Pipetting Tips

Today I have attended a couple of amazing talks and I will write about one of them. I will write about the second one when I will receive lecture notes, by the way it will be about "multiple labelling in immunocytochemistry".

As you can guess by the heading of this post I will write about the correct way of pipetting. It might sound silly however I believe that quite large proportion of people don’t know how pipetting accuracy and precision can be improved.

So the point number one: there are two ways of pipetting, one being forward and another one reversed.

Forward pipetting is used for simple liquids such as water and it is the most conventional way. Briefly, you press until the first stop when pipetting and upon release you go until the second stop. (see image below)

However, when working with foaming, viscous or volatile fluids the reverse pipetting is the most beneficial. In this case you press until the second stop when pipetting and upon release you go only until the first stop. (see image below)

If using filtered tips ensure the liquid doesnt touch the filter when using this method.

In addition to that pre-wetting the tip (pipetting up and down 3 times) is highly beneficial when using forward pipetting as it creates humid environment inside the tip thus reduces evaporation. When using reverse pipetting it is not essential as the tip is pre-wetted by pipetting additional liquid.

In a scenario where cold reagents are used it is essential to maintain your tips at the same temperature as the liquid as it will also reduce evaporation.

In addition, it is essential to hold pipette upright when pipetting and submerge it only for 2-5 mm into the liquid. While when expelling the liquid should be released onto the wall of a container and should be dragged on its surface to remove any droplets.

Lastly, the pipette should not be held for more than 5 minutes as it will be heated from the hands thus affecting the accuracy.

There are more rules that you can find online on how to assess accuracy of your pipette and how often they should be serviced, but ensure that you do not try to calibrate pipette by yourself as it can interfere with its accuracy and affect not only your results but also your peers. I included 2 images to demonstrate reverse and forward pipetting.

The rest of my week was as usual: a lot of meetings with potential supervisors, writing first assignments and etcetera. However today was fun day as apart from those lectures one of the restaurants in Manchester made free chicken and chips to all students. I think I’m starting to love Manchester as there are always so many great deals in terms of food and so many unique restaurants for example: the Botanist or Alchemist. In addition, the university has many events when there are drinks and free food provided. :)