CREDIT: Rebecca Lampert
Rebecca Lampert is the product manager for liquid handling at BRANDTECH Scientific, where she is responsible for a portfolio of liquid handling instruments and consumables. She brings 10 years of experience in the life sciences industry, including hands-on laboratory work and roles in sales, business development, and product strategy. Rebecca holds a degree in Biology from Cornell University.
Q: Many labs work with viscous, volatile, or otherwise challenging liquids. Why do these types of liquids create problems for accuracy and consistency?
A: “At its core, air displacement pipetting relies on predictable liquid behavior. Challenging liquids disrupt that predictability.
Viscous liquids, like glycerol or detergents, flow slowly and resist aspiration and dispensing. That can lead to under-aspiration, incomplete dispensing, or liquid clinging to the tip walls. Volatile liquids, like ethanol or other solvents, evaporate quickly and generate vapor pressure inside the tip. That pressure imbalance can cause dripping or inconsistent volumes. Small changes in environmental conditions can also affect the behavior of the air cushion.
When all of these factors come together, they can introduce meaningful performance variability.
The key takeaway here is that the pipette itself isn’t necessarily the problem—the liquid physics are. Once you recognize that, you can begin to adapt both your technique and your equipment to compensate.”
Q: How do typical lab environments compare to the controlled conditions used when pipettes are calibrated, and what impact can that have on performance?
A: “Pipettes are typically calibrated with distilled water at room temperature and under controlled humidity. Real labs are rarely that controlled.
Temperature differences between the pipette, the tip, and the liquid can significantly impact the accuracy of air displacement pipetting. For example, pipetting cold liquids with a room-temperature pipette can cause the air cushion to contract, which affects the volume dispensed. The best way around this is to, whenever possible, allow the pipette, tips, and liquids to reach the same temperature before use.
Humidity can also influence evaporation rates, which matters when you’re working with small volumes or volatile solvents. Even differences in atmospheric pressure between locations can affect pipetting results.”
Q: When working with challenging liquids, how should pipetting technique adapt?
A: “Technique adjustments can make a significant difference. For viscous liquids, I’d recommend slowing down both aspiration and dispensing speeds and using reverse pipetting when appropriate. Reverse pipetting is especially helpful because it reduces the impact of incomplete dispensing and improves reproducibility.
For volatile liquids, pre-wetting the tip helps saturate the air cushion, which improves consistency. Reverse pipetting can also be useful here.
The important thing is being intentional and consistent with your technique across replicates and among team members.”
Q: Technique is only part of the equation. How can pipette design shape results?
A: “Pipette design plays a bigger role than many people realize. Ergonomics matter because fatigue directly impacts consistency. If a pipette requires excessive force to operate, you’ll often see variability increase over the course of a long protocol.
Pipettes such as the Transferpette® S and Transferpette® pro are designed with low operating forces, smooth piston movement, and a lightweight, comfortable grip. These features help reduce user-to-user variability and minimize repetitive strain during extended use.
Ease of maintenance is another important design consideration. Pipettes that are simple to clean and recalibrate make it easier for labs to maintain performance over time, which directly impacts reproducibility. The Transferpette line is fully autoclavable, and maintenance parts, such as O-rings, can be easily replaced in the lab.
The newer Transferpette pro also includes a feature that allows the user to temporarily adjust settings for challenging conditions, such as viscous liquids, cold reagents, or differences in tip shape.
In practice, users perform gravimetric tests using the liquid they plan to work with. Based on the measured difference between the expected and actual dispensed volume, a calculator or reference table indicates the appropriate adjustment setting. From there, you simply change the setting on the pipette—it’s about as simple as adjusting the volume on the pipette. If you want to go back to pipetting something that’s more aqueous, you just put it back to zero, and you’re done.”
Q: How does tip fit and quality influence accuracy and consistency, and what “tips” do you have for selecting these consumables?
A: “Tip fit is absolutely critical. A poor seal between the tip and the pipette compromises the air cushion and immediately introduces variability. High-quality tips provide uniform wall thickness, consistent geometry, and a reliable seal. When tips are inconsistently molded or fit too loosely, you’ll see inconsistent aspiration volumes or even leaking.
Pipettes are typically calibrated using the manufacturer’s tips during the manufacturing process, so it’s generally safest to use the tips recommended for that specific model. If your pipette accepts high-quality third-party tips, I recommend validating the compatibility first. The Transferpette pipettes have a universal nose cone, so they’re compatible with the tips we manufacture and with high-quality third-party tips.
At the end of the day, even the best pipette can only perform as well as the tip attached to it.”
Q: What steps can lab leaders take to reduce pipetting-related variability and ensure consistent performance across teams?
A: “There are a few tactics I’d recommend for reducing pipetting variability. Tools certainly play a role, but the way we work with pipettes can introduce variability as well.
One of the most important steps is standardizing technique. Training should go beyond how to push the plunger and explain why technique matters. Oftentimes, end users have received training from different institutions, so approaches can vary. Retraining lab members makes sure everyone is aligned.
It’s helpful to standardize equipment where possible. Using the same pipette model and tips across teams reduces variability caused by differences in operating force, balance, and plunger feel. Labs should also implement routine calibration and preventative maintenance schedules rather than waiting for failures to occur.
Finally, document best practices for challenging liquids. This might include guidance on when to use reverse pipetting or features like the temporary user adjustment available on the Transferpette pro. Creating shared SOPs around these practices helps reduce person-to-person variability.
If labs have any questions, we’re always happy to provide support. Best of luck with optimizing your pipetting techniques for challenging liquids!”
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