Automated Low-Cost In Situ IR and NMR Spectroscopy Characterization of Clinical-Scale ¹²⁹Xe Spin-Exchange Optical Pumping

We present on the utility of in situ nuclear magnetic resonance (NMR) and near-infrared (NIR) spectroscopic techniques for automated advanced analysis of the ¹²⁹Xe hyperpolarization process during spin-exchange optical pumping (SEOP). The developed software protocol, written in the MATLAB programming language, facilitates detailed characterization of hyperpolarized contrast agent production efficiency based on determination of key performance indicators, including the maximum achievable ¹²⁹Xe polarization, steady-state Rb–¹²⁹Xe spin-exchange and ¹²⁹Xe polarization build-up rates, ¹²⁹Xe spin-relaxation rates, and estimates of steady-state Rb electron polarization. Mapping the dynamics of ¹²⁹Xe polarization and relaxation as a function of SEOP temperature enables systematic optimization of the batch-mode SEOP process. The automated analysis of a typical experimental data set, encompassing ∼300 raw NMR and NIR spectra combined across six different SEOP temperatures, can be performed in under 5 min on a laptop computer. The protocol is designed to be robust in operation on any batch-mode SEOP hyperpolarizer device. In particular, we demonstrate the implementation of a combination of low-cost NIR and low-frequency NMR spectrometers (∼$1,100 and ∼$300 respectively, ca. 2020) for use in the described protocols. The demonstrated methodology will aid in the characterization of NMR hyperpolarization hardware in the context of SEOP and other hyperpolarization techniques for more robust and less expensive clinical production of HP ¹²⁹Xe and other contrast agents.