Re: [DIYbio] Miniprep without EDTA

>>> substituting HCl since you can get pure HCl (37% in water) from
>>> swimming pool supply stores under the name "muriatic acid" but since
>>> HCl is a strong acid, getting the pH within the acceptable range
>>> without a buffer was complicated.  Other weak acids might be
>>> acceptable substitutes for vinegar.
>
>
> Are you meaning complicated because no buffer, or because of needing to
> titrate
> to get the right concentration?


It is complicated because there is no buffer and we are essentially
titrating a strong base (the lysis solution contains NaOH) with a
strong acid, so once the NaOH is neutralized the pH quickly drops
below 2 which is too low for the DNA to bind the silica. We need the
pH to get in the 4-6 range. If you look at this titration curve
http://www.files.chem.vt.edu/chem-ed/titration/graphics/titration-strong-weak.gif
showing the titration of HCl and acetic acid against NaOH, there is a
lot more room for error in the acid concentration when using acetic
acid. It's possible to do it with a strong acid but your measurements
would have to be very precise or you would need to use a buffer.

-cory

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