Metrohm 787 KF Titrino - Manual (Page 31)

2.6 Parameters, key
787 KF Titrino
27
Mechanisms of the KFT parameters in Ipol mode
• The position and curve characteristics of the line between the ranges of excess water
or excess iodine depends on the type of sample and the ingredients of the working
media.
• The endpoint has to be set close to the range margin, but always within the iodine
excess range. If the endpoint is set too close to the limit, an overdose of KF reagent
may be dispensed. The steeper the curve at the preset polarization current I(pol), the
more delicate it is to titrate to a steady and reproducible endpoint. For the titration of
troublesome samples, the particular conditions must be optimized by trial and error.
Always mind the color of the working medium at the end point as your guideline.
Remark: In most cases the preset default parameters provide precise and
reproducible results.
• If you select negative values for a polarization, you should choose negative values for
all other parameters too in order to have compatible parameter sets.
• In measurements with the setting "Upol", all parameters work in a similar manner as in
measurements with the setting " Ipol".
U/mV
I/µA
+
+
I(pol)
EP at U
Titration
(Back titration)
Titration
(direct titration)
Excess H
2
O
Excess Iodine
darker
solution