How to use a pipette: Viscous liquids (video)

How to use a pipette: Viscous liquids

Welcome back! Thick and viscous liquids can sometimes be a problem, to pipette with. They have low elasticity. Usually enter the tip more slowly than other liquids and tend to stick to the tip wall, when being dispensed.

There are however a few techniques to try when pipetting viscous liquids. First and foremost, you typically want to pipette at a slower speed and pause before finishing every aspiration or dispense. This simply gives the liquid more time to smoothly move into and out of the tip.

One great technique for such liquids is called reverse pipetting. Here you'll aspirate more than you need, dispense the desired amount and discard a smaller post-dispense volume as a waste. This can help to ensure, that the right amount will be dispensed, since most of the errors should be contained in the post dispense.

Also an additional benefit of reverse pipetting is that there's no blowout. That is no final push of air to expel all liquid out of the tips. Some liquids, especially thick ones, tend to foam or form air bubbles, when air is introduced to them. So reverse pipetting can help with that problem as well.

Electronic pipettes can usually be programmed to contain a post dispense, so the pipette knows to aspirate a bit extra liquid for the waste dispense.

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