HIRANUMA APPLICATION DATA

Karl Fischer Titrator

Watercontents

Data No.

KF4

Jun.6.
2017

Oil products

1. Abstract
Water content of Oil products are determined by Karl Fischer coulometric titrator. In coulometric titration,
iodine of Karl Fischer reagent is generated by electrolysis and generated iodine quantitatively reacts with water.
Reaction formula is described below.
H2O ＋ I2 ＋ SO2 ＋ 3RN ＋ CH3OH → 2RN・HI ＋ RN・HSO4CH32RN・HI → I2 ＋ 2RN ＋ 2H＋ ＋ 2e－Kerosene and diesel oil do not interfere the Karl Fischer reaction and direct injection method could apply.
Anode solution for Oil is selected to dissolve samples.
It is known that some of the oil additives interfere Karl Fischer reaction. In that case, azeotropic distillation
method with Oil evaporator is appropriate. Water is separated from oil sample by distillation and introduced toelectrolytic cell with carrier gas.
Mercaptanes and hydrogen sulfide in oil interfere Karl Fischer reaction. Since these side reactions occur
quantitatively, water content result could be corrected with concentration of mercaptanes and hydrogen sulfide.
1 ppm of mercaptanes or hydrogen sulfide lead 0.3 ppm or 0.6 ppm higher water content respectively.

2. Apparatus and Reagents(1) Apparatus
Titrator：

Karl Fischer Coulometric titrator

AQ-2200A

Evaporator：

Oil Evaporator

EV-2000L

Electrolytic cell：Standard Cell

Fritless Cell
(2) Reagents for direct injection method
Anode solution：
Hydranal coulomat AG-H (for Oil, nonhalogenated)
Cathode solution：
Hydranal coulomat CG(3) Reagents for azeotropic distillation method
Anode solution：

Hydranal coulomat AG (for general use, nonhalogenated)

Cathode solution：

Hydranal coulomat CG

Distillation solvemt：

Dehydrated toluene

Carrier gas：

Nitrogen gas

3. Procedure
3.1. Direct injection method(1) Fill 100 mL of anode solution and one ampoule of cathode solution into the electrolytic cell as shownin 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 electrolytic 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.
Anode solution

Cathode solution

Fig.3.1. Preparation of the reagents.
Note(1) Do not touch the tip of needle toanode solution.
(2) When injecting, set the tip ofneedle as below figure.

(3) Before pulling out the needle,
draw alittleairdripping of sample.

Fig.3.2. Injection of sample.

toprevent3.2. Azeotropic distillation method(1) Fill 100 mL of anode solution and one ampoule of cathode solution into the electrolytic cell as shownin Fig.3.1.
(2) Start blanking to attain stable background.
(3) Connect electrolytic cell and evaporation chamber with tube. Flow carrier gas with 50 mL/min.
(4) Fill 5mL of distillation solvent in evaporation chamber and heat the chamber at 120 C.
(5) Keep blanking to attain stable background with carrier gas flowing into electrolytic cell.
(6) Wash the syringe with sample.
(7) Draw the sample into syringe and then weigh the syringe.
(8) Inject sample from rubber septum of distillation chamber as shown in Fig.3.3 and Fig.3.4.
(9) Start titration. Measurement parameter is shown in Table 4.2.
(10) Weigh the syringe again and then set the difference of weight to sample size.

Fig.3.3. Schematic diagram of azeotropic distillation method.
Note(1) Do not touch the tip of needle todistillation solvent level.
(2) When injecting, set the tip of needle as
below figure.

(3) If air is drawn at inside of evaporationchamber, distillation solvent would beinvolved. When drawing air, do it after
pulling out the needle from evaporationchamber to prevent weighing error.

Fig.3.4. Sample injection into evaporation chamber.4. Parameters and results
Table 4.1. Parameters for direct injection method.
Condition File
Cal ModeInterval Time
Current
S.Timer
Blank Value
Unit Mode
Auto Interval
Minimum Count
Back Ground
Sample Size Input
Cell Type

0:Sample weight (net)
X=(H2O-BLANK)/SIZE20
SLOW00
AUTO
05ON
Every Time
Standard / Fritless

sec
minug
gug

Table 4.2. Parameters for azeotropic distillation method.
Condition File
Cal ModeInterval Time
Current
Min.Timer
Blank Value
Unit Mode
Auto Interval
Minimum Count
Back Ground
Sample Size Input
Cell Type

0:Sample weight (net)
X=(H2O-BLANK)/SIZE
40SLOW50
AUTO05ON
Every Time
Standard / Fritlesssecminuggug

Table 4.3. Results of water content measurement in Oil products
SampleSize (g)water(μg)

Watercontent

AG-H
CG

2.34832.34822.4432

65.5
61.5
63.5

27.9 ppm
26.2
26.0

AG-H
CG

2.08171.98042.0600

72.7
68.4
70.4

34.9 ppm
34.5
34.2

SampleApparatus

Cell

Reagent

kerosene

AQ

Standard

diesel oilAQ

StandardTable 4.4. Results of water content measurement in Oil products
SampleSize (g)water(μg)

Watercontent

AG-HCG0.9719
0.91080.8408

977.9
914.9
839.2

0.1006 %0.10050.0998

StandardAGCG

0.72670.94840.9051

246.6
329.1
311.9

339.3 ppm
347.0
344.6

Fritless

AG0.82010.81520.9452

300.4
289.4
330.4

366.3 ppm
355.0
349.6

SampleApparatus

Cell

Reagent

Biodiesel

AQ

Standard

Transmission
fluid

AQ+EV-L

5. Note(1) Use dried syringe and syringe vial for preventive of contamination by atmospheric water.
(2) To measure 100 µg or less water detection, make sure stability of blanking. Low and stable backgroundvalue is important factor for trace level of water measurement.
(3) Put appropriate anode solution in use according to the solubility of the sample. For example, Hydranal
Coulomat AG-H and Oil are suitable for oils with direct injection method.
Note : these reagents does not correspond to Fritless cell.