Culture tubes in borosilicate glass, in sizes from 10 × 75 mm (4 mL) to 20 × 150 mm (36 mL). Plastic tubes come in polystyrene and polypropylene, sterile or non-sterile, in 12 × 75 mm (5 mL) and 17 × 100 mm (15 mL). They are from Globe Scientific and McKesson, alongside the closures and dispensers that go with them: Diamond polypropylene caps from 13 mm to 25 mm, flange plug caps, Uni-Flex safety closures and metal tube dispensers.
How to choose
Glass or plastic?
Borosilicate glass takes a flame, dry heat and repeated autoclaving, and it stands up to organic solvents. Plastic tubes are sterile out of the pack and single-use, which removes the washing and re-sterilizing step and the risk that goes with it. Glass is the choice for heating and solvents; plastic is the choice for routine sterile work in volume.
Polystyrene or polypropylene?
Polystyrene is glass-clear and rigid, which is why 12 × 75 mm polystyrene tubes are the standard for flow cytometry and anything read by eye. It cannot be autoclaved and is attacked by many solvents. Polypropylene is translucent rather than clear, but it tolerates far more chemicals, can be autoclaved and handles higher centrifuge speeds.
How are culture tubes sized?
By outside diameter and length in millimetres, so a 16 × 100 mm tube is 16 mm across and 100 mm long. Order caps by the same outside diameter: a 16 mm tube takes a 16 mm cap. Check rack and centrifuge-bucket fit against the diameter too.
Sterile or non-sterile?
Sterile tubes are for inoculating cultures and any aseptic work, where a contaminant shows up as a false result. Non-sterile tubes suit chemistry, serology and sample handling where the contents are not being grown, and they cost less by the case.
