Pipette "pipette gun" use and purchase

A pipette, also known as a pipette gun, is an instrument
used to transfer liquids in quantitative quantities.
In analytical testing, pipettes are generally used to pipette small or small amounts of liquid
.
Pipettes can be divided into gas piston pipettes and positive displacement pipettes
according to the principle.
Gas piston pipettes are mainly used for standard pipetting, and positive piston pipettes are mainly used to handle special liquids
such as volatile, corrosive and viscous.
How to choose a pipette 1.
The short movement distance of the thumb to complete a pipetting cycle means higher comfort; Comparing pipettes of the same range requires thumb force to complete a drain (be sure to press to the end) is key to comfort, less force means less risk of finger damage from long-term use; 2.
Loading and unloading the suction head, the same as the less labor, the better; 3.
The weight of the pipette is moderate, too heavy will increase the burden on the hand, but too light also often means that the material may be slightly worse; 4.
Other auxiliary designs, such as the matte design of the shell and the finger hook design, help to further improve comfort
.
How to use the pipette Before pipetting, make sure that the pipette, tip and liquid are at the same temperature
.
While aspirating the liquid, keep the pipette upright and insert the tip 2-3 mm
below the liquid surface.
Before aspirating, the liquid can be aspirated several times to moisten the suction nozzle
.
There are two pipetting methods
available.
One is forward pipetting
.
Press the button to the first stop point with your thumb, then slowly release the button back to the original point
.
Then press the button to the first stop to drain the liquid, stop for a while and continue to press the button until the second stop to blow out the residual liquid
.
Finally release the button
.
The second is reverse pipetting
.
This method is generally used to transfer highly viscous liquids, bioactive liquids, easily foaming liquids or very small amounts of liquids, first inhale more liquid than the set range, and do not need to blow out the residual liquid when transferring the liquid
.
Press the button to the second stop point and slowly release the button to the origin
.
Then press the button to the first stop point to drain the liquid of the set range, continue to hold the button at the first stop, remove the tip with residual liquid, and discard
.
Working principle of pipette The basic principle of pipette work is that the piston realizes aspiration and discharge through the telescopic movement of the
spring.
Under the push of the piston, part of the air is expelled, the liquid is sucked in under the action of atmospheric pressure, and then the piston pushes the air to discharge the liquid
.
Due to the elasticity of the spring, the speed and force
of pipetting can be well controlled by this feature of the spring in the use of the pipette.
The common micropipette type uses a built-in gas piston, the piston is designed inside the pipette, relying on pushing air to aspirate and discharge liquid, and the piston is not in direct contact
with the liquid.
Another type of pipette is an active displacement piston designed inside the tip and in direct contact with the liquid, which is suitable for handling
liquids with large viscosities or prone to bubbles.
Common sense and advice for using pipettes 1.
Choose a medium-range tip
.
2.
Appropriate
force when installing the tips.
3.
The depth and angle of the tip contacting the liquid level are consistent
.
4.
For room temperature samples, the tip is pre-rinsed to improve the sampling accuracy
.
5.
Maintain a reasonable aspiration speed Suggestions for use 1.
Maintain a correct posture
when pipetting.
2.
Check the sealing condition of the pipette regularly, and replace the sealing ring
in time once the seal is found to be aging or leakage.
3.
Correct the pipette 1-2 times a year (depending on the frequency of use).

4.
Most pipettes, before use and after a period of use, should be coated with a layer of lubricating oil to maintain tightness
.