High-Pressure Clinical-Scale 87% Parahydrogen Generator.

Abstract

We present an automated parahydrogen generator (ParaSun) for clinical-scale applications in parahydrogen-induced polarization (PHIP) and signal amplification by reversible exchange (SABRE) at high pressures. The device employs a vacuum-pumped, Sunpower cryo-cooler (typically employed for cooling cellular network antennas) to achieve up to ∼87% parahydrogen enrichment at a temperature as low as ∼40 K and a maximum outlet pressure of ∼490 PSI. The device reaches the target temperature set-point in under 1 h. It employs a FeO(OH) catalyst for the ortho- to para-state conversion. A mass-flow controller (MFC) facilitates the controlled flow of H2 gas at a rate of 150 standard cubic centimeters per minute (sccm). This design bridges the gap between rudimentary 50% enrichment liquid-N2 baths and far costlier, near-unity-enrichment configurations employing high-H2 throughputs and <25 K temperatures. The design presented here should be of interest for those pursuing a wide variety of PHIP applications, including those involving the production of inhalable or injectable hyperpolarized contrast agents for biomedical imaging.