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Compact NMR
ARTICLE IN PRESS Trends in Analytical Chemistry ■■ (2016) ■■
Contents lists available at ScienceDirect
Trends in Analytical Chemistry j o u r n a l h o m e p a g e : w w w. e l s e v i e r. c o m / l o c a t e / t r a c
Preface
Compact NMR
Most NMR and MRI instruments impress with their large magnets. These are required by todays superconducting magnet technology to generate high field strengths, which provide the high sensitivity for MRI and spectroscopy, and the high frequency dispersion of the chemical shifts needed to analyze large molecules. The large and delicate magnets make NMR instruments special so that they are rarely found in the analysis laboratory or on the chemical workbench next an infrared spectrometer or a chromatograph. This situation has changed in the last four years with the advent of commercial table-top NMR spectrometers. They employ permanent magnets with field strength between 1 and 2 tesla corresponding to roughly 40–80 MHz resonance frequency for protons. Permanent magnets for NMR have been around for decades, but not small ones suitable for NMR spectroscopy with compact instruments, because they are temperature-sensitive and hard to shim. Since spectroscopy-grade compact magnets have become available, the interest in compact NMR is on the rise. Today, benchtop NMR spectrometers are complementing current high-field NMR spectrometers and open up new niches of applications. This special issue of Trends in Analytical Chemistry provides an overview of the state of the art of compact NMR, its applications and its developments. Following an introduction by Bernhard Blümich to the NMR methods available with compact instruments, applications of NMR spectroscopy in the chemistry laboratory and under the fume hood are reviewed by Karwapal Singh and Bernhard Blümich. A major market for compact NMR spectrometers is academic teaching, the topic addressed by Susanne Riegel and Garett Leskowitz. The small size of compact NMR spectrometers enables process control applications, which are reviewed by Klas Meyer at al. Despite the sensitivity being inferior to high-
field instruments, it is good enough to run ultrafast two-dimensional NMR experiments as explained by Boris Gouilleux at al., and Megan Halse explains how the sensitivity of such compact NMR devices can be boosted by hyperpolarization methods. While spectroscopy with compact NMR instruments is new, relaxation measurements have been conducted with small instruments for over four decades, beginning with the analysis of food and emulsions, a topic which is summarized by Gisela Guthausen. Alina Adams reports how the same technology is applied to the analysis of polymer materials. Other applications of NMR relaxometry concern the analysis of human blood, which is reviewed by David Cistola and Michelle Robinson, and the identification of disease markers in an automated way using microfluidic technology and functionalized magnetic nanoparticles as explained by Zhi-Xiang Luo at al. from an industrial point of view. The magnets of compact NMR relaxometers provide magnetic fields too inhomogeneous to resolve the chemical shift. But how chemical information can be retrieved after all in such inhomogeneous fields from the heteronuclear indirect coupling is explained by Marcus Donaldson et al. Bernhard Blümich Institut für Technische und Makromolekulare Chemie, RWTH Aachen University, Worringerweg 2, 52056 Aachen, Germany E-mail address: [email protected] Ernö Pretsch ETH Zürich Institute of Biogeochemistry and Pollutant Dynamics (IBP) Universitätstrasse 16, CH-8092 Zürich, Switzerland E-mail address: [email protected]
http://dx.doi.org/10.1016/j.trac.2016.07.001 0165-9936/© 2016 Elsevier B.V. All rights reserved.
Please cite this article in press as: Bernhard Blümich, Ernö Pretsch, Compact NMR, Trends in Analytical Chemistry (2016), doi: 10.1016/j.trac.2016.07.001
Contents lists available at ScienceDirect
Trends in Analytical Chemistry j o u r n a l h o m e p a g e : w w w. e l s e v i e r. c o m / l o c a t e / t r a c
Preface
Compact NMR
Most NMR and MRI instruments impress with their large magnets. These are required by todays superconducting magnet technology to generate high field strengths, which provide the high sensitivity for MRI and spectroscopy, and the high frequency dispersion of the chemical shifts needed to analyze large molecules. The large and delicate magnets make NMR instruments special so that they are rarely found in the analysis laboratory or on the chemical workbench next an infrared spectrometer or a chromatograph. This situation has changed in the last four years with the advent of commercial table-top NMR spectrometers. They employ permanent magnets with field strength between 1 and 2 tesla corresponding to roughly 40–80 MHz resonance frequency for protons. Permanent magnets for NMR have been around for decades, but not small ones suitable for NMR spectroscopy with compact instruments, because they are temperature-sensitive and hard to shim. Since spectroscopy-grade compact magnets have become available, the interest in compact NMR is on the rise. Today, benchtop NMR spectrometers are complementing current high-field NMR spectrometers and open up new niches of applications. This special issue of Trends in Analytical Chemistry provides an overview of the state of the art of compact NMR, its applications and its developments. Following an introduction by Bernhard Blümich to the NMR methods available with compact instruments, applications of NMR spectroscopy in the chemistry laboratory and under the fume hood are reviewed by Karwapal Singh and Bernhard Blümich. A major market for compact NMR spectrometers is academic teaching, the topic addressed by Susanne Riegel and Garett Leskowitz. The small size of compact NMR spectrometers enables process control applications, which are reviewed by Klas Meyer at al. Despite the sensitivity being inferior to high-
field instruments, it is good enough to run ultrafast two-dimensional NMR experiments as explained by Boris Gouilleux at al., and Megan Halse explains how the sensitivity of such compact NMR devices can be boosted by hyperpolarization methods. While spectroscopy with compact NMR instruments is new, relaxation measurements have been conducted with small instruments for over four decades, beginning with the analysis of food and emulsions, a topic which is summarized by Gisela Guthausen. Alina Adams reports how the same technology is applied to the analysis of polymer materials. Other applications of NMR relaxometry concern the analysis of human blood, which is reviewed by David Cistola and Michelle Robinson, and the identification of disease markers in an automated way using microfluidic technology and functionalized magnetic nanoparticles as explained by Zhi-Xiang Luo at al. from an industrial point of view. The magnets of compact NMR relaxometers provide magnetic fields too inhomogeneous to resolve the chemical shift. But how chemical information can be retrieved after all in such inhomogeneous fields from the heteronuclear indirect coupling is explained by Marcus Donaldson et al. Bernhard Blümich Institut für Technische und Makromolekulare Chemie, RWTH Aachen University, Worringerweg 2, 52056 Aachen, Germany E-mail address: [email protected] Ernö Pretsch ETH Zürich Institute of Biogeochemistry and Pollutant Dynamics (IBP) Universitätstrasse 16, CH-8092 Zürich, Switzerland E-mail address: [email protected]
http://dx.doi.org/10.1016/j.trac.2016.07.001 0165-9936/© 2016 Elsevier B.V. All rights reserved.
Please cite this article in press as: Bernhard Blümich, Ernö Pretsch, Compact NMR, Trends in Analytical Chemistry (2016), doi: 10.1016/j.trac.2016.07.001