Glossary
Luer-Lock
Luer-lock fittings twist a needle onto the syringe tip with a thread instead of a press fit. Why that secure joint matters for filters and thick solutions.
A luer-lock is the threaded form of the common syringe cone with its 6% taper. 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 — pushing solution across a 0.22 µm filter membrane, moving a viscous solution, or using a narrow gauge needle — can make a slip fitting separate and spray its contents. At the bench this costs the sample and soils the workspace — more than an annoyance, so filtration steps and larger transfers are routinely done with luer-lock syringes.
By contrast, the typical U-100 insulin syringes have a permanently attached needle and no detachable hub, which is precisely what gives them their extremely low dead volume. Our guide to syringes and needles explains when to pick which, and the shop carries both alongside vials.
Related terms
Reconstitution and aliquot