At the risk of insulting your intelligence I am posting some basic information about pipettes and pipetting so you won’t have any excuses for poor practice at the lab bench. The main reason that it is important to use our pipettes correctly is that we share them. Its not just your work that will be affected if you seriously contaminate a pipette or throw it out of calibration.
If you have an undergrad or new volunteer or employee doing anything with our pipettes show them this post and make them read the manual (below).
So, here is the manual for our Rainin single and multichannel manual pipettes. You don’t need to read the whole thing but if you are new(ish) to pipettes, or even if you’re a pro, read the first six sections. You will probably learn something, I did.
Here is a video of one of the classic misuses of a pipette. Well done guy! Also, nice use of Herb Alpert and his Tijuana Brass.
Here is a stupid video that appears to be an ad for the current Rainin pipettes. Very odd and the others in the series are even odder.
Here is a video explaining how to use a pipette. Its longish and boring but if you are new or an undergrad watch it.
Believe it or not there is an English girl band called The Pipettes. They don’t seem to have anything to offer vis a vis the laboratory instrument but, here you go, they’re the best band called The Pipettes that I’ve ever come across.
Here is my list of what to do/not do with our pipettes:
For accuracy and precision, when these are important . . .
- Use the Rainin LTS tips – these are the ones we have in the lab in the red, green and blue boxes.
- Pipettes are more accurate in the middle of their volume range. When possible select a pipette that won’t be at either extreme of its volume range.
- Don’t pipette volumes above the nominal maximum volume for a pipette and don’t go below 10% of the maximum. So, for example, the working range of a p20 pipette is 2-20ul.
- Insert the pipette tip just a few millimeters below the surface of the liquid you are pipetting. Make the insertion depth consistent.
- Do your aspirations and ejections with the pipette within 20 degrees of vertical.
- Always wind the pipette down to your volume.
- Touch the pipette tip to the inside surface of the receptacle when ejecting.
- Pause for a second after both the aspiration (with the end of the tip still submerged) and the ejection (with the tip touching a surface).
- Move the plunger with a smooth stroke when aspirating and ejecting.
- Pause for a second at the first stop when ejecting then push down to the second stop.
For the sake of the pipette and your work . . .
- Don’t pipette volumes above the nominal maximum volume for a pipette.
- Try not to drop the pipettes on a bench or the floor.
- Don’t whack the pipette into the tip – just press it gently.
- Never put a pipette down on the bench when it has a tip with a volume in it or a used tip attached.
- Better yet, never put a pipette down on the bench with a tip attached.
- Better yet, never put a pipette down on the bench. This is a rule that is very easy to observe in our lab as the benches all have a steel bar that pipettes can be hung on easily.
- Never release the plunger of a pipette such that the plunger spring does the work – your thumb should be controlling the plunger all the way between both stops in both directions.
- Pipette larger volumes slowly. The p200s and p1000s in particular, are capable of pulling with enough force that they can suck liquids up into their barrels. They are much more likely to do this if you release the plunger quickly.
- Work as vertically as you can.
- Change tips if the solution forms bubbles. If you are pipetting a volume repeatedly such that there is no need to change tips due to contamination (making multiple aliquots for example) you should still change the tip regularly. Obviously you can save tips by doing multiple aliquots with each tip but solutions with detergents in them can froth and bubbles can easily move up into the pipette barrel.
- Clean the barrel of the pipette if you know its contaminated. After you remove the metal tip ejector you can unscrew the barrel so you can wash it. Do this somewhere clean and be very careful to keep the internal parts that you will expose clean and in tact. Be careful there is a spring under tension in there.
If you have any questions read the manual, search the web and ask your colleagues.