| KEM Product |
|
Karl
Fischer Moisture Titrator
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|
Volumetric method
|
| ASTM E203
Standard Test Method for Water Using Volumetric Karl Fischer
Titration |
|
The sample,
containing a maximum of 100 mg of water, is dissolved or dispersed
in a suitable liquid and titrated with KF reagent, which consists of
iodine, sulfur dioxide, organic base, and a solvent (typically an
alcohol, such as methanol, ethylene glycol, or 2-methoxyethanol).
The titration end point is determined amperometrically with a
platinum electrode which senses a sharp change in cell resistance
when the iodine is reduced by sulfur dioxide in the presence of
water. |
|
ISO 760 Determination of water -- Karl Fischer
method (General method) |
| |
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Measuring method :
Volumetric method
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Measuring range
: 0.1mg ~ 500mg，10 ppm
~ 100% H2O |
|
|
Coulometric method
|
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ASTM E1064 Standard Test Method for Water in
Organic by Coulometric Karl Fischer Titration
|
|
This test method is based on the
Karl Fischer reaction for determining water-the
reduction of iodine by sulfur dioxide in the
presence of water to form sulfur trioxide and
hydriodic acid. The reaction becomes
quantitative only when pyridine or other organic
base and methanol or other alcohol are present.
Unlike the volumetric Karl Fischer reagents that
include iodine, the coulometric technique
electrolytically generates iodine, with 10.71 C
of generating current corresponding to 1 mg of
water in accordance with Faraday’s law. |
| |
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Measuring method :
Coulometric method
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|
Measuring range
: 10µg
~
100mg |
|
Sensitivity
: 0.1µg H2O |
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Precision
: RSD < 0.3% |
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ASTM D6869
Standard Test Method for Coulometric and Volumetric
Determination of Moisture in Plastics Using the Karl
Fischer Reaction (the Reaction of Iodine with Water) |
|
Samples are heated to vaporize water
that is transported by a nitrogen carrier gas to the
titration cell. The moisture collected in the solution
within the titration cell is determined using the
reaction of water with I2. |
|
Endpoint detection is made by
instrumented methods. Determination of the moisture
present is made using the reaction of I2 with
water. |
|
Coulometric instruments use Faraday’s
law to measure the moisture present with 10.71 Coulombs
(C) of generating current corresponding to 1 mg of water
(2I-
®
I2 + 2e-).
Volumetric instruments measure the volume of solution
containing I2 that is required to keep the
current constant. |
| ISO 15512
Plastics -- Determination of water
content |
|
