HIRANUMA APPLICATION DATA

Watercontents

Karl Fischer Titrator

Data No. KF18

Nov.29.
2018

Validation test with water standard
KF Coulometry – Heat evaporation method

1. Abstract
A heat evaporation method using Karl Fischer titrator combined with solid evaporator is suitable forinsoluble sample in anode solution, such as plastics and inorganic compounds. The measurement of with theheat evaporation method is carried out by heating the sample while a carrier gas is blown into the evaporationchamber and introducing the evaporated moisture together with the carrier gas into the electrolysis cell.
This application introduces an example of measurement of solid water standard for validation of titrator
system with solid evaporator.

2. Apparatus and Reagents(1) Apparatus for heat evaporation methodTitrator：

Hiranuma Karl Fischer Coulometric titrator

AQ-series

Evaporator：

Hiranuma Solid Evaporator

EV-2000

Electrolytic cell：Standard Cell
Fritless Cell (No cathode solution required)(2) Reagents
Anode solution：

HYDRANAL Coulomat AG

Cathode solution：

HYDRANAL Coulomat CG

Dehydrated methanol：

HYDRANAL MethanolCarrier gas：

Nitrogen gas (Dew Point : -65 C or less)(3) Water standard material(i)

HYDRANAL- Standard sodium tartrate dihydrate (Honeywell)
CoA : 15.64 %(*1), Permissible range of recovery rate :  5 %(*2), Heat temperature : 160 °C(ii) HYDRANAL- Water Standard KF-Oven, 140-160°C (Honeywell)
CoA : 5.04 %(*1), Permissible range of recovery rate :  4 %, Heat temperature : 140 - 160 °C(iii) Water Standard Oven 1 % (Merck)
CoA : 0.99 %(*1), Permissible range of recovery rate :  3 %, Heat temperature : 140 - 400 °C(*1) CoA values described in the test report are different with each production lot.
(*2) Permissible range of standard material (i) is set to our own criterion for inspection of evaporator, notdescribed on the document of this standard.

3. Procedure(1) Fill 100 mL of anode solution and 50 mL of dehydrated methanol into anode compartment. Fill one
ampoule of cathode solution into cathode compartment (Fig.3.1). When fritless cell is used, cathodesolution is not necessary.
(2) Start blanking to attain stable background.

(3) Flow N2 carrier gas with flow rate 200 mL/min.
(4) Set the formed aluminum foil into the evaporation chamber of EV-2000 (Fig.3.2).
(5) Connect electrolytic cell and evaporation chamber with tube (Fig.3.3).
(6) Blanking become stable and then start pre-heating at set temperature.
(7) After the pre-heating procedure finished, confirm blanking stable with carrier gas flowing.
(8) Make formed aluminum foil to use balance dish.
(9) Weigh the sample on the aluminum foil. Weighing amounts are approximately 0.05 g for standard
material (i), 0.1 g for standard material (ii) and 0.2 g for standard material (iii).
(10) Put the sample with aluminum foil into evaporation chamber from stopper of the chamber.
(11) Start titration. Measurement parameter is shown in Table 4.1.
(12) Blank measurement is also performed with same procedure except for sample addition.
Cathode solution

Anode solution

Fig.3.1. Preparation of the reagents. (Standard Cell)

Mold

Fig.3.2. Forming the aluminum foil.

Fig.3.3. Schematic diagram of heat evaporation method.

4. Parameters and results
Table 4.1 Parameters for heat evaporation method.
Condition File
Cal Mode

EV. FileInterval Time
CurrentMin.Timer
Blank Value
Unit Mode
Auto Interval
Minimum Count
Back Ground
Sample Size Input*Cell Type0:Sample weight (net)
X=(H2O-BLANK)/SIZE
30 secMEDIUM
5 min0 μg
AUTO0 g
5 μg
ONEvery Time
Standard / Fritless* Step 1 Temp.
Time
Step 2 Temp.
Time
Step 3 Temp.
TimePre. Heat End TimeEnd B.G.
Cooling Time
B.G. Count
Back Purge Time

160
00000505605(* Set the electrolytic cell and heating temperature appropriately.)

°C
min°C
min°C
minminμg
minsecTable 4.3 Results of water content measurement of water standard.
WaterStandard

Temp.
(°C)

Cell

No.

Samplesize (g)

Water
(μg)

Water
content (%)

(i)

160

Standard

10.05298149.415.4053

Avg.

15.41820.06159506.115.4571SD

0.035 %

30.05278110.615.3901

RSD

0.23%

10.02163327.315.4042Avg.

15.436%20.03785853.415.4852SD

0.043 %

30.05778896.315.4182

RSD

0.28

10.1426

7242.65.0790Avg.

5.083 %

20.1406

7181.3

5.1076SD

0.023 %

30.11805973.05.0619

RSD0.4510.1430

7294.15.1008Avg.

5.088 %

20.10115143.95.0879

SD0.013 %30.10805479.95.0740RSD

0.26

10.12361240.11.0033Avg.

1.007 %

20.1223

1230.41.0061SD

0.004 %

30.1523

1539.01.0105RSD

0.36

10.26612668.61.0029Avg.

1.005 %

20.23722391.31.0081SD

0.003 %

30.24192431.81.0053RSD

0.26

15.64%
Fritless

(ii)

150

Standard

5.04%
Fritless

(iii)

300

Standard

0.99%
Fritless

Recoveryrate (%)

Statistics result%

98.698.7%
100.8%
100.9%
101.7%
101.6%

5. Note(1) Validation test of titrator with solid evaporator is evaluated from the recovery rate of the result withrespect to the CoA value written in the test report of the water standard. Permissible range of recovery
rates differed depending on the type of water standard materials. The recovery rate of standards (i), (ii)and (iii) should fall within the range of ± 5 %, ± 4 % and ± 3 % respectively.
(2) Select the type of water standard that is close to the water content or heating temperature of youractual sample.
(3) The optimized electrolysis control for fritless cell of AQ series released after 2009 improves themeasurement accuracy of fritless cell. It can be used with the evaporator as well. Suitable reagent for
fritless cell is required. For example, Hydranal coulomat AG and AG-Oven are compatible with fritlesscell.
(4) When nitrogen gas for carrier gas is not available, optional a dry air pump for EV-2000 can be used
to supply air carrier gas. When using air as a carrier gas, pay attention to the following points.
(i) Background moisture tends to be higher than nitrogen gas.
(ii) When the sample has tendency of thermal decomposition, it wouldl be promoted in the air.

Keywords：Karl Fischer, Coulometric titration, Heat evaporation, Water standard, Validation, Fritless cell