The micropipette is probably the most used tool in the laboratory. They’re used by scientists in a wide range of sectors including academia, hospital and forensics labs as well as drug and vaccine development to transfer precise, very small amounts of liquid
Whilst it can be annoying and frustrating to spot air bubbles in the disposable pipette tip if they’re not spotted or ignored it can have a huge impact on the reliability and reproducibility of results.
The good news is that there are some simple measures you can take to prevent air bubbles, and improve lab efficiency, operator satisfaction as well as the accuracy and precision of results.
Below, we explore the consequence of getting an air bubble in your pipette tip and what you should do next.
The Consequence of Bubbles in the Pipette Tip
Even if you use the most accurate, top of the range, well maintained, serviced and calibrated pipettes the reliability of your results can be affected by lab errors. When bubbles get into the tip it can have several outcomes.
● When the user spots the air bubble they must spend time dispensing the aspirated liquid appropriately, eject the tip and start the process again.
● Undetected air bubbles may result in low volume transfer, thus altering the concentration of reaction mixes leading to failed experiments and questionable or unreliable results.
These outcomes can have several consequences (1).
● Decreased Lab Efficiency – Tests and assays will have to be repeated, incurring labour and material costs, which can be quite substantial.
● Questionable or Incorrect Test Results – If incorrect results are released there can be more serious consequences including misdiagnosis and poor patient outcomes.
● Retraction of Manuscripts From Journals – If peers fail to replicate your results due to air bubbles causing inaccurate results papers may be withdrawn.
Best Practices to Prevent Air Bubbles
In the majority of cases air bubbles in pipette tips are caused by operator error. Poor technique due to insufficient training or fatigue is usually the underlying problem.
Pipetting is a skilled operation which requires 110% attention, proper training and practice to achieve consistent and accurate results.
Whilst there are several things you can do to reduce general pipetting errors, below we’ve highlighted some best practices that can be employed to avoid air bubbles in pipette tips.
Improve User Technique
Pipette Slowly
If the plunger is released too quickly when aspirating, air bubbles can be introduced into the tip. This can be especially problematic when transferring viscous liquids. A similar effect can occur if the plunger is released too quickly after dispensing.
To avoid air bubbles when aspirating, take care to operate the piston of manual pipettes in a smooth and regular manner, applying consistent force.
Use The Correct Immersion Depth
Failure to immerse the pipette tip deep enough below the meniscus of the liquid reservoir can result in the aspiration of air and thus bubble formation.
However, immersing the tip too deep can aspirate more liquid due to increased pressure or droplets can occur on the outside of the tip so it’s important to immerse the pipette tip to the correct depth.
The recommended depth varies between pipette size, type and make. Whilst manufacturer recommendations should be followed here’s a general guide provided by the National Physical Laboratory.
Guide To Depth Of Tip Immersion
Pipette Volume (µl) & Immersion Depth (mm)
- 1 – 100: 2 – 3
- 100 – 1,000: 2 – 4
- 1,000 – 5,000: 2 – 5
Pre-Wet Pipette Tips
When pipetting volumes greater than 10µl pipette tips are usually pre-wetted by filling them several times with the liquid being dispensed and expelling it to waste to improve accuracy.
Failure to pre-wet them can result in air bubbles, especially when using viscous or hydrophobic liquids. To avoid air bubbles ensure you pre-wet tips when pipetting volume greater than 10µl.
Use Reverse Pipetting Techniques If Appropriate
Viscous Substances: A common problem when pipetting viscous substances such as protein or nucleic acids solutions, glycerol and Tween 20/40/60/80 is the frequent formation of bubbles when the forward pipetting technique is used.
Pipetting slowly, using the reverse pipetting technique reduces the risk of bubble formation when transferring viscous solutions.
ELISA Technique
Reverse pipetting is also recommended when pipetting small volumes into 96 well micro test plates for ELISA techniques. When air bubbles are drawn into the pipette or dispensed into wells when adding reagents it can influence the optical density values and the results. Reverse pipetting is recommended to minimise or eliminate this issue.
Use Ergonomic Pipettes
Old style pipettes that haven’t been designed with ergonomics in mind require more physical effort, you get tired and your pipetting technique becomes sloppy and poor. Errors mentioned above such as quick plunger release may occur more frequently.
By investing in a more ergonomic solution you will be able to maintain excellent technique and prevent air bubbles formation due to poor technique.
Take Time to Train Staff
Regularly training and assessing staff in pipetting techniques can ensure that operator error and air bubble formation are reduced.
Consider More Automated Solutions
As noted above most air bubbles are caused by the operator. It may be possible to reduce operator error and comfort by using electronic pipettes or a flexible liquid handling platform such as the Agilent Bravo Liquid Handling Robot.
Use Good Quality Pipette Tips
Micropipettes are usually purchased with care, but often little thought is given to the quality of the disposable pipette tip. Due to the influence that a tip has on the pipetting results, the standardISO 8655 requires an extra calibration if the pipettes and tips from different manufacturers are used.
This could be because many cheap tips can look fine initially but when you study them carefully they may have flashes, protrusions, scratches, and air bubbles, or be bent or contain impurities.
Buying good quality tips made of high-grade polypropylene may reduce the occurrence of air bubbles.
To Conclude
Getting air bubbles in your pipette tip has an impact on the lab’s efficiency as well as inaccuracy and imprecision of results. We’ve noted several things you can do to avoid air bubbles getting into the pipette tip.
However, if poor quality pipette tips are causing air bubbles to get into your pipette tip, you will be pleased to know that our universal fit pipette tips are made to the highest standards and are made with premium-grade pure polypropylene.
Suzhou Ace Biomedical company produce high-quality 10,20,50,100,200,300,1000 and 1250 µL volumes universal pipette tips, 96 tips/rack. Exceptional durability – all ACE tip racks stand up to the demands of use with multichannel pipettors. Sterile, Filter, RNase-/DNase-free, and nonpyrogenic.
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Post time: Dec-29-2022