Development of Karl Fischer Reagents

II-1 Organic Compounds
Examples of substances that can be measured directly:
The following inactive carbonyl compounds can be dissolved in a generaluse
dehydrated solvent and measured directly.
Formaldehyde,
chloral
However, these substances tend to react with methanol at room temperature
(above 25 � C) and we recommend a titration method whereby the sample is
dissolved in a ketone-type dehydrated solvent.
[Examples of Measurement]
(1) Volumetric titration
Reagents used:Karl Fischer Reagent SS-Z (or SS)
Dehydrated Solvent KTX (or CP) 25-50ml
86
Substance
n-Butyraldehyde
Isobutyraldehyde
Crotonaldehyde
Propionaldehyde
Formalin
Chloral hydrate
Dehydrated
solvents
Ketone-type
"
"
"
General-use
"
Sample
Quantity (g) Measurement
Value (mg)
0.4020
0.3952
0.4239
0.2014
0.0328
0.1752
3.56
0.96
0.67
7.36
17.42
19.27
Moisture
Content (%)
0.886
0.243
0.158
3.65
53.1
11.0
Note: Dehydrated Solvent KTX should be used in combination with
Karl Fischer Reagent SS-Z, and Dehydrated Solvent CP with
Karl Fischer Reagent SS.
Measuring moisture content in acetaldehydes
Given the intensity of the interference reaction that occurs with
acetaldehydes, Dehydrated Solvent PP should be used as it contains no
pyridine-sulfur dioxide. The following guidelines should apply.
If the acetaldehyde has a high moisture content, 0.2ml samples can be
measured. If the moisture content is less than about 0.2%, however, the
sample will be too small and this method cannot be used. Accordingly,
when measuring trace amounts of moisture, 5-10ml of sample should be
added to 5ml of Dehydrated Solvent PP in the apparatus shown in the
diagram. The sample should be vaporized using dried nitrogen during the
titration.