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Physical & Chemical properties

Vapour pressure

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Administrative data

Link to relevant study record(s)

Reference
Endpoint:
vapour pressure
Type of information:
experimental study
Adequacy of study:
key study
Study period:
From November 20, 2017 to January 11, 2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 104 (Vapour Pressure Curve)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method A.4 (Vapour Pressure)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Type of method:
effusion method: Knudsen cell
Key result
Test no.:
#1
Temp.:
20 °C
Vapour pressure:
0 Pa
Test no.:
#2
Temp.:
25 °C
Vapour pressure:
0 Pa

Sample Weights:

 The mass of sample in the respective cell is presented in the following table:

Sample weights

Parameter

Cell empty

Cell + test substance

Cell + test substance + cap

Test substance

Unit

g

g

g

g

Knudsen-cell 1

2.56636

3.46360

3.67201

0.89724

Knudsen-cell 2

2.53938

3.28628

3.49600

0.74690

Knudsen-cell 3

2.56784

3.38204

3.59543

0.81420

Knudsen-cell 4

2.57505

3.50254

3.71505

0.92749

 

Measurement data

The data of the evaluated experiments is presented in the following tables:

Measurement data experiment 1

Experiment

1

 

 

 

Nom. Temperature

30

°C

 

 

Date and time START

 

20.11.2017 14:45

21.11.2017 12:55

22.11.2017 12:00

Date and time END

 

21.11.2017 10:55

22.11.2017 10:55

23.11.2017 11:10

Parameter

Weight m

Weight m

Weight m

Weight m

Unit

g

g

g

g

Knudsen-cell 1

3.67201

3.64136

3.63255

3.62945

Knudsen-cell 2

3.49600

3.46506

3.45980

3.45817

Knudsen-cell 3

3.59543

3.56311

3.55598

3.55400

Knudsen-cell 4

3.71505

3.68365

3.67456

3.67002

Measurement data experiment 2

Experiment

2

 

 

 

Nom. Temperature

45

°C

 

 

Date and time START

 

23.11.2017 12:15

27.11.2017 11:20

28.11.2017 12:25

Date and time END

 

24.11.2017 11:15*

28.11.2017 11:25

29.11.2017 11:25

Parameter

Weight m

Weight m

Weight m

Weight m

Unit

g

g

g

g

Knudsen-cell 1

3.62945

3.62512

3.62345

3.62338

Knudsen-cell 2

3.45817

3.45523

3.45388

3.45386

Knudsen-cell 3

3.55400

3.55052

3.54897

3.54894

Knudsen-cell 4

3.67002

3.66400

3.66164

3.66147

*The samples were stored in an exsiccator after the weighings until start of the next measurement series due to organisational reasons.

 

Measurement data experiment 3

Experiment

3

 

 

 

Nom. Temperature

60

°C

 

 

Date and time START

 

29.11.2017 12:15

30.11.2017 12:30

01.12.2017 11:30

Date and time END

 

30.11.2017 11:20

01.12.2017 10:35

02.12.2017 08:30

Parameter

Weight m

Weight m

Weight m

Weight m

Unit

g

g

g

g

Knudsen-cell 1

3.62338

3.62339

3.62160

3.62158

Knudsen-cell 2

3.45386

3.45389

3.45189

3.45214

Knudsen-cell 3

3.54894

3.54890

3.54561

3.54500

Knudsen-cell 4

3.66147

3.38827

3.34721

3.34701

 

Measurement data experiment 4

Experiment

4

 

 

 

Nom. Temperature

75

°C

 

 

Date and time START

 

02.12.2017 09:45

03.12.2017 11:38

04.12.2017 12:20

Date and time END

 

03.12.2017 09:59

04.12.2017 11:30

05.12.2017 11:25

Parameter

Weight m

Weight m

Weight m

Weight m

Unit

g

g

g

g

Knudsen-cell 1

3.62158

3.62097

3.61963

3.61966

Knudsen-cell 2

3.45214

3.45139

3.45000

3.45014

Knudsen-cell 3

3.54500

3.54397

3.54276

3.54277

Knudsen-cell 4

3.34701

3.34657

3.34530

3.34528

 

Measurement data experiment 5

Experiment

5

 

 

 

Nom. Temperature

90

°C

 

 

Date and time START

 

05.12.2017 12:20

06.12.2017 11:30

07.12.2017 12:00

Date and time END

 

06.12.2017 10:40

07.12.2017 11:10

08.12.2017 10:30*

Parameter

Weight m

Weight m

Weight m

Weight m

Unit

g

g

g

g

Knudsen-cell 1

3.61966

3.61834

3.61761

3.61723

Knudsen-cell 2

3.45014

3.44905

3.44851

3.44816

Knudsen-cell 3

3.54277

3.54171

3.54103

3.54069

Knudsen-cell 4

3.34528

3.34433

3.34382

3.34358

*The samples were stored in an exsiccator after the weighings until start of the next measurement series due to organisational reasons.


Measurement data experiment 6

Experiment

6

 

 

 

Nom. Temperature

105

°C

 

 

Date and time START

 

11.12.2017 11:45

12.12.2017 12:40

13.12.2017 12:25

Date and time END

 

12.12.2017 11:45

13.12.2017 11:30

14.12.2017 11:50*

Parameter

Weight m

Weight m

Weight m

Weight m

Unit

g

g

g

g

Knudsen-cell 1

3.61723

3.61458

3.61290

3.61169

Knudsen-cell 2

3.44816

3.44597

3.44488

3.44352

Knudsen-cell 3

3.54069

3.53869

3.53754

3.53628

Knudsen-cell 4

3.34358

3.34189

3.34061

3.34000

*The samples were stored in an exsiccator after the weighings until start of the next measurement series due to organisational reasons.

 

Measurement data experiment 7

Experiment

7

 

 

 

Nom. Temperature

120

°C

 

 

Date and time START

 

18.12.2017 12:55

19.12.2017 14:25

20.12.2017 11:55

Date and time END

 

19.12.2017 13:25

20.12.2017 11:10

21.12.2017 11:20*

Parameter

Weight m

Weight m

Weight m

Weight m

Unit

g

g

g

g

Knudsen-cell 1

3.61169

3.60698

3.60355

3.60410

Knudsen-cell 2

3.44352

3.44000

3.43693

3.43722

Knudsen-cell 3

3.53628

3.53206

3.52862

3.52928

Knudsen-cell 4

3.34000

3.33670

3.33348

3.33515

*The samples were stored in an exsiccator after the weighings until start of the next measurement series due to organisational reasons.

 

Measurement data experiment 8

Experiment

8

 

 

 

Nom. Temperature

135

°C

 

 

Date and time START

 

08.01.2018 12:35

09.01.2018 12:15

10.01.2018 11:55

Date and time END

 

09.01.2018 11:15

10.01.2018 11:05

11.01.2018 11:15

Parameter

Weight m

Weight m

Weight m

Weight m

Unit

g

g

g

g

Knudsen-cell 1

3.60410

3.60137

3.60061

3.60060

Knudsen-cell 2

3.43722

3.43483

3.43444

3.43440

Knudsen-cell 3

3.52928

3.52561

3.52509

3.52506

Knudsen-cell 4

3.33515

3.33150

3.33273

3.33275

 

Measurement data experiment 9

Experiment

9

 

 

 

Nom. Temperature

150

°C

 

 

Date and time START

 

11.01.2018 12:10

15.01.2018 09:40

16.01.2018 12:10

Date and time END

 

12.01.2018 11:25*

16.01.2018 11:10

17.01.2018 11:40

Parameter

Weight m

Weight m

Weight m

Weight m

Unit

g

g

g

g

Knudsen-cell 1

3.60060

3.60045

2.99074

2.98724

Knudsen-cell 2

3.43440

3.43430

2.95041

2.94542

Knudsen-cell 3

3.52506

3.52485

3.27000

3.26712

Knudsen-cell 4

3.33275

3.33241

3.33291

3.33115

*The samples were stored in an exsiccator after the weighings until start of the next measurement series due to organisational reasons.

 

Observations

30°C.At the first measurement of experiment 1, all cells were slightly contaminated. Therefore, the cells were meticulously cleaned and weighed. This weight was used as initial weight for the subsequent measurements. To avoid bias, this measurement was not used for calculations.

60°C.At the first measurement of experiment 3, cell 4 got broken. Therefore a new cell was filled with test substance. Therefore, the cell was weighed. This weight was used as initial weight for the subsequent measurements. To avoid bias, this measurement was not used for calculations.

90°C.At the first measurement of experiment 5, all cells were slightly contaminated. Therefore, the cells were meticulously cleaned and weighed. This weight was used as initial weight for the subsequent measurements. To avoid bias, this measurement was not used for calculations.

90°C.At the second measurement of experiment 5, cell 1 was slightly contaminated. Therefore, the cell was meticulously cleaned and weighed. This weight was used as initial weight for the subsequent measurements. To avoid bias, this measurement was not used for calculations.

90°C.At the third measurement of experiment 5, cell 4 was slightly contaminated. Therefore, the cell was meticulously cleaned and weighed. This weight was used as initial weight for the subsequent measurements. To avoid bias, this measurement was not used for calculations.

105°C.At the third measurement of experiment 6, cell 4 was slightly contaminated. Therefore, the cell was meticulously cleaned and weighed. This weight was used as initial weight for the subsequent measurements. To avoid bias, this measurement was not used for calculations.

120°C.At the third measurement of experiment 7, all cells were slightly contaminated. Therefore, the cells were meticulously cleaned and weighed. This weight was used as initial weight for the subsequent measurements. To avoid bias, this measurement was not used for calculations.

150°C.At the second measurement of experiment 9, all cells were slightly contaminated. Therefore, the cells were meticulously cleaned and weighed. This weight was used as initial weight for the subsequent measurements. To avoid bias, this measurement was not used for calculations.


Calculation of results

Equation :The vapour pressure was calculated using the equation:

with

 Equation parameters

Parameter

Explanation

Source/Value

p

vapour pressure in Pa

to be calculated

m

weight loss in kg

value given in tables chapter9.2is divided by 1000

t

time in s

as given in tables chapter9.2

A

area of aperture in m2

7.854 * 10-7m2

K

correction factor

0.909

R

universal gas constant in J/Mol*K

8.314472

T

temperature in K

as given in tables chapter9.2

M

molecular weight in kg/Mol

0.3444

 

The correction constant is depending on the relation length/radius of the aperture of the Knudsen cell and is stated in the literature ]as follows:

Correction factor K

Relation

0.2

K

0.909

With the chosen length of the aperture 0.1 mm and the chosen radius 0.5 mm, a relation of 0.2 was calculated, and a correction factor of 0.909 was chosen.

 

Calculation results:

All calculation results are given in the tables below and on the following pages.

In all tables, E-0X represents multiplication with 10-X. Experiment 1-4 and 8-9 (nominal temperature 30 – 75 and 135 - 150 °C) showed no reproducible weight loss. Therefore they were not used for calculation.

Calculation results experiment 5

Experiment

5

 

 

 

 

 

 

 

 

Real Temperature in K

363.2

 

 

 

 

 

 

 

 

Real Temperature in °C

90.0

 

 

 

 

 

 

 

 

Date of Measurement

06.12.2017 10:40

07.12.2017 11:10

08.12.2017 10:30

Elapsed Time in s

80400

85200

81000

Parameter

Weight loss

to be used

Vapour pressure

Weight loss

to be used

Vapour pressure

Weight loss

to be used

Vapour pressure

Unit

g

yes/no

Pa

g

yes/no

Pa

g

yes/no

Pa

Knudsen-cell 1

0.00132

yes

5.40E-03

0.00073

no

 

0.00038

yes

1.54E-03

Knudsen-cell 2

0.00109

yes

4.46E-03

0.00054

yes

2.08E-03

0.00035

yes

1.42E-03

Knudsen-cell 3

0.00106

yes

4.33E-03

0.00068

yes

2.62E-03

0.00034

yes

1.38E-03

Knudsen-cell 4

0.00095

yes

3.88E-03

0.00051

yes

1.97E-03

0.00024

no

 

Mean

 

no

 

 

yes

2.23E-03

 

yes

1.45E-03

Standard deviation:

 

 

 

 

 

3.50E-04

 

 

8.45E-05

Mean of measured values:

 

1.836E-03

 

 

 

 

 

 

Standard deviation:

 

5.498E-04

RSD:

 

29.9%

 

 

 

If “no” is stated in the respective column: measurement was not considered for the calculation of the mean.


Calculation results experiment 6

Experiment

6

 

 

 

 

 

 

 

 

Real Temperature in K

378.2

 

 

 

 

 

 

 

 

Real Temperature in °C

105.0

 

 

 

 

 

 

 

 

Date of Measurement

12.12.2017 11:45

13.12.2017 11:30

14.12.2017 11:50

Elapsed Time in s

86400

82200

84300

Parameter

Weight loss

to be used

Vapour pressure

Weight loss

to be used

Vapour pressure

Weight loss

to be used

Vapour pressure

Unit

g

yes/no

Pa

g

yes/no

Pa

g

yes/no

Pa

Knudsen-cell 1

0.00265

yes

1.03E-02

0.00168

yes

6.86E-03

0.00121

yes

4.82E-03

Knudsen-cell 2

0.00219

yes

8.50E-03

0.00109

yes

4.45E-03

0.00136

yes

5.41E-03

Knudsen-cell 3

0.00200

yes

7.77E-03

0.00115

yes

4.69E-03

0.00126

yes

5.01E-03

Knudsen-cell 4

0.00169

yes

6.56E-03

0.00128

yes

5.22E-03

0.00061

no

 

Mean

 

yes

8.28E-03

 

yes

5.31E-03

 

yes

5.08E-03

Standard deviation:

 

 

1.56E-03

 

 

1.08E-03

 

 

3.04E-04

Mean of measured values:

 

6.222E-03

 

 

 

 

 

 

Standard deviation:

 

1.786E-03

RSD:

 

28.7%

 

 

 

If “no” is stated in the respective column: measurement was not considered for the calculation of the mean.

 

Calculation results experiment 7

Experiment

7

 

 

 

 

 

 

 

 

Real Temperature in K

393.2

 

 

 

 

 

 

 

 

Real Temperature in °C

120.0

 

 

 

 

 

 

 

 

Date of Measurement

19.12.2017 13:25

20.12.2017 11:10

21.12.2017 11:20

Elapsed Time in s

88200

74700

84300

Parameter

Weight loss

to be used

Vapour pressure

Weight loss

to be used

Vapour pressure

Weight loss

to be used

Vapour pressure

Unit

g

yes/no

Pa

g

yes/no

Pa

g

yes/no

Pa

Knudsen-cell 1

0.00471

yes

1.83E-02

0.00343

yes

1.57E-02

-0.00055

yes

-2.23E-03

Knudsen-cell 2

0.00352

yes

1.37E-02

0.00307

yes

1.41E-02

-0.00029

yes

-1.18E-03

Knudsen-cell 3

0.00422

yes

1.64E-02

0.00344

yes

1.58E-02

-0.00066

yes

-2.68E-03

Knudsen-cell 4

0.00330

yes

1.28E-02

0.00322

yes

1.47E-02

-0.00167

yes

-6.78E-03

Mean

 

yes

1.53E-02

 

yes

1.51E-02

 

no

 

Standard deviation:

 

 

2.51E-03

 

 

8.17E-04

 

 

 

Mean of measured values:

 

1.517E-02

 

 

 

 

 

 

Standard deviation:

 

1.451E-04

RSD:

 

1.0%

 

 

 

If “no” is stated in the respective column: measurement was not considered for the calculation of the mean. 


Evaluation

The measured values for temperature and vapour pressure were evaluated as follows:

Evaluation of calculated values

Parameter

T

Mean p

1/T

log p

Unit

K

Pa

1/K

log Pa

Values

363.2

1.84E-03

2.7533E-03

-2.7360

378.2

6.22E-03

2.6441E-03

-2.2060

393.2

1.52E-02

2.5432E-03

-1.8190

In this table, E-0X represents multiplication with 10-X.

  

Parameters of linear regression

Parameter

Value

Slope

-4371.8

Intercept

9.3179

Correlation Coefficient r

-0.9978

Coefficient of Determination r2

0.9955

 


Results

Test substance:

The following vapour pressures were determined experimentally and considered as valid (mean and standard deviation given):

Experimentally determined vapour pressures

T

T

p

Stand. Dev. p

RSD p

°C

K

Pa

Pa

%

90.0

363.2

1.84E-03

5.50E-04

29.9%

105.0

378.2

6.22E-03

1.79E-03

28.7%

120.0

393.2

1.52E-02

1.45E-04

1.0%

In this table, E-0X represents multiplication with 10-X.

Stand. Dev. = Standard Deviation; RSD = Relative Standard Deviation

 

For the test substance following vapour pressures at 20°C and at 25°C were calculated from the regression equation:

Results test substance

Vapour pressure at 20°C:

2.54 * 10-06Pa

Vapour pressure at 25°C:

4.52 * 10-06Pa

 

The linear regression of log p vs. 1/T gave a correlation coefficient r of - 0.989, showing good repeatability and precision. Therefore, the determination is considered as valid.

Positive control

 

Results positive control

Vapour pressure (positive control) at 30°C:

2.03*10-1Pa

Criteria for the vapour pressure of the positive control at 30°C

1.44*10-1± 0.1Pa

The vapour pressure met the validity criteria. Therefore the study can be considered as valid.


 

Conclusions:
Under the study conditions, vapour pressure of the test substance was determined to be at 2.54E-06 Pa and 4.52E10-06 Pa at 20°C and 25°C respectively.
Executive summary:

A study was conducted to determine the vapour pressure of the substance according to OECD Guideline 104 and EU Method A.4. The vapour pressure of the test substance was determined by the effusion method: Knudsen Cell. Vapour pressure for test substance was determined at eight different temperatures (30, 45, 60, 75, 90, 105, 120, 135 and 150 °C) according to effusion method (weight loss). Experiment 1-4 and 8-9 (nominal temperature 30 - 75 and 135 - 150 °C) showed no reproducible weight loss. When visible contaminations, caused by explosive evaporation of the test substance, were observed, the cells were meticulously cleaned and weighed. This weight was used as initial weight for the subsequent measurements. To avoid bias, these measurements were not used for calculations. Three experiments could be evaluated as they showed relevant and reproducible weight loss. All evaluated experiments showed good reproducibility, giving relative standard deviations of less than 30 % (limit value from the guideline 30 %) and good correlation. Therefore, the result of the test can be considered valid. Under the study conditions, vapour pressure of the test substance was determined to be at 2.54E-06 Pa and 4.52E10-06 Pa at 20°C and 25°C respectively (Krebs, 2018).

Description of key information

The vapour pressure was determined according to OECD Guideline 104 and EU Method A.4 (Krebs, 2018).

Key value for chemical safety assessment

Vapour pressure:
0 Pa
at the temperature of:
20 °C

Additional information