A260 or Fluoromete ??? Which is correct

WSchick at aol.com WSchick at aol.com
Wed Mar 20 07:28:38 EST 1996


In a message dated 96-03-19 21:48:09 EST, john.brennand at gbapr.zeneca.com
(john brennand) writes:

>
>We now routinely double check by 1st checking A260, and then running 1 
>ug of the DNA on an agarose gel and eyeballing the intensity compared 
>with a bit of DNA of similar size who's concentration you are happy 
>with.

Doesn't Ethidium Bromide also detect RNA? 
 
In solution fluorescence, note that there will be different response to
Hoechst depending on the base ratios, so standards should be similar in
content to your sample.
 
Molecular Probes has some new fluors that distinguish between dsDNA and
ssDNA, with little interference from RNA, proteins, buffers, etc.  They have
types for gelstaining and for pico amounts in solution.

Fluorescent checks in solution with PicoGreen or OliGreen or Hoechst use only
1 or 2 ul of sample.  If you do 260, you may lose ten times that just on the
walls, so if you only have a small sample, Fluorescence in solution may be
better.


Walt Schick


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