The inventive device is provided with a unit (1) comprising a body (3) which interacts with a pipette tip (24) in a vertical position in order to retain the content of the pipette tip (24) in the unit (1) and comprises a nozzle (2) having a capillary channel (4) insertable into a straw (25) oriented in a transversal position with respect to the body in such a way that, when the body is in a vertical position, said nozzle (2) is in a horizontal position. The inventive method consists in sampling a liquid substance initially contained in a top-open container (45) with the aid of the pipette tip (24) in the vertical position, in transferring the content of pipette tip (24) to the body (3) of the unit (1) prior to filling the straw (25) with the predetermined dose of a liquid substance transferred thereto from the unit (1).
