100K Microcon wet-wet: Update
Earlier in the week I retested the 100K microcons in our wet-wet EQ format. When I last ran them this way I calculated very little flow and very small permeability values. I noted that there was a rather large air pocket collecting on the underside of the membrane in the plastic support structure; most likely the reason for small flow. This time I introduced 200uL of water onto the backside of membrane to ensure no air was resting against the membrane.
The three clusters of bars represent the three membranes I tested; each bar within the cluster represents the calculated permeability at a specific time point in the testing. The plots show that as time progresses through the EQ-experiment the permeability increases; but I am currently at a loss to explain why. The lowest permeability values for each membrane (~50) are greater in this wet-wet format then they were for the wet-dry tests (~20).
Better looking plot (good job), but strange answers. I didn’t think it was possible to assay the permeability at different times in the EQ format. Are you sure the 200 ul on the backside isn’t confounding your numbers? There isn’t a good reason that wet-wet should improve things for these membranes so we have to be very skeptical of this data. Go over everything you did to make this figure with Tom when he has a moment.
These rates are also higher than we have typically seen in our own membranes and 10X higher than previous data for wet-dry experiments on the microcons. I find it hard to believe, so hopefully you can get to the bottom of it.
Is anything funny going on with the centrifuge, since Jess recently saw some unusually high flows through our membranes too?