Spec vs Flourimeter for [DNA] ?

the End jgraham at bronze.ucs.indiana.edu
Tue Nov 30 21:05:49 EST 1993

The Hoefer miniflourimeter got trashed here a while back. The thread can
be found at the iubio gopher server "ftp.bio.indiana.edu".

While the device may work for some samples, notably complex chromosomal
genomic DNA's, it is unreliable for plasmids and other DNA of limited 
complexity. While one or two individuals claimed that it worked for them on
all samples, others measuring genomic DNA had good results, but 
a majority of users found it unreliable (as reported in the thread).

I personally have found it a dismal failure. One interesting thing that
I noticed when I still struggled with ours is that the "control" Calf
Thymus DNA supplied by Hoefer, while giving proportional flourimeter readings 
appropriate for the quantity measured, actually measured quite differently as 
absorbance at 260 nm. It was either 1/2-1/3 or 2-3X the amount indicated
on the label. I called Hoefer and asked about the discrepancy, but they 
were unable to say how the "standard" they supplied had been assayed,
as it was done at another company.

Go with the A260, if the 260/280 ration is appropriate. That is the 
proven method.

J. Graham
Biology and Chemistry
Indiana Unviersity

PS. The Hoescht dye used with the miniflourometer is reported to interact
only with adenosine and thymine bases, hence the need to standardize
with an identical DNA which must be highly purified and measured in an

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