Eppendorf BioSpectrometer kinetic - Manual (Page 98)

Evaluation procedure
Eppendorf BioSpectrometer
® kinetic
English (EN)
98
12.8 Kinetics
An absorbance value A or an absorbance difference standardized to a minute ΔA/min is determined using
the measurement procedures available for selection. This determined absorbance value is entered in the
concentration calculation using a factor or (only for
Advanced kinetics) with an end-point standard.
12.8.1 Measurement procedures
Endpoint
At the end of the waiting period (incubation period, Delay parameter), an absorbance value is measured
and used for the concentration calculation.
Two point
After the delay the measuring point is taken and after the measuring time has expired a second one is
taken. ΔA/min is calculated from the absorbance and the time difference.
A
1
, t
1
= absorbance and time for the first measuring point.
A
2
, t
2
= absorbance and time for the second measuring point.
Linear regression
After the delay has expired measuring points are recorded at fixed time intervals from the start to the end of
the measuring time. A linear regression is carried out via the measuring points in the absorbance/time
diagram. Result: absorbance value in ΔA/min.
12.8.2 Reagent blank value
For the methods of the Advanced kinetics group, the measurement of a reagent blank can be
preprogrammed in the parameters. Primary application: compensation of a reagent drift in the "Linear
regression" measurement procedure. Instead of a sample, the reagent blank contains the reagent and
demineralized water, and is measured according to the same measurement procedure as the sample. The
measurement is made at the start of the sample series; the absorbance result is then subtracted from the
sample absorbance result before the evaluation:
A
RB, corr
= corrected absorbance result (in A or ΔA/min) of the sample.
A = measured absorbance result (in A or ΔA/min) of the sample.
A
RB
= absorbance result (in A or ΔA/min) of the reagent blank.
1 2
1 2
min t t
A A A
'
RB corr RB
A A A
,