Views: 106 Author: Yammi Publish Time: 2025-01-06 Origin: Site
A pipette is a piece of laboratory equipment used to measure or dispense small amounts of liquid in milliliter (mL) or microliter (μL) volumes.
There are three basic types of pipettes: glass, plastic and electric. Typically, electric pipettes are used for a wide variety of experimental procedures in chemistry, molecular biology, medical research, and more. In the next section, we will describe how pipettes work, how they are constructed, and what types they are.
The working principle of pipettes is based on two main mechanisms, the air displacement method and the positive displacement method. Each type of pipette has a piston that moves inside a capillary tube or cylinder. In exhaust pipettes, a certain amount of air is left between the piston and the liquid. In volumetric pipetting, the piston is in direct contact with the fluid.
Exhaust method: The telescopic movement of a spring causes the piston to draw in and expel fluid. In response to the push of the piston, some air is released and the fluid is drawn in by atmospheric pressure, after which the air is pressed out to release the fluid. Thus, it is possible to control the speed and force of pipetting while using a pipette, as it operates by utilizing the expansion and contraction properties of a spring. It is mainly used in pipettes.
Volumetric pipettes: Repetitive pipettes or specialized volumetric pipettes often use the volumetric principle. Direct contact with the liquid is achieved by means of a disposable piston that moves within the tip. The sample is then drawn into the tip by the upward movement of the piston (there is no air cushion as in exhaust pipettes). As the piston descends, the selected volume is discharged.
Plunger: it is used to draw up and dispense the desired volume of liquid.
Eject button: It causes the metal bar to drop and eject the pipette tip.
Volume adjustment knob: The volume of the sample to be transferred can be set by rotating the volume adjustment knob to increase and decrease the concentration. It cannot be rotated in fixed volume pipettes.
Volume window: Displays the set volume, the displayed position value depends on the size of the pipette.
Shaft: It is a tube-like structure filled with air in an exhaust pipette. When the piston is pressed down, some air is released from the shaft, which helps in liquid aspiration. Conversely, releasing the piston helps in liquid dispensing while refilling the shaft with air.
Tip cone: This is the area where the pipette tip is attached.
Pipette tip: It is an implement made of polypropylene or plastic, molded and in contact with the liquid.
A single channel pipette is a non-disposable instrument with an exhaustive design that produces accurate measurements using a single disposable tip. Multichannel pipettes are comparable to single-channel pipettes, except that they can accommodate multiple tips at the same time. Liquid is drawn from the same well into different channels simultaneously.
Manual and motorized single-channel variable-volume and fixed-volume pipettes are available, with manual being the most economical and traditional design. In contrast, electronic micropipettes are expensive but offer several advantages, such as improved ergonomics, less user variation, and greater accuracy and precision.
A single channel pipette is a non-disposable instrument with an exhaustive design that produces accurate measurements using a single disposable tip. Multichannel pipettes are comparable to single-channel pipettes, except that they can accommodate multiple tips at the same time. Liquid is drawn from the same well into different channels simultaneously.
Manual and motorized single-channel variable-volume and fixed-volume pipettes are available, with manual being the most economical and traditional design. In contrast, electronic micropipettes are expensive but offer several advantages, such as improved ergonomics, less user variation, and greater accuracy and precision.
While manual pipettes use the mechanical action of the thumb to move the piston (up to 3 cm), motorized pipettes are designed to improve ergonomics by reducing the necessary force.
Fixed range pipettes are best suited for handling thick or viscous liquids. Pipette ranges cannot be changed in fixed-volume pipettes, facilitating quicker operation for the user.
Load the tip into the pipette and remove the tip from the tip box.
Using the volume adjustment knob, adjust the volume to be transmitted.
While maintaining a vertical grip on the pipette, press the plunger to the first position.
Place the tip in the liquid component being sampled.
With the tip still submerged, slowly release the plunger to draw up the liquid. If the liquid is viscous, pause at the end.
Place the tip of the pipette inside the tube or container in which the liquid was collected.
Completely depress the plunger until it stops at the second stop and fill the appropriate tube with liquid.
Press the eject button to remove the used tip and place it in the appropriate trash can.
It facilitates uniform distribution of cells in cell inoculation and avoids foaming and bubble formation.
It makes media exchange of T-bottle cell cultures easy and maintains the sterility of the culture and prevents contamination.
The 96-well microtiter plate is commonly used for microtiter plate applications such as ELISA, PCR, or cell culture, and is compatible with 8-channel or 12-channel variants of multichannel pipettes.
Serological pipettes are used in routine laboratory environments and applications involving cell and tissue culture.