Eppendorf BioPhotometer plus - Manual (Page 44)

11 Evaluation procedure
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BioPhotometer plus — Operating manual
11.2.2 Multi-point calibration: calibration line
For the evaluation via a calibration line the selection "LINEAR" is programmed in the parameter
"REGRESSION".
From 2 to 10 standards which can be measured once, twice or three times, a linear equation is
calculated via linear regression (concentration as function of absorbance):
a
0
= Interface of the calibration line with the concentration axis ("offset": concentration of a
sample with absorbance 0)
a
1
= slope of the calibration line ("factor")
After calculating the regression the device forms a CV value (see above) as measure for the
scattering of the measured values around the calibration line (exception: two point calibration with
single measurement of both standards). If the CV is greater than 10% it will be displayed. In this
case the calibration will only be stored after confirmation. For more than 2 standards the CV
value is always displayed (even for a value below 10%).
In the function list the calibration data can be printed.
11.2.3 Multi-point calibration: Calibration curve
For the evaluation via a calibration curve the selection "NON-LINEAR" is programmed in the
parameter "REGRESSION".
From 5 to 10 standards measured once, or 4 to 10 standards measured twice or three times, an
equation for the third degree polynome (concentration as function of absorbance) is calculated
via a non-linear regression.
a = coefficients (the coefficients are defined using the method of smallest squares)
After calculating the regression the device forms a CV value as measure for the scattering of the
measured values around the calibration line (see above). If the CV exceeds 10% the calibration is
only stored after confirmation.
The details above about the CV value and printing the calibration data apply accordingly.
11.3 Dilution
Dilutions entered into the method procedure are taken into account when calculating the results:
C
Dil, corr
= result converted using the dilution factor
V
P
= volume of the sample in the measuring solution
V
Dil
= volume of the diluent in the measuring solution
EN
Oper
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