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Knol WC, Pirok BWJ, Peters RAH. Detection challenges in quantitative polymer analysis by liquid chromatography. J Sep Sci 2020; 44:63-87. [PMID: 32935906 PMCID: PMC7821191 DOI: 10.1002/jssc.202000768] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 09/14/2020] [Accepted: 09/14/2020] [Indexed: 12/19/2022]
Abstract
Accurate quantification of polymer distributions is one of the main challenges in polymer analysis by liquid chromatography. The response of contemporary detectors is typically influenced by compositional features such as molecular weight, chain composition, end groups, and branching. This renders the accurate quantification of complex polymers of which there are no standards available, extremely challenging. Moreover, any (programmed) change in mobile-phase composition may further limit the applicability of detection techniques. Current methods often rely on refractive index detection, which is not accurate when dealing with complex samples as the refractive-index increment is often unknown. We review current and emerging detection methods in liquid chromatography with the aim of identifying detectors, which can be applied to the quantitative analysis of complex polymers.
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Affiliation(s)
- Wouter C Knol
- Analytical Chemistry Group, van't Hoff Institute for Molecular Sciences (HIMS), Faculty of Science, University of Amsterdam, Amsterdam, The Netherlands.,Centre for Analytical Sciences Amsterdam, Amsterdam, The Netherlands
| | - Bob W J Pirok
- Analytical Chemistry Group, van't Hoff Institute for Molecular Sciences (HIMS), Faculty of Science, University of Amsterdam, Amsterdam, The Netherlands.,Centre for Analytical Sciences Amsterdam, Amsterdam, The Netherlands
| | - Ron A H Peters
- Analytical Chemistry Group, van't Hoff Institute for Molecular Sciences (HIMS), Faculty of Science, University of Amsterdam, Amsterdam, The Netherlands.,Centre for Analytical Sciences Amsterdam, Amsterdam, The Netherlands.,DSM Resins & Functional Materials, Analytical Technology Centre, Waalwijk, The Netherlands
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2
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Botha C, Höpfner J, Mayerhöfer B, Wilhelm M. On-line SEC-MR-NMR hyphenation: optimization of sensitivity and selectivity on a 62 MHz benchtop NMR spectrometer. Polym Chem 2019. [DOI: 10.1039/c9py00140a] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The development of sophisticated synthetic routes for polymeric materials and more complex formulation used in current polymers require more advanced analytical techniques. A direct correlation between molar mass distribution and chemical composition is provided.
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Affiliation(s)
- Carlo Botha
- Karlsruhe Institute of Technology (KIT)
- Institute for Chemical Technology and Polymer Chemistry
- 76131 Karlsruhe
- Germany
| | - Johannes Höpfner
- Karlsruhe Institute of Technology (KIT)
- Institute for Chemical Technology and Polymer Chemistry
- 76131 Karlsruhe
- Germany
| | - Britta Mayerhöfer
- Karlsruhe Institute of Technology (KIT)
- Institute for Chemical Technology and Polymer Chemistry
- 76131 Karlsruhe
- Germany
| | - Manfred Wilhelm
- Karlsruhe Institute of Technology (KIT)
- Institute for Chemical Technology and Polymer Chemistry
- 76131 Karlsruhe
- Germany
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3
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Oosthoek-de Vries AJ, Bart J, Tiggelaar RM, Janssen JWG, van Bentum PJM, Gardeniers HJGE, Kentgens APM. Continuous Flow 1H and 13C NMR Spectroscopy in Microfluidic Stripline NMR Chips. Anal Chem 2017; 89:2296-2303. [PMID: 28194934 PMCID: PMC5337998 DOI: 10.1021/acs.analchem.6b03784] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2016] [Accepted: 01/23/2017] [Indexed: 12/28/2022]
Abstract
Microfluidic stripline NMR technology not only allows for NMR experiments to be performed on small sample volumes in the submicroliter range, but also experiments can easily be performed in continuous flow because of the stripline's favorable geometry. In this study we demonstrate the possibility of dual-channel operation of a microfluidic stripline NMR setup showing one- and two-dimensional 1H, 13C and heteronuclear NMR experiments under continuous flow. We performed experiments on ethyl crotonate and menthol, using three different types of NMR chips aiming for straightforward microfluidic connectivity. The detection volumes are approximately 150 and 250 nL, while flow rates ranging from 0.5 μL/min to 15 μL/min have been employed. We show that in continuous flow the pulse delay is determined by the replenishment time of the detector volume, if the sample trajectory in the magnet toward NMR detector is long enough to polarize the spin systems. This can considerably speed up quantitative measurement of samples needing signal averaging. So it can be beneficial to perform continuous flow measurements in this setup for analysis of, e.g., reactive, unstable, or mass-limited compounds.
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Affiliation(s)
| | - Jacob Bart
- Institute
of Molecules and Materials, Radboud University, 6525 HP Nijmegen, The Netherlands
- Mesoscale
Chemical Systems, MESA+ Institute of Nanotechnology, University of Twente, 7522
NB Enschede, The Netherlands
| | - Roald M. Tiggelaar
- Mesoscale
Chemical Systems, MESA+ Institute of Nanotechnology, University of Twente, 7522
NB Enschede, The Netherlands
| | - Johannes W. G. Janssen
- Institute
of Molecules and Materials, Radboud University, 6525 HP Nijmegen, The Netherlands
| | - P. Jan M. van Bentum
- Institute
of Molecules and Materials, Radboud University, 6525 HP Nijmegen, The Netherlands
| | - Han J. G. E. Gardeniers
- Mesoscale
Chemical Systems, MESA+ Institute of Nanotechnology, University of Twente, 7522
NB Enschede, The Netherlands
| | - Arno P. M. Kentgens
- Institute
of Molecules and Materials, Radboud University, 6525 HP Nijmegen, The Netherlands
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4
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Meyer K, Rademann K, Panne U, Maiwald M. Quantitative NMR spectroscopy for gas analysis for production of primary reference gas mixtures. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2017; 275:1-10. [PMID: 27951425 DOI: 10.1016/j.jmr.2016.11.016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Revised: 11/24/2016] [Accepted: 11/25/2016] [Indexed: 06/06/2023]
Abstract
Due to its direct correlation to the number of spins within a sample quantitative NMR spectroscopy (qNMR) is a promising method with absolute comparison abilities in complex systems in technical, as well as metrological applications. Most of the samples studied with qNMR are in liquid state in diluted solutions, while gas-phase applications represent a rarely applied case. Commercially available NMR equipment was used for purity assessment of liquid and liquefied hydrocarbons serving as raw materials for production of primary reference gas standards. Additionally, gas-phase studies were performed within an online NMR flow probe, as well as in a high-pressure NMR setup to check feasibility as verification method for the composition of gas mixtures.
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Affiliation(s)
- K Meyer
- Bundesanstalt für Materialforschung und -prüfung (BAM), Richard-Willstätter-Straβe 11, D-12489 Berlin, Germany.
| | - K Rademann
- Department of Chemistry, Humboldt-Universität zu Berlin, Brook-Taylor-Str. 2, D-12489 Berlin, Germany
| | - U Panne
- Bundesanstalt für Materialforschung und -prüfung (BAM), Richard-Willstätter-Straβe 11, D-12489 Berlin, Germany; Department of Chemistry, Humboldt-Universität zu Berlin, Brook-Taylor-Str. 2, D-12489 Berlin, Germany
| | - M Maiwald
- Bundesanstalt für Materialforschung und -prüfung (BAM), Richard-Willstätter-Straβe 11, D-12489 Berlin, Germany
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5
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Dong X, Wang R, Zhou X, Li P, Yang H. Current mass spectrometry approaches and challenges for the bioanalysis of traditional Chinese medicines. J Chromatogr B Analyt Technol Biomed Life Sci 2016; 1026:15-26. [DOI: 10.1016/j.jchromb.2015.11.048] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Revised: 11/23/2015] [Accepted: 11/25/2015] [Indexed: 12/11/2022]
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6
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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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7
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Analysis of complex polymers by multidetector field-flow fractionation. Anal Bioanal Chem 2013; 406:1585-96. [DOI: 10.1007/s00216-013-7308-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Revised: 08/08/2013] [Accepted: 08/13/2013] [Indexed: 10/26/2022]
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8
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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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9
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Abstract
A technique where a separation technique is coupled with an online spectroscopic detection technology is known as hyphenated technique, e.g., GC-MS, LC-PDA, LC-MS, LC-FTIR, LC-NMR, LC-NMR-MS, and CE-MS. Recent advances in hyphenated analytical techniques have remarkably widened their applications to the analysis of complex biomaterials, especially natural products. This chapter focuses on the applications of hyphenated techniques to pre-isolation and isolation of natural products, dereplication, online partial identification of compounds, chemotaxonomic studies, chemical finger-printing, quality control of herbal products, and metabolomic studies, and presents specific examples. However, a particular emphasis has been given on the hyphenated techniques that involve an LC as the separation tool.
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Affiliation(s)
- Satyajit D Sarker
- Department of Pharmacy, School of Applied Sciences, University of Wolverhampton, Wolverhampton, WV11LY, UK.
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10
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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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11
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Fratila RM, Velders AH. Small-volume nuclear magnetic resonance spectroscopy. ANNUAL REVIEW OF ANALYTICAL CHEMISTRY (PALO ALTO, CALIF.) 2011; 4:227-249. [PMID: 21391818 DOI: 10.1146/annurev-anchem-061010-114024] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Nuclear magnetic resonance (NMR) spectroscopy is one of the most information-rich analytical techniques available. However, it is also inherently insensitive, and this drawback precludes the application of NMR spectroscopy to mass- and volume-limited samples. We review a particular approach to increase the sensitivity of NMR experiments, namely the use of miniaturized coils. When the size of the coil is reduced, the sample volume can be brought down to the nanoliter range. We compare the main coil geometries (solenoidal, planar, and microslot/stripline) and discuss their applications to the analysis of mass-limited samples. We also provide an overview of the hyphenation of microcoil NMR spectroscopy to separation techniques and of the integration with lab-on-a-chip devices and microreactors.
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Affiliation(s)
- Raluca M Fratila
- MIRA Institute for Biomedical Engineering and Technical Medicine, Faculty of Science and Technology, University of Twente, 7500 AE Enschede, The Netherlands.
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12
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Provera S, Rovatti L, Turco L, Mozzo S, Spezzaferri A, Bacchi S, Ribecai A, Guelfi S, Mingardi A, Marchioro C, Papini D. A multi-technique approach using LC–NMR, LC–MS, semi-preparative HPLC, HR–NMR and HR–MS for the isolation and characterization of low-level unknown impurities in GW876008, a novel corticotropin-release factor 1 antagonist. J Pharm Biomed Anal 2010; 53:517-25. [DOI: 10.1016/j.jpba.2010.06.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2010] [Revised: 06/11/2010] [Accepted: 06/14/2010] [Indexed: 10/19/2022]
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13
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Tang JA, Jerschow A. Practical aspects of liquid-state NMR with inductively coupled solenoid coils. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2010; 48:763-770. [PMID: 20665467 DOI: 10.1002/mrc.2651] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Sensitivity enhancement by the use of inductively coupled milli- and microcoils has been demonstrated in solid-state as well as liquid-state NMR. In this work, we discuss the practical aspects of using inductively coupled solenoid coils of different sizes in a liquid-state NMR spectrometer. The sensitivity and resolution enhancements from these resonant coils, with sizes ranging between 3.0 and 0.75 mm i.d., are measured for (23)Na single-pulse and multidimensional imaging experiments and compared to the results obtained with the conventional liquids NMR 5.0-mm saddle coil. Enhancements in voxel-based sensitivity (SNR per √scans) were measured in multidimensional MR images and were found to be as large as 20.4 with the 0.75-mm coil.
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Affiliation(s)
- Joel A Tang
- Department of Chemistry, New York University, New York, NY 10003, USA
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14
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Provera S, Guercio G, Turco L, Curcuruto O, Alvaro G, Rossi T, Marchioro C. Application of LC-NMR to the identification of bulk drug impurities in NK1 antagonist GW597599 (vestipitant). MAGNETIC RESONANCE IN CHEMISTRY : MRC 2010; 48:523-530. [PMID: 20535779 DOI: 10.1002/mrc.2611] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Liquid chromatography-NMR (LC-NMR) spectroscopy was used to obtain detailed information regarding the structure of the major bulk drug impurities present in GW597599 (vestipitant). The one-dimensional (1)H LC-NMR experiments were performed in both continuous and stop-flow modes on a sample of GW597599 (vestipitant) enriched with mother liquor impurities. The information derived from both LC-NMR and LC-MS data provided the structural information of all major impurities. The full characterisation of the impurities by high-resolution NMR spectroscopy was ultimately performed on appropriately synthesised compounds.
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Affiliation(s)
- Stefano Provera
- Molecular Discovery Research, GlaxoSmithKline Medicines Research Centre, Via Fleming 4, 37135 Verona, Italy.
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15
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Target-guided separation of Bougainvillea glabra betacyanins by direct coupling of preparative ion-pair high-speed countercurrent chromatography and electrospray ionization mass-spectrometry. J Chromatogr A 2010; 1217:4544-54. [PMID: 20494364 DOI: 10.1016/j.chroma.2010.04.061] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2010] [Revised: 04/14/2010] [Accepted: 04/21/2010] [Indexed: 11/23/2022]
Abstract
In this study, preparative ion-pair high-speed countercurrent chromatography was directly coupled to an electrospray ionization mass-spectrometry device (IP-HSCCC/ESI-MS-MS) for target-guided fractionation of high molecular weight acyl-oligosaccharide linked betacyanins from purple bracts of Bougainvillea glabra (Nyctaginaceae). The direct identification of six principal acyl-oligosaccharide linked betacyanins in the mass range between m/z 859 and m/z 1359 was achieved by positive ESI-MS ionization and gave access to the genuine pigment profile already during the proceeding of the preparative separation. Inclusively, all MS/MS-fragmentation data were provided during the chromatographic run for a complete analysis of substitution pattern. On-line purity evaluation of the recovered fractions is of high value in target-guided screening procedures and for immediate decisions about suitable fractions used for further structural analysis. The applied preparative hyphenation was shown to be a versatile screening method for on-line monitoring of countercurrent chromatographic separations of polar crude pigment extracts and also traced some minor concentrated compounds. For the separation of 760mg crude pigment extract the biphasic solvent system tert.-butylmethylether/n-butanol/acetonitrile/water 2:2:1:5 (v/v/v/v) was used with addition of ion-pair forming reagent trifluoroacetic acid. The preparative HSCCC-eluate had to be modified by post-column addition of a make-up solvent stream containing formic acid to reduce ion-suppression caused by trifluoroacetic acid and later significantly maximized response of ESI-MS/MS detection of target substances. A variable low-pressure split-unit guided a micro-eluate to the ESI-MS-interface for sensitive and direct on-line detection, and the major volume of the effluent stream was directed to the fraction collector for preparative sample recovery. The applied make-up solvent mixture significantly improved smoothness of the continuously measured IP-HSCCC-ESI-MS base peak ion trace in the experimental range of m/z 50-2200 by masking stationary phase bleeding and generating a stable single solvent phase for ESI-MS/MS detection. Immediate structural data were retrieved throughout the countercurrent chromatography run containing complete MS/MS-fragmentation pattern of the separated acyl-substituted betanidin oligoglycosides. Single ion monitoring indicated clearly the base-line separation of higher concentrated acylated betacyanin components.
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16
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Application of LC-NMR and HR-NMR to the characterization of biphenyl impurities in the synthetic route development for vestipitant, a novel NK1 antagonist. J Pharm Biomed Anal 2010; 53:389-95. [PMID: 20478677 DOI: 10.1016/j.jpba.2010.04.027] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2010] [Revised: 04/16/2010] [Accepted: 04/22/2010] [Indexed: 11/22/2022]
Abstract
Vestipitant (1) is a novel NK1 antagonist currently under investigation for the treatment of CNS disorders and emesis. The first synthetic step comprised a Grignard synthesis. An impurity was identified and initially expected to be a symmetric biphenyl. This paper reports the work to synthesise the supposed structure and the spectroscopic analyses (LC-NMR and HR-NMR) to correctly identify the real structure and understand the chemical pathway of the impurity.
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17
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Li J, Ma C, Wang H, Wang Y, Wu L, Wang Y. On-line identification of 4''-isovalerylspiramycin I in the genetic engineered strain of S. spiramyceticus F21 by liquid chromatography with electrospray ionization tandem mass spectrometry, ultraviolet absorbance detection and nuclear magnetic resonance spectrometry. J Chromatogr A 2010; 1217:1419-24. [PMID: 20060537 DOI: 10.1016/j.chroma.2009.12.072] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2009] [Revised: 11/26/2009] [Accepted: 12/22/2009] [Indexed: 11/25/2022]
Abstract
LC-hyphenated techniques were applied to the on-line identification of isovalerylspiramycin I (isp I), a spiramycin-like macrolide in the crude extract of fermentation broth from a genetically engineered strain of S. spiramyceticus F21. In the structural characterization of the large molecular secondary metabolite of isp I, LC-DAD-UV-ESI-MS(n) analysis played a crucial role, and stop-flow LC-(1)H NMR measurement, with bitespiramycin used as reference, was a valuable complement approach. This rational approach proved to be an efficient means for the rapid and accurate structural determination of known microbial secondary metabolites, by which targeted isolation of component(s) of interest can be subsequently performed for further biological and pharmacological studies in drug development.
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Affiliation(s)
- Jingyan Li
- Key Laboratory of Biotechnology of Antibiotics, Ministry of Health, Peking Union Medical College & Chinese Academy of Medical Sciences, Beijing 100050, China
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18
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Determining the absolute, chemical-heterogeneity-corrected molar mass averages, distribution, and solution conformation of random copolymers. Anal Bioanal Chem 2009; 396:1589-98. [DOI: 10.1007/s00216-009-3320-9] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2009] [Revised: 11/12/2009] [Accepted: 11/15/2009] [Indexed: 10/20/2022]
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19
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Limtiaco JFK, Jones CJ, Larive CK. Characterization of Heparin Impurities with HPLC-NMR Using Weak Anion Exchange Chromatography. Anal Chem 2009; 81:10116-23. [DOI: 10.1021/ac901812y] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- John F. K. Limtiaco
- Department of Chemistry, University of California, Riverside, California 92521
| | | | - Cynthia K. Larive
- Department of Chemistry, University of California, Riverside, California 92521
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20
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Berek D. Two-dimensional liquid chromatography of synthetic polymers. Anal Bioanal Chem 2009; 396:421-41. [DOI: 10.1007/s00216-009-3172-3] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2009] [Revised: 09/18/2009] [Accepted: 09/19/2009] [Indexed: 10/20/2022]
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21
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Kühnle M, Kreidler D, Holtin K, Czesla H, Schuler P, Schaal W, Schurig V, Albert K. Online coupling of gas chromatography to nuclear magnetic resonance spectroscopy: method for the analysis of volatile stereoisomers. Anal Chem 2008; 80:5481-6. [PMID: 18533684 DOI: 10.1021/ac8004023] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The identification of volatile cis/trans-stereoisomers was accomplished by employing a hyphenated GC-NMR system. The chromatographic and spectroscopic conditions were optimized with respect to the (1)H NMR detection. A special processing technique was developed to handle the recorded NMR spectra in the gas phase with very low sample amounts. The processed stopped-flow (1)H NMR spectra of the investigated chromatographic peaks unequivocally revealed the structure of the corresponding compounds.
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Affiliation(s)
- Maximilian Kühnle
- Institute of Organic Chemistry, Chemisches Zentralinstitut, University of Tuebingen, Auf der Morgenstelle 18, D-72076 Tuebingen, Germany
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23
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Ute K, Niimi R, Hatada K, Kolbertb AC. Characterization of Ethylene—Propylene—Diene Terpolymers (EPDM) by 750 MHz On-line SEC-NMR. INTERNATIONAL JOURNAL OF POLYMER ANALYSIS AND CHARACTERIZATION 2006. [DOI: 10.1080/10236669908014173] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Koichi Ute
- a Department of Chemistry , Graduate School of Engineering Science, Osaka University , Toyonaka, Osaka , 560-8531 , Japan
| | - Ryo Niimi
- a Department of Chemistry , Graduate School of Engineering Science, Osaka University , Toyonaka, Osaka , 560-8531 , Japan
| | - Koichi Hatada
- a Department of Chemistry , Graduate School of Engineering Science, Osaka University , Toyonaka, Osaka , 560-8531 , Japan
| | - Andrew C. Kolbertb
- b DSM Copolymer , Baton Rouge , LA , 70821-2591 , USA
- c AlliedSignal Inc. , 101 Columbia Road, Morristown , NJ , 07962 , USA
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24
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Schefer AB, Braumann U, Tseng LH, Spraul M, Soares MG, Fernandes JB, da Silva MFGF, Vieira PC, Ferreira AG. Application of high-performance liquid chromatography–nuclear magnetic resonance coupling to the identification of limonoids from mahogany tree (Switenia macrophylla, Meliaceae) by stopped-flow 1D and 2D NMR spectroscopy. J Chromatogr A 2006; 1128:152-63. [PMID: 16904679 DOI: 10.1016/j.chroma.2006.06.059] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2005] [Revised: 06/09/2006] [Accepted: 06/19/2006] [Indexed: 11/17/2022]
Abstract
Separation and characterization of limonoids from Switenia macrophylla (Meliaceae) by HPLC-NMR technique has been described. Analyses were carried out using reversed-phase gradient HPLC elution coupled to NMR (600 MHz) spectrometer in stopped-flow mode. Separated peaks were collected into an interface unit prior to NMR measurements, which were performed with suppression of solvent signals by shaped pulses sequences. Structure elucidation of the limonoids was attained by data obtained from 1H NMR, TOCSY, gHSQC and gHMBC spectra without conventional isolation that is usually applied in natural products studies.
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Affiliation(s)
- Alexandre B Schefer
- NMR Division, Bruker BioSpin GmbH, D-76287 Rheinstetten, Silberstreifen, Germany.
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25
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Bieri S, Varesio E, Veuthey JL, Muñoz O, Tseng LH, Braumann U, Spraul M, Christen P. Identification of isomeric tropane alkaloids from Schizanthus grahamii by HPLC-NMR with loop storage and HPLC-UV-MS/SPE-NMR using a cryogenic flow probe. PHYTOCHEMICAL ANALYSIS : PCA 2006; 17:78-86. [PMID: 16634283 DOI: 10.1002/pca.889] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Two fully automated HPLC-NMR methods are reported and compared for the structure elucidation of four isomeric tropane alkaloids from the stem-bark of an endemic Chilean plant, Schizanthus grahamii Gill. (Solanaceae). The first approach interfaced a conventional HPLC column to NMR by means of a loop storage unit. After elution with a mobile phase consisting of deuterated water and standard protonated organic solvents, the separated analytes were momentarily stored in a loop cassette and then transferred one-at-a-time to the NMR flow probe for measurements. The second strategy combined HPLC with parallel ion-trap MS detection and NMR spectroscopy using an integrated solid-phase extraction (SPE) unit for post-column analyte trapping. The SPE cartridges were dried under a gentle stream of nitrogen and analytes were sequentially eluted and directed to a cryogenically cooled flow-probe with an NMR-friendly solvent. The structures of the four isomeric alkaloids, 3alpha-senecioyloxy-7beta-hydroxytropane, 3alpha-hydroxy-7beta-angeloyloxytropane, 3alpha-hydroxy-7beta-tigloyloxytropane and 3alpha-hydroxy-7beta-senecioyloxytropane, were unambiguously determined by combining NMR assignments with MS data.
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Affiliation(s)
- Stefan Bieri
- Laboratory of Pharmaceutical Analytical Chemistry, School of Pharmaceutical Sciences EPGL, University of Geneva, 20 Bd d'Yvoy, 1211 Geneva 4, Switzerland
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Pauli GF, Jaki BU, Lankin DC. Quantitative 1H NMR: development and potential of a method for natural products analysis. JOURNAL OF NATURAL PRODUCTS 2005; 68:133-49. [PMID: 15679337 DOI: 10.1021/np0497301] [Citation(s) in RCA: 334] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Based on a brief revision of what constitutes state-of-the-art "quantitative experimental conditions" for (1)H quantitative NMR (qHNMR), this comprehensive review contains almost 200 references and covers the literature since 1982 with emphasis on natural products. It provides an overview of the background and applications of qHNMR in natural products research, new methods such as decoupling and hyphenation, and analytical potential and limitations, and compiles information on reference materials used for and studied by qHNMR. The dual status of natural products, being single chemical entities and valuable biologically active agents that need to be purified from complex matrixes, results in an increased analytical demand when testing their deviation from the singleton composition ideal. The outcome and versatility of reported applications lead to the conclusion that qHNMR is currently the principal analytical method to meet this demand. Considering both 1D and 2D (1)H NMR experiments, qHNMR has proved to be highly suitable for the simultaneous selective recognition and quantitative determination of metabolites in complex biological matrixes. This is manifested by the prior publication of over 80 reports on applications involving the quantitation of single natural products in plant extracts, dietary materials, and materials representing different metabolic stages of (micro)organisms. In summary, qHNMR has great potential as an analytical tool in both the discovery of new bioactive natural products and the field of metabolome analysis.
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Affiliation(s)
- Guido F Pauli
- Department of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, University of Illinois at Chicago, Illinois 60612, USA.
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Fura A, Shu YZ, Zhu M, Hanson RL, Roongta V, Humphreys WG. Discovering Drugs through Biological Transformation: Role of Pharmacologically Active Metabolites in Drug Discovery. J Med Chem 2004; 47:4339-51. [PMID: 15317447 DOI: 10.1021/jm040066v] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Aberra Fura
- Bristol Myers Squibb, Pharmaceutical Research Institute, P.O. Box 5400, Princeton, New Jersey 08534, USA.
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García-Campaña AM, Gámiz-Gracia L, Baeyens WRG, Alés Barrero F. Derivatization of biomolecules for chemiluminescent detection in capillary electrophoresis. J Chromatogr B Analyt Technol Biomed Life Sci 2003; 793:49-74. [PMID: 12880854 DOI: 10.1016/s1570-0232(03)00364-7] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
An overview is presented on the power and drawbacks of the relatively unfamiliar chemiluminescence-based detection technique applied in analysis by capillary electrophoresis, for determining chemically derivatized biomolecules. Examples of the most common systems are given for many series of biologically active compounds as well as for some pharmaceuticals. The most common chemiluminescent systems include the application of peroxyoxalate ester chemiluminescence, acridinium esters, luminol and derivatives, detection based on the tris(2,2'-bipyridine)ruthenium(III) system, the huge potentials offered by direct oxidations-though often with still unelucidated reaction mechanisms-and the powerful area of bioluminescence techniques, revealing as well the fast developing area of microchip-based analysis employing this specific luminescence principle.
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Affiliation(s)
- Ana M García-Campaña
- University of Granada, Faculty of Sciences, Department of Analytical Chemistry, Fuentenueva s/n, E-18071, Granada, Spain.
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Biomedical applications of directly-coupled chromatography–nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS). ACTA ACUST UNITED AC 2003. [DOI: 10.1016/s1567-7192(03)80011-6] [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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31
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Connelly JC, Connor SC, Monte S, Bailey NJC, Borgeaud N, Holmes E, Troke J, Nicholson JK, Gavaghan CL. Application of directly coupled high performance liquid chromatography-NMR-mass spectometry and 1H NMR spectroscopic studies to the investigation of 2,3-benzofuran metabolism in Sprague-Dawley rats. Drug Metab Dispos 2002; 30:1357-63. [PMID: 12433803 DOI: 10.1124/dmd.30.12.1357] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The urinary excretion of metabolites of 2,3-benzofuran was studied in Sprague-Dawley rats (n = 5) given a single dose of 150 mg/kg i.p. Urine samples were collected at defined intervals up to 7 days postdose and analyzed using (1). H NMR and directly coupled high performance liquid chromatography (HPLC)-NMR, HPLC-(mass spectrometry) MS and HPLC-MS-NMR methods. The principal metabolites were determined to be 2-hydroxyphenylacetic acid and 2-(2-hydroxyethyl)phenyl hydrogen sulfate, representing 24.3 +/- 6.0% and 19.6 +/- 6.4% of the dose, respectively. This indicates that metabolism of benzofuran to the polar species excreted in urine involves cleavage of the furan ring.
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Affiliation(s)
- John C Connelly
- Department of Biological Chemistry, Faculty of Medicine, Imperial College of Science, Technology, and Medicine, London, United Kingdom
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Lienau A, Glaser T, Krucker M, Zeeb D, Ley F, Curro F, Albert K. Qualitative and quantitative analysis of tocopherols in toothpastes and gingival tissue employing HPLC NMR and HPLC MS coupling. Anal Chem 2002; 74:5192-8. [PMID: 12403570 DOI: 10.1021/ac020316k] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Gingival samples treated with toothpastes containing tocopherols (vitamin E) were investigated employing HPLC chromatography. The aim was to verify that vitamin E is actually enriched in the tissue, which could have beneficial effects on oral health. After determination of the tocopherols available in the toothpastes, control samples from healthy test persons and subjects suffering from gingivitis were analyzed. Subsequently, gingival tissues from diseased test persons who treated their teeth with the toothpastes containing tocopherols using various kinds of concentrations or applications were investigated. The first step of the analysis was a fast and careful extraction employing matrix solid-phase dispersion (MSPD). Afterward, the separation of the different tocopherol homologues existing was performed by HPLC chromatography on highly selective C30 RP phases. The identification of the tocopherol homologues was performed using the on-line coupling of HPLC with NMR spectroscopy and mass spectrometry.
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Affiliation(s)
- Annette Lienau
- Institute of Organic Chemistry, University of Tuebingen, Germany
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Abstract
The methods used for saponin determination in plant materials are presented. It is emphasised that the biological and spectrophotomeric methods still being used for saponin determination provide, to some extent, valuable results on saponin concentrations in plant material. However, since they are sensitive to the structural variation of individual saponins they should be standardized with saponin mixtures isolated from the plant species in which the concentration is measured. However, one plant species may contain some saponins which can be determined with a biological test and others which cannot. That is why biological and colorimetric determinations do not provide accurate data and have to be recognized as approximate. Thin-layer chromatography on normal and reversed-phases (TLC, HPTLC, 2D-TLC) provides excellent qualitative information and in combination with on-line coupling of a computer with dual-wavelength flying-spot scanner and two-dimensional analytical software can be used for routine determination of saponins in plant material. The densitometry of saponins has been very sensitive, however, to plate quality, spraying technique and the heating time and therefore appropriate saponin standards have to be run in parallel with the sample. Gas-liquid chromatography has limited application for determination since saponins are quite big molecules and are not volatile compounds. Thus, there are only few applications of GC for determination of intact saponins. The method has been used for determination of TMS, acetyl or methyl derivatives of an aglycones released during saponin hydrolysis. However, structurally different saponins show different rates of hydrolysis and precise optimisation of hydrolysis conditions is essential. Besides, during hydrolysis a number of artefacts can be formed which can influence the final results. High performance liquid chromatography on reversed-phase columns remains the best technique for saponin determination and is the most-widely used method for this group of compounds. However, the lack of chromophores allowing detection in UV, limits the choice of gradient and detection method. The pre-column derivatisation with benzoyl chloride, coumarin or 4-bromophenacyl bromide has been used successfully in some cases allowing UV detection of separation. Standardisation and identification of the peaks in HPLC chromatograms has been based on comparison of the retention times with those observed for authentic standards. But new hyphenated techniques, combining HPLC with mass spectrometry and nuclear magnetic resonance are developing rapidly and allow on-line identification of separated saponins. Capillary electrophoresis has been applied for saponin determination only in a limited number of cases and this method is still being developed.
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Affiliation(s)
- W A Oleszek
- Department of Biochemistry, Institute of Soil Science and Plant Cultivation, Pulawy, Poland.
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Thompson RS, Guler LP, Nelson ED, Yu YQ, Kenttämaa HI. Mechanistic study of stereoselective gas-phase reactions of phosphenium ions with cis- and trans-1,2-diaminocyclohexanes. J Org Chem 2002; 67:5076-84. [PMID: 12126391 DOI: 10.1021/jo0107305] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The 1,3-dioxolane-2-phosphenium ion, 1,3-benzodioxole-2-phosphenium ion, and o-biphenylenephosphenium ion are reported to react in a stereoselective manner with cis- and trans-1,2-diaminocyclohexanes in the gas phase in a Fourier transform ion cyclotron resonance mass spectrometer. Elimination of NH3 from an addition product was observed only for the trans isomer. Several reaction mechanisms were experimentally and computationally examined (B3LYP/6-31G(d)//HF/6-31G(d) + ZPVE level of theory). The most plausible mechanism is initiated by addition of one of the amino groups to the electrophilic phosphorus atom followed by proton transfer between the amino groups. A change to a diaxial conformation for the trans isomer facilitates anchimeric assistance by the now nucleophilic phosphorus atom as the C-N bond breaks to release NH3. Intramolecular proton transfer competes with the conformational change and ultimately leads to ethylene glycol elimination. The transition states for the critical steps of these two reactions are calculated to be nearly equal in magnitude, which rationalizes the observation of both reactions for the trans-diamine. In contrast, the adduct of the cis isomer can eliminate NH3 via a concerted 1,2-hydride shift without a need for a conformational change. However, the barrier associated with this reaction was found to be substantially greater than for proton transfer between the N- and O-atoms. The latter reaction dominates and ultimately leads to ethylene glycol elimination.
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Affiliation(s)
- Rukeyser S Thompson
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907-1393, USA
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Bao D, Thanabal V, Pool WF. Determination of tacrine metabolites in microsomal incubate by high performance liquid chromatography-nuclear magnetic resonance/mass spectrometry with a column trapping system. J Pharm Biomed Anal 2002; 28:23-30. [PMID: 11861105 DOI: 10.1016/s0731-7085(01)00639-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
A column trapping system has been incorporated into high performance liquid chromatography-nuclear magnetic resonance-mass spectrometry (HPLC-NMR-MS) to reduce data acquisition time of NMR experiments. The system uses a trapping column to capture analytes after the HPLC column and back flush trapped analyte to the flow cell of the NMR probe for detection. A dilution solvent is mixed with eluent from HPLC column to reduce the influence of the organic content in the mobile phase before column trapping. The trapping column is also coupled with a mass spectrometer (MS) to get complementary MS data on the same peak. Studies on 1-hydroxylated 9-amino-1,2,3,4-tetrahydro-acridine (1-OH tacrine), indomethacin and testosterone with the column trapping system showed good recovery of analytes and over 3-fold mean increase in UV-VIS signal intensity. The time saving on NMR experiments with the column trapping system was demonstrated by the analysis of dog microsomal incubate with tacrine.
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Affiliation(s)
- Donghui Bao
- PGRD, Ann Arbor Laboratories, 2800 Plymouth Rd, Ann Arbor, MI 48105, USA
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Affiliation(s)
- Yehia Mechref
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, USA
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Abstract
An overview of chromatography-mass spectrometry coupling is presented here, focussing mainly on possibilities offered by this detection technique. GC-MS and HPLC-MS are the two most often used variants, which have quite different characteristics. Various mass-spectrometric possibilities are briefly discussed: ionization techniques, determination of elemental formulas, structural information and the question of sensitivity and selectivity. Options for mass-spectrometric instrumentation and applications of tandem mass spectrometry are also mentioned.
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Affiliation(s)
- K Vékey
- Chemical Research Center, Hungarian Academy of Sciences, Budapest.
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Hou T, Smith J, MacNamara E, MacNaughton M, Raftery D. Analysis of multiple samples using multiplex sample NMR: selective excitation and chemical shift imaging approaches. Anal Chem 2001; 73:2541-6. [PMID: 11403297 DOI: 10.1021/ac0100751] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Two improved approaches for the rapid analysis of multiple samples using multiplex sample NMR are described. In the first approach, frequency-selective 90 degrees radio frequency pulses and large pulsed field gradients are applied to excite and detect multiple samples in rapid succession. This method is advantageous for samples with relatively long longitudinal (T1) relaxation times. In the second approach, chemical shift imaging is applied to acquire both the spectral and spatial information of multiple samples simultaneously. Chemical shift imaging is more time-consuming than selective excitation; however, it is advantageous for detecting samples with short T1's and for signal averaging. Both approaches demonstrate the potential of multiplex sample NMR for carrying out high-throughput NMR detection.
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Affiliation(s)
- T Hou
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907-1393, USA
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Gavaghan CL, Nicholson JK, Connor SC, Wilson ID, Wright B, Holmes E. Directly coupled high-performance liquid chromatography and nuclear magnetic resonance spectroscopic with chemometric studies on metabolic variation in Sprague--Dawley rats. Anal Biochem 2001; 291:245-52. [PMID: 11401298 DOI: 10.1006/abio.2000.5034] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We report here the first combined use of NMR-PR (pattern recognition) analysis and directly coupled HPLC--NMR analysis to identify metabolic subpopulations in normal laboratory animals and their discriminating endogenous urinary biomarkers. Urine samples obtained from control Sprague-Dawley rats (n = 68) were analyzed using (1)H NMR spectroscopy and principal components (PC) analysis to investigate physiological variability. Two distinct subpopulations of animals were classified based on metabolite excretion profiles. Analysis of the PC loadings established the spectral regions that were responsible for classification of the subpopulations and was used to direct the identification of biomarkers using a directly coupled HPLC--NMR analysis. One population had low urinary hippurate levels together with an increased concentration of 3-(3-hydroxyphenyl)propionic acid (3-HPPA)and 3-hydroxycinnamic acid (3-HCA). The other subpopulation excreted high levels of hippurate. Thus, we report the bimodal occurrence of hippuric acid and chlorogenic acid metabolites in a genetically homogeneous population of rats maintained under identical conditions, which may have significance in relation to the understanding of the consequences of biochemical variation in animals used for drug toxicity testing.
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Affiliation(s)
- C L Gavaghan
- Biological Chemistry, Biomedical Sciences Division, Imperial College of Science, Technology and Medicine, University of London, Sir Alexander Fleming Building, South Kensington, London SW10 2AZ, United Kingdom
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41
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Montaudo MS. Determination of the Compositional Distribution and Compositional Drift in Styrene/Maleic Anhydride Copolymers. Macromolecules 2001. [DOI: 10.1021/ma0010231] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Maurizio S. Montaudo
- Istituto per la Chimica e la Tecnologia dei Materiali, Polimerici, Consiglio Nazionale delle Ricerche. Viale A. Doria, 6−95125 Catania, Italy
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Keifer PA. NMR spectroscopy in drug discovery: tools for combinatorial chemistry, natural products, and metabolism research. PROGRESS IN DRUG RESEARCH. FORTSCHRITTE DER ARZNEIMITTELFORSCHUNG. PROGRES DES RECHERCHES PHARMACEUTIQUES 2001; 55:137-211. [PMID: 11127963 DOI: 10.1007/978-3-0348-8385-6_5] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
Abstract
NMR spectroscopy has enjoyed many advances recently, and the pace of development shows no signs of slowing. This article focuses on advances that have affected solution-state NMR. These advances fall into three general categories: new experimental techniques (new pulse sequence tools), improved hardware and more powerful software. These advances are allowing NMR to help solve important problems in the field of drug discovery. Their impact is widespread. NMR spectroscopy is now being used to determine protein structures, to monitor ligand-receptor binding, to study diffusion, to analyze mixtures using LC-NMR, to analyze solid-phase synthesis resins and to determine the structures of organic small molecules. NMR spectroscopy can provide both qualitative and quantitative information, and can be used in both routine analytical applications and demanding research applications. The applications described here can benefit numerous disciplines in drug discovery, including natural products research, synthetic medicinal chemistry, metabolism studies, drug production, quality control, rational drug design and combinatorial chemistry.
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Affiliation(s)
- P A Keifer
- Varian NMR Systems and NMR Consultant, 6329 South 172nd Street, Omaha, NE 68135, USA.
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Abstract
The validation of reference compounds for natural products is a domain of the same physico-chemical methods that are used for their isolation, especially those techniques involving coupled high-resolution chromatography. Acknowledging the great problem of co-eluting impurities contained in the 'biogenetic cocktail' of a plant extract, there is a strong demand for non-chromatographic alternatives in the quality assessment of reference compounds. Because of this, the concept of qNMR is introduced as a versatile tool based on qualitative and quantitative 1H-NMR allowing the precise and simultaneous determination of both the compound content as well as the amount and nature of the impurities. As opposed to measuring carbons, 1H-NMR benefits from much higher sensitivity and is far more versatile for routine analysis with respect to time and cost. Since quantification of impurities is reliant upon their identification and, therefore, limited by knowledge about their structure, the concept emphasizes the high demand for qualitative reference dossiers including quality NMR data for profiling potential impurities which may be analogues, isomers, or degradation or oxidation products of the reference compounds. The qNMR concept is developed with focus on its potential in the certification and quality control of reference compounds. Taking into account published work in the field of quantitative NMR, selected natural products are analysed in order to elaborate suitable experimental parameters and to obtain preliminary validation data. The method is discussed with respect to sensitivity, precision and selectivity. Typical relative errors are found to be below 2% for the quantification of both the major analyte and the minor impurities even when the latter are contained at the 1% level only. Documentation of the conformity of signal integration and precision is based on measurements of a certified reference standard. Determination of the natural 13C isotope is suggested as an elegant method of validation because the content values could be reproduced with errors below 1%. The qNMR concept offers a rapid and efficient way to assess the purity of natural products in a single analytical step without the need of performing multiple analyses, while still offering the option to retain the substance. Thus, qNMR pays tribute to the increasing demands in reference compound certification, but also holds out the prospect of easy access to the valid characterisation of natural products tested in vitro or in vivo for their biological and pharmacological effects.
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Affiliation(s)
- G F Pauli
- Institut für Pharmazeutische Biologie und Phytochemie, Westfälische Wilhelms-Universität, Hittorfstrasse 56, D-48149 Münster, Germany.
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Abstract
The coupling of high performance liquid chromatography with nuclear magnetic resonance spectroscopy (LC-NMR) is one of the most powerful methods for the separation and structural elucidation of unknown compounds in mixtures. The recent progress in pulse field gradients and solvent suppression, the improvement in probe technology, and the construction of high field magnets have given a new stimulus to this technique, which has emerged since the mid 1990s as a very efficient method for the on-line identification of organic molecules. LC-NMR thus represents a potentially interesting complementary technique to LC-UV-MS in phytochemical analysis for the detailed on-line structural analysis of natural products. Recent applications have fully demonstrated the usefulness of this technique. A brief review of the applications of LC-NMR in natural product chemistry is presented in this paper, and a summary of the basic principles and modes of operation of LC-NMR is provided. Selected examples of LC-NMR analyses of plant metabolites in crude extracts or in enriched fractions are outlined and used to illustrate the different strategies for employing the technique. The practical possibilities and limitations of LC-NMR in its application to the analysis of crude plant extracts are discussed by means of several examples. Analytical strategies involving LC multi-coupled (hyphenated) techniques for the chemical screening and dereplication of crude plant extracts are presented. An analysis of the future development of the technique with respect to its application in phytochemical analysis is also given.
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Affiliation(s)
- J L Wolfender
- Institute of Pharmacognosy and Phytochemistry, University of Lausanne, BEP, CH-1015 Lausanne, Switzerland
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Rozing GP, Dermaux A, Sandra P. Instrumentation for Capillary Electrochromatography. ACTA ACUST UNITED AC 2001. [DOI: 10.1016/s0301-4770(01)80074-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
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46
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Lindon JC, Nicholson JK, Wilson ID. Directly coupled HPLC-NMR and HPLC-NMR-MS in pharmaceutical research and development. JOURNAL OF CHROMATOGRAPHY. B, BIOMEDICAL SCIENCES AND APPLICATIONS 2000; 748:233-58. [PMID: 11092602 DOI: 10.1016/s0378-4347(00)00320-0] [Citation(s) in RCA: 164] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The methodology for the direct coupling of HPLC with NMR spectroscopy and the simultaneous double coupling of HPLC with NMR and mass spectrometry (MS) is described. Indications of the necessary technical developments to achieve this are given, and the applications of these new techniques to studies of pharmaceutical relevance are reviewed. These include studies of combinatorial chemistry libraries, synthetic chemical impurities, characterisation of drug mixtures, identification of natural products of possible pharmaceutical interest and identification of xenobiotic metabolites in human, animal and in vitro systems. In addition, HPLC-NMR has been used to investigate xenobiotic metabolite reactivity. Finally, the potential future directions of the techniques are discussed.
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Affiliation(s)
- J C Lindon
- Biological Chemistry, Biomedical Sciences, Imperial College of Science, Technology and Medicine, South Kensington, London, UK.
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Abstract
Hyphenated HPLC-NMR is a fast growing technology, allowing rapid and detailed structural characterization of unknown mixtures. The technical aspects of the technology are reviewed on the basis of system configuration, operation, solvent suppression, HPLC and NMR optimization, and detection. The combined use of HPLC-NMR and HPLC-MS is also described and discussed. Various applications of HPLC-NMR and integrated HPLC-NMR-MS in drug discovery, especially in the separation and structure elucidation of drug impurities, reaction mixtures, degradation products, in vitro and in vivo metabolites, and combinatorial library samples, are illustrated.
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Affiliation(s)
- S X Peng
- The Procter & Gamble Company, Health Care Research Center, 8700 Mason-Montgomery Road, Mason, OH 45040, USA.
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48
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Abstract
A review of the basic aspects of fluorescence line-narrowing spectroscopy (FLNS) and its coupling with thin-layer chromatography (TLC) and polyacrylamide gel electrophoresis (PAGE) for off-line high-resolution low temperature spectral characterization is discussed. This is followed by a description of the on-line interfacing of capillary electrophoresis (CE) and capillary electrochromatography (CEC) with FLN detection. CE/ CEC-FLNS instrumentation and its applications for spectral identification of closely related analytes are also presented. Future prospects of micro and capillary high performance liquid chromatography (HPLC) with on-line high-resolution low temperature spectroscopic identification are considered.
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Affiliation(s)
- R Jankowiak
- Department of Chemistry, Iowa State University, Ames 50011, USA.
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49
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Pasch H. Hyphenated Techniques in Liquid Chromatography of Polymers. ADVANCES IN POLYMER SCIENCE 2000. [DOI: 10.1007/3-540-48764-6_1] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
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50
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2.7.5. HPLC/NMR and related hyphenated NMR methods. ACTA ACUST UNITED AC 2000. [DOI: 10.1016/s1464-3456(00)80018-6] [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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