glasspowder recipe from FAQ

Wed Aug 23 16:47:47 EST 1995

I attempted to make glass powder yesterday following protocol #1 from the FAQ.
To 'test' the powder I purified a known amount of plasmid with the final
product, and the same amount with a commercial glass powder. The commercial
stuff worked great, but when checked on a gel, the 'cleaned' dna prepared
from the stuff I had made appeared to be stuck in the well.

There were a few obvious places where things could have messed up..

I used Sigma S5631 Silica. Is this the right stuff?
I understood 'add nitric acid to 50%' to mean having a final
volume that was 50% nitric acid.(which when using ~70% nitric acid
came to about 3 volumes of nitric acid/volume glass suspension)
'Heat till almost boiling': I heated it till it was steaming, 'fuming'
and was 100C.
When washing, I couldnt get the final pH to be neutral, it remaind
at ~6.5, but then again, that is the pH of our millipore water and
also the pH of the commercial glass powder.
Any suggestions on what might have gone wrong?



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