Glossary
Luer-Lock
A luer-lock is a threaded syringe connection that screws the needle on rather than pushing it. Why it matters for filtration and viscous transfers in the lab.
Luer-lock is the screw-thread variant of the standard 6% taper syringe connection. A luer-slip holds the needle on the hub by friction alone; with a luer-lock, a threaded collar is turned down and physically secures the joint. Because the taper is standardised, luer-lock and luer-slip parts have the same cone shape and fit each other dimensionally — the only difference is how the connection is held.
Why the locking fitting matters
It comes down to pressure. Anything that generates back-pressure — forcing liquid through a 0.22 µm syringe filter, moving a viscous solution, or working with a fine gauge needle — can make a slip fitting separate and spray its contents. In the lab that means a lost sample and a contaminated work surface, not just a nuisance, so filtration steps and larger transfers are routinely done with luer-lock syringes.
The flip side is that most U-100 insulin syringes come with a permanently attached needle and no detachable hub, which is precisely what gives them their extremely low dead volume. How to choose between the two types is covered in the syringe and needle guide; browse syringes and vials.
Related terms
aliquot · reconstitution