Estimation of pore size distribution using concentric double pulsed-field gradient NMR

Area of Science:

• Materials Science
• Analytical Chemistry
• Biophysics

Background:

• Porous materials are crucial in biology, geology, and oil extraction.
• Conventional pulsed-field gradient (PFG) NMR is effective for simple porous systems.
• Estimating pore size distribution in complex, heterogeneous materials remains a significant challenge.

Purpose of the Study:

• To demonstrate the estimation of pore size distribution in well-calibrated phantoms using NMR for the first time.
• To validate the concentric double pulsed-field gradient (CDPFG) NMR technique for heterogeneous systems.
• To assess the reliability and safety of CDPFG NMR for biological applications.

Main Methods:

• Utilized a 2-D NMR technique varying gradient amplitude (q) and relative angle (φ).
• Employed five well-defined phantoms with 1-5 pore sizes (5-25 μm).
• Applied CDPFG NMR without prior assumptions on pore size distribution models.

Main Results:

• Estimated pore size distributions closely matched theoretical distributions for all phantoms.
• Demonstrated experimental reliability of the CDPFG method.
• Showcased increased sensitivity to small pore sizes without high magnetic field gradients.

Conclusions:

• CDPFG NMR provides accurate and robust pore size distribution estimation for polydisperse systems.
• The method is experimentally reliable and offers theoretical advantages over 1-D PFG NMR.
• CDPFG NMR's safety profile makes it suitable for biological applications.