To add to this discussion:
Many of the comments to my question that started this thread do not
sufficiently differentiate between accuracy and precision.
While we all want an assay that is internally consistent (i.e., high
precision), we do care a lot about accuracy ("the degree of closeness of
measurements of a quantity to that quantity's actual (true) value" [from
http://en.wikipedia.org/wiki/Accuracy_and_precision])
One person actually stated that accuracy is not that important, but
rather that precision is important. I disagree. When it comes to
calculating kinetic parameters or binding spectrometry, an accurate
reading (i.e. true) of the protein concentration is paramount.
So what I have been hearing (corrections welcome) is the following;
1. The Nanodrop may have an issue with precision due to various factors,
such as evaporation while on the pedestal, dirt on the pedestal, and
drifting from calibration. But if you squint, one can be happy with the
machine....
2. Bradford also as issues (low correlation with dye binding between
standard protein used for calibration and one's sample). However, this
assay can be highly precise.
There were only few comments on the NanoPhotometer™ Pearl, so more
real-life experiences on that instrument would be helpful.
Cheers.
Arnon
--
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Arnon Lavie, Professor
Dept. of Biochemistry and Molecular Genetics
University of Illinois at Chicago
900 S. Ashland Ave.
Molecular Biology Research Building, Room 1108 (M/C 669)
Chicago, IL 60607
U.S.A.
Tel: (312) 355-5029
Fax: (312) 355-4535
E-mail: [email protected]
http://www.uic.edu/labs/lavie/
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