Metrohm 840 PC Control 5.0 / Touch Control - Manual (Page 207)

4 Parameters
PC Control / Touch Control
195
• Karl Fischer titration (KFT) for determining the water content by
the Karl Fischer method with automatic pre- and post-conditioning.
A typical feature of the Karl Fischer titration is the controlled reagent
addition, which depends on the control difference (current meas-
ured value – endpoint), with the aim of reaching the measured value
given as being the predefined target endpoint as quickly and accu-
rately as possible. Overtitrating is avoided to a great extent. The ti-
tration termination at the endpoint takes place either drift-controlled
or after a waiting period. The volume added up to the endpoint
gives the calculable reagent consumption.
EP
KFT Ipol
KFT Upol
EP
V/mL
Control
range
Continuous
addition
Initial
addition
V/mL
V/mL
U/mV
t/s
I/mA
Fig. 4.4: Reagent addition for KFT
The measuring modes pH (potentiometric pH measurement), U (po-
tentiometric voltage measurement), Ipol (voltametric measurement with
selectable polarization current) and Upol (amperometric measurement
with selectable polarization voltage) can be selected for all titrations.