Metrohm viva 1.0 (process analysis) - Manual (Page 970)

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viva 1.0 (for Process analysis)
Calibration
Way in which the content of the substances in the sample is determined
from their evaluation quantities.
Calibrator
The 894 Professional CVS is equipped with a built-in calibrator with pre-
cisely specified reference values that are defined in the corresponding cali-
bration certificate. This innovative component permits the performance of
voltammetric measurements with increased reliability and precision. The
measuring input of the 894 Professional CVS is automatically adjusted to
the reference values of the calibrator before each measurement and thus
yields stable, precise and reproducible results over a long period, even
under suboptimal measuring conditions. In this way, the 894 Professional
CVS automatically recalibrates itself before each measurement.
Command variable
Variable generated by a command in the method run (see Chapter
2.3.3.4, page 23).
Command
Smallest subset of a track; defines a single step in the method run.
DT (Dilution Titration)
Calibration method based on a dilution titration and mainly used for sup-
pressor determination in electroplating baths. It consists of a two-stage
process, in which a calibration is first carried out with a suppressor stand-
ard solution before the sample solution is measured.
Calibration with standard
For the calibration, a basic solution with no added organic substances,
called VMS (Virgin Make-up Solution), is measured first (see Glossary,
page 964). The area of the oxidation peak obtained with the anodic
sweep is evaluated and the charge is calculated. This charge is used as
start value Q(0) for the further calibration. Small amounts of a diluted sup-
pressor standard solution are then dosed into the basic solution. The peak
areas are standardized in order to improve the comparability of the mea-
suring results obtained. This is achieved by setting up the quotient Q/Q(0)
of the currently measured signal Q and the start value Q(0) and plotting it
against the effective addition volume VEFF for each step (see Glossary,
page 959). The addition of standard solution is repeated until the Eval-
uation ratio defined in the method (usually Q/Q(0) = 0.5) has been
achieved. The recorded calibration curve is then used to calculate the Cal-
ibration factor, which expresses the suppressor concentration in the
measuring vessel for the Evaluation ratio (see Chapter 5.6.7.7.11, page
635).