Posted 26 April 2010 - 12:42 PM
I noticed that when I fill one side with water it does not permeate the membrane and fill the second cuvette, as I expected it would. I then took another fresh piece of membrane, which was in the shape of a square pocket (sealed on 3 sides, open on the fourth), and i was able to fill the pocket with DI water through the one open side. No water leaked out.
I am quite confused by these results. The MW of water is 2 orders of magnitude below the cut off for the membrane. Why isn't the water permeating? Any insight is greatly appreciated.
Posted 26 April 2010 - 04:41 PM
Posted 27 April 2010 - 05:15 AM
Surface tension is the answer! The MWCO is only for diffusion gradients.
Okay that was my thinking as well. I tried filling both cuvettes with water and adding an organic dye to one side but i did not see migration to the other side. Maybe this is because the diffusion was just really slow. I'll reattempt this today. Thanks for clarifying that.
Posted 27 April 2010 - 06:53 AM
also, are you expecting the water or color to pour through the membrane? they will diffuse slowly through the membrane.
genius does what it must
i do what i get paid to do