Consider these liquid handling best practices for micro-pipetting.
- When holding your pipette, a straight up-and-down position, like in a hand-shake is ideal. Not only does this provide improved posture for ergonomics, but angling the pipette will draw up more solution, causing inaccuracy.
- Pre-wet the tip by drawing and dispensing 1-3 times before pipetting. Accuracy is improved by increasing humidity within the pipette shaft and decreasing evaporation of the sample within the tip.
- For solution draw, depress the pipette plunger to the first stop, then insert the pipette tip straight into the solution, immersing the tip into your solution at approximately 1 cm immersion below the meniscus. Immersed tips at >1cm can carry-over liquid. Avoid touching the sides of the container which will increase “wicking” and loss of volume during draw.
- Release the plunger smoothly and steadily to aspirate the liquid.
- Pull the tip straight out of the liquid while avoiding touching the sides of the container. Hold for a moment before dispensing.
- When dispensing, touching the tip to the inside wall of the tube creates the “wicking” effect which, in this case, is helpful to fully dispense any residual sample left in the tip.
- During solution dispense, depress the plunger smoothly and steadily - past the first stop, all the way to “blow-out” to ensure all residual sample is delivered.
- A forward pipetting technique is most effective when using nucleic acids, buffers, aqueous solutions, and other standard reagents and chemicals.
- A reverse pipetting technique is most effective when using viscous solutions such as whole blood, serum, protein or glycerol. Review your pipette manual for proper reverse pipetting technique.
- As outlined in the article “Liquid Handling Best Practices”, follow the ergonomic recommendations discussed:
- Establish a bench top comfort zone.
- Maintain a relaxed posture.
- Avoid the “winged” pipetting technique.
- Use ergonomic tools for pipetting.
- Practice hand exercises and upper quadrant stretches after each 20 minutes of continuous pipetting. Refer to www.rsitips.com/rsi-prevention-exercises for recommended techniques.
Ergonomic safety and best practices, when combined with proper pipetting technique, can contribute to accuracy, precision, safety and comfort while performing pipetting in the lab.
Be sure to check out the infographic "For Laboratory Technicians, the Risk is Real" for more on the risks of poor pipetting practices.