Liquid sample assay device

An assay device for determining the presence of specific analytes in a liquid sample comprises a container for collecting the sample liquid and a removable cap for sealing the container. The cap includes one or more test strips, such as chromatography strips, supported thereon for visually displaying the results of the assay. A reservoir attached to the underside of the cap, collects, through a passageway, a predetermined volume of liquid from the container when it is inverted thereby submerging the reservoir in the sample liquid. The liquid collected in the reservoir is transferred to the chromatography strips by a wicking system. A valve member located in the reservoir automatically swells upon absorbing a portion of the liquid in the reservoir. Such swelling causes the valve member to close the passageway to form a hermetic seal between the liquid contained within the container and the outside thereby preventing such liquid from becoming contaminated and any leakage of the contained liquid.