multi N/C 2100S Function and setup
35
For low TOC concentrations a single point calibration is permitted for the
multi N/C (CeO2) – the blank value of the device is low and the NDIR detector linear.
To minimize sources of error during a single point calibration due to an incorrect
standard preparation, the following procedure is recommended:
Preparation of 3 standards with identical concentration
Measuring these standards
Calculation of the calibration curve from the mean of these standards
When using a single point calibration, the blank value of the preparation water must be
taken into account.
3.5.2 Day factor
Via the day factor it is possible to check and correct the calibration with a standard
solution. All subsequent measurement results are multiplied by this factor.
The day factor is calculated in accordance with the equation (5).
=
(5)
3.5.3 Calibration method in multiWin
Every parameter (procedure) of a method can be calibrated. The parameters of a
method to be calibrated can be individually defined. Not all parameters need necessarily
be calibrated.
For every carbon parameter up to three calibration functions can be stored in a method.
The allocation is automatic.
The calibration function is calculated in relation to the mass m per injected sample.
Linear and quadratic calibration functions are calculated in accordance with the
equations (6) and (7) through regression calculation.
= (
+
)/ (6)
= (
+
+
)/ (7)
c … target concentration of the standards
V … Sample volumes
I
Net
… net integer
k
0
, k
1
, k
2
… calibration coefficient
The net integer is the raw integer corrected by the preparation water.
The regression type (linear or quadratic) can be defined by the user. It is possible to
select individual measuring points or measured values for the calculation of the current
calibration (manual outlier selection). Individual standards can, where required, also be
redetected or additional measuring points added to the calibration.
Single point calibration
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