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Contributions towards variable temperature shielding for compact NMR instruments.

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Summary

This study introduces active heat shielding for compact NMR instruments, enabling precise temperature control of flowing samples. This innovation overcomes magnet sensitivity issues, improving measurement quality for diverse applications.

Keywords:
benchtop NMRcontinuous processesinline analyticsmodel predictive controlprocess analytical technologytemperature control

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Area of Science:

  • Analytical Chemistry
  • Physical Chemistry
  • Instrument Engineering

Background:

  • Compact NMR instruments face limitations with temperature-sensitive permanent magnets.
  • Temperature fluctuations degrade magnetic field homogeneity and NMR measurement quality.
  • Existing internal temperature controls and passive insulation are insufficient for dynamic sample conditions.

Purpose of the Study:

  • To develop an active heat shielding system for benchtop NMR instruments.
  • To enable variable temperature control for flowing or reacting NMR samples.
  • To mitigate temperature disturbances affecting permanent magnet stability.

Main Methods:

  • Designed an active heat shielding system using a variable compressed airstream (flow and temperature).
  • Employed system identification and thermography for surface temperature measurements.
  • Implemented a model predictive control (MPC) strategy to minimize thermal disturbances.

Main Results:

  • Successfully minimized disturbance effects from probe and sample temperatures on the permanent magnet.
  • Demonstrated effective active heat shielding for variable-temperature NMR measurements.
  • Validated the capability to maintain stable magnetic field homogeneity under varying sample conditions.

Conclusions:

  • The active heat shielding methodology significantly extends the applicability of compact NMR.
  • Enables reliable NMR analysis of flowing samples at temperatures deviating from ambient.
  • Advances the use of benchtop NMR for challenging reaction monitoring and process control.