The viscosity of the sample will have a direct influence on which pipette is required. For aqueous samples which are low viscosity, an air displacement pipette is ideal. These pipettes are driven by a piston in an airtight sleeve which generates a vacuum. For more viscous or heavy liquids, a positive displacement pipette should be used. These pipettes are driven by a disposable piston which comes into direct contact with the sample.
How will samples required for PCR, ELISA, or other immunoassay applications affect which pipette should be used?
What to Know Before Buying Pipettes