penetrant (permeant)

https://doi.org/10.1351/goldbook.PT06879
Entity from a phase in contact with one of the @MT06878@ surfaces that passes though the @MT06878@.
Source:
PAC, 1996, 68, 1479. (Terminology for membranes and membrane processes (IUPAC Recommendations 1996)) on page 1484 [Terms] [Paper]