Global NMR Discussion Meetings

Instrumentation

  • A Palm-Top time-domain NMR spectrometer for the research laboratory

    Dr. Beau Webber (Lab-Tools Ltd., UK)

    LinkedIn: @Beau Webber

    Abstract: Take this Lab-Tools NMR TD spectrometer down off the shelf, plug it in, insert your sample, and you are up and measuring. Measure, plot and fit your results real-time in any of a number of ways, at the lab bench or from a remote location. This TD NMR spectrometer has been designed as a compact precision tool to measure quantitatively the physical properties of your sample. This TD NMR spectrometer can be used to study liquids, solids, polymers and porous materials. This gives data on sample component masses and molecular movement of the atoms and molecules, which lead to qualities which are variously described as mobility, dynamics, stiffness, viscosity or rigidity. Two NMR probes typically cover a wide range of NMR active nuclei : 1H, 19F, 11B, 7Li, 23Na. If you need variable-temperature, then plug in the Peltier thermo-electrically cooled module. -60C to +80C. This enables a wide range of materials-science measurements, and is also the basis of a thermodynamic NMR Cryoporometry system for measuring pore-sizes from nano-meters to micro-meters. In a hurry ? Or have another experiment or sample to do ? These spectrometers are priced so you can just add more on your research bench.

    1. Dr. Beau Webber Avatar
      Dr. Beau Webber

      Updates on an Even More Compact Precision NMR Spectrometer and a Wider Range V-T Probe, for General Purpose NMR and for NMR Cryoporometric Nano- to Micro-Pore Measurements. J. Beau W. Webber. Micro. 2024; 4(3):509-529. DOI: 10.3390/micro4030032.

      Reply
    2. Riley Hooper Avatar
      Riley Hooper

      Very cool! Are the spectrometers controlled on home-built software, and how much customizability is there in the programming for e.g. playing with pulse sequences or other experimental parameters? Are there any plans to add frequency-domain capabilities?

      Reply
      1. Dr. Beau Webber Avatar
        Dr. Beau Webber

        Hi Riley,
        The software has been written in my lab in an array processing language called Apl. It is multi-tasking, and also handles the graphics, and talks to the RF Gate-Array over an Ethernet.
        New and modified pulse-sequences can be written, and either down-loaded into the firm-ware pulse sequence pipeline, or run in the high-level Apl.
        All the front-panel and menu parameters can be set, or saved / loaded to disc. (Tomorrow we are discussing adding an AI assistant to this.)
        There are some frequency-domain capabilities already built in. However my magnets are not homogeneous enough for resolving 1H spectra yet. But I have captured some low-resolution 19F spectra easily.
        Cheers,
        Beau

        Reply
        1. Riley Hooper Avatar
          Riley Hooper

          Interesting, thanks!

          Reply
    3. Amit Bhattacharya Avatar
      Amit Bhattacharya

      Hi Dr. Webber, impressive work! Could you elaborate on how T1rho measurements correlate with viscosity ?

      Reply
      1. Dr. Beau Webber Avatar
        Dr. Beau Webber

        Thanks Amit,
        We have a preliminary equation, but we are still analysing the results.
        But we believe we may have publishable results, just need to validate them in other well defined systems. This data is only days old.
        Can you please contact me on LinkedIn, and I will let you have more info when we are sure we are happy with the results.
        Cheers, Beau

        Reply
    4. Amit Bhattacharya Avatar
      Amit Bhattacharya

      Thank you Dr. Webber.

      Reply
    5. Raj Chaklashiya Avatar
      Raj Chaklashiya

      Hi Dr. Webber, nice presentation! I am intrigued by the small size of the NMR spectrometer and have a few questions:
      1) How transportable is the spectrometer? I am assuming that its smaller size makes it significantly more mobile than other spectrometers, and perhaps capable of being used “on the field” in certain locations where it would otherwise not be possible for a bigger spectrometer to be used (e.g. near a cave, near a river, etc.)
      2) Up to what magnetic field are you able to reach while maintaining the small spectrometer size?

      Reply
      1. Dr. Beau Webber Avatar
        Dr. Beau Webber

        Hi Raj,
        Yes it is very transportable : It fits into a laptop bag, with the 0.5T 20 MHz 1H magnet, and a regulated 8 hour battery supply.
        Very suitable for mobile use in the field indeed.
        The 0.5T magnet is the highest I yet have – but watch this space !
        Thanks for the interest,
        Beau

        Reply
      2. Dr. Beau Webber Avatar
        Dr. Beau Webber

        Hi Raj,
        Yes it is very transportable : It fits into a laptop bag, with the 0.5T 20 MHz 1H magnet, and a regulated 8 hour battery supply.
        Very suitable for mobile use in the field indeed.
        The this magnet is the highest I yet have – but watch this space !
        Thanks for the interest,

        Reply
        1. Raj Chaklashiya Avatar
          Raj Chaklashiya

          Very cool, thank you! I look forward also to seeing how the highest field usable changes in the future!

          Reply

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  • UV-Induced PET Depolymerization in m-Cresol Monitored by Time-Resolved Diffusion NMR on a Benchtop Spectrometer

    Farwa Khalid (Insitute of physical chemistry, Polish Academy of Sciences, Poland)

    Abstract: PET (polyethylene terephthalate) is commonly used in bottles, fabrics, and packaging due to its transparency, durability, and mechanical properties. Its extensive use, combined with its natural degradation under sunlight and UV rays, slowly and uncontrollably contributes to environmental pollution [1]. Efforts to address waste PET face challenges in achieving energy-efficient and selective depolymerization through physical sorting or existing chemical methods[2]. The depolymerization of PET in m-cresol under UV light is key to breaking it down into valuable monomers[3].
    This study investigates UV-induced depolymerization of PET in m-cresol, focusing on real-time monitoring with Benchtop NMR. A flow-based experimental setup ensures continuous UV light exposure, while Diffusion NMR provides insights into diffusion properties and molecular size distribution during the process. Real-time diffusion data reveals the depolymerization kinetics, transitioning from high-molecular-weight polymer chains to low-molecular-weight monomers. This method offers valuable insights into the mechanistic pathway of PET depolymerization, potentially improving sustainable plastic waste management.
    References
    [1] F. Cao, L. Wang, R. Zheng, L. Guo, Y. Chen, and X. Qian, “Research and progress of chemical depolymerization of waste PET and high-value application of its depolymerization products,” Nov. 03, 2022, Royal Society of Chemistry. doi: 10.1039/d2ra06499e.
    [2] S. Zhang et al., “Selective depolymerization of PET to monomers from its waste blends and composites at ambient temperature,” Chemical Engineering Journal, vol. 470, Aug. 2023, doi: 10.1016/j.cej.2023.144032.
    [3] S. S. Karim et al., “Model analysis on effect of temperature on the solubility of recycling of Polyethylene Terephthalate (PET) plastic,” Chemosphere, vol. 307, Nov. 2022, doi: 10.1016/j.chemosphere.2022.136050.

    1. Kirill Sheberstov Avatar
      Kirill Sheberstov

      Hi Farwa, I have a question regarding the interpretation of DOSY experiments. In case of signal overlap, under which conditions is it possible to distinguish the two overlapping components? Would a signal display mono or biexponential decay? Thank you.

      Reply
    2. FARWA kHALID Avatar
      FARWA kHALID

      I have used a PGSTE-WET to suppress the solvent signals interfering with the PET peaks. Selecting a gradient strength value where the interfering signal is attenuated and only the desired signal appears. This way, I filter out the solvent peaks in the DOSY spectrum.Also, we are using Tailored fitting Normalization to get the polydispersity index.

      Reply
    3. Blake Wilson Avatar
      Blake Wilson

      Hi Farwa, great presentation. How does the wavelength of UV light influence the results you see?

      Reply
      1. Farwa khalid Avatar
        Farwa khalid

        Hi,
        The wavelength of the UV light greatly affects the photodegradation. I even tried the experiment with 270nm wavelength, but I didn’t see the degradation efficiently, even though this one has high energy, because PET shows maximum absorption closer to 300-320nm due to the aromatic ring and ester group. In 270 nm, I did not see the degradation product (Monomer) peak in the region around 9ppm, as it is shown in 365nm proton NMR spectra in my presentation and also I have calculated the peak area of the polymer peak its almost constant in 270nm.

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  • Rapid Melting Strategies for benchtop DNP: A Step Toward Replenishable Hyperpolarization in Liquid-State NMR

    Yang Wang (Very High Field NMR Center of Lyon (CRMN Lyon), France)

    LinkedIn: @Yang Wang; X: @WangYan35529716; Bluesky: @yangwangcz.bsky.social‬

    Abstract: Hyperpolarization techniques can boost NMR sensitivity by over 10,000-fold [1]. Among these, dissolution dynamic nuclear polarization (dDNP) is well established but suffers major drawbacks: it is destructive, single-use, and results in dilution upon sample dissolution, leading to rapid signal decay and incompatibility with multi-scan NMR experiments [2].
    We are developing a benchtop DNP platform designed to enable replenishable hyperpolarization without dilution. This approach uses hyperpolarizing materials (HYPOPs) [3] within a compact benchtop polarizer [4], coupled directly to a benchtop NMR spectrometer for solution-state detection. Our long-term goal is a closed-loop system allowing repeated freeze-DNP-melt-flow cycles.
    A critical challenge is maintaining polarization during the melt. In our current system, the sample is transferred from a 77 K DNP cryostat inside a 1 T benchtop polarizer into a dedicated melting station. This first prototype uses a guided high-flux (500 L/min), high-temperature (630 °C) air stream to melt a 250 µL sample in 5 seconds.
    We are now working to reduce the melt time below 1 second by increasing airflow, temperature, and integrating high-power laser light. Ultimately, we aim to couple this rapid melt setup with DNP and solution-state hyperpolarized NMR for multi-scan acquisition capability.
    References:
    [1] Ardenkjær-Larsen, J. H., et al. PNAS 100.18 (2003): 10158-10163.
    [2] Golman, K., et al. Cancer Res. 66.22 (2006): 10855-10860.
    [3] El Daraï, T., Cousin, S.F., Stern, Q., et al. Nat. Commun. 12 (2021): 4695.
    [4] Bocquelet, C., et al. Sci. Adv. 10 (2024): eadq3780.

    1. KSHAMA SHARMA Avatar
      KSHAMA SHARMA

      Hi Yang! Thank you for the presentation.

      I was wondering if you observe any noticeable time lag associated with activating the heat gun during the melting process? If so, have you considered alternative heating methods, such as infrared or laser-based systems that might allow for a more rapid and controlled melt?

      Regarding the freeze-melt and then flow cycles, how reproducible are your polarization levels across repeated runs?

      Reply
      1. Yang Wang Avatar
        Yang Wang

        Hi Kshama,

        Thank you for your questions !

        Indeed, the heat gun does require a few seconds after activation to reach the target temperature. To address this, I preheat the gun to the desired temperature before exposing the sample, so that the hot air is already at the setpoint at the very start of the melting process.

        I have also considered three alternative heating strategies. Among them, infrared laser heating is particularly promising. We have recently acquired a 1 kW, 1 μm wavelength IR laser system, which is currently being installed. I hope to begin testing it in the coming months and are looking forward to sharing new results with you.

        In parallel, we are also simulating microwave heating approaches, although the heating speed appears to be limited in this case…

        Regarding your question on reproducibility, we unfortunately do not yet have experimental data. However, we are planning a series of repeated melt-DNP experiments in the coming months to verify the polarization reproducibility across cycles.

        Best regards,
        Yang

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  • Advancing GHz-class NMR: High sensitivity through larger volume cryoprobe and optimal control sequences

    David Joseph (Max Planck Institute for Multidisciplinary Sciences, Germany)

    X: @DaJo_1729

    Abstract: Improving the sensitivity of nuclear magnetic resonance (NMR) spectroscopy requires advancements in both instrument technology and experimental methodology. In this study, we introduce the first proton-detected large volume cryoprobe designed for 1.2 GHz instruments, leveraging optimal control pulse sequences to enhance performance (Sci. Adv. 9,eadj1133, 2023). Our results demonstrate up to a 56% increase in sensitivity and more than a twofold reduction in experimental time compared to the small volume cryoprobes in use at the moment. Additionally, we systematically optimized the experimental conditions to fully exploit the capabilities of GHz-class magnets. To further extend the benefits of our approach, we developed a library of optimal control triple resonance experiments, enabling boosted sensitivity for advanced NMR applications.

    1. Cory Widdifield Avatar
      Cory Widdifield

      When comparing the results from the 5 mm TCI probe at 1.2 GHz with the 5 mm TCI probe at 950 MHz, what is the most surprising/interesting/useful insight that you have personally encountered? In the future, what do you think might be the most useful/interesting insights enabled by performing experiments at 1.2 GHz?

      Reply
      1. David Joseph Avatar
        David Joseph

        The most useful insight is that bio-NMR experiments perform much better using optimal control pulses. A 5 mm TCI at 950 MHz approaches the power availability limit for broadband pulses, particularly for the 13C and 15N channels. At 1.2 GHz, a 5 mm TCI can only be used with optimal control pulses. However, using optimal control pulses with fields starting from 800 MHz would provide free signal enhancement and save valuable experimental time.

        The most interesting insights would come from performing experiments at 1.2 GHz to study biomolecular dynamics. All B₀-dependent parameters, such as CSA and alignment, reach their maximum values at this frequency, enabling access to data on motions that would otherwise be impossible to observe with lower field magnets. Increased resolution at 1.2 GHz would also be useful for studying larger proteins and intrinsically disordered proteins.

        Reply
        1. Cory Widdifield Avatar
          Cory Widdifield

          Thank you for your response, David.

          Reply
    2. Gottfried Otting Avatar
      Gottfried Otting

      These are important reference data.
      1) Wouldn’t one expect that the sensitivity obtained with a Shigemi tube is either the same or less than that obtained with a conventional 5 mm tube?
      2) Which compound and signal did you use to measure the sensitivities in the presence of different salt concentrations – ubiquitin or sucrose?
      3) Does CSA relaxation of ubiquitin amide protons broaden their 1H NMR signals noticeably more than at, say, 950 MHz?

      Reply
      1. David Joseph Avatar
        David Joseph

        1) The sensitivity of a Shigemi depends on the amount of sample available. It is especially sensitive when a lower volume of sample is available. There is also an optimal height that provides the best signal-to-noise ratio when using a Shigemi tube. Our concern here was B_1 inhomogeneity, which is lower with a Shigemi tube. However, since the pulses also compensate for ±20% inhomogeneity, we only see only a slight improvement in sensitivity when using a Shigemi tube.

        2) It was p53 1-73, a disordered protein, in a Tris-Bis buffer, using optimal control HNCA sequence.

        3) Thanks for the question! I just looked it up, and for an HNCO experiment, the difference is around 3 Hz, while for an HSQC, it’s around 1 Hz (along the proton dimension). It is broader at 1.2 GHz.

        Reply
    3. David Joseph Avatar
      David Joseph

      1) The sensitivity of a Shigemi depends on the amount of sample available. It is especially sensitive when a lower volume of sample is available. There is also an optimal height that provides the best signal-to-noise ratio when using a Shigemi tube. Our concern here was B_1 inhomogeneity, which is lower with a Shigemi tube. However, since the pulses also compensate for ±20% inhomogeneity, we only see only a slight improvement in sensitivity when using a Shigemi tube.

      2) It was p53 1-73, a disordered protein, in a Tris-Bis buffer, using optimal control HNCA sequence.

      3) Thanks for the question! I just looked it up, and for an HNCO experiment, the difference is around 3 Hz, while for an HSQC, it’s around 1 Hz (along the proton dimension). It is broader at 1.2 GHz.

      Reply
    4. Bijaylaxmi Patra Avatar
      Bijaylaxmi Patra

      Hi David, brilliant presentation. Clear, concise, and insightful.
      You mentioned a useful tip about using buffers with lower conductivity and larger ions. Could you please elaborate on why this is beneficial and how exactly it helps in practice?

      Reply
      1. David Joseph Avatar
        David Joseph

        Hi, thank you! This has to do with noise contribution from the sample, which is especially problematic for the cryoprobe. The noise from the sample is proportional to its conductivity and dielectric properties. Using a buffer with larger ions will lower the mobility, thus lowering the conductivity of the buffer and reducing the noise from the sample. This increases the signal-to-noise ratio of the spectrum.

        Reply
    5. David Joseph Avatar
      David Joseph

      Hi, thank you! This has to do with noise contribution from the sample, which is especially problematic for the cryoprobe. The noise from the sample is proportional to its conductivity and dielectric properties. Using a buffer with larger ions will lower the mobility, thus lowering the conductivity of the buffer and reducing the noise from the sample. This increases the signal-to-noise ratio of the spectrum.

      Reply

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