Desalting with Dialysis Cassettes
One area of use to explore for the membranes is desalting, the removal of salts from solutions (such as those containing proteins). Two dialysis products made my Thermo/Pierce were tested to develop a protocol and test manufacturer’s claims.
These products are the mini-dialysis unit on the left and the dialysis cassette on the right; both have cellulose membranes with cutoffs of 10 kDa. The set up is shown below.
4M NaCl in deionized water was dialyzed in deionized water with a dilution factor of 1:400. No heat was applied and stirring was run at a low setting. A conductivity probe was use to measure the amount of salt in the dialysate. Transport was normalized based on membrane surface area.
Based on a 1:400 dilution 4M NaCl should produce a dialysate equilibrium [NaCl] of .01M in all cases; this was observed within 2-9% error for 4 trials. When concentration was normalized by surface area (294, 123.2 mm2) the mini dialysis units showed higher diffusion.