Which plastic is used for cryogenic purposes such as pipet tips and test tubes?

• A. Polypropylene
• B. Polyethylene
• C. Polystyrene
• D. Polycarbonate

Answer: (A)

When choosing plastics for cryogenic labware, the key is maintaining toughness and dimensional stability at very low temperatures. Polypropylene stays ductile and resists cracking even when exposed to extreme cold, such as liquid nitrogen temperatures, and it also handles repeated sterilization and chemical exposure well. This combination—low-temperature toughness, chemical resistance, and sterilization compatibility—makes it the best material for pipet tips and test tubes used in cryogenic applications. Polystyrene tends to become brittle at cryogenic temperatures, polycarbonate is pricier and more prone to certain failures, and polyethylene doesn’t match polypropylene’s overall balance of toughness and stability at these temperatures.