Karl Fischer moisture titratorThe Karl Fischer titration method is used to determine the endpoint for measuring moisture using the permanent stop method. When both I2 and I - are present in the solution, the above reaction occurs on two electrodes, where I2 is reduced on one electrode and I - is oxidized on the other electrode, resulting in a current passing through the solution. If there is only I - and no I2 in the solution, then there is no current passing through the solution. When there is a trace amount of Karl Fischer reagent present in the solution at the endpoint of titration, both I - and I2 are present simultaneously. At this time, the solution conducts electricity, and the ammeter pointer deflects, indicating that the endpoint has been reached. Calculate the moisture content based on the amount of iodine consumed in the titration reaction.
Working Principle:
The Karl Fischer titration instrument determines moisture by quantitative reaction of iodine, sulfur dioxide, pyridine, and methanol, with the reaction equation: H ₂ O+I ₂+SO ₂+CH ∝ OH+3RN → [RHN] SO ₄ CH ∝+2 [RHN] I. The volumetric method calculates moisture by measuring the consumption of titrant, while the Coulomb method calculates the amount of electricity generated by electrolysis to produce iodine.
The consumables for Karl Fischer titration mainly include the following types:
Volumetric consumables: including titrants (such as Karl Fischer reagent) and dehydrating solvents, suitable for liquid and soluble solid samples.
Coulombic consumables: containing anolyte and catholyte, used for trace moisture detection.
Accessories and maintenance:
Electrolytic cell components: such as five necked flasks, titration cups, etc.
Maintenance tools: molecular sieves (requiring regular replacement), electrode cleaning agents, etc.