Spectroquant Pharo 300 - Page 92

Operation Spectroquant
®
Pharo 300
92
ba75703d07 04/2014
Determining the
calibration function
You have the following options to create a method:
 Measure and store:
Carry out a series of measurements with the following sample solutions
while at the same the photometer takes over the values:
– Blank sample to determine the reagent blank value
(with deionized water instead of sample, see section 4.5.9)
– at least one, up to ten standard solutions in different concentrations.
The photometer stores nominal value/absorbance value pairs of the indi-
vidual measurements and determines the resultant characteristics of the
calibration. When doing so, you can select the following line types: Poly-
gon line, Straight line or Parabola.
 Enter as value pairs:
Entry of the value pairs, Nominal value (concentration) / Measured absor-
bance of an already available
test series with the following sample solu-
tions:
– Blank sample to determine the reagent blank value
(with deionized water instead of sample, see section 4.5.9)
– at least one, up to ten standard solutions in different concentrations.
Based on the entered value pairs, the photometer determined the charac-
teristics for the calibration. When doing so, you can select the following
line types: Polygon line, Straight line or Parabola.
 Enter a function:
Entry of a function to calculate the concentration from the absorbance
(reverse calibration function). You can enter on the photometer the coeffi-
cients of a polynomial equation of the following type:
c = a0 + a1·A + a2·A
2
+ a3·A
3
+ a4·A
4
+ a5·A
5
Note
Entering the formula is especially simple if you measure with a commercial
test set for which the manufacturer has given the value for the coefficients a1.
It is often called the "Factor" and corresponds to the reciprocal value of the
slope of the straight line of the calibration function.
If a linear
function (straight line) should be entered, it is necessary to enter
the coefficients a0 and a1 to receive correct measured values.
with:
c Measurement result, e.g. concentration
a0 to a5 Coefficients (input range 0.000 to 1000,000)
A Absorbance