Pipettes & Pipettors
Pipettes and pipettors are laboratory instruments used to aspirate (collect) and dispense liquids. A pipette is categorized either as To Contain (TC) or To Deliver (TD). To Contain pipets are designed for a particular volume as designated by the pipette size, for example 15mL, and can often be sealed for freezing or long-term storage. A TC pipet is less accurate than TD types. Common types of TC pipettes include aspirating, dropping, and volumetric. To Deliver (TD) pipettes are designed to dispense a predetermined volume with a high degree of accuracy, for example 2 microliters.
While some pipettes are designed specifically to transfer liquids, others have high-precision measuring capabilities. Pipette types that are used to measure liquids or fluids include serological, microcapillary, aspirating, bacteriological, Ostwald Folin, Mohr, and Pasteur. Pipettes that are designed to transfer liquids include dropping, transfer, and volumetric.
A pipettor is an instrument used to dispense liquid while pipetting. Standard pipettors are usually rubber bulbs or other mechanisms that are manually operated. Electronic models can be programmed to dispense a predetermined volume of liquid into the receptacle. A single-channel model dispenses liquid into one receptacle at a time. Multichannel models simultaneously dispense an equal volume of liquid into more than one receptacle, usually eight or twelve, and are used to speed processing and ensure consistent results.
Pipette tips are used to protect pipettes, speed processing, or prevent cross-contamination. Universal pipette tips are designed to fit most standard diameter pipettes. Specialty tips include filtering tips that protect the mechanism from contamination and aspirating tips that increase user safety by reducing or eliminating spray. Robotic tips are available in racks that are used with automated pipettors. Racked tips allow users to change tips without handling, which reduces the risk of contamination. This is especially important when working in sensitive environments that require sterile surfaces.