small volume dialysis

[Klaus Lehnert]

In article ,  says...
>
>Hi, there:
>I am going to dialysis some proteins (30 KDa) in very small 
volume (20 ul).

Hi Ke Wu,
it doesn't get any cheaper and easier than that:
Take an eppendorf tube (0.5-1.5ml)
punch a hole in the lid
fill your sample
take a coin-sized piece of dialysis tubing (one layer)
put on top of tube
close lid, thereby squeezing the dialysis membrane
(opt: seal the rim of lid/tube with small strip of parafilm; 
necessary only foe low-quality tubes).
put tube into floater
put upside-down into dialysis buffer
make sure there is no air bubble trapped in the punched-out 
hole.
invert from time to time to make sure all your protein comes 
into contact with the membrane.
After dialysis, simply spin tube, this gets you all liquid to 
the bottom. 

Works always well for me, no significant loss, very little 
increase in volume

Have fun

KLAUS