An old, never answered question: Qiagen's miniprep buffers - analytical chemistry anyone?

D.K. dk at no.email.thankstospam.net
Wed Feb 20 10:34:58 EST 2002

Naturally, I am talking about composition of N3, PB, and PE buffers
used in their silica-based filter columns. Discussions about this go 
back to at least 1995, reccur regularly since Qiagen would not divulge
the composition, yet nobody has ever come up with a "hack". 

Well, just how difficult is it really? Common sense plus MSDS
data tell basically everything about content except exact 
concentrations used (which _are_ very important). Here is what 
is known: 

        P1, P2 are standard alkaline lysis solutions.
        N3 has acetate and GuCl in it, pH 4.3
Hmm, notably lower pH and also we add unusually a lot of it 
(250+250+350 instead of 250); there must be a reason for this. 
Does it have K in it or is SDS precipitated by guanidine alone?
        PB is a mixture GuCl and isopropanol at pH 7.0
I am willing to bet it is buffered with 50 mM MOPS. 
        PE comes as 5X concentrate with pH 7.7
Probably just Tris at unknown concentration and likely no EDTA.

So, to reproduce these super-duper secret solutions, one only 
needs to determine these concentrations (after that, actual miniprep
test against supplied solutions will be in order) : 

- Ac- 
- K+
- 2-propanol
- GuCl (as it is bound to be present at high concentrations, just
  Cl- or even conductivity will probably be good enough)
- Tris (amine reaction?)

Can anyone suggest simple ways to assay these things? If the tests
are quick enough, out of sporting interest I promise to perform them 
and report all the results back. I really wish Qiagen had come to its
sense and told the composition of every solution it sells (just as they 
do with maxi preps and Promega does with its own, inferior, version
of minipreps). 

Any takers? C'mon, we should be at least as good as those kids that 
hack Intel procesors! (Just finished reading an article on how to make 
PPGA board to work with newer FC-PPGA chips without buying an 
adapter; going to try it out, I guess :-)). 


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