Development, simulation, and validation of NMR relaxation-based exchange measurements

Area of Science:

• Geophysics
• Physical Chemistry
• Analytical Chemistry

Background:

• Two-dimensional (2D) nuclear magnetic resonance (NMR) correlation experiments are emerging tools for studying molecular exchange in porous media.
• The T(2)-T(2) relaxation exchange spectroscopy (REXSY) experiment is a notable but time-consuming method for this purpose.

Purpose of the Study:

• To develop novel 2D NMR methods for quantifying exchange in porous media with reduced acquisition times.
• To compare the performance of these new methods against the established REXSY experiment.

Main Methods:

• Derivation of model equations for an arbitrary N-pool system for the novel 2D methods.
• Validation through simulation studies and experimental testing using an aqueous urea model system.
• Quantitative comparison of exchange rate fitting uncertainty per unit time.

Main Results:

• The novel 2D NMR methods demonstrate superior performance compared to REXSY for specific model systems.
• Reduced acquisition times are achieved without compromising the accuracy of exchange quantification.
• The developed methods provide a more efficient approach to studying exchange dynamics.

Conclusions:

• Novel 2D NMR methods offer a significant advancement for studying exchange in porous media.
• These techniques provide a faster and potentially more accurate alternative to existing methods like REXSY.
• The findings have implications for a wide range of applications involving porous materials.