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Welcome to our latest video tutorial on sample injection instructions using the QM-125 benchtop NMR spectrometer from Q Magnetics. Whether you're a chemistry enthusiast, a researcher, or a student, we'll guide you through a step-by-step process of sample injection, providing you best practices for loading NMR sample when using the QM-125.



Here's a breakdown of the sample injection tutorial:

  1. Open the flow path by removing the caps from the inlet and outlet port. When the instrument is not in use, keep the flow path enclosed with the caps.

  2. Start by securing the stainless-steel syringe port to the inlet.

  3. Secure the drain tube to the outlet. The entire volume of the flow-path inside the instrument is 360 microliters.

  4. Draw sample with a 1 mL syringe and blunt-tip needle.

  5. Inject the sample via the syringe port. If the sample contains suspended solids or undissolved material, use a syringe filter while injecting.

  6. Before removing the syringe, first remove the drain tube and close the end of the flow path with a port cap.

  7. Now remove the syringe and injection port, and close the front of the flow path to contain the sample for measurement.

This tutorial demonstrates how easy and convenient sample injection is with the QM-125 benchtop NMR. Stay tuned for more informative tutorials on NMR spectroscopy with the QM-125 from Q Magnetics.



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Check out this video of the QM-125 making its first appearance at an ACS Expo during the Spring 2023 Conference. The QM-125 was met with overwhelming interest and positive reception as it's the only NMR spectrometer that provides 125 MHz 1H-NMR data from the benchtop.



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The Q Magnetics 125 MHz benchtop NMR spectrometer is a powerful and convenient tool for monitoring chemical reactions. No reconfiguration is required to periodically transfer samples by flow from an external reaction vessel, or to track reactions carried out directly in the polymer sample tube. In this post, we demonstrate monitoring of a Diels-Alder reaction. This particular reaction has recently been studied as a route to producing phthalic anhydride from lignocellulosic biomass, a promising renewable feedstock [1].


125 MHz NMR reaction monitoring in non-deuterated DMSO


An equimolar solution of cyclohexadiene and maleic anhydride was prepared in non-deuterated DMSO, then immediately injected by syringe into the spectrometer’s sample tube. Spectra were recorded every 5 minutes for 3 hours. No shimming or other spectrometer adjustments were made after the sample was injected, or during the 3-hour period. No solvent-suppression techniques were used or needed. The figure above shows integrations of the vinylic proton signals from the reactants and the adduct product plotted versus time. These signals are sufficient to track the progress of the reaction and quantitatively characterize the second-order kinetics. All other expected signals are also present (DMSO and its satellites at 3.09, 2.54, 1.98; cyclohexadiene at 2.09; adduct at 3.29, 3.03, 1.12-1.68).


When the spectrometer’s polymer sample tube is filled using the front-panel fittings, there is no change of the sample geometry. This means there is normally no need for shimming before starting scans, as would be required with a spectrometer that uses NMR tubes. Data collection can start immediately after a sample is injected or immediately after it is transferred by flow from an external vessel. No special insert is required for sample delivery by flow. If a precipitation accident occurs and the sample tube becomes blocked, it can be quickly replaced without disturbing the magnet, and experiments can resume within a few minutes.


References

1. Eyas Mahmoud, Donald A. Watson and Raul F. Lobo, Green Chem. 16, 167 (2014).

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