Daily Factor; Calibration Method - Endress+Hauser analytikjena multi N/C pharma HT Operating Manual

Function and design
3.6.2

Daily factor

3.6.3

Calibration method

30
Take the blank value of the preparation water into account for measurements in the
range of low concentration (<10 mg/l).
Single point calibration
For low TOC concentrations such as those in the pharmaceutical industry, single point
calibration is a very good solution. A big advantage is that the device blank value is low
and that the NDIR detector performs linear measurement across a wide range of con-
centrations.
Proceed as follows to minimize errors during manual standard solution creation:
Prepare 3 standard solutions at the same concentration.
¡
Measure the standard solutions.
¡
¡ Determine the calibration curve from the average value in the results.
Take the blank value of the preparation water into account during single point calibra-
tion.
Calibration with a standard solution can be checked and corrected via the daily factor.
The software multiplies all subsequent measurement results with this factor.
The daily factor F is calculated in accordance with the following formula:
F = c /c
target actual
Each parameter (TC, TOC, TIC, etc.) of a method can be calibrated in the multiWin soft-
ware. Not all parameters require calibration, however.
You can store up to three calibration functions for different concentration ranges for
each parameter in a method. The software automatically assigns the measurement re-
sults to the correct calibration range.
The software determines the calibration function in relation to mass m per injected
sample. It determines linear or quadratic calibration functions in accordance with the
following equations via regressive calculation:
Linear calibration function: c = (k
Quadratic calibration function: c = (k
c: target concentration of the standards
V: Sample volume
I : Net integral
Net
k , k , k : calibration coefficient
0 1 2
The net integral is the raw integral corrected by the blank value of the preparation wa-
ter.
You can specify the regression type (linear or quadratic). Individual measuring points or
measured values for the calculation of the current calibration (manual outlier selection)
can be selected. If necessary, you can define individual standards again, or also add ad-
ditional measurement points to the calibration.
Up to 20 calibration points can be used, with a tenfold determination per calibration
point. The calibration function can be determined either from the average values of the
repeat measurements or from all individual determinations.
x I + k )/V
1 Net 0
2
x I + k x I + k )/V
2 Net 1 Net 0
multi N/C pharma HT