Metrohm tiamo 1.1 Manual - Manual (Page 444)

416 Method
The diagram shows KF titration curves at different polarization currents. It is
clear to see that the position of the end point varies with the polarization
current. The curves have different slopes, i.e. dynamics must also be
adapted. Polarization currents smaller than 10 µA are not suitable for this
application. The following table gives an idea of the optimal control pa-
rameters for various polarization currents.
Ipol 10 µA 20 µA 30 µA
EP 50 mV 100 mV 150 mV
Dynamics 70 mV 100 mV 120 mV
Max. rate
1.5 ... 2240 µg/min, [ maximum ]
Maximum rate with which iodine is produced outside the Dynamics .
Min. rate
0.3 ... [ 15.0 ] ... 999.9 µg/min, minimum
This parameter defines the minimum rate with which iodine is produced in-
side the dynamics. The smaller the rate the slower the titration and the
higher the accuracy.
Stop criterion
Stop criterion
drift , [ rel. drift ]
Switches off titration when the end point has been reached and the stop cri-
terion has been met.
Stop drift
1 ... [ 5 ] ... 999 µg/min
Switches off titration when the end point and stop drift have been reached.
This parameter is only shown for Stop criterion = drift .
Relative stop drift
0 ... [ 5 ] ... 999 µg/min
Switches off titration when the end point and stop drift have been reached.
The stop drift is calculated according to the actual drift at start of titration +
entered value for relative stop drift. This parameter is only shown for
Stop
criterion = rel. drift
Titration parameters
Parameters defining the run of the titration.
Command name
25 characters, [ KFC # ]
Name of the command.
Extraction time
[ 0 ] ... 999999 s
The titration is not stopped until the extraction time has elapsed (even when
the EP has already been reached). For example, the entry of an extraction
time is a good idea for the titration of sparingly soluble samples.