A novel closed loop. continuous flow (CF) reactor system for parahydrogen enhanced nuclear magnetic resonance (NMR) of liquids via heterogeneous catalysis is introduced which enables recycling of unreacted liquid substrate reactant. This system consists of an HPLC pump. a liquid substrate reservoir incorporating a gas diffuser. https://www.jmannino.com/quick-save-Canon-imageCLASS-MF227dw-Monochrome-Multifunction-Laser-Printer-great-choice/