Metrohm tiamo 2.3 Manual - Manual (Page 795)

￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ 5 Method
tiamo 2.3 ￭￭￭￭￭￭￭￭ 779
Measured value
Range
-200.0 ... 200.0 µA
Time
Range
0.0 ... 999999.9 s
Volume
Range
0.00000 ... 9999.99 mL
5.6.3.5 KFT
5.6.3.5.1 KFT - Overview
Menu item: Method ▶ Insert ▶ New command...
Command for volumetric Karl Fischer Titrations.
Principle
With this command, volumetric titrations for determining the water con-
tent by the Karl Fischer method with automatic conditioning are carried
out. A typical feature of the Karl Fischer titration is the controlled reagent
addition, which depends on the control difference (current measured
value – endpoint), with the aim of reaching the measured value given as
being the predefined target endpoint as quickly and accurately as possi-
ble. Overtitrating is avoided to a great extent. The titration 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 con-
sumption.
Reagent addition takes place in three phases during the titration:
￭ Initial dosing
During this phase the dosing rate increases continuously. It starts with
the Min. rate and increases to the Max. rate.
￭ Continuous dosing
The dosing continues to be carried out at the Max. rate until the
Control range is reached.
￭ Control range
Dosing is finely controlled in this range. Shortly before the endpoint is
reached, dosing is carried out only at the Min. rate.