There are multiple potential consequences if you don’t have proper pipetting technique. Some of these consequences are:
Inaccurate results
Damaged equipment
Lack of safety
Contamination
Dilution
To achieve proper pipetting technique, follow the instructions from the pipette manufacturer you’re using and follow your own laboratory’s protocols. Most importantly, practice.
Below, you can find some common bad pipetting techniques we’ve heard about from customers over the years.
A common practice in pipetting procedures is reverse pipetting, which is especially common when handling smaller volumes of liquids. Reverse pipetting occurs when the plunger is depressed past the first level to aspirate a portion of the sample from the sample and then depressed only to the first stop to deliver the portioned sample. Reverse pipetting sometimes leads to over-pipetting instead of under-pipetting, delivering higher and inaccurate volumes. Whether it’s under or over, you don’t want it in your lab.
Mouth pipetting is the practice of using your mouth to suck a specific volume of a specimen (e.g., blood, cell cultures, urine, other microbial stews) into an open-ended tube. This method uses air pressure created by the sucking motion to hold the specimen in place before transferring it to another location. It’s also the most common method of poisoning, infection, and contamination within laboratories.
What else should you avoid when pipetting?
- Don’t forget to pre-wet the pipette tip. Aspirating using a completely dry tip means the liquid volume can be lost due to evaporation, skewing your sample uptake volume and your results.
Don’t wipe the pipette tip. This can steal sample volume from the pipette.
Don’t use the incorrect pipetting mode. Get to know your sample. Is it especially aqueous? Foamy? Learn the right mode of pipetting based on each unique solution.
Don’t rush. There’s no Guinness record for fastest pipettor. Pause after aspirating liquid to prevent under-pipetting.
Don’t use the wrong pipette tips. You wouldn’t wear shoes two sizes too big for you. Make sure the pipette tips fit your pipette to prevent sample leakage and damage to equipment.
Don’t pipette at an angle. Your pipette should be vertical when aspirating liquid. Dragging or touching the pipette tip to the inside of a container while aspirating can lead to under or over pipetting, altering your desired volume.
Don’t forget about the temperature. Sweaty palms while pipetting? Don’t handle it for too long then. Human body heat and atmospheric temperature can affect the sample within the pipette which can be especially harmful to your experiment if the sample is temperature-sensitive, like cell culture.
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