3.5 Installing the Optrode
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Optrode
The sensor must be firmly installed on the titration head. Particularly when
automation is used, you have to account for the cable movement.
During the titration, it is important that the solution is well mixed. The stir-
ring rate should be high enough to form a small vortex. If the stirring rate
is too high, then air bubbles will be aspirated. This results in incorrect
measured values. If the stirring rate is too low, then the solution at the
sensor will not be mixed correctly.
In order for the measurement to be taken in a well-mixed solution after
the addition of the titrant, the titration tip should be positioned where tur-
bulence is high. Furthermore, the distance between the addition of the
titrant and the electrode should be as large as possible. Therefore, take
into account the stirring direction (counterclockwise or clockwise) when
positioning the electrode and titration tip.
The sensor's optical window is to be positioned facing the flow direction.
This removes small air bubbles from the measuring gap.
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