Attention, This Is How Your Pipette and Its Tip Was Accidentally Damaged

Wrong operations of the pipette tip

The pipette is a small piece of equipment that is frequently used in the laboratory, and its portability and accuracy are very important performances. In order to be able to ensure its performance, we need to pay attention to the following inadvertent wrong actions during use.

1. When installing the tip, beat the tip repeatedly
Sometimes, we will beat the tip repeatedly to make the pipette and the pipette tip connected tightly, when installing the tip. For one thing, it will make the tip deform and affect the accuracy. For another, it will even bring damage to the instrument, as the air tightness between the instrument and the tip does not heal for a long time.

2. When aspirating, quickly loosen the lift rod
Most instruments use a spring to generate a negative pressure inside so that the liquid is pressed into the tip. A sudden increase in internal and external pressure may result in fluid flooding into the instrument, which may cause the instrument to be rusted, corroded, or contaminated.

3. When there is still liquid in the tip, place the pipette flat or upside down
By doing so, under the action of gravity, a large amount of liquid may flow back into the instrument, making the pipette rusted, corroded, or contaminated, etc.

4. Over-range use
The internal pipette adjusts the volume through the screw thread. The required range is usually the rotation range of the thread. If the adjustable range is forced to exceed the range too much, in rare cases, the thread will be stuck and cannot be restored, and in the worst case, the connecting parts will be directly damaged.

5. Ignore the recommendations and direct high temperature and autoclaving
At present, not all parts of many pipettes can withstand high temperature and high pressure sterilization, and the unbearable parts may be severely deformed, causing the instrument to be unable to recover; For the 100% high temperature and high pressure sterilization instrument if not simply disassembled first, but putting the whole into the sterilization pot may also be damaged due to the different expansion speed of each part.

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Correct operations of the pipette tip

Then how to install and use the pipette and its tip correctly? Follow these steps.
1. Tip installation
The correct installation method is called rotary installation. Insert the pipette top into the pipette tip (no matter whether it is a bulk pipette tip or a boxed pipette tip), while pressing down gently, slightly turn it left and right to tighten.

2. Pipetting volume setting
Coarse adjustment: quickly adjust the volume value to close to your expected value by rotating the button;

Fine adjustment: When the volume value is close to your expected value, you should place the pipette horizontally in front of your eyes, and slowly adjust the volume value to the expected value through the adjustment wheel to avoid the impact of visual errors; When adjusting from a large volume to a small volume, it is a normal adjustment method, just adjust it to just right volume; When adjusting from a small volume to a large volume, it is necessary to adjust the scale that exceeds the set volume first, and then return to the set volume to ensure the best accuracy. (This is because there is a certain gap in the counter, which needs to be filled).

3. Pre-washing the pipette tip
After we install a new pipette tip or increase the volume value, we should absorb and discharge the liquid to be transferred two to three times. The purpose is to form a homogeneous liquid membrane on the inner wall of the pipette tip to ensure the precision and accuracy of the pipetting work, and to make the entire pipetting process highly reproducible. To inhale highly volatile liquids, pre-wash the tip four to six times and saturate the gas in the white sleeve chamber so that the negative pressure will disappear automatically.

The viscous liquid can be accurately pipetted by pre-wetting the pipette tip. First, aspirate the sample liquid and then discharge it. The inner wall of the pipette tip will absorb a layer of liquid to make the surface adsorption saturated, and then suck the sample liquid, and finally discharge the liquid. The volume will be very precise.

4. Aspiration
First press the pipette discharge button to the first stop, and then immerse the pipette tip vertically into the liquid surface. If the immersion is too deep, the hydraulic pressure will have a certain impact on the accuracy of liquid suction. Of course, the specific immersion depth should also be flexibly controlled according to the size of the liquid container.

5. Dispensing
When discharging liquid, the tip should be close to the wall of the container, first press the discharge button to the first stop point, and after a slight pause, press to the second stop point. It can ensure that there is no residual liquid in the tip. If there is the residual liquid after this operation, the tip should be replaced.

6. Remove the tip
Do not mix the removed tip with the new tip.
After the pipette is used up, adjust back to the maximum range.

Use notes and maintenance of the pipette tip

1. Check air leakage.
Visual inspection:
After the liquid has been absorbed, let the pipette stand vertically for 15 seconds, and observe whether any droplets flow out slowly. It has air leakage if outflow appears.

Possible causes and solutions:
Tips do not match
Use the original matching tip

The tip is not tightened when assembling
Pay attention to the method of assembling the tip

Poor airtightness inside the pipette
Ask the engineer of the instrument manufacturer to deal with it

2. Maintenance
Regularly clean the pipette, just use alcohol cotton to mainly wipe the outer shell, which can keep the appearance and reduce the possibility of contamination to the sample; Disassemble the whole pipette after the highly volatile and highly corrosive liquid is absorbed. Rinse the piston rod and the white sleeve inner wall with distilled water, and dry it before installation and use.