Which of the following is a correct statement about automatic micropipettors?

• A. Air Displacement (disposable tip, reusable piston)
• B. Positive Displacement (reusable tip, disposable piston)
• C. Dispenser/Dilutor Pipet
• D. All of the above

Answer: (D)

Automatic micropipettors cover different ways of moving precise liquid volumes, either by using an air cushion or by contacting the liquid directly. In air-displacement devices, a disposable tip is used to prevent cross-contamination, while the piston that drives the air is reused. In positive-displacement devices, the liquid is in direct contact with a piston inside the tip, so the piston is disposable and the system accommodates tricky liquids without an air cushion. A dispenser or dilutor pipet is another form of automated liquid handling used to dispense fixed volumes or perform dilutions quickly. Since each description describes a valid automated pipetting approach, all of the above statements together correctly characterize automatic micropipettors.