Roche Cedex Bio - Absorbance Calculations and Checks

Roche Diagnostics
C-6
Operator’s Manual · Version 3.4
8 Data analysis methods Cedex Bio analyzer
Photometric measurements
Absorbance
This section explains the absorbance calculations and the associated checks.
Calculation of absorbance
Calculation is carried out after every measurement by the absorbance photometer.
There are up to 40 absorbance measurements (cycles) consisting of 1 or 2 out of 12
available wavelengths.
The absorbance signal is corrected using the following values:
The values obtained from photometric measurements are converted to absorbance
values. This conversion is carried out for all points measured at the requested
wavelength.
Cuvette blank correction
Cuvette blank correction is carried out in every absorbance calculation.
All absorbencies are corrected using a blank, that is the absorbance of a water-filled
cuvette at the corresponding wavelength.
Calibration Control Sample
Calculation of absorbance
lll
Cuvette blank correction
Monochromatic measurement lll
Bichromatic measurement lll
Volume correction
lll
Absorbance checks
High Absorbance check lll
Reagent Range check l
High Activity check ll
Low Activity check ll
Table 1 Calculations and checks for absorbance measurements
Raw absorbance of each point (n) at the requested wavelength λ.
Intensity of each point (n) at the requested wavelength λ.
Intensity of air (without cuvette) at the requested wavelength λ.
measured absorbance
cuvette blank correction
(mono/bichromatic)


volume correction++
A
raw cuv
λ n,()
I
cuv
λ n,()
I
air
λ()
-----------------------
log–=
A
raw cuv
λ n(,)
I
cuv
λ n(,)
I
air
λ()