In air-displacement micropipettors, the tip is made of which material?

• A. Polypropylene
• B. Polyethylene
• C. Polystyrene
• D. Polyvinyl chloride

Answer: (A)

In air-displacement micropipette tips, the material needs to be chemically resistant, easy to sterilize, and able to form a smooth interior that minimizes sample binding for accurate transfer. Polypropylene fits these needs well: it is resistant to many common lab solvents, can be autoclaved, and provides a smooth bore that reduces adsorption of nucleic acids or proteins, supporting precise and repeatable pipetting. It’s also inexpensive for mass production and maintains dimensional stability, which is crucial for the tips to fit the pipette reliably. Other plastics may be too flexible, less heat-tolerant, or have surface properties that lead to more sample loss or contamination. Therefore, polypropylene is the standard material used for these tips.