About the Do’s and Don’ts for Pipette Operation

Pipette is a perfect tool to transport a measured volume of liquid. It is widely used as a media dispenser in labs. For different purposes and needs of accuracy and precision, we can find pipettes in several designs in the market, glass and polyethylene ones. Adjustable and electronic pipettes are available too, such as Advanced Half Autoclave Single Channel Adjustable Pipettes, Advanced Fully Autoclave Single-Channel Adjustable Pipettes, and Advanced Fully Autoclave 8/12 Channels Adjustable Pipettes.

The pipette is always needed wherever the precise transfer of liquid is required in the lab. Regardless of what type the pipette you have, you should handle them with care. Placing the pipette 1/4 of an inch from the bottom of the container is the right way to prevent damage when you draw the liquid. You’d better tap the side of the pipette to remove excess droplets very gently when the required volume of the liquid is drawn up. Always hold the pipette at a 10-20 degree angle when you dispense. Never blow through a pipette and try to remove extra liquid.

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.

To make sure the pipettes work accurately and also to prevent pollution from previous contents, you should clean them after use.

Operation Procedures of Pipette

To do a correct liquid operation using a normal pipette, there are some operating steps to follow, first, connect the suction head, then press the piston exhaust, insert the suction head approximately 2 mm below the liquid level, next, inhale liquid and transfer to the destination container, finally, push off the suction head. It takes about 10 seconds for the whole process.

Maintenance Procedures of Pipette

In experimental operation, when there is liquid in the suction nozzle of the pipette, do not place it horizontally or inversely to prevent the liquid from flowing into the piston chamber to corrode the pipette piston.

Besides, use the pipette correctly to absorb and drain liquid to achieve high precision; when it occurs leakage in operation, stop for one to three seconds after suction to see whether the liquid level in the suction head drops, if the liquid level drop, first to check whether there is a problem with the suction head, if it is, just replace the suction head, if not, call for professional maintenance personnel to repair.

Operation steps

A pipette is an indispensable tool for the experimental operation. The operators should use it correctly, or it will cause errors 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. 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.
3. Rinse
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 flushed 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.