Freeze and Squeeze

[D. KIM]

I have been using (expensive) microfuge filter cups (e.g. S&S Ultra-Free 
MC).  These cups cost about US$1 each, but we had a bag of them, and 
noone was using them in the lab.  I would take a bit of the gel slice 
(this is a SMALL piece of gel) and freeze in the -80 (I am impatient).  
I'd then put the frozen gel into the cup and let thaw, then spin out the 
liquid in the microfuge (a 5 second pulse).  I use the eluted liquid 
directly for ligations.

I have since run out of the cups, and cannot justify purchasing more.  I 
have instead tried placing the gel slice (frozen) into the top of an 
"aerosol barrier" pipet tip, and place the tip into a 1.5 ml tube.  Put 
the tube into a microfuge and spin for a 3 - 5 second pulse.  The barrier 
effectively prevents bits of agarose from passing through, and the liquid 
seems to be fine for ligation.  These barrier tips are much cheaper than 
Ultra-Free cups.

I may try using barrier tips for other filtration needs.  Maybe I can 
make a micro spin-column out of one . . .

Daniel Kim