Hach-Lange LUMISTOX 300 LPV321 User Manual - Manual (Page 38)

LUMIStox 300 Operating Manual Dr. Bruno Lange GmbH
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Page: 38
4.3 Calculation of the GL value in conformity with DIN
Definitions:
Io: Luminescence of the bacteria suspensions before the sample is added
(initial luminescence)
It: Luminescence of the tests solutions after the incubation period t (final
luminescence after addition of the sample)
IoK, ItK: Initial and final luminescence of the control solutions (2% NaCl)
fK: Correction factor
Ic: Io of the test solutions, corrected by fK
%inhib.t: Percentage inhibition of the luminescence after the incubation period t
GL value: The factor of the test dilution (i.e. the G-value) with which %inhib.t <20 is
reached.
1. Calculating fK: fK = ItK/IoK
2. Calculating Ic: Ic = fK x Io
3. Calculating %inhib. t: %inhib.t = (Ic - It) x 100 / Ic