Overview of Pipette

A pipette is a laboratory tool used for accurate measurement and transfer of a specific volume of liquid. It is an essential instrument in various scientific disciplines, including biology, chemistry, and analytical chemistry. Here is an overview of pipettes:

General Description

A gun-shaped one is a classical type of pipette, which is often applied to remove small or trace amounts of liquid in a laboratory. Pipetting guns with different specifications are also designed with gun heads of various sizes. Even though manufacturers are likely to attribute to many shapes, the working principles and operation methods are almost the same. Besides, the pipette belongs to precise instruments, so it should be really carefully used and stored to prevent damage and broken measuring range.

Main Categories

In terms of the application, the pipetting gun can be divided into several types– micro-sampler, air cushion sampler, positive displacement, multichannel sampler, electronics, and distributors.
The micro-sampler was first invented by Schnitger (a scientist at the German Institute of Physiology and Chemistry) in 1956. The later development included not only more precise displacing, but also wider varieties with respective applications, such as micro-distributor and multi-channel micro-sampler, which closely follow two physical principles as follows.
(1) Sampling with air cushion (also known as piston stroke).
(2) Piston positive displacement sampling without air cushion.

Types of Pipettes:

  1. Volumetric Pipette:
    • Used for precise measurement of a single fixed volume. It is commonly used in analytical chemistry and titration.
  2. Micropipette:
    • Designed for small volume measurements, typically in the microliter (µL) range. It is widely used in molecular biology, biochemistry, and clinical labs.
  3. Pasteur Pipette:
    • A simple, thin glass tube used for transferring small volumes of liquids. It is commonly used in microbiology and biochemistry.
  4. Serological Pipette:
    • Used for transferring measured volumes of liquid. They are commonly used in cell culture and microbiology.
  5. Pipette Controller:
    • A device used with a pipette for accurate and controlled aspiration and dispensing of liquids.

Components of a Pipette:

  1. Tip/Nozzle:
    • The narrow end of the pipette where the liquid is aspirated or dispensed. It’s designed to fit with specific tips that come in various sizes.
  2. Pipette Barrel:
    • The main body of the pipette that contains the piston or plunger mechanism.
  3. Volume Adjustment:
    • A mechanism (usually a dial or button) for setting and adjusting the desired volume to be aspirated or dispensed.
  4. Ejector Button:
    • A button used to release the pipette tip after use.
  5. Plunger/Piston:
    • The part of the pipette that moves within the barrel to aspirate and dispense liquid.

Working Principle:

  • Pipettes operate based on the principle of creating a vacuum or positive pressure to draw in or dispense a specific volume of liquid. The volume is determined by the internal mechanism and user settings.

Accuracy and Precision:

  • Accurate pipetting is crucial in obtaining reliable experimental results. Pipettes should be calibrated and maintained regularly to ensure accurate measurements.

Calibration and Maintenance:

  • Pipettes need to be calibrated at regular intervals to verify their accuracy. They should also be cleaned and serviced to ensure proper functioning.

Usage Guidelines:

  • Proper technique, including correct posture and angle, should be followed while pipetting to prevent errors.

Safety Considerations:

  • Pipette tips should be disposed of properly, and the pipette itself should be decontaminated after use with hazardous substances.

Applications:

  • Pipettes are used in various fields such as molecular biology, microbiology, clinical diagnostics, chemistry, and more, where precise liquid handling is crucial for experiments and analyses.