Vacuum Filter: Create seal when testing using small numbers of wells

Integrated Devices (Centrifuge, Washer, etc)
1

Hi,

I am developing a method using vacuum filtration in 96 well filters. As i understand it, you need to have every well with liquid in order to create a seal and pull liquid through. But that is not ideal if we want to do any small scale testing before scaling up.

Does anyone have any tips on how to close the unused wells to ensure there is a seal so i can use small subsets of wells for testing?

Thanks!

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You can seal the wells with foil or heat seals on the top. This was standard practice for us when using Cytiva PreDictor plates either on the automation or manually.

However, I will add my experience with automated vacuum filtration has been very poor. As soon as one well becomes empty the majority of the vacuum will pull through that well. The problem only gets worse as you go along and eventually you’ll get about half the wells dry while the other half still have some volume remaining in the wells. I’m sure there’s workarounds, but we moved to RoboColumns instead. That may not help your situation at all, just adding my thoughts.

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Positive pressure units are a game changer, as they can address separate positions until each are empty.
Even when sealings empty wells, uneven liquid characteristics may defeat the automated execution, when some wells empty earlier than others on a vacuum chamber.
What is your application? Is there another option to vacuum filtration?

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I am trying to filter 1.5 e6 of lysed mammalian cells in 500 ul with a dual filter of 8um and 0.3.

It’s been a real pain to work with the vacuum to be honest. Difficult to determine if the filter is overloading or if the vacuum method just isn’t very good. I think its the latter

Positive pressure sounds a lot better.

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Echoing the previous comments about vacuum being a headache and positive pressure being much better. Some options to check out are the Hudson FilterPress and the Hamilton MPE.

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If you need a quick fix, maybe centrifugation is also possible. If a plate centrifuge is available, that can accommodate the necessary stack height, that would be my alternative of choice.
Depending on your membranes and subsequent protocol, also mineral oil could be used to plug the membrane after emptying in the vacuum chamber.