About The Do’s And Don’ts For Pipette Operation
The working principle of the pipette is that the piston moves through the telescopic movement of the spring to achieve aspiration and discharge. Under the push of the piston, part of the air is exhausted, and the liquid is sucked in at atmospheric pressure, and then the air is pushed out by the piston to discharge the liquid. When using a pipette, it can be operated in accordance with the flexibility of the spring, which can control the speed and strength of pipetting.
A pipette is an indispensable tool for the experimental operation. The operators should use it correctly, or it will cause the error and even experiment failure.
1. Tip assembly
The pipette sleeve is pressed down firmly and can be rotated to a small extent when needed.
Don’ts: Hit the tip with force, which will cause damage to the tip or even wear of the pipette sleeve, affecting its sealing effect.
2. Volume setting
Please select the correct pipette before the operation. When adjusting from small to large volume, it will rotate continuously in the direction of the required volume, and reach back to the required volume after reaching more than 1/3 of the required volume. By doing so is to guarantee the best accuracy. When adjusted from large to small, which is the normal adjustment method, it is directly rotated continuously to the required volume.
Repeat the aspirate and drain two to three times with the same sample, and provide the same contact surface for each aspiration to ensure the consistency of operation.
Don’ts: Please do not rinse the high temperature or low-temperature liquid.
4. Tip immersion angle
When aspirating, keep it vertical and do not make the inclination angle exceed 20°.
5. Tip immersion depth
0.1-10μL: 1-2mm; 10-200μL: 2-3mm; 200-2000μL: 3-6mm; over 2000μL: 6-10mm
6. Tip immersion time
After aspiration, hold it in the liquid for one second and then gently remove the tip, which is especially important for large-capacity pipettes or for viscous samples.
7. Suction speed
Continuously and eventually pipette, control the pipetting speed, too fast will cause the liquid splash, liquid or aerosol to rush into the inside of the pipette, contaminating the piston and other components.
8. Liquid discharge and suction
Discharge the liquid by pressing the piston to the first gear. And then press the second gear to suck the liquid.
Notes during operation
(1) When sucking the liquid, be sure to release the thumb slowly and smoothly. Never let it suddenly loosen, in case the solution is sucked too fast and flush into the liquid extractor to corrode the plunger and cause air leakage.
(2)In order to obtain higher precision, the tip must be sucked before the sample solution and then officially pipetted. Because the serum protein solution or organic solution is taken up, a “liquid membrane” will remain on the inner wall of the tip, resulting in errors due to the small amount of discharge.
(3)For liquids with high concentration and viscosity, an error will be generated. It can be determined by experiment for the amount of compensation to eliminate the error. By changing the reading of the reading window with the adjustment knob, the compensation amount can be set.
(4) Do not use a pipette to mix the liquid.
(5) Do not use a large-scale pipette to remove a small volume of liquid to avoid affecting accuracy. Also, if you need to remove a larger amount of liquid over the volume, use a suction pipette.