sensitivity of sequencers

John H McDonald mcdonald at UDel.Edu
Tue Sep 4 09:12:29 EST 2001

I'm using a technique that requires sizing small amounts of
fluorescein-labeled restriction fragments. The ABI 373A that I use can
detect a band with about 100 attomoles of fluorescein molecules. Does
anyone know if any of the newer sequencers are substantially more

Alternately, does anyone know of ways to modify the 373A to increase its
sensitivity? I've replaced the fifth filter on the filter wheel with a
530-nm longpass filter, but that increases the background so much that
there is no increase in the ability to detect bands. Is the background due
to autofluorescence of the glass, and if so, is there a different kind of
glass with lower autofluorescence? Or does the laser produce small amounts
of light above 530 nm, and if so, can I just filter out the longer
wavelengths before they reach the gel?


John H. McDonald
University of Delaware
Newark, Delaware
mcdonald at udel.edu


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