Hello, I am currently working with a Hamilton FAS to test a double-sided bead clean-up method on our Hamilton Star. We are using the MPH since our sample numbers will vary, and we are finding that after aspiration steps there are droplets that are left on the side of the wells. We confirm that all of the liquid is at the bottom and there is no mixing being done prior to the aspiration. Has anyone seen this before and know what is causing it? I’m fairly new to using the Hamilton but even the FAS is puzzled by this. My concern is that sometimes the droplets contain small amounts of beads and that there will be loss in material. TIA!
-Kristina
Hi Kristina,
is it a PEG based buffer? It might be sticky, so you could either try to add 0.05% Tween20 to increase viscosity or pipett slower so that you have no retention of liquid against the well.
best
Dominik
€: Adding to that: What kind of plate are we talking about?
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There is PEG but I don’t think I can add Tween. I will suggest slowing the pipetting to the FAS. Thank you for the suggestion!
Agree with Dominik’s suggestion of pipetting slower
Also, I’ve found that I sometimes get droplets stuck on well walls during cleanups when I’m aspirating too far above the bottom of the plate. I can’t think what the mechanism would be - some weird trick of static electricity? But I do know that lowering the aspiration height has fixed the problem for me in at least two cases. If your magnet has a spring, I like to set it so that it’s just barely compressed.
Thank you! We will also try lowering the height. These are great suggestions.
Sorry, just seeing that you asked about the plate type. We are using Bio-rad full skirted plates, catalog number HSP9601.
Ah okay, I tried to perform bead-cleanups in those as well and was not successful. They suck to mix in, so I prefer to transfer the whole reaction to a round well plate such as Azenta’s 4ti-0110. It is one additional plate you need for each cleanup, but it was worth it for us.
