An apparatus for ion chromatography comprising a suppressor comprising a housing and a liquid conduit segment disposed in the housing, the liquid conduit segment including a membrane, the membrane having an inlet section adjacent the inlet of the conduit segment and an outlet section adjacent the outlet of the conduit segment, the inlet section having ion exchange sites capable of transmitting ions of one charge, positive or negative, and the outlet section being substantially non-retentive electrostatically for charged ionic species. Also, the method of using the apparatus.