Function and setup
multi N/C pharma UV
32
The combination of measurements with the smallest variation coefficient or the
smallest standard deviation is used to calculate the analysis results. The unused
measurements are considered as outliers and deleted.
The average value of the final result is calculated from the concentrations determined
for the individual detections after eliminating the outliers.
3.5
Blank Values
3.5.1
Blank water values
Especially for measurements with low TOC concentrations (µg/l range), there is a
significant TOC content in the water used for preparing the standard. The weighed in
standard concentration and the TOC blank value of the preparation water are often in
the same order of magnitude. This blank value can be taken into account during
calibration.
The TOC content of the preparation water is measured separately before the
calibration. The mean integer determined for the preparation water is then deducted
at calibration from the determined integer of each measuring point (gross integer).
𝐼𝐼
𝑛𝑛𝑛𝑛𝑛𝑛
=
𝐼𝐼
𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔
− 𝐼𝐼
𝑃𝑃𝑔𝑔𝑛𝑛𝑃𝑃𝑃𝑃𝑔𝑔𝑃𝑃𝑛𝑛𝑃𝑃𝑔𝑔𝑛𝑛𝑃𝑃𝑃𝑃𝑛𝑛𝑛𝑛𝑔𝑔
(9)
The calibration function is calculated from the net integers. Mathematically this
corresponds to a parallel movement of the calibration line.
The blank value for the preparation water is also considered when determining the
daily factor.
If the sample needs to be diluted, the blank value of the dilution water might also be
of interest. This value can be determined separately or entered manually in multiWin.
The blank value of the dilution will then be considered automatically when calculating
the concentration of diluted samples.
This value can change over time and must be redetermined before the start of each
measuring series. Otherwise the value last entered will be used.
The blank value for the dilution is always specified as standardized to 1 ml in
multiWin.
For every measurement the actual dilution water integer (I
DBW
) is calculated from the
dilution blank value in accordance with the sample volume and the dilution ratio used
(equation (10)) and deducted from the experimentally determined raw integer
(equation (11)). The raw integer determined for each measurement I
raw
is corrected by
the blank value of the dilution water used.
𝐼𝐼
𝐷𝐷𝐷𝐷𝐷𝐷
=
𝑉𝑉
𝐷𝐷𝐷𝐷𝐷𝐷
∗ �𝑉𝑉
𝑔𝑔𝑃𝑃𝑠𝑠𝑃𝑃𝑠𝑠𝑛𝑛
−
𝑁𝑁𝑁𝑁𝑠𝑠𝑁𝑁𝑛𝑛𝑔𝑔𝑁𝑁𝑛𝑛𝑃𝑃𝑛𝑛𝑔𝑔𝑃𝑃𝑔𝑔𝑃𝑃𝑠𝑠𝑃𝑃𝑔𝑔𝑁𝑁𝑁𝑁𝑃𝑃𝑠𝑠𝑃𝑃𝑠𝑠𝑛𝑛
𝑁𝑁𝑁𝑁𝑠𝑠𝑁𝑁𝑛𝑛𝑔𝑔𝑁𝑁𝑛𝑛𝑃𝑃𝑛𝑛𝑔𝑔𝐷𝐷𝑃𝑃𝑠𝑠𝑁𝑁𝑛𝑛𝑃𝑃𝑔𝑔𝑛𝑛
∗ 𝑉𝑉
𝑔𝑔𝑃𝑃𝑠𝑠𝑃𝑃𝑠𝑠𝑛𝑛
�
(10)
𝐼𝐼
𝑛𝑛𝑒𝑒𝑒𝑒
=
𝐼𝐼
𝑔𝑔𝑃𝑃𝑟𝑟
− 𝐼𝐼
𝐷𝐷𝐷𝐷𝐷𝐷
(11)
Mean value
Preparation blank
Dilution blank
Use of the dilution blank