Od600 Mode For Cell Growth Measurements; Direct Measurement Mode - Thermo Scientific SPECTRONIC 200 User Manual

SPECTRONIC 200E USER GUIDE

OD600 Mode for Cell Growth Measurements

Factor
OD600 Mode for Cell Growth Measurements

Direct Measurement Mode

28 SPECTRONIC 200E User Guide
Select Factor Based Concentration mode by pressing the right arrow key until FACTOR
displays on the instrument
Figure 45.
Use the keys to set the factor. Place a cuvette with your sample solution in the sample
stage and press as indicated on the screen. Live measurements of your sample begin. The
concentration is displayed on the screen.
Cell growth is often measured via an "OD600" measurement. This is a measure of the extent
to which the spectrophotometer beam is attenuated by scattering caused by the cells
suspended in the growth medium. OD600 stands for "Optical Density at 600 nm". Optical
Density is a synonym for Absorbance. In the SPECTRONIC 200E, OD 600 measurements
are performed in absorbance mode at 600 nm.
The SPECTRONIC 200 replaces the SPECTRONIC 20, known as the SPEC 20, which has
been used by life scientists to measure cell densities for over 50 years. The fact that OD600
measurements are a scatter measurement means that the amount of transmitted light that
reaches the detector varies depending on the optical design of the spectrophotometer.
Differences in the optical design of the SPECTRONIC 200E compared to the SPEC 20
mean that the SPECTRONIC 200E is roughly twice as sensitive to cell concentration.
If working only with SPECTRONIC 200E instruments, high sensitivity to scatter allows
users to make more accurate measurements and to work with lower concentrations of cells
than might be required in a SPECTRONIC 20.
(Figure 45).
Thermo Scientific