An air displacement pipette uses a piston to create an air cushion that aspirates and dispenses liquids, keeping the piston separate from the sample. It works by moving a piston to displace air, forming a vacuum to draw in liquid (aspirate) and then pushing air to expel the liquid (dispense). This method is accurate for standard aqueous solutions but can be affected by volatile or viscous liquids.
How It Works
Aspiration (Intake)
The piston moves down to push out air, then moves up to create a partial vacuum, drawing liquid into the pipette tip.
Dispensing (Output)
The piston moves down again, forcing the air cushion to expel the liquid.
Blow-Out
Some pipettes have a second “stop” to fully expel residual liquid from the tip.
Key Characteristics
Air Cushion
The air separates the piston from the sample, preventing direct contact.
Best For
Aqueous, non-viscous liquids under standard laboratory conditions.
Accuracy
High for routine applications, but sensitive to temperature, pressure, and solution density.
