4 calculating the ec value – Hach-Lange LUMISTOX 300 LPV321 User Manual User Manual
Page 39
LUMIStox 300 Operating Manual
Dr. Bruno Lange GmbH
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Page: 39
4.4 Calculating the EC value
Definitions:
Γ:
Gamma value calculated from %Ht
Konz:
Concentration of the sample in a test solution
EC50/20:
Concentration of the sample in the test that causes 50% (20%) inhibition
4.
Calculating gamma
Γ = %inhib.t / (100 - %inhib.t)
5.
Take the
Γ
-values as the y-coordinates (ordinates) and the associated
concentrations as the x-coordinates (abscissa) and plot them in a two-
dimensional logarithmic coordinate system (range of ordinates: -0.95 to +0.95).
6.
The EC50 value is given by the point of intersection with the x-axis at
Γ
= 1.
7.
The EC20 value is given by the point of intersection with the x-axis at
Γ
= 0.25.