If you compare a biologist with a cook and the lab with the kitchen, the pipette will be analogous to the most important cooking tool – the knife. But while the knife’s design has remained more or less the same since man moved from stone to metal some five to twelve thousand years ago, laboratory pipettes have undergone a breath-taking (pun intended) revolution in the last thirty years.
Older generations of researchers remember glass pipettes of different capacities from the slim ones that were able to take up one hundred microliters (really) to the 50 mL ones. On Saturdays, when there was almost nobody around apart from crazy Belarusian PhD students, my supervisor would furtively use mouth pipetting for her media! Don’t try this at home! Then came the rubber pipette bulbs followed by the mechanical pipette filler, both of which still required a lot of thumb action and, finally, the electric pipette controllers aka “pipetteboys” made their great entrance to labs worldwide.
The Piston-Driven ‘Gilson’ Pipette
While glass and plastic pipettes are still routinely used to dispense tens of milliliters of liquid, the most-loved tool of a modern biologist is a piston-driven automatic pipette or ‘Gilson’, because as with Hoover (a brand of vacuum cleaner) the brand name has become a generic name for the tool. Among piston-driven pipettes, there is a wide range to choose from, and while the more expensive pipettes do seem to have the best reputation, it is also possible to source cheaper branded pipettes with good accuracy. I have always found online forums to be useful for recommendations about pipettes, and indeed other laboratory equipment.
A set of ‘Gilsons’ is often given to a new researcher as an introduction to lab life. You look after them and you might feel uneasy if somebody else uses them. Their robust design supports autoclaving and you should be able to disassemble, clean, and assemble your pipettes like a soldier does with their rifle.
The errors that can occur with manual pipetting stem mostly from the operator and not from the pipette itself. According to a recent paper in Chem. Lab Med, manual pipettes can match the accuracy of electronic pipettes when calibrated properly, (1).
There is more to modern pipetting than single dose 1-10 µL, 10 -100 µL, 100 µL- 1 mL and 5 mL pipettes, however. You don’t have to spend your time pipetting 100 x 20 mL aliquots one by one. The automatic pipette follows the older pipette’s trend of automation, moving from manual to electronic operation.
Electronic and Multi-Channel Pipettes
Electronic pipettes allow you to set instructions on a controller display and dispense multiple aliquots from one liquid uptake. They are more expensive than their piston-driven counterparts but you may persuade your lab head to buy one for the lab by citing the undoubtable time saving it will guarantee. Another advantage of electronic pipettes is that they can greatly reduce the risk of repetitive strain injury.
A multichannel pipette has multiple dispenser heads, usually 6, 8 or 12. It allow great timesaving because you can rapidly dispense aliquots into 96-well plates for high-throughout experiments.
Here Be Robots
If you have a multichannel pipette head you can actually use your multichannel pipette as a part of a robot. For example, Opentrons’ pipetting robot OT_One consists of a robot arm capable of moving in 3D above a platform that fits up to 15 microplates. A standard pipette attached to the arm and the liquid dispenser is controlled via an app.
Another semi-robot with the human name Andrew has two arms, one of which is holding different automatic pipettes, while the other can grab a pipette from the holder arm, and aspire and dispense liquid from a container to a tube.
Andrew and similar “personal assistant robots” that allow the use of existing pipettes are much cheaper than full blown automatic liquid handlers (proper robots) that only large and rich institutions can afford.
Should we be afraid that robots will take over our jobs? Not any time soon – pipetting is only one step in an experiment and the most mind-numbing one at that. The robot may save you from repetitive strain injury but it’ll not replace your knowledge about why and what to pipette.
- Lippi et al. (2016) Estimating the intra- and inter-individual imprecision of manual pipetting. Chem. Lab Med. V 5 (7)