [PMID: 17335181 DOI: 10.1021/ac062327+] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We demonstrate a nuclear magnetic resonance (NMR) experiment using continuous flow in a microfluidic channel for studying the transfer of spin coherence in nonequilibrium chemical processes. We use the principle of remote detection, which involves spatially separated NMR encoding and detection coils. As an example, we provide the map of chemical shift correlations for the amino acid alanine as it transitions from the zwitterionic to the anionic form. The presented method uniquely allows for tracking the migration of encoded spins during the course of any chemical transformation and can provide useful information about reaction mechanisms.
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Affiliation(s)
- M Sabieh Anwar
- Department of Chemistry, University of California, Berkeley and Division of Materials Science, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Building 11-D64, Berkeley, California 94720, USA.
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Petr J, Maier V, Horáková J, Sevcík J, Stránský Z. Capillary isotachophoresis from the student point of view – images and the reality. J Sep Sci 2006; 29:2705-15. [PMID: 17305231 DOI: 10.1002/jssc.200600249] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
A review of some fundamental aspects of ITP from the student point of view, imaginations of some basic facts and laws, use of ITP, and the recent trends are presented. The results of theoretical computations of ITP separation processes are added for comparison of imaginations with the exact mathematical description.
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Affiliation(s)
- Jan Petr
- Department of Analytical Chemistrý, Palackỳ University, Trída Svobody 8, Olomouc, Czech Republic.
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Almeida VK, Larive CK. Insights into cyclodextrin interactions during sample stacking using capillary isotachophoresis with on-line microcoil NMR detection. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2005; 43:755-61. [PMID: 16049945 DOI: 10.1002/mrc.1626] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
On-line capillary isotachophoresis (cITP)-NMR experiments were used to probe the interactions of the pharmaceutical compounds S-alprenolol, S-atenolol, R-propranolol, R-salbutamol and S-terbutaline with beta-cyclodextrin (beta-CD) during cITP concentration. In cITP, ionic analytes are concentrated and separated on the basis of their electrophoretic mobility. Because neutral molecules have an electrophoretic mobility of zero, they are normally not concentrated or separated in electrophoretic experiments like cITP. Most of the analytes studied were concentrated by cITP sample stacking by a factor of around 300. For analytes that formed a strong inclusion complex, beta-CD co-concentrated during cITP sample stacking. However, once the focusing process was complete, a discrete diffusional boundary formed between the cITP-focused analyte band and the leading and trailing electrolyte, which restricted diffusion into and out of the analyte band.
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Webb AG. Nuclear magnetic resonance coupled microseparations. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2005; 43:688-96. [PMID: 16049953 DOI: 10.1002/mrc.1616] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The increased separation efficiency afforded by reducing the size of the separation column has resulted in 'microseparations' becoming an important component in many chemical and biochemical applications. The coupling of microseparations with NMR detection is an area of increasing interest owing to the high structural information of NMR. In order to couple efficiently with the separation, the NMR detector must be reduced in size to correspond to that of the separation peak. This paper summarizes some of the approaches used in coupling NMR detection with pressure-driven and electrophoretic microseparations, the design of small NMR detectors and applications of this technology.
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Affiliation(s)
- A G Webb
- Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, 61801, USA.
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Webb AG. Microcoil nuclear magnetic resonance spectroscopy. J Pharm Biomed Anal 2005; 38:892-903. [PMID: 16087050 DOI: 10.1016/j.jpba.2005.01.048] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2004] [Revised: 01/15/2005] [Accepted: 01/22/2005] [Indexed: 11/16/2022]
Abstract
In comparison with most analytical chemistry techniques, nuclear magnetic resonance has an intrinsically low sensitivity, and many potential applications are therefore precluded by the limited available quantity of certain types of sample. In recent years, there has been a trend, both commercial and academic, towards miniaturization of the receiver coil in order to increase the mass sensitivity of NMR measurements. These small coils have also proved very useful in coupling NMR detection with commonly used microseparation techniques. A further development enabled by small detectors is parallel data acquisition from many samples simultaneously, made possible by incorporating multiple receiver coils into a single NMR probehead. This review article summarizes recent developments and applications of "microcoil" NMR spectroscopy.
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Affiliation(s)
- A G Webb
- Department of Electrical and Computer Engineering, and Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, 4221 Beckman Institute, 405 N. Mathews, Urbana, IL 61801, USA.
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On-line sample preconcentration techniques in capillary electrophoresis. ACTA ACUST UNITED AC 2005. [DOI: 10.1016/s0166-526x(05)45003-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Kaniansky D, Masár M, Bodor R, Zúborová M, Olvecká E, Jöhnck M, Stanislawski B. Electrophoretic separations on chips with hydrodynamically closed separation systems. Electrophoresis 2003; 24:2208-2227. [PMID: 12858394 DOI: 10.1002/elps.200305474] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
This review focuses on capillary electrophoretic separations performed on capillary electrophoresis chips (CE chips) with hydrodynamically closed separation systems in a context with transport processes (electroosmotic flow (EOF)) and hydrodynamic flow (HDF)) that may accompany the separations in these devices. It also reflects some relevant works dealing with conventional CE operating under such hydrodynamic conditions. The use of zone electrophoresis (ZE), isotachophoresis (ITP) and their on-line combination (ITP-ZE) on the single-column and column-coupling CE chips with the closed separation systems and related problems are key topics of the review. Some attention is paid to sample pretreatment in the separations performed on the CE chips. Here, mainly potentialities of the ITP-ZE combination in trace analysis applications of the miniaturized systems are discussed in a broader extent. Links between the ZE separation and detection provide a frame for the discussion of current status of the detection on the CE chips. Analytical applications illustrate potentialities of the CE chips operating with the closed separation systems (suppressed HDF and EOF) to the determination of small ions present in various matrices by ZE, ITP and ITP-ZE.
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Affiliation(s)
- Dusan Kaniansky
- Department of Analytical Chemistry, Faculty of Science, Comenius University, Bratislava, Slovakia.
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Abstract
NMR spectroscopy is increasingly being used to characterize microliter and smaller-volume samples. Substances at picomole levels have been identified using NMR spectrometers equipped with microcoil-based probes. NMR probes that incorporate multiple sample chambers enable higher-throughput NMR experiments. Hyphenation of capillary-scale separations and microcoil NMR has also decreased analysis time of mixtures. For example, capillary isotachophoresis/NMR allows the highest mass sensitivity nanoliter-volume flow cells to be used with low microliter volume samples because isotachophoresis concentrates the microliter volume sample into the nanoliter volume NMR detection probe. In addition, the diagnostic capabilities of NMR spectroscopy allow the physico-chemical aspects of a capillary separation process to be characterized on-line. Because of such advances, the application of NMR to smaller samples continues to grow.
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Affiliation(s)
- Andrew M Wolters
- Department of Chemistry and the Beckman Institute, University of Illinois, Urbana 61801, USA
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