Development of Karl Fischer Reagents

[Procedures]
Chapter I: Basic Knowledge
a) All moisture is removed from the dehydrated solvent using the procedures
described in the previous section.
b) The sample (A', g) is immediately placed in a titration flask.
c) A specific amount (C, ml) of excess Karl Fischer reagent SS-Z (titer
F'mg/ml) is then added and the sample is stirred for the required period of
time.
d) The sample is then titrated to the end point (D, ml) using a standard
water/methanol solution (titer f, mg/mg).
e) Moisture content (W', %) is calculated according to the following formula.
(C x F')-(D x f )
W' = x 100
A' x 1000
4. Moisture Vaporization Method
The moisture vaporization method is used with solid samples that do not
readily dissolve in dehydrated solvents, or for samples that cause
interference reactions. Moisture vaporization is carried out using a
commercially available moisture vaporization system in combination with a
volumetric titration system.
[Procedures]
a) An oven is maintained at a temperature suitable for vaporizing the
moisture content of the sample. Nitrogen gas, which has previously been
passed through a drying tube, is passed through the moisture
vaporization system at the rate of approximately 300ml/min.
b) The titration system is dehydrated by means of pre-titration in the titration
system in a flow of nitrogen gas.
c) The sample is then quickly transferred to a sample boat and placed in an
oven that has been maintained at the required temperature.
d) The vaporized water is absorbed into a dehydrated solvent (GEX, MS or
ME).
e) Karl Fischer titration is then carried out according to the direct titration
method.
Note:Dehydrated solvent GEX or MS should be used in a mixture
consisting of one part of propylene glycol to three parts of
dehydrated solvent by volume.
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