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Supply Chain Problems Renew Interest in Pipette Tips Sterilization

pipette tips

Earlier this year many lab publications were reporting severe pipette-tip shortages, with wait times of at least 3 to 6 months for some tips. 

Six months later, many labs are still hearing that their orders for pipette tips may not be filled until January 2022. One lab tech summarized the situation aptly:

“This is f****** insane. 2021 is shaping up to be worse than 2020. We are getting lead times of 3-6 months for some basic supplies. … Our company might have to shut down if we don’t find a solution soon. This is nuts.”

It’s true that COVID-19 testing efforts play a role in driving this shortage. The US alone is still carrying out more than 1 million lab COVID tests each day, with each test requiring four pipette tips

But this supply chain issue runs deeper than just a huge surge in new testing. Late last year an extreme weather event in Texas knocked out polypropylene resin suppliers (needed to make pipette tips, among other items). As we communicate with manufacturers globally, we find that supply and labor mismatches are persistent. Some areas have enough workers to run three shifts, but can only get materials to supply one or two. Meanwhile, in other countries, raw materials continue to be plentiful, but qualified workers are not. 

All of this is compounded by the global shipping issues driving delays at our own factor: There are too few ships with too few pallets, too few trucks to meet them, too few workers to unload them—all exacerbated by impossible-to-predict external factors

Sterilizing and Reusing “Disposable” Pipette Tips

Owing to the shortage, an increasing number of labs are reusing their pipette tips—and discovering all over again that pipette tips can be extremely annoying to sterilize. Tips have a nasty habit of stubbornly clinging to a little bead of water. Some labs go so far as wrapping everything in foil prior to autoclaving in an attempt to “keep the moisture out.” 

This is exactly the wrong approach, because it tends to interfere with sterilization while also trapping moisture.

The keys to successfully autoclaving pipette tips are:

  • Good air circulation—First and foremost, to ensure sterilization the autoclave’s steam needs to touch all surfaces of the pipette tip. But good air circulation also prevents the load from trapping steam pockets. That reduces the risk of water condensing in the pipette tips and becoming trapped.
  • Time—Plan ahead. If you let pipette tips sit in the autoclave as it cools, they will dry on their own. You can speed this process along by transferring your sterilized tip boxes to a heated drying cabinet (or even a spare incubator set at 55ºC). Consider running an overnight cycle so your tips are ready in the morning when you arrive.
  • Chose the “drying” options on your autoclave—Any good lab autoclave will have a “drying” option that can be added to most cycles. The sterilization cycle runs as normal during such a cycle. Then, at the end of the dwell period, the autoclave drains the chamber under pressure while it cools. It then seals the chamber once more and draws a vacuum, causing most of the fluid to evaporate. It doesn’t produce bone-dry loads, but it greatly reduces the moisture available for the tips to capture.

Pipette Tip Sterilization Procedures

With all of this in mind, autoclave sterilization of pipette tips is an easy three step process:

  1. Load your pipette tips into an autoclavable tip tray. If it’s a box-style tray with a lid, then be sure to prop the lid open. (The lid’s locking tab is good for this; hold it in place with a little tape.)
  2. Run your normal sterilization cycle with the “drying” option activated.
  3. Let the damp tips dry in the warm autoclave or transfer them to a drying cabinet/incubator.

After several uses these pipette tips will begin to degrade. At that point, you’ll want to follow a pipette-specific red bag waste procedure prior to disposal.