A sample distribution system 1 has a regulator 4 for receiving a pipetting unit 2 that has at least one exchangeable pipette tip 3, wherein the regulator 4 is configured to change the position of the pipetting unit 2 in relation to a base plate 5, and to detect the presence or absence of pipette tips 3 with a sensor unit 12.
According to the invention, the sensor unit 12 is a photoelectric sensor, in particular a reflection photoelectric sensor, with a detection range. The sensor unit 12 and the pipetting unit 2 can also move in relation to one another, in order to determine the presence of a pipette tip 3, if the pipette tip is in the detection range of the sensor unit 12.