A device for separating components such as fibrin monomer from blood by centrifugation about a central axis comprising a first annular chamber (70) defined by an outer cylindrical wall (72) and an inner cylindrical wall (71) both walls being concentrically accommodated about an axis of rotation, and by a top wall (73) and a bottom wall (74), where the bottom wall is formed by a piston (55) displaceable within the first chamber. The device including a second chamber (75) below the first chamber and communicating with the first chamber through a first conduit (4) and being defined by said outer cylindrical wall (72), the bottom wall (74) of the first chamber, and another bottom wall (76). The device also includes a capsule (45) accommodated in the second chamber and including a plurality of compartments for receiving respective compositions promoting the separation.