How to Pipette Properly (and the most common mistakes people make when pipetting)
Posted by Maxi Scientific on Jan 14th 2025
Pipetting is an essential skill in any laboratory. Whether you are conducting PCR, preparing serial dilutions, or setting up cell culture experiments, the accuracy and precision of your pipetting technique can significantly impact the reliability of your results. As an experienced scientist, I’ve seen how small mistakes can lead to big experimental failures. This guide will walk you through proper pipetting techniques, highlight common pitfalls to avoid, and share advanced tips to take your pipetting skills to the next level. So here's how to do it RIGHT:
- Choose the Right Pipette and Tip:
- Match the pipette’s volume range to the amount you’re pipetting.
- Use high-quality tips that fit snugly and are free of defects.
- Set the Volume Correctly:
- Always adjust the pipette volume within its recommended range.
- Avoid forcing the dial past its upper or lower limits.
- Pre-Wet the Tip:
- Aspirate and dispense the liquid 2-3 times before pipetting. This ensures consistent delivery by conditioning the tip.
- Use the Correct Pipetting Angle:
- Hold the pipette vertically when aspirating and at a 20-30° angle when dispensing.
- Avoid tilting the pipette excessively to prevent errors in volume.
- Immerse the Tip Properly:
- Immerse only the first few millimeters of the tip in the liquid.
- Immersing too deeply can cause contamination or uneven aspiration.
- Aspirate and Dispense Slowly:
- Press the plunger smoothly to the first stop and release it slowly to aspirate.
- Dispense at a controlled rate to avoid splashing or introducing bubbles.
- Pause for Equilibration:
- After aspirating, wait 1-2 seconds before removing the tip from the liquid to ensure full uptake.
- Touch Off the Tip:
- Gently touch the pipette tip against the container wall when dispensing to release any residual liquid.
Common Mistakes in Pipetting
- Using the Wrong Pipette:
- Selecting a pipette with a volume range that’s too large or small reduces accuracy and precision.
- Not Pre-Wetting the Tip:
- Skipping this step can lead to inconsistent results, especially with viscous liquids.
- Plunging Too Quickly:
- Rapid plunger movements can introduce bubbles and cause inaccurate volume delivery.
- Incorrect Tip Immersion:
- Immersing the tip too deeply or too shallowly can lead to aspiration errors or contamination.
- Holding the Pipette Incorrectly:
- Tilting the pipette while aspirating can draw air into the tip, leading to inaccuracies.
- Neglecting Calibration:
- Using an uncalibrated pipette can result in significant volume discrepancies.
- Reusing Tips:
- Reusing tips can cause cross-contamination, especially in sensitive experiments.
Pipetting Hacks and Tricks You Might Not Know
- Use Reverse Pipetting for Viscous Liquids:
- For samples like glycerol or serum, reverse pipetting minimizes air bubbles and ensures accurate dispensing.
- Keep a Consistent Grip:
- Warm hands can heat the pipette, affecting accuracy. Use light pressure and work quickly to minimize temperature effects.
- Mark Your Tips:
- When working with multi-well plates, mark the last well pipetted to avoid skipping or duplicating wells.
- Utilize Low Retention Tips:
- These tips reduce liquid adhesion, ensuring accurate dispensing of viscous or small-volume samples.
- Practice One-Handed Tip Ejection:
- Mastering this technique can improve efficiency during high-throughput tasks.
- Rinse Tips When Necessary:
- For highly concentrated solutions, rinsing the tip by aspirating and dispensing the sample ensures full delivery.
- Use a Pipetting Aid for Repetitive Tasks:
- Ergonomic tools or motorized pipettes can reduce strain and improve accuracy during prolonged experiments.
- Monitor Pipette Calibration Dates:
- Keep a log of calibration dates and recalibrate regularly to maintain accuracy.
If you have any more questions, feel free to reach out to us, we'll be happy to help!