Membrane extractors comprising a membrane house inside of a valve have
been developed to separate compounds of interest from a sample matrix
and introduce these compounds into a mass spectrometer. Experimental
control over parameters that affect permeability or that may damage. t
he membrane, such as the membrane temperature, is provided with the va
lve. The valve was tested for response and response times with the val
ve separated from the mass spectrometer by various interface tube leng
ths. Data for steady state response measurements showed no significant
change With the valve at different distances from the ion source, Pol
ar compounds show a strong response time dependency on the interface t
ube length, This adsorption phenomenon is minimized by simply heating
the interface tube, Other factors affecting the performance of the dev
ice are discussed.