These mixed cellulose esters membrane discs are a convenient, high recovery way to dialyze micro-volumes of protein or nucleic acid solutions (<100 µL). With the “drop dialysis” technique, a floating filter disc replaces the dialysis sac.
Recoveries of DNA and protein samples have been reported in excess of 98% (Marusyk, R. and Sergeant, A., “A Simple Method for Dialysis of Small-Volume Samples,” Analytical Biochem. 105, pp. 403–404, 1980).
Drop Dialysis Technique
1. Fill the bottom of a Petri dish with buffer.
2. Float the membrane filter disc on the surface of the buffered solution.
3. Deposit 5–100 µL of sample on the center of the membrane. Place a tight-fitting lid on the Petri dish to prevent evaporation.
Marker dyes may help in determining the dialysis time required. Most samples are dialyzed in less than 30 minutes.