Midi-preps

Bill Melchior wmelchior at ntet.nctr.fda.gov
Tue Sep 21 16:11:34 EST 1993


In article <1993Sep20.212825.17557 at ohsu.edu>, nishir at ohsu.edu writes in 
part:

> Solution II (good for about 2 weeks)              
              ^^^^^^^^^^^^^^^^^^^^^^^^ 
> To make 100 mls: 
>    0.8 g NaOH (0.2 M) 
>    10 mls 10% SDS (1%) 

Plasmid protocols frequently call for making this fresh (eg, Maniatis et
al).  I, on the other hand, haven't seen any problems with a solution well
over a year old (stored in a polythylene bottle as suggested by Kieser in
Plasmid 12:19-36, 1984, who does NOT suggest making it fresh).  Birnboim,
Meth. Enz. 100:243-255, 1983, says, "The shelf life at room temperature is
about a week or longer, depending upon the source of SDS; ...."  I'd like
to know if nishir or anyone else has actually had bad experiences with old
alkaline SDS, or is it just folklore?  What happens when the solution goes 
bad?

Comments welcomed; Bill
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