Flow injection analysis with the chromatomembrane--a new device for gaseous/liquid and liquid/liquid extraction

A new device makes extraction procedures work continuously by realizing chromatographic principles in flow-injection analysis. The method allows independent mass transfer between two phases within a chromatomembrane cell. In spite of the small size of the cell-volume (about 3 cm(3)) the relevant contacting area is extended to 2 m(2). A mixing of phases is simply prevented, and an additional step of phase separation is no longer necessary. A chromatomembrane is generated from porous hydrophobic material (PTFE) with two types of pores, namely, macropores and micropores. Whenever two phases flow within the cell the aqueous one exclusively fills the large pores because of the capillary pressure produced by polar liquids in micropores. On the other hand these micropores remain available only for the extraction agent, e.g. non-polar liquids or gases. The mass exchange is significantly increased compared with conventional techniques. The wide field of practical applications can be seen from several results obtained from trace determinations in liquid and gaseous phases.