How is pipetting performed?

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Operating principle of a micropipette

Air displacement micropipettes and positive displacement micropipettes operate differently.

Air displacement micropipettes
  • There is an “air cushion” between the piston and the liquid sample.
  • The piston is part of the micropipette itself.
Cross-sectional diagram of a micropipette with air cushion. From top to bottom: piston, tip, air cushion, disposable tip and sample Information pictogram
Positive displacement micropipettes
  • The piston and the liquid sample are directly in contact.
  • The piston is disposable because it is joined to the tip.
Cross-sectional diagram of a positive displacement propette. From top to bottom: the piston, the disposable piston, the disposable capillary, the piston seal and the sample. Information pictogram
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How these two micropipettes work explains their limitations.

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