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Updated: May 8, 2026
06:42
Cryogenic Sample Loading into a Magic Angle Spinning Nuclear Magnetic Resonance Spectrometer that Preserves Cellular Viability
Published on: September 1, 2020
Dipolar-Filtered Magic Sandwich Echo as an alternative method for NMR cryoporometry.
Bruno Trebbi1, Jefferson Gonçalves Filgueiras1, Rodrigo Henrique Dos Santos Garcia1
1Instituto de Física de São Carlos, Universidade de São Paulo, Avenida Trabalhador São-carlense, 400, São Carlos, 13566-590, São Paulo, Brazil.
Summary
We developed a new NMR method, Dipolar-Filtered Magic Sandwich Echo (DFMSE) cryoporometry, for precise pore size analysis in mesoporous materials. This technique offers accurate internal normalization and reliable characterization of complex porous systems.
Area of Science:
- Materials Science
- Analytical Chemistry
- Physical Chemistry
Background:
- Cryoporometry determines mesoporous material pore sizes by analyzing probe fluid freezing/melting.
- Proton Nuclear Magnetic Resonance (¹H NMR) is suitable for cryoporometry due to selective detection of melted fractions and low-field instrument compatibility.
Purpose of the Study:
- To introduce an alternative ¹H NMR implementation for cryoporometry using the Dipolar-Filtered Magic Sandwich Echo (DFMSE) sequence.
- To demonstrate DFMSE's ability for internal normalization and signal suppression, enhancing accuracy and eliminating external references.
Main Methods:
- Utilized the Dipolar-Filtered Magic Sandwich Echo (DFMSE) sequence for ¹H NMR cryoporometry.
- Employed variable filter times to acquire signals from total sample (solid + liquid) or exclusively the liquid fraction.
- Validated the method using controlled-pore samples and a cadmium imidazolate framework.
Main Results:
- DFMSE cryoporometry achieved internal normalization, compensating for instrumental and environmental variations.
- Pore size distributions determined by DFMSE closely matched conventional cryoporometry and N₂ adsorption.
- The method successfully characterized complex porous materials like metal-organic frameworks.
Conclusions:
- DFMSE cryoporometry provides a robust and accurate method for pore size analysis in mesoporous materials.
- The internal normalization capability simplifies the experimental setup and improves reliability.
- This technique is applicable to a wide range of porous materials, including complex frameworks.
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