A device comprises a first cavity (300) and a second cavity (400), wherein the first cavity (300) is positioned in the second cavity (400), and may seal and compress the second cavity (400) so that the liquid in the second cavity (400) is discharged out quantitatively. The device may fully mix a buffer solution with a sample and achieves the function of integration of collection and test. Further, a collecting device also may achieve the quota-sampling function.
