NanoPhotometer
®
N120/
NP80/N60/N50/C40
User Manual Version 4.3.1
83
Ratios
Protein samples e.g. from whole cell lysates may contain nucleic acids. To check the purity
of the isolated protein, the 260/280 ratio is calculated to give an indication of the nucleic acid
contamination. A pure protein preparation has an expected 260/280 ratios of
0.57. If a ratio
is detected out of the acceptable range an alert icon
is shown in the results/table area. A
push on the alert icon shows additional information. The ranges for acceptable ratio values
can be defined in preferences.
The ratio is calculated with or without background correction according to if the background
correction is activated during the measurements or not as follows:
Without background correction:
260/280 ratio =
A
260
A
280
With background correction:
260/280 ratio =
A
260
-
A
BKG
A
280
-
A
BKG