microplate readers for DNA + ethidium

Thu May 30 10:30:59 EST 1991

In reply to Benedik's message regarding fluorescence DNA assays in 
microtiter plates:

It is not necessary to excite in the UV.  I have been doing similar assays
with ethidium: excitation at 545 nm and emission at 575 nm.  These wavelengths
are not optimal but aren't too bad;  fluorescent-activated cell sorters use 
excitation in the visible for a variety of dyes.

I use a Pandex Fluorescence Concentration Analyzer (FCA; Pandex Division,
Travenol Labs).  My machine uses special plates that must be sealed before
use (contact me for details), but newer instruments supposedly can use 
regular plates.  I have also seen ads for machines from Millipore,
Flow Laboratories, and Perkin Elmer.

In my system, this assay allows measurement of much less than 100 ng DNA in a 
few microliters.  Also, the DNA can be recovered in high yield from the 
hydrophobic wells of the plate, after the measurement.

Bill Melchior
National Center for Toxicological Research
Jefferson, AR  72079

wmelchior at ntdoc.nctnet.gov

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