Metrohm viva 1.1 (ProLab) - Manual (Page 1068)

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viva 1.1 (for process analysis)
RC (Response Curve)
The response curve is a standardized calibration curve for electroplating
bath additives with a suppressing effect. It involves a two-stage process, in
which a calibration curve is first recorded with a standard solution before
the sample solution is measured.
Calibration with standard
In order for a calibration curve to be produced, a basic solution spiked
with additives, called the electrolyte solution, is measured first. 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. Then, standard solution is incrementally added to the electro-
lyte solution. The peak areas are standardized in order to improve the
comparability of the measuring results obtained. This is achieved by set-
ting up the quotient Q/Q(0) of the currently measured signal Q and the
start value Q(0) and plotting it against the concentration of the standard
in the measuring cell. Standard solution addition is repeated (at least three
times). The calibration curve recorded in this way is then saved to the
database.
Sample measurement
The additive concentration in the sample is determined with the same
parameters as for the calibration. Two options are available for this:
￭ With solution exchange
First, the electrolyte solution is measured, 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 standardization in
the further course of the determination. Then, the electrolyte solution
is discarded and exchanged for sample. The area Q of the oxidation
peak obtained with the anodic sweep is evaluated again and used
together with the previously recorded calibration curve for determining
the concentration (Q/Q(0)).
￭ Without solution exchange
First, the electrolyte solution is measured, 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 standardization in
the further course of the determination. Then, the sample is added to
the electrolyte solution. The area Q of the oxidation peak obtained
with the anodic sweep is evaluated again and used together with the
previously recorded calibration curve for determining the concentration
(Q/Q(0)).
Example: