Buffering sat'd NaI sol'ns

Michael Cooley szcooley at dale.ucdavis.edu
Thu Oct 20 11:44:53 EST 1994

David J. Meyer (meyerdj at biovx1.biology.ucla.edu) wrote:
: Hello, Netters!

:    I recently made my own glassmilk DNA purification reagents following the
: bionet.molbio.methds-reagnts FAQ. It seems to work very well, save a problem
: I am having with my NaI solution‹ it has turned yellow. I made up the solution
: in 100 mM pH 6 buffered sodium phosphate, and after 3 weeks at room temp in
: low-actinic glass (brown bottle) it is about the color of Folin's reagent.
: A working aliquot, nearly empty in a similar bottle, was brown.

:    I guess I'm not really surprised to find I2 in a slightly acidic NaI sol'n,
: so I was wondering if anyone else has experienced this. Does refrigeration of
: the solution help much? Is this really unique to the low pH stock
: solution, or does it eventually happen with stock made in water or TE 8?
: How common is the
: problem of DNA not binding to basic solutions if good quality (ACS reagent)
: NaI is used?

:    I realize that this has probably come up before, so please RSVP EMAIL and
: I'll post a summary.

:    Thanks for your advice!

: -- 
: ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

: David J. Meyer
: Department of Biological Chemistry
: University of California-Los Angeles

: meyerdj at biovx1.biology.ucla.edu

I'm glad your glassmilk is working since I also am trying this. But I was 
puzzled that in the preparation of the NaI solution you make no mention 
of sodium sulfite. The FAQ use sodium sulfite in all three protocols and 
no use of phosphate. 

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