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5
Protein Applications
Measure Protein A280
Thermo Scientific
NanoDrop Eight User Guide 51
Detection Limits for Protein A280 Measurements
Detection limits and reproducibility specifications for purified BSA proteins are
provided
. The BSA lower detection limit and reproducibility values apply to any
protein sample type. The upper detection limits are dependent on the
of the instrument and the sample’s extinction coefficient.
To calculate upper detection limits for other (non-BSA) protein sample types
To calculate upper detection limits in mg/mL for proteins, use the following equation:
(upper absorbance limit
instrumen
t
/mass extinction coefficient
sample
) * 10
For example, if the sample’s mass extinction coefficient at 280 nm is 6.7 for a 1%
(10 mg/mL) solution, the equation looks like this:
(200 / 6.7) * 10 = 298.5 (or ~300)
Calculations for Protein A280 Measurements
The Protein A280 application uses the
to correlate
absorbance with concentration. Solving
Beer’s law for concentration yields the
equation at the right.
Beer-Lambert Equation (solved for concentration)
c = A / (
* b)
where:
A = UV absorbance in absorbance units (AU)
= wavelength-dependent molar absorptivity coefficient (or
extinction coefficient) in liter/mol-cm
b = pathlength in cm
c = analyte concentration in moles/liter or molarity (M)
Note
: Dividing the measured absorbance of a sample
solution by its molar extinction coefficient yields the molar
concentration of the sample. See
for more information regarding molar vs. mass
concentration values.
Summary of Contents for NanoDrop Eight
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