Development of Karl Fischer Reagents
Development of Karl Fischer Reagents
Development of Karl Fischer Reagents
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II-2. Inorganic Compounds<br />
3) Hydrochloric acid<br />
The reagent hydrochloric acid can be titrated directly by adding about<br />
0.03g <strong>of</strong> sample to 50ml <strong>of</strong> Dehydrated Solvent MS.<br />
4) Hydr<strong>of</strong>luoric acid<br />
The reagent hydr<strong>of</strong>luoric acid can be titrated directly by adding about<br />
0.03g <strong>of</strong> sample to 50ml <strong>of</strong> Dehydrated Solvent MS.<br />
However, as hydr<strong>of</strong>luoric acid erodes glass parts <strong>of</strong> the titration cell and<br />
the electrodes, teflon-coated parts should be used.<br />
5) Hydrocyanic acid<br />
The reagent hydrocyanic acid can be dissolved in Dehydrated Solvent<br />
MS for direct titration.<br />
[Examples <strong>of</strong> Measurement]<br />
(1) Volumetric titration<br />
<strong>Reagents</strong> used: <strong>Karl</strong> <strong>Fischer</strong> Reagent SS-Z (or SS)<br />
Dehydrated Solvent GEX (or MS) 25-50ml<br />
116<br />
Substance<br />
97% Sulfuric acid<br />
92% Sulfuric acid<br />
Nitric acid<br />
Nitric acid (85%)<br />
Hydrochloric acid (38%)<br />
Hydr<strong>of</strong>luoric acid (48%)<br />
Hydrocyanic acid<br />
Phosphoric acid (85%)<br />
Hydrogen chloride gas<br />
Dehydrated<br />
solvent<br />
General-use<br />
"<br />
"<br />
"<br />
"<br />
"<br />
"<br />
"<br />
Sample<br />
quantity (g)<br />
0.2423<br />
0.1145<br />
0.0360<br />
0.1155<br />
0.0379<br />
0.0368<br />
0.3888<br />
0.0533<br />
Measurement<br />
value (mg)<br />
07.69<br />
08.74<br />
35.04<br />
16.87<br />
23.67<br />
18.96<br />
05.56<br />
07.85<br />
Moisture<br />
content (%)<br />
03.17<br />
07.63<br />
97.30<br />
14.60<br />
62.50<br />
51.50<br />
01.43<br />
14.70<br />
Hydrogen chloride gas reacts with <strong>Karl</strong> <strong>Fischer</strong> reagent and cannot be<br />
titrated directly. The moisture content is titrated after condensation in a trap<br />
at -78 � C, using the following procedures.<br />
a) To ensure that the system is free <strong>of</strong> moisture, nitrogen gas that has first<br />
been dried with silica gel and phosphorus pentaoxide is passed inside<br />
titration flask D in the direction L � M � y at a rate <strong>of</strong> approximately<br />
0.5l/min. (The moisture content <strong>of</strong> the nitrogen that passed through the<br />
system is titrated.)
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