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Pipette Types and Usage

Sep 17, 2025

Overview

This lecture introduces the different types of pipettes used in aseptic lab work, explaining their features, correct handling, and basic operating procedures.

Types of Pipettes

  • Serological (blowout) pipettes have an etched or colored band indicating all liquid must be expelled for accurate measurement.
  • Serological pipettes often contain a cotton plug to protect the pipetting device from contamination.
  • Measuring or drain-out pipettes lack the etched band and may or may not include a cotton plug; liquid should not be blown out past the end.
  • Both pipette types may measure up to 10 mL with 0.1 mL increments.

Using Pipetting Devices

  • Attach the pipette to the pipetting device by inserting and gently twisting for a secure seal.
  • The pipetting device plunger is used to draw in and expel liquid; avoid leaks by checking the seal.
  • For blowout pipettes, start the plunger slightly above the bottom for extra pressure to expel the last drops.

Micropipettes

  • Micropipettes can typically dispense 100–1000 microliters (ÎĽL); 1000 ÎĽL equals 1 mL.
  • Volume is adjusted by twisting the plunger; never set outside the stated minimum or maximum range.
  • Always use sterile, disposable tips when using micropipettes to prevent contamination.

Micropipette Operation

  • Hold the pipette in your dominant hand, use your thumb for the plunger.
  • The plunger has two stops; press to the first stop to aspirate liquid, and to the second stop to dispense all liquid.
  • Obtain a sterile tip by pressing the pipette into a tip within the box and immediately replacing the lid.
  • Eject the used tip with the ejector button—do not remove it by hand.

Key Terms & Definitions

  • Serological Pipette — A pipette designed to be “blown out” for full volume delivery, marked by an etched band.
  • Blowout Pipette — Another term for serological pipette, requiring all liquid to be expelled.
  • Measuring (Drain-Out) Pipette — Pipette used to measure liquid without blowing out the last drop.
  • Micropipette — Adjustable pipette for very small volumes (ÎĽL range), used with disposable tips.
  • Plunger Stops — Two positions on the micropipette plunger; the first for aspiration, the second for dispensing.

Action Items / Next Steps

  • Practice attaching both types of pipettes to the pipetting device.
  • Review correct micropipette operation, especially using the two plunger stops.
  • Always use proper sterile technique when handling pipettes and tips.