Best way to get DNA from gel bands?

Paul N Hengen pnh at
Fri Jul 28 14:53:09 EST 1995

In article <QIAGEN-270795100410 at> QIAGEN at (QIAGEN) writes:

>> My current method: QIAquick from Qiagen. Faster than their Qiaex bead
>> method. Gel slice is melted in chaotropic salt (probably NaI), then spun
.                                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>> through a dna binding filter in a microfuge.

| It is a pleasure to hear from a happy user like yourself, and we are 
| impressed by your knowledge of our QIAquick and QIAEX for gel extraction
| from agarose. Please allow us to clarify one point. 
| Neither our QIAquick Gel Extraction nor QIAEX II contains NaI to melt the 
| gel slice. We designed our QX1 buffer to eliminate NaI, because NaI is 
| difficult to get rid of, and residual NaI may reduce the efficiency of 
| downstream enzymatic reactions such as blunt-end ligation. In addition,
| NaI is sensitive to light (that's why most solubilization buffers are 
| stored in a brown bottle and our QX1 is not), therefore you cannot
| quantitate your DNA with a spectrophometer if the DNA contains residual NaI.
| Thank you for your support, 

Yeah yeah, but you are being negatively informative here. You say it's
NOT NaI, but you didn't say what it really is! -> probably guanidine HCl
or guanidine thiocyanate...but if it were really so important to know,
the components of the chaotropic binding solution should be on the label.
I have yet to see a label that says:

This product does not contain the following components:

     dirt (*note: see TIBS (1994) Vol. 19, page 183)
     kitchen sink

But I fear the day will come sooner than we think...

* Paul N. Hengen, Ph.D.                           /--------------------------/*
* National Cancer Institute                       |Internet: pnh at |*
* Laboratory of Mathematical Biology              |   Phone: (301) 846-5581  |*
* Frederick Cancer Research and Development Center|     FAX: (301) 846-5598  |*
* Frederick, Maryland 21702-1201 USA              /--------------------------/*
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