Metrohm 799 GPT Titrino - Manual (Page 37)

2.6 Parameters, key
799 GPT Titrino
33
If you have entered the endpoint and the control range (dynamics), the default values for
the other control parameters should suffice for the first titration. If you encounter
difficulties in optimizing your titration, the following table will be of use.
How to proceed if ...
Problem Possible causes and corrective measures
Dosing at the end too long and
with too small increments.
"Never ends!"
• Increase "min.rate". Perform an experiment with a
much higher min.rate.
• Change switch-off criterion. Attempt, e.g. to increase
the stop drift or use a shorter t(delay) as stop
criterion.
• Possibly pass an inert gas through the titration
vessel.
"Overshoots". Titration is not
controlled, i.e. at the end single
pulses are not dosed.
• Lower "max.rate".
• Set larger control range.
• Set "min.rate" much lower.
• Optimize arrangement of electrode and buret tip and
improve stirring, see page 217. This is particularly
important with very fast titration reactions and with
steep curves.
Titration time is too long. • Set higher "min.rate".
• Set higher "max.rate".
• Lower "dynamics".
Scatter in titration results is too
great.
• Set "min.rate" lower.