Abstract: The analytical device includes a base adapted to support a porous member having dispersed throughout at least one analyte responsive substance which undergoes a detectable response to the presence and concentration of the analyte in the test sample. A cover integral with the base is provided with a reaction well adapted for storing a dried reaction component and for receiving the liquid test sample deposited on the analytical device whereby the liquid test sample and the reaction component form a liquid reaction mixture therein. A passage is included in the reaction well for selectively transferring the reaction mixture therethrough. This passage is normally spaced from the porous member and effectively closed to transfer therethrough of the reaction mixture, and is selectively movable toward the porous member to effectively open to passage therethrough of the reaction mixture whereby the analyte responsive substance will undergo a detectable response to the analyte present in the liquid reaction mixture.