Northern Blot problem

Angela Hofstra Hofstra at
Mon Aug 21 14:23:42 EST 1995

Karen.Straube-West wrote:
>Hi Bionetters,
>We are suddenly having difficulty with our Northern blots using total RNA.
>The appropriate bands are present, but they are smeary. Even the rRNA on
>the gel looks smeary. It isn't bad RNA because it looks fine on a
>non-denaturing gel.
>We've checked, and the pH of our formaldehyde is about 3.2. Our protocol
>says it should be >4.0. Question: Could this be the problem? If so, can we
>raise the pH of our formaldehyde or should we buy new stuff? I'd appreciate
>any advice.
>Dr. Karen Straube-West
>SUNY Health Science Center
>750 East Adams Street
>Syracuse, NY 13210

I believe that formaldehyde can be deionized with the same protocol used 
for formamide:  5g of BioRad AG 501-X8 resin for every 100 mL 
formaldehyde.  Stir 1 hour at room temperature then filter through 
Whatman #1.

Hope this helps.


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