APS & TEMED in acid gels

J C Ford jford at grove.iup.edu
Mon Jan 27 12:28:15 EST 1997


>>
>>Is this really true?  I was under the impression that the porosity
>>was governed by the % acrylamide and by the ratio of acrylamide/bis
>>(or other cross-linker).  The concentration of TEMED and/or
>persulphate
>>shouldn't have any effect unless they become limiting - so that the
>>gel fails to polymerise completely no matter how long it is left.
>>Since they only catalyse the polymerisation of the acrylamide monomer
>>they play no real role in the eventual structure of the gel.
>>	Can someone correct or confirm my assumption?
>>		Bernard

You're assuming that the cross-linker reacts with the same kinetic parameters 
as the monomer.  T'aint so.  Thus, changing APS or TEMED concentrations will 
change the relative reactivities of the cross-linker and the monomer, and 
consequently, pore size.

Now, whether the change significantly alters your gel ... that's another 
question.  That's why I suggested, in my original response, that you try it 
with several samples which would also be run under the original conditions.  
Chances are that a modest change will have little visible effect (famous last 
words).

JCF



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