Development of Karl Fischer Reagents

Chapter I: Basic Knowledge
Measuring Moisture Content of Strong-Base Amines
Put 10g of salicylic acid into a titration flask (electrolysis cell).
Add 50ml of Dehydrated Solvent GEX or MS (100ml in the case
of Aquamicron AX) and mix together. Add the sample (amine)
after dehydrating it with Karl Fischer reagent. Then initiate Karl
Fischer titration. The amount of sample that can be measured
will vary according to the type of amine.
4. Procedures for Karl Fischer Titration
Q11
How should we actually carry out volumetric titration?
Please describe the preparations and procedures involved.
To measure moisture content by means of volumetric titration, you will first
need to prepare the following items.
�Titration agent: Karl Fischer Reagent SS-Z (or SS)
(It is necessary to assess the titer before use.)
�Titration solvent: Select the dehydrated solvent to suit the samples.
�A Karl Fischer volumetric titration system
(Reagents manufactured by Mitsubishi Chemical can be used with
any commercially available system.)
Next, the amount of the sample is determined according to the anticipated
moisture content.
In general, one of the following three methods of titration are used. The
procedures for each are explained below.
(1) Direct titration
(2) Back titration
(3) Water vaporization
1. Sample Size
It is important to determine the size of the sample according to the moisture
content. If there is excessive moisture, Karl Fischer reagent will be wasted,
and if there is too little, there will be significant effect on titration error and
the results will lack precision. The following table can be used as a guide
when determining the appropriate amount of sample in relation to
anticipated moisture content. The figures shown here assume that the Karl
Fischer reagent has a titer of 3mg/ml. If the titer is different, it will be
necessary to adjust the figures accordingly.
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