The thermal quenching approach of two mixed solutions was first introduced in the 1960s, where the technique was tested by using a model reaction of the reduction of Fe 3+ to Fe 2+ ions of quinol by EPR spectroscopy. For biological and water-containing samples, precise cryo-fixation requires the formation of vitreous ice at freezing rates of ≥10 5 K/s and/ or the use of cryoprotectants (e.g., glycerol) to prevent crystalline ice formation. Cryo-fixation has become a routine technique to preserve materials and their structure at a native state and has been widely adopted across various experimental techniques, with significant advances in cryo-electron microscopy (cryo-EM) where sample preparation is generally achieved via plunge-freezing using liquid ethane or an ethane/ propane mixture as a cryogen. Furthermore, similar approaches have been adapted for ssNMR, where cryo-quenched samples have been prepared by spraying the reaction mixture into a cryogenic medium, either propane (at -188 0 C) or isopentane (at -140 0 C), or onto the surface of rotating copper plate cooled to approximately to -193 0 C. However, the reported sample preparation and rotor packing vary and can be complicated. For samples fixed in a cold propane, the following rotor packing was done under inert conditions with a cryogenic solvent removal. Where methodologies reported by Tycko et al., use specifically home-built equipment, one of the experimental setups uses a rotating copper plate that is placed in a custom-designed glove box to avoid ice formation on top of the plate. The sprayed mixture creates a thin film that is scraped off the surface of the plate and transferred to the NMR rotor. Another setup used by Tycko lab performed freeze-trapping by spraying the reaction mixture into stirred cold isopentane, which is removed via suction for 5-15 s, leaving a dense slurry of frozen solution and some residual isopentane. The mixture and holder are placed in liquid nitrogen, then the frozen sample is transferred to a packing funnel with a rotor inside. The temperature is lowered to -160 0 C, melting isopentane, and the frozen mixture is broken up and packed using precooled packing tools.