A spongy swab is mounted against the distal face of a piston at the end of a push rod. Once humected with a sample fluid, the swab and piston assembly is inserted into a tubular body like the plunger of a syringe. As the swab is pushed and squeezed against the distal end of the body up to a trippable stop, part of the fluid is excreted into a chromatographic immunoassay testing device through a first aperture in a distal section of the body. The remainder of the sample is kept in a sealed chamber between the piston and the end wall of the tubular body until it is excreted through a second aperture for a secondary test by pushing the piston beyond the trippable stop. That preserves the sample within the spongy swab that has been used to collect it； thus preventing the adsorption of the analytes on the surface of a reservoir, and to provide a convenient and rapid way to extract the remainder of the specimen.
