There are multiple critical factors to consider when selecting a manual pipette. First and foremost are accuracy, precision and volume, followed by ergonomic features, compatibility, durability and serviceability.
Manual pipettes generally cover a range from 0.1 µL to 10,000 µL (10 mL), with specific instruments designed for subsets of this range. Adjustable volume pipettors offer flexibility for different experimental needs, whereas fixed volume pipettors provide consistency and are suitable for repetitive tasks where the same volume is required repeatedly.
Manual pipettes are designed to be precise and should be maintained regularly to ensure consistency. Best practices include regular cleaning and autoclaving, inspection of seals and O-rings, and calibration, according to the end-users’ SOPs. Calibration every 6 to 12 months is common, but it depends on specific usage and company regulatory requirements.
Rebecca Lampert, product marketing manager at BrandTech Scientific., said it’s most important to consider your particular pipetting environment.
“Different techniques are needed when pipetting challenging liquid types like cold or foaming liquids,” said Lampert. “The temperature of the environment and atmospheric pressure can also impact results. Depending on the specific liquid type and environment conditions, different pipetting technique such as pre-wetting, reverse pipetting, and pipetting speed can improve accuracy of results.”
An example is the new "User Adjustment" feature on BrandTech's Transferpette pro, which allows researchers to quickly and easily temporarily change pipette settings to pipette according to their liquid type and pipetting environment. The feature is especially useful in highly regulated environments.
Here are a couple other tips from Lampert when working with manual pipettes:
Avoid repetitive strain injuries
Using a pipette with low plunger and tip ejection force, as well as comfortable grip is crucial when trying to prevent risk of repetitive strain injuries. If a pipette is accurate but uncomfortable or difficult to maintain, it won’t perform well long-term. Some pipettes, such as the Transferpette pro, have the added benefit of a rotating finger rest, so users can adjust the finger rest position to whichever is most comfortable for them personally. Over long hours and days of pipetting, comfort directly impacts ability to achieve high performance.
Avoid this rookie mistake
Do not work outside of the optimal volume range. Even if you are technically pipetting within the operating volume of the pipette, working consistently at the extreme limits of the pipette reduces accuracy and precision. Staying in the middle-to-upper range of the pipette whenever possible produces the best results.