Development of Karl Fischer Reagents
Development of Karl Fischer Reagents
Development of Karl Fischer Reagents
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Substance<br />
Calcium hydroxide<br />
"<br />
Magnesium hydroxide<br />
Nickel hydroxide<br />
"<br />
4. Oxides<br />
Key Points<br />
Heating<br />
temperature( � C)<br />
110<br />
900<br />
150<br />
150<br />
600<br />
Sample<br />
quantity (g)<br />
0.6375<br />
0.0289<br />
0.4956<br />
0.1222<br />
0.1092<br />
Note:<br />
*Adhesion water, ** bonded water<br />
Chapter II: Applications - 1<br />
Measurement<br />
value (µg)<br />
2953<br />
6708<br />
670<br />
1797<br />
22098<br />
Moisture<br />
content (%)<br />
0.463*<br />
23.2**<br />
0.135*<br />
1.47*<br />
20.2**<br />
Metallic oxides generally react with the iodine in <strong>Karl</strong> <strong>Fischer</strong> reagent in<br />
accordance with the following formula. In particular, alkaline metal and<br />
alkaline earth oxides (strong basicity) react quantitatively and rapidly.<br />
MO+2HI � MI2+H2O<br />
A number <strong>of</strong> substances, such as magnesium oxide, zinc oxide, silver<br />
(I)oxide, mercury (I) oxide and copper (I) oxide, react with <strong>Karl</strong> <strong>Fischer</strong><br />
reagent in accordance with the formula below.<br />
ZnO+I2+SO2+CH3OH�ZnI2+HSO4CH3<br />
Manganese dioxide reacts with <strong>Karl</strong> <strong>Fischer</strong> reagent as shown below.<br />
Lead dioxide and red lead cause similar reactions.<br />
MnO2+I2+2SO2+2CH2OH�MnI2+2HSO4CH3<br />
As a result, direct titration is not possible and moisture content is<br />
measured using the moisture vaporization method. For measurement<br />
using moisture vaporization, the heating temperature for normal<br />
adhesion water is set at 100~200�C. 119
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