A purity monitor is provided. The purity monitor includes a cryo-cooler and a piezo-electric crystal microbalance that may have a matte finish. The cryo-cooler includes a nozzle and plumbing components disposed to supply a fluid having a working pressure of up to 10,000 psig to the nozzle. The nozzle provides for locating substantially all of a pressure drop of the cryo-cooler near an exit thereof. The nozzle sprays fluid onto the piezo-electric crystal microbalance and the piezo-electric crystal microbalance measures a mass of non-volatile residue (NVR) left thereon by the spraying. Respective temperatures of the fluid and the piezo-electric crystal microbalance are controllable based on a type of the NVR.