Reverse pipetting is aspirating a bit extra to dispense the proper amount. Reverse pipetting is handy while pipetting viscous, foaming, and high vapor pressure or other low surface tension liquids. The technique is mainly recommended for solutions with high viscosity or a tendency to foam up since it reduces the risk of splashing or bubble and foam formation. Reverse pipetting is more precise for dispensing smaller volumes of liquids containing biological solutions and other proteins than the usual pipetting method, mainly used for buffers, alkalis, and diluted acids. Read on to learn more!
The Main Steps of Reverse Pipetting
A positive displacement pipette is a perfect instrument to precisely and accurately transfer these kinds of liquids. Still, reverse pipetting will provide an effective workaround while using a regular air-displacement pipette. To reverse the pipette, you should:
- Set the pipette to your desired volume, Depress the plunger entirely – past the first stop to the second (blowout) stop.
- Immerse the tip into the liquid, slowly releasing the plunger to a full extension.
- Dispense by pressing right to the first stop.
- A tiny amount of liquid will remain in the tip. Blowout this residual volume into a separate container and then properly dispose of the used tip
Remember, reverse pipetting could reduce accuracy, and precision is usually user-dependent.
Electronic Pipettes and Reverse Pipetting
A few electronic pipettes have a mode for reverse pipetting, which allows the user to set the following parameters:
- The desired volume
- The excess volume, around three to five percent of the average volume of the pipette
- Specify whether the excess volume should be discarded or included in the next aspiration.
- The dispensing speed
- The aspiration speed
If you’d like to learn more about pipetting techniques, visit the Lab People!
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