• the analyte, A, at partial pressure p 0 a [bar] • the interferent, I, at partial pressure p 0 i [bar]. Assume A and I are the only components of the inlet gas that interact with (a) the catalyst of the CF and (b) the recognition element of the GS. Treating the inlet gas as ideal and at constant temperature, (v , p 0 a , p 0 i ) fully characterize it for the purpose of modeling the CF-GS device.