Calculations For Od600 Measurements - Thermo Scientific NanoDrop One User Manual

Calculations for OD600 Measurements

Similar to the nucleic acid applications, the
OD600 application uses a
Beer-Lambert equation
concentration where the extinction coefficient
and pathlength are combined and referred to as
a "factor."
The OD600 application offers a user-specified
factor, to be used in conjunction with Beer's
Law to calculate sample concentration. If the
factor is known, enter the factor. Otherwise, use
8
1x10 , which is the generally accepted factor
for most bacterial cell suspensions such as E.
coli.
Calculated cell concentrations are based on the
absorbance value at 600 nm, the entered factor
and the sample pathlength. A single-point
absorbance correction may be applied.
Thermo Scientific
modification of the
to calculate sample
Measured Values
A600 absorbance
Note: For micro-volume absorbance measurements
and measurements taken with nonstandard (other than
10 mm) cuvettes, the spectra are normalized to a 10 mm
pathlength equivalent.
• Cell culture absorbance values are measured at
600 nm using the normalized spectrum. If no
Absorbance Correction is specified, this is the
reported A600 value and the value used to calculate
cell concentration.
• If an Absorbance Correction
normalized and (absorbance) corrected absorbance
value at 600 nm is reported and used to calculate
cell concentration.

) absorbance
A(
• Normalized and (absorbance) corrected (if used)
absorbance value at any specified
Monitored Wavelength
Sample Pathlength
• For micro-volume measurements, the software
selects the optimal pathlength (between 1.0 mm and
0.03 mm) based on sample absorbance at the
analysis wavelength.
• For cuvette measurements, pathlength is determined
by the cuvette Pathlength setting in the software (see
General Settings).
• Displayed spectra and absorbance values are
normalized to a 10 mm pathlength equivalent.
•
Reported Values
Cell concentration. Reported in cells/mL.
Calculations are based on Beer-Lambert equation using
corrected A600 absorbance value.
6
Measure OD600
is specified, the
Additional

( ) is also reported.
NanoDrop One User Guide 143