Millipore Membrane Separation
This gel shows the separation using two 100k Microcon membranes and 1mg/mL brain extract. 500uL of 1mg/mL brain extract was loaded into the Microcon and spun at 14000g for 5min. 400uL passed through the membrane (100ul remained on top). It appears that their “cutoff” as we would consider it is much lower, more like 50kD. Very little of the small molecular weight species are removed from the retentate, even though 4/5ths of the solution passes through the membrane. It seems that these membranes are good for high flow, quick concentration of a complex mixture, but not great separation.
Perhaps we should spin 100 ul or so only through the millipore devices so we can do a more direct comparison of the transfer to filtrate vs ours. I suspect that we might also see some concentration of the lower molecular weight species in our membranes. But perhaps drop for drop we have higher transfer.
Unfortunately our cut-off is considerably bigger and so the comparison wouldn’t be fair.