A fluid transfer device includes a syringe barrel having a chamber, a first plunger slidably movable inside the chamber, and a second plunger slidably movable inside the chamber. The distal end portion of the first plunger is engageable with the proximal end portion of the second plunger such that when the distal end portion of the first plunger and the proximal end portion of the second plunger are engaged, the second plunger is movable by the first plunger. A check valve may be incorporated into the distal end portion of the second plunger to allow a fluid to pass therethrough in a direction towards the proximal end portion of the second plunger and prevent a fluid to pass therethrough in a reverse direction. A fluid transfer assembly and a sampling method are also described.