A device is disclosed for collecting a liquid sample and diluting the liquid sample by virtue of being adapted for use with a container having a volume of diluting liquid. The device comprises a housing adapted for mating with the container where the mated housing and container form a chamber. A bibulous pad is attached to the housing for collecting a predetermined amount of a liquid sample. Additionally, the device, when used with the container, creates a pressure differential between the interior of the housing and the chamber. The pressure differential is sufficient to move a predetermined volume of the diluting liquid through the bibulous pad and into the housing. The device can be used for assaying for a component of a sample. The device has particular use in immunochromatography and for convenience can also contain a strip of bibulous material confined in the housing. In a method for collecting a liquid sample and subsequently diluting the sample with a predetermined volume of a liquid, the sample is collected on an bibulous pad at the base of a housing. The pad is designed to absorb a predetermined amount of the sample. Next, a pressure differential is created between the housing and a container having a volume of diluting liquid to cause a predetermined volume of the liquid to pass through the pad and into the housing.