HIRANUMA APPLICATION DATA

Watercontents

Karl Fischer Titrator

Data No.

KF
14V

Nov.29.
2018

Ketones and Aldehydes – KF Volumetry, Direct-Injection
Methyl ethyl ketone, Acetone, and Cyclohexanone

1. Abstract
Water contents of ketones and aldehydes could be determined by Karl Fischer volumetric titrator. In
volumetric titration, titrant have a factor which is the capacity to react with water per 1 mL of titrant. Factor is
pre-determined before sample measurement and water content of sample is calculated from consumed titrant
volume by sample measurement.
When the sample is liquid, generally sample is measured by direct injection into the titration cell.
Dehydrated methanol is generally used for titration solvent. However, in the measurement of ketones andaldehydes, since these react with methanol to produce water, the measurement result tends to be higher than thetrue value (formula (1)).
R2CO+2CH3OH →R2C(OCH3)2+H2 O・・・(1)For above reason, Karl Fischer reagent without methanol should be used for water determination of ketonesand aldehydes. There are commercially available reagents with a special composition for ketones andaldehydes. This chapter introduces an example for the water determination in methyl ethyl ketone, acetone andcyclohexanone with water added to them to 1 %. These samples are often used as paint solvents, raw materialsof adhesives, and synthetic resins.

2. Apparatus and Reagents(1) Apparatus
Titrator：

Hiranuma Karl Fischer Volumetric titrator

Titration cell：Standard Cell

Titrant：

HYDRANAL Composite 5K

Titration solvent：

HYDRANAL Working Medium K(2) Reagents

3. Procedure(1) Fill 50 mL of titration solvent into the titration cell as shown in Fig.3.1.
(2) Start blanking to attain stable background.
(3) Wash the syringe with sample.
(4) Draw the sample into syringe and then weigh the syringe.
(5) Inject sample from rubber septum of titration cell as shown in Fig.3.2.
(6) Start titration. Measurement parameter is shown in Table 4.1.
(7) Weigh the syringe again and then set the difference of weight to sample size.

AQV-series

Titration solvent

Fig.3.1 Preparation of the reagents

Note(1) Do not touch the tip of needle totitration solvent.
(2) When injecting, set the tip of needle asbelow figure.

(3) Before pulling out the needle, draw alittle air to prevent dripping of sample.

Fig.3.2 Injection of sample

4. Parameters and results
Table 4.1 Parameters
Condition File
Cal Mode

0:Sample weight (net)
X=(H-b)×F×1000/SIZEInterval Time

30sec

Max Volume

20mL

Min Feed Vol.

0.01

mL

0min

S.Timer
KF Factor

5.4839mg/mL

KF Buret No.

1

KF Speed(OUT)

12mL/minKF Speed(IN)24mL/minBack GroundSample Size Input

OFFEvery TimeBlank Value0

Unit Mode

AUTO

E.P Detection

mLuA

Solvent

S,O,CE

C.P Level

150µA

E.P Level

200µA

0g

Auto Interval

Table 4.2 Results of water content measurement in ketones
SampleSampleSize (g)

Titer
(mL)

Water
(mg)

Watercontent (%)

Methyl ethyl ketone

0.5410

1.04

5.759

1.06450.4792

0.92

5.095

1.06320.5652

1.08

5.981

1.0582

0.4925

0.91

5.039

1.02310.5003

0.93

5.150

1.02940.4171

0.77

4.264

1.02230.4023

0.74

4.098

1.01860.3848

0.71

3.932

1.02180.3841

0.71

3.932

1.0237

AcetoneCyclohexanone

Statistics result

Avg.
SDRSD

1.062%

0.003

%

0.31%

Avg.
SDRSD

1.025%

0.004%

0.38%

Avg.
SDRSD

1.021%

0.003

%

0.25%

5. Note(1) When the side reaction cannot be suppressed even though you use reagent for ketones, phenomena
such as unstable blanking or undetectable endpoint can be obtained. In that case, it may be improvedby reducing the amount of sample or replacing titration solvent with new one.
(2) Sampling tools should be dried up well before use.
(3) Purge and fill the titrant to fill it homogeneously into the buret.