Pipettes are such a routine part of everyday life in the lab that it can be easy to take them for granted. Their accuracy is vital, and there are many things we can adopt as best practices for success. Here are a few tips (no pun intended) gathered from around the Web by Kim Steinhauser of the Promega Metrology Department–the group charged with keeping our pipettes and other lab equipment functional and accurate.
- Pre-wet tip. Aspirate liquid into the tip and dispense two or three times before taking up the desired volume.
- Immerse to appropriate depth during aspiration. Immerse the tip below the meniscus. Large volume pipettes should be immersed to 5-6 mm, while smaller volume pipettes should be immersed to 2-3 mm.
- Pause consistently after aspiration and before removing the tip from the liquid. The liquid will continue moving into the tip after the plunger stops, so this consistent pause before removing the tip from the liquid will ensure the amount of liquid drawn into the pipette is accurate.
- Use consistent plunger pressure and speed.
- Aspirate sample at a 90° angle and dispense at a 45° angle. These angles are optimal for ensuring all material is drawn up into, and expelled from, the tip.
- Reduce heat transfer by holding the pipette loosely and setting down when not in use.
- Store pipettes vertically to avoid contamination.
- Store pipettes dialed to highest volume setting.
- Store away from heat and moisture.
- Pipette tips should be removed prior to storage.
- Keep pipettes clean and free of contaminants
- When cleaning pipettes with bleach solution, do not saturate as fluid can make its way to the piston and cause corrosion.
These tips were gathered from this source material:
- How to improve your pipetting technique
- Tips to improve pipetting technique
- Gilson guide to pipetting (pdf)
- How should I store my micropipettes?