Why Does the Pipette Always Fail To Work? Maybe You Choose the Wrong Tip

Wanna get better results? We need to know the tools we choose. For the pipette, if we want to get full use of it, we cannot ignore its tip. HAWACH will discuss the classifications, use notes, and other matters about the tip.

Three types of pipette tip available

People are usually very cautious when buying pipettes and are willing to spend a lot of money to buy a good brand with higher accuracy; however, when buying tips, they don’t pay enough attention to them, and they will buy cheap ones. In fact, the tip is also a key factor that affects the results of the experiment, and may also affect the life of the pipette.

Now, there are 3 types of pipette tips available, ordinary pipette tips, filtered pipette tips, and low adsorption pipette tips. For the ordinary tip, it is widely used in general laboratories resistant to organic solvents, and it is more cost-effective with good adaptability. The ordinary tips and even with its box can be autoclaved at 121℃/15psi. The tube body has good transparency and scale line, which is easy to confirm and observe when using.

Unlike the ordinary tip, the filtered tip is able to avoid cross-contamination, prevent liquid sucking-back and also protect the pipette itself. Of course, the price is a bit more expensive than ordinary tips. Various capacities are available and its color is transparent. It not only ensures the safety of experimenters, guarantees sample safety: no heat source, no Dnase/Rnase, no PCR inhibitors, to prevent cross-contamination, but also ensure the safe use of the pipette, as it prevents the liquid from rushing into the cavity and extend the service life with high accuracy and precision.

For the low adsorption tip, it is generally used for experiments that require high sensitivity, or precious samples or reagents that are easy to remain, which can greatly reduce sample loss, avoid protein absorption, and facilitate the removal of viscous materials, genomic DNA, or delicate cell cultures, which is the best guarantee for obtaining highly accurate experimental results.

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Differences between pipette tips with filter and without filter

Filtered pipette tips are generally made of natural polypropylene, while cheap tips are likely to use recycled polypropylene plastic (in this case, we can at most say that its main component is polypropylene). What’s more, during tip manufacture, a small number of additives will be added to the tip and commonly used materials include:
1. Color-developing material.
In the market, we usually see the blue tip and yellow tip, and they are for 1000ul and 200ul respectively.
2. Release agent.
The release agent helps separate the tip from the mold quickly after forming. The less release agent, the higher quality.

Four matters to note when using filtered tips

1. Before use: Check the pipette markings, accuracy grades, scale marking positions, etc.
2. Aspiration: Pinch the pipette upper end with your thumb and middle finger of your right hand, insert the tube lower mouth into the solution to be absorbed. Neither too shallow nor too deep. 10-20mm is suggested. If it is too shallow, it will cause cavitation, sucking the solution into the ear ball and contaminate the solution, and if it is too deep, it will stick too much solution on the outside of the tube. With left hand to take the washing ear ball, connect to the upper mouth of the tube and the solution is slowly inhaled.

First, the solution is inhaled about 1/3 of the capacity of the tube, and the index finger of the right hand is pressed on the mouth of the tube, taken out, held horizontally, and turned the tube to make the solution contact the part above the scale, to replace the water in the inner wall, and then the solution is released from the lower mouth of the tube and abandoned. After repeated washing 3 times, the solution can be sucked up to the scale, and immediately press the mouth of the tube with the index finger of your right hand.

3. Liquid level adjustment: take up the pipette, keep the tube end is still against the solution container inner wall, the tube body is kept upright, and the index finger is slightly relaxed (sometimes the pipette can be turned slightly) to make the solution in the tube slowly flow out from the lower mouth until the bottom of the solution meniscus is tangent to the marking line. Press the tube mouth with your index finger immediately. Remove the tip of the drop against the wall, remove the pipette, and insert it into the container that holds the solution.

4. Release the solution: If the container that receives the solution is an Erlenmeyer flask, the Erlenmeyer flask should be tilted 30°, the pipette should be upright, and the tube lower end should be close to the inner wall. Slightly loosen your index finger to allow the solution to slowly flow down the bottle wall. The pipette should be removed after the tip of the pipette touches the inner wall of the bottle for about 15 seconds. The small amount of solution remaining at the end of the tube cannot be caused to flow out with strong external force, because the volume of the solution retained at the end has been considered on time.

Pipette tip immersion depth and angle

We often use pipette in many experiments, and their importance is obvious. Otherwise, it will affect the experimental results and even lead to experiment failure, causing loss of sample and labor. It not only spends extra time and money, but also wastes samples that have been accumulated so hard, and misses the opportunity to publish the research results first.

Here is a reference for the tip immersion depth:

2µL and 10µL specifications: immersion depth 1 mm;
20μL and 100μL specifications: immersion depth 2-3 mm;
200µL and 1000µL specifications: immersion depth 3-6 mm;
5000μL and 10mL specifications: immersion depth 6-10 mm.
Please note, apply lubricating oil to the piston to keep the seal tight, before and after most pipettes are used.

For the immersion angle of the tip, it’s better to control the inclination within 20° and keep vertical.

Installation of tip:

It’s never easy to install the pipette tip, especially for multichannel pipettes. Insert the pipette sleeve handle into the pipette tip and turn it left and right or shake it back and forth to tighten it forcefully in order to achieve a good sealing effect.

Pipette tip rinse:

For normal temperature samples, tip rinsing helps to improve accuracy; but for high temperature or low-temperature samples, tip rinsing will reduce the accuracy of the operation.

Pipette tip suction speed:

The pipetting operation should be kept smooth and appropriate pipetting speed; too fast pipetting speed will easily cause the sample to enter the sleeve handle, causing damage to the piston and seal ring and cross-contamination of the sample.

Conclusion
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 guarantee its performance, we need to master the necessary product knowledge. If you want to know more information about pipette tips, contact us freely.