Indirect Zero-Field Nuclear Magnetic Resonance Spectroscopy

Area of Science:

• Nuclear Magnetic Resonance Spectroscopy
• Analytical Chemistry
• Physical Chemistry

Background:

• Zero to ultralow field (ZULF) Nuclear Magnetic Resonance (NMR) offers unique insights but suffers from low sensitivity.
• Signal Amplification By Reversible Exchange (SABRE) hyperpolarization can significantly boost NMR signal intensity.
• Integrating hyperpolarization with ZULF NMR techniques is crucial for enhanced analytical capabilities.

Purpose of the Study:

• To develop and demonstrate a two-field correlation spectroscopy (COSY) technique in the ZULF regime.
• To integrate SABRE hyperpolarization with 2D NMR for increased sensitivity in ZULF COSY.
• To explore the application of this enhanced ZULF NMR method for chemical analysis.

Main Methods:

• Development of two-field correlation spectroscopy (COSY) for ZULF liquid-state NMR.
• Integration of Signal Amplification By Reversible Exchange (SABRE) hyperpolarization with 2D NMR.
• Field cycling for acquiring COSY spectra at varying magnetic field strengths, including zero-field.
• Readout at higher fields (>5 μT) to mitigate low-frequency noise.

Main Results:

• Successful demonstration of ZULF COSY spectra with enhanced sensitivity using SABRE hyperpolarization.
• Acquisition of spectra across different magnetic field regimes, providing insights into J-coupling and Zeeman-dominated interactions.
• Evaluation of polarization transfer and apodization techniques for optimal spectral quality.
• Exemplified chemical analysis for [1-13C]pyruvate, [15N]acetonitrile, and [3-19F]pyridine.

Conclusions:

• The integration of SABRE hyperpolarization with ZULF COSY significantly improves NMR sensitivity.
• This method allows for detailed analysis of chemical samples in both zero and ultralow magnetic fields.
• The developed technique offers a promising pathway towards more sensitive and cost-effective NMR spectroscopy for chemical analysis.