Development of Karl Fischer Reagents
Development of Karl Fischer Reagents
Development of Karl Fischer Reagents
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Substance<br />
Potassium chloride<br />
"<br />
Lithium chloride<br />
Cesium iodide<br />
Sodium iodide<br />
Barium fluoride<br />
Aluminum fluoride<br />
Zinc fluoride<br />
6. Carbonates, Bicarbonates<br />
Key Points<br />
Heating<br />
temperature( � C)<br />
100<br />
750<br />
200<br />
200<br />
400<br />
800<br />
800<br />
500<br />
Sample<br />
quantity (g)<br />
0.9903<br />
1.0021<br />
0.1035<br />
9.5975<br />
2.9079<br />
0.5323<br />
0.6244<br />
0.8577<br />
Chapter II: Applications - 1<br />
Measurement<br />
value (µg)<br />
1056<br />
3044<br />
5117<br />
18<br />
1510<br />
291<br />
55<br />
596<br />
Moisture<br />
content (%)<br />
0.107<br />
0.304<br />
4.940<br />
2ppm<br />
519ppm<br />
547ppm<br />
88ppm<br />
695ppm<br />
Direct measurement is not possible with carbonates and bicarbonates<br />
as they react with <strong>Karl</strong> <strong>Fischer</strong> reagent and cause interference. The<br />
degree <strong>of</strong> interference depends on the solubility <strong>of</strong> each substance. For<br />
example, alkaline metal carbonates and bicarbonates react as shown in<br />
the formulae below.<br />
K2CO3+I2+SO2+CH3OH�2KI+CO2+HSO4CH3<br />
KHCO3+I2+SO2+CH3OH�KI+HI+CO2+HSO4CH3<br />
Direct measurement is possible with calcium carbonate. Since it does<br />
not dissolve in dehydrated solvent it is dispersed and the moisture<br />
content extracted. This is only possible with volumetric titration.<br />
Direct measurement is not possible with sodium bicarbonate and the<br />
moisture vaporization method is also unsuitable as the substance<br />
releases water when heated. In general, for carbonates that are stable<br />
when heated, the moisture content is measured using the moisture<br />
vaporization method.<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, OL II (or MS, CM) 25-50ml<br />
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