Reverse Pipetting
What is reverse pipetting and how to do it correctly?
- One of the most commonly employed techniques for viscous liquid handling is reverse pipetting.
- In this method, more liquid is drawn into the pipette than is needed. The desired volume is then dispensed, leaving the excess behind.
- This technique is particularly useful for reducing the formation of air bubbles and ensuring accurate volumes. By ensuring that the pipette tip is fully wetted and then dispensing only the desired volume, reverse pipetting can improve accuracy, especially for very viscous solutions.
- Level 0 is the resting position for the plunger; level 1 is the first stop and level 2 is the second stop, which is used to completely empty the tip.
- For reverse pipetting; press plunger all the way down to level 2, insert tip upright (at a 0° angle) and aspirate the full volume of the tip by de-pressing the plunger back to level 0.
- Then slightly tilting the pipette (at a 30°– 45° angle) dispense the liquid by pressing the plunger slowly down to level 1 (there should be excess liquid remaining in the tip at the end of this step).
- For reverse pipetting multiple times, after the first dispense move the tip back into the viscous solution and aspirate slowly up to level 0. Repeat these steps as many times as necessary, taking care to be slow and considerate to ensure no air bubbles are formed.