Development of Karl Fischer Reagents

(4) Moisture vaporization - Coulometric titration
Reagents used: Aquamicron AX (or AS) 150ml
Aquamicron CXU 10ml
Substance
Detergents
Soaps
Cleansers
16. Cosmetics
Key Points
Heating Temperature
( � C)
180
150
600
Sample Quantity
(g)
0.0324
0.4901
0.0330
Chapter III: Applications - 2
Measurement Value
(µg)
5084
1517
2475
Moisture Content
(%)
15.700
00.310
07.500
Creams, emulsions, rinses, hair tonics, lotions and other cosmetics
have high moisture content. Accordingly, volumetric titration is the main
method used with these items. When carrying out the volumetric titration
it is convenient to use a high-titer Karl Fischer reagent. An oil-type
dehydrated solvent is used for products with a high oil content, such as
creams. A general-purpose dehydrated solvent is used for hair tonics
and lotions.
Coulometric titration can also be used. However, the high moisture
content of these products means that titration will be prolonged, even
with small samples. For this reason, volumetric titration should be used
whenever possible.
Sampling devices should be selected carefully. Viscous products such
as creams should be sampled with a sampling spoon and dissolved
directly in the dehydrated solvent.For lotions and similar products, a
sampling flask with pipette is convenient. For cosmetics that will not
dissolve in dehydrated solvent, volumetric or coulometric titration
should be used in combination with moisture vaporization.
[Examples of Measurement]
(1) Volumetric titration
Reagents used: Karl Fischer Reagent SS-Z (or SS)
Dehydrated Solvent GEX, OL II (or MS, CM) 25-50ml
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