Function and setup multi N/C 2100S
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The determination limit of the calibration specifies the lowest concentration that can be
differentiated quantitatively from the zero point with a given probability.
3.5.5 Other calculations
For all measurements where multiple injections are carried out the average value (AV),
standard deviation (SD) and variation coefficient (VC) are calculated and displayed. For
each sample a tenfold determination can be carried out as a maximum.
The control and analysis software multiWin offers the option for an automatic outlier
selection. In the method a maximum limit for a variation coefficient or also for a
standard deviation can be entered.
The minimum number of measurements agreed in the method will be carried out. If the
distribution of the measured values is then above the agreed value (SD or VC) additional
injections are carried out from the same sample until the specified maximum number of
measurements has been reached.
After each measurement the variation coefficient or standard deviation are calculated
for all combinations of measurements. If the variation coefficient or the standard
deviation of at least one combination are smaller than the specified maximum variation
coefficient or standard deviation, no further measurements are carried out. 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.
If carbon and nitrogen are detected in parallel, the outlier selection takes place
separately for each parameter.
The average value of the final result is calculated from the concentrations determined
for the individual detections after eliminating the outliers.
3.6 Blank Values
3.6.1 Blank water values
Especially for measurements with low TOC concentrations (µg/l range) the TOC content
of the water used for preparing the standard can often not be neglected. The weighted-
in standard concentration and the TOC blank value of the preparation water are often in
the same order of magnitude. The 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).
=
(12)
The calibration function is calculated from the net integers. Mathematically this
corresponds to a parallel movement of the calibration line.
Limit of quantitation
Outlier selection
Mean value
Water to prepare
standard solutions
preparation water blind
value
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