precipitating from Qiaquick

[QIAGEN]

In article <51u40m$hp9 at paperboy.ccc.nottingham.ac.uk>,
pdxrmb at vaxb.ccc.nottingham.ac.uk wrote:

> I have been using Qiagens qiaquick columns for the purification of PCR
products and bands form gels. Direct elution yields good quality DNA, but
the concentration is a little low - I would prefer a nice high
concentration stock for storage etc. Ethanol precipitation produces very
low yields (as judged from EtBr gels)despite there being plenty of DNA in
the eluate- is there a reason for this ?
> I thought maybe carryover of chaotropic salt may effect the
precipitation conditions ? but wasnt exactly ur why this shoud be. any
advice/infromation would be gratefully received. thanks in advance-
Richard M Badge.

To increase the DNA concentration in the eluate from QIAquick columns,   
the minimal volume of elution buffer should be used. The lowest volume of   
elution buffer recommended is 30ul, which will give you about 24-26ul of   
eluate with a DNA concentration sufficient for most subsequent   
applications. Since the eluate is almost free of salt, it is possible to   
add increased volumes of eluate even to salt sensitive subsequent   
applications. (We recomment to elute with 10 mM Tris, pH 8.5, to provide   
optimum pH for elution. This salt concentration should be considered in   
subsequent applications) If the eluate must be further concentrated by   
EtoH precipitation, addition of 1/10 volume of 3M NaAc, pH 5 is required   
to give correct salt concentration for precipitation.
For efficient elution, be sure to pipette the elution buffer directly in   
the center of the QIAquick membrane.
Please contact your local QIAGEN Technical Support Team if you have more   
questions. We look forward to hearing from you.

Sincerely,
QIAGEN

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