Application Note
YSI, a Xylem Brand • XA00148
Titration of Water in Liquid Samples
VOLUMETRIC KARL FISHER SERIES
Introduction
This application can be used for many liquid samples as long as no side reactions occur and the sample dissolves in the
KF reagent. Liquid samples that do not or only partially dissolve in alcohols can often still be titrated in Methanol or similar
solvents. If the water is extracted from the sample dispersed in the solvent during the titration, the extraction time should
be increased. The solubility of the sample can be improved by adding toluene, chloroform, long-chain alcohols or similar
solvents. Various special KF solvents for oils or fats are also available. In this application, 1-component reagents are used to
determine the water content. The use of 2-component reagents is also possible if the corresponding titration parameters
are used.
If a sample causes side reactions, it can be recognized from the titration curve. After the water has been titrated (the
steep rise in the curve at the beginning), the titration curve rises steadily until the max. time has been reached, the µA end
criterion is not met. Some side reactions can be prevented by titration with special reagents (ketones), for others it helps to
titrate in the cold. Some side reactions cannot be prevented.
KF-Titration with side reaction; A: Water + side reaction; B: side reaction
B
A
Instrument
Titrator TL 7500 KF or higher
Exchange Unit WA 10
Electrode, Cable, and Electrolyte
Electrode KF1100
Lab Accessories
Magnetic stirrer TM 235 KF
Karl-Fischer titration vessel TZ 1770
Glass syringe (or disposable syringe) with needle
Reagents
1 1-component titrant, e.g. Composite 2 or 5 or a similar reagent
2 1-component solvent, e.g. CompoSolver E, Methanol or a similar solvent
3 Molecular sieve, dry
All reagents should be in analytical grade or better.
Titration Procedure
Reagents
Karl Fischer reagents are available as ready-to-use solutions
The molecular sieve must be replaced or dried regularly, at
least every 4 weeks.
Cleaning of the electrode
The KF 1100 electrode does not require any special
treatment. The two platinum pins must not touch each other.
For cleaning, Isopropanol or other solvents that do not attack
glass and platinum are suitable.
Sample preparation
The titration cell is lled with approx. 30 ml solvent and
the conditioning is started. The solvent can be used for
several titrations.
The sample is drawn into a syringe with a needle. If
possible, the syringe should be rinsed with a small
amount of sample before. After conditioning is nished,
the sample is injected through the septum into the
titration cell and the titration is started. The amount of
sample is determined by weighing back.
0.5 * Titer [ ]
W (g) =
expected water content [%]
mg
mL
2
Titration parameter
Suitable method parameters for the reagents used should be selected for the KF titration. Appropriate default methods are
stored in the titrator. The parameters used here are well suited for most applications.
The default method “Sample 1-Comp.” is well suited
for 1-component reagents:
Default Method Sample 1-Comp
Method type Automatic Titration
Mode KF
Conditioning On
Extraction time 10 s
Fixed delay time 1 s
Step size 0.005 mL
Pre-titration aus
Polarization voltage 100 mV
Maximum Titration Time 600 s
Minimum Titration Time 60 s
Maximum Titration Volume 50 mL
Drift 100 µg/min
Endpoint 20.0 µA
Delta Endpoint 3.0 µA
Endpoint delay 10 s
Dosing Speed 30%
The default method “Sample 2-Comp.” is well suited
for 2-component reagents:
Default Method Sample 2-Comp
Method type Automatic Titration
Mode KF
Conditioning On
Extraction time 10 s
Fixed delay time 0 s
Step size 0.004 mL
Pre-titration aus
Polarization voltage 100 mV
Maximum Titration Time 600 s
Minimum Titration Time 60 s
Maximum Titration Volume 50 mL
Drift 50 µg/min
Endpoint 20.0 µA
Delta Endpoint 18.0 µA
Endpoint delay 10 s
Dosing Speed 30%
Calculation:
Water [%] =
(EP – B) * T * M * F1
W * F2
B 0 Blank value
EP - Consumption of titrant
M 1 Molecular mass of
W manual Sample weight in [g]
F1 0.1 Conversion factor 1
F2 1 Conversion factor 2
The calculation is done here as % water. F1 may need to be adjusted for other units.
APPLICATION NOTE XA00148
YSI, a Xylem brand
1725 Brannum Lane
Yellow Springs, OH 45387
TitroLine® is a registered trademark
of Xylem or one of its subsidiaries.
© 2021 Xylem, Inc. XA00148 0121
+1.937.767.7241
titration.ysi@xyleminc.com
YSI.com
YSI.com/Titration
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