How to Proper use of pipettes and tips

Like a chef using a knife, a scientist needs pipetting skills. A seasoned chef may be able to cut a carrot into ribbons, seemingly without a thought, but it never hurts to keep some pipetting guidelines in mind—no matter how experienced the scientist. Here, three experts offer their top tips.

“One must be careful to have the right technique when manually dispensing liquid,” says Magali Gaillard, senior manager, portfolio management, MLH Business Line, Gilson (Villiers-le-bel, France). “Some of the most common pipetting errors are related to the careless use of pipette tips, inconsistent rhythm or timing, and improper handling of the pipette.”

Sometimes, a scientist even selects the wrong pipette. As Rishi Porecha, global product manager at Rainin Instruments (Oakland, CA), says, “Some common errors in pipetting include not using the correct volume pipette for a specific task and using an air-displacement pipette to handle nonaqueous liquid.” With viscous fluids, a positive-displacement pipette should always be used.

Before getting to specific pipetting procedures, some general concepts should be considered. “Each time pipette users begin work for the day, they should consider what experiment they are doing, what liquids they are working with, and what throughput they desire prior to selecting a pipette,” Porecha says. “Realistically, no lab has all the pipettes that a user might desire, but if a user takes a look at what tools are available in the lab and department, they might get a better idea of what existing pipettes to implement in an assay or of what pipettes they might want to purchase.”

The features available in today’s pipettes extend beyond the device itself. Advances in liquid handling have made it possible for users now to connect their pipette to the cloud. With this connectivity, a user can download protocols or create custom ones. Pipetting data can even be captured in the cloud, which is one way to identify any missteps and enhance the pipetting process, especially by tracking the ongoing accuracy, or lack of it.

With the right equipment in hand, the next challenge is getting the steps right.

Key of  Success

With an air-displacement pipette, the following steps increase the likelihood of accurately and repeatedly measuring a specific volume:

1. Set the volume on the pipette.
2. Depress the plunger.
3. Immerse the tip to the correct depth, which can vary by the pipette and tip, and smoothly let the plunger go to its resting position.
4. Wait about one second for the liquid to flow into the tip.
5. Put the pipette—held at 10–45 degrees—against the wall of the receiving chamber, and smoothly depress the plunger to the first stop.
6. Wait one second and then depress the plunger to the second stop.
7. Slide the tip up the vessel wall to remove the pipette.
8. Allow the plunger to return to its rest position.