Patent ID: 8231843

Claim:
A method of detecting the presence of an air bubble in a pipe used in an automatic analyzer including a nozzle for sucking or discharging a sample, a syringe having a plunger for generating pressure to suck the sample into the nozzle and discharge the sample from the nozzle, a pipe for connecting the nozzle and the syringe, pressure measurement means for measuring the pressure inside the pipe, storage means for storing a pressure fluctuation measured inside the pipe, and a motor for moving the plunger of said syringe, said method comprising the steps of: measuring a pressure fluctuation within a predetermined period of time during operation of a sample suctioning into the nozzle or a sample discharging from said nozzle, said pressure fluctuation being measured by said pressure measuring means; storing said pressure fluctuation into said storage means, and; detecting whether or not an air bubble is present inside the pipe on the basis of a pressure fluctuation at a reverse rotation of said motor for compensating a backlash of said syringe, where said pressure fluctuation at said reverse rotation is stored in said storage means.