Dialysate concentration by PEG 35k - (Feb/21/2007 )

Hi,
You know hi-MW PEG can be used to concentrate dialysate just by placing tubin on dry powder. I got a little bit different idea. Solutions on both sides of dialysis membrane try to reach equilibrium, right? So, what would happen if you have 1 mg/ml of protein in dialysis tubing and add eg. 10 mg/ml of PEG 35000 to dialysis buffer? Would protein concentrate to ~10 mg/ml? That would be cool and I'm willing to risk. What do you think?

won't work. you are mixing apples with oranges. in your scenario, neither the peg nor the protein can pass through the dialysis bag (due to their size and the permeability of the membrane) but their respective concentrations are not enough to significantly influence the passage of water through the membrane so you will not change the concentration of either.