Patent ID: 7799574

Claim:
An in-duct bubble presence determining method in a dispensing apparatus comprising a dispensing nozzle, a duct, a pressure sensor, and a presence determining unit, which performs dispensing by filling the duct to which the dispensing nozzle is connected with a liquid, making the liquid move in the duct to absorb a liquid sample including one of a specimen and a reagent through the dispensing nozzle, and discharging the absorbed liquid sample, comprising the steps of: the dispensing nozzle discharging the liquid in the duct; the pressure sensor detecting a transition of a pressure in the duct at the time of the discharge; the presence determining unit calculating a number of pulses in a pressure transition waveform based on the detected pressure transition; and the presence determining unit determining a presence of a bubble in the liquid filling the duct based on the calculated number of pulses.