Measure dsDNA, ssDNA or RNA
Thermo Scientific NanoDrop One User Guide 19
The Nucleic Acid applications use a modification of the
Beer-Lambert equation (shown at right) to calculate
sample concentration where the extinction coefficient
and pathlength are combined and referred to as a
“factor.”
Extinction Coefficients vs Factors
Using the terms in the Beer-Lambert equation, factor (f) is defined as:
factor (f) = 1/( * b)
where:
= wavelength-dependent molar extinction coefficient in ng-cm/μL
b = sample pathlength in cm
As a result, analyte concentration (c) is calculated as:
c = A * [1/( * b)]
or
c = A * f
where:
c = analyte concentration in ng/μL
A = absorbance in absorbance units (A)
f = factor in ng-cm/μL (see below)
For the dsDNA, ssDNA and RNA applications, the
generally accepted factors for nucleic acids are used in
conjunction with Beer’s Law to calculate sample
concentration. For the Custom Factor application, the
user-specified factor is used.
Factors Used
• dsDNA (factor = 50 ng-cm/μL)
• ssDNA (factor = 33 ng-cm/μL)
• RNA (factor = 40 ng-cm/μL)
• Custom Factor (user entered factor between 15 ng-cm/μL and
150 ng-cm/μL
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