Pipette

A laboratory tool used to transport a measured volume of liquid

A pipette is a laboratory tool commonly used in chemistry, biology, and medicine to transport a measured volume of liquid, often as a media dispenser. Pipettes come in several designs for various purposes with differing levels of accuracy and precision, from single-piece glass pipettes to more complex adjustable or electronic pipettes.

Types of Pipettes

Pipettes can be broadly categorized into several types based on their design and function:

Volumetric Pipettes

File:Volumetric pipette.jpg

A volumetric pipette is used for precise volume measurements.

Volumetric pipettes are designed to deliver a single, specific volume of liquid with high accuracy. They are typically made of glass and have a bulb-like expansion in the middle. These pipettes are calibrated to deliver the exact volume marked on the pipette when the liquid is drained by gravity.

Graduated Pipettes

File:Graduated pipette.jpg

Graduated pipettes are used for measuring various volumes.

Graduated pipettes, also known as measuring pipettes, have a series of graduations along their length, allowing the user to measure different volumes of liquid. They are less accurate than volumetric pipettes but offer more flexibility in volume measurement.

Micropipettes

Micropipettes are used to measure and transfer very small volumes of liquid, typically in the microliter range. They are commonly used in molecular biology and biochemistry laboratories. Micropipettes can be single-channel or multi-channel, and they often have adjustable volume settings.

Pasteur Pipettes

Pasteur pipettes are simple glass or plastic pipettes.

Pasteur pipettes, also known as droppers, are simple glass or plastic pipettes used to transfer small amounts of liquid. They are not calibrated for specific volumes and are often used for qualitative purposes.

Operation

The operation of a pipette depends on its type. For volumetric and graduated pipettes, the liquid is drawn into the pipette by creating a vacuum with a pipette bulb or pump. The liquid is then released by gravity or by applying pressure to the bulb or pump.

Micropipettes operate using a piston-driven mechanism. The user sets the desired volume, depresses the plunger to the first stop, immerses the tip in the liquid, and then releases the plunger to draw the liquid into the tip. The liquid is dispensed by depressing the plunger to the second stop.

Applications

Pipettes are essential tools in laboratories for:

• Preparing solutions and reagents
• Transferring liquids between containers
• Performing titrations
• Conducting enzyme assays
• Handling samples in clinical chemistry

Related pages

• Burette
• Laboratory glassware
• Microliter
• Titration