113
4.6.2.3 End-Point titration
The goal of End-Point titration consists in titrating as precisely as possible to an end point given in terms of pH,
mV or µA. In the case of pH und mV you can also titrate to two end points. Consumption in the end point will be
used as a result.
The classical examples of pH End-Point titration include total acidity in wine or beverages and the p+m value
(alkalinity). A classic example of µA End-Point titration is present in the determination of sulphurous acid (SO
2
) in
wine and beverages.
The first stage of End-Point titration consists in the continuous dosing up to a delta value away from the set end
point. The dosing speed can be adjusted. Subsequently, titration is performed in a drift-controlled manner with
linear step sizes between the delta value and the end point.
Example (Fig. 61): Determination of the alkalinity (m value)
pH in the point:
4.50
delta pH value:
1.00
linear step width:
0.02
dosing speed:
12 %
End-Point delay:
5 s
drift:
medium (25 mV/min)
Up to a pH value of 5.50, titration is performed with the set dosing speed. Subsequently, the method will change
to a linear step size of 0.02 ml, until the end point of pH 4.50 is either reached or fallen short of. Should this value
raise again to above pH 4.50 within 5 seconds, another titration step of 0.02 ml will be added. Consumption will
be determined precisely at pH 4.50.
Fig. 61
4.6.3
Result
At first, the calculation options (dynamic and linear titration only) are specified (Fig. 62).
Fig. 62
