Pipette Choosing Based on Pipette Principle

1. How does a pipette work?

Pipetting tools can be divided into gas piston pipettes and external piston pipettes (also called dispensers) according to the principle.
Gas piston pipettor, its working principle is to push the piston through the telescopic movement of the spring, remove part of the air, using the atmospheric pressure to inhale the liquid, and then push the air to discharge the liquid by the piston. Most pipettes on the market are of the gas piston type.
External piston pipette like bottle top dispenser, The working principle is to remove and dispense liquid through the continuous movement of the piston in the dispensing tube or the tip. The piston is in direct contact with the liquid without air column.

2.  Appropriate pipette choosing

a. Select an appropriate volume according to the size of the sample volume to be processed. Pipette using range with 30%-100% of the nominal maximum volume. Do not use a large-capacity pipette to pipetting small volumes of liquid, it may affect accuracy.  If you need to pipette a larger amount of liquid outside the range, such as more than 10ml, it is recommended to use a large-volume pipette tool like pipette pump, bottle top dispenser etc.

b. Choose incompatible pipetting tools according to the nature of the sample. Gas piston pipettes are suitable for pipetting aqueous solutions, such as water, buffers, diluted salt solutions and acid-base solutions. The external piston pipette is suitable for pipetting viscous solutions, volatile solutions, and liquids that are prone to bubbles.

c. Choose a suitable pipette according to the pipetting container, a single-channel pipette can be used for ordinary test tubes or centrifuge tubes. For relatively deep test tubes, you can choose an external piston type or a large-capacity pipette to work with the pipette. Reagent tank, 96/384-well plate or 8-row, multi-channel (8-channel/12-channel) pipettes can significantly improve work efficiency compared to single-channel models.

d. At high altitudes, atmospheric pressure changes, so the pipetting accuracy of gas piston pipettes can be greatly affected. External piston pipettes are recommended.