USES OF PIPETTES

Pipettes are tools that are used in clinical and research laboratories to remove small volumes of liquids with high precision.

WHAT IS A PIPETTE?

Pipettes are tools for transferring or measuring small volumes of liquids from one container to another very accurately.
There are different models of pipettes, they were made of glass; Currently, there are many options to choose from.
The emphasis of this chapter is on fixed volume pipettes and variable volume pipettes with mechanical control, recently, pipettes with electrical control have also been marketed. This chapter talks about maintenance and calibration of mechanical pipettes .

PRINCIPLES OF PIPETTE OPERATION

Mechanical or piston pipettes usually work by applying manual pressure on the piston. The piston inside a cylinder with a fixed length moves and guides a specific volume of liquid into or out of the pipette.
There are two types of piston pipettes: a fixed volume pipette that moves a fixed volume of liquid, the nominal volume of NV, and a variable volume pipette that moves different volumes according to the specific characteristics of the pipette. .
Adjusting the variable volume on the pipette is done with the movement of the piston and according to the limit of the piston’s performance . In this type of pipettes, the nominal volume is the maximum volume that the pipette can hold. Types of fixed and variable pipettes
are also divided into two types A and B.

Type A: In this type, there is a volume of air between the piston head and the liquid inside the pipette cylinder.
Type B: In this type, the piston is in direct contact with the liquid. They are less; But unlike B-type pipettes, when they are used to withdraw very small volumes, they do not have enough accuracy because the air in them is condensed and compressed.
All pipettes have disposable sampler tips to minimize contamination. To ensure the solidity of the connection of the sampler head and the volume transferred by pipette, it is suggested to use the head of the sampler recommended by the manufacturer or the tip of the sampler that is used for pipettes of a specific volume. In order to identify the different volumes
on the pipettes, some manufacturers use color codes.