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Benchtop nuclear magnetic resonance spectrometer
A Benchtop nuclear magnetic resonance spectrometer (Benchtop NMR spectrometer) refers to a Fourier transform nuclear magnetic resonance (FT-NMR) spectrometer that is significantly more compact and portable than the conventional equivalents, such that it is portable and can reside on a laboratory benchtop. Instead of requiring dedicated infrastructure, rooms and extensive installations these instruments can be placed directly on the bench in a lab and moved as necessary (''e.g.,'' to the fumehood). These spectrometers offer improved workflow, even for novice users, as they are simpler and easy to use. They differ from relaxometers in that they can be used to measure high resolution NMR spectra and are not limited to the determination of relaxation or diffusion parameters (''e.g.,'' T1, T2 and D).
== Magnet development ==
This first generation of NMR spectrometers used large Electromagnets weighing hundreds of kilograms or more. Smaller permanent magnet systems were developed in the 1960's-70's at proton resonance frequencies at 60 and 90 MHz and were widely used for chemical analysis using continuous wave methods. Superconducting magnets were developed to achieve stronger magnetic fields for higher resolution and increased sensitivity . However, these instruments are expensive, large, and require specialized building facilities.〔Dalitz, F., Cudaj, M. Maiwald, M., Guthausen, G. Prog. Nuc. Mag. Res. Spec. 2012, 60, 52-70〕 In addition, the cryogens needed for the superconductors are hazardous, and represent an ongoing maintenance cost.〔http://business.time.com/2012/08/24/helium-prices-hit-the-roof-leaving-balloon-sales-deflated/〕〔http://blogs.scientificamerican.com/observations/2010/06/30/the-coming-shortage-of-helium/ accessed Jan 18/13〕 As a result, these instruments are usually installed in dedicated NMR rooms or facilities for use by multiple research groups.
Since the early 2000s there has been a renaissance in permanent-magnet technology and design,〔Danieli E., Mauler J., Perlo J., Blümich B., Casanova F., J Mag. Res 2009, 198 (1), 80–87〕 with advances sufficient to allow development of much smaller NMR instruments with useful resolution and sensitivity for education, research and industrial applications.〔Danieli E., Perlo J., Blümich B., Casanova F., Angewandte Chemie 2010, 49 (24), 4133–4135〕 Samarium–cobalt and neodymium magnets in particular are strong enough for instruments up to 90 MHz. These smaller designs, which operate with magnet temperatures from room temperature to 45oC, allow instruments to be made small enough to fit on a lab bench, and safe to operate in a typical lab environment. They require only single phase local power and with UPS systems can be made to portable and can perform NMR analyses at different points in the manufacturing area.
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