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Physical & Chemical properties

Vapour pressure

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Reference
Endpoint:
vapour pressure
Type of information:
experimental study
Adequacy of study:
key study
Study period:
from 2017-05-02 to 2017-06-30
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 104 (Vapour Pressure Curve)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method A.4 (Vapour Pressure)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Type of method:
effusion method: Knudsen cell
Key result
Temp.:
20 °C
Vapour pressure:
0 Pa
Temp.:
25 °C
Vapour pressure:
0 Pa

All calculation results are given in the tables below. In all tables, E-0X represents multiplication with 10-X. Experiments 1 to 4 and 9 (nominal temperature 30 to 75 and 150 °C) showed no reproducible weight loss. Therefore, these values 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

02.06.2017 12:30

07.06.2017 10:10

08.06.2017 12:10

Elapsed Time in s

85800

81000

89400

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

0.00152

yes

7.93E-03

0.00168

yes

9.29E-03

0.00093

yes

4.66E-03

Knudsen-cell 2

0.00124

yes

6.47E-03

0.00121

yes

6.69E-03

0.00047

no

 

Knudsen-cell 3

0.00111

yes

5.79E-03

0.00091

yes

5.03E-03

0.00086

yes

4.31E-03

Knudsen-cell 4

0.00202

yes

1.05E-02

0.00110

yes

6.08E-03

0.00100

yes

5.01E-03

Mean

 

yes

7.69E-03

 

yes

6.77E-03

 

yes

4.66E-03

Standard deviation:

 

 

2.10E-03

 

 

1.81E-03

 

 

3.51E-04

Mean of measured values:

 

6.372E-03

 

 

 

 

 

 

Standard deviation:

 

1.553E-03

RSD:

24.4%

 

 

 

 

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

09.06.2017 11:25

13.06.2017 11:55

14.06.2017 11:50

Elapsed Time in s

81600

92700

83700

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

0.00620

yes

3.47E-02

0.00639

yes

3.15E-02

0.00552

yes

3.01E-02

Knudsen-cell 2

0.00431

yes

2.41E-02

0.00463

yes

2.28E-02

0.00365

yes

1.99E-02

Knudsen-cell 3

0.00356

yes

1.99E-02

0.00460

yes

2.27E-02

0.00317

yes

1.73E-02

Knudsen-cell 4

0.00554

yes

3.10E-02

0.00577

yes

2.84E-02

0.00492

yes

2.69E-02

Mean

 

yes

2.75E-02

 

yes

2.64E-02

 

yes

2.36E-02

Standard deviation:

 

 

6.66E-03

 

 

4.35E-03

 

 

5.96E-03

Mean of measured values:

 

2.579E-02

 

 

 

 

 

 

Standard deviation:

 

2.010E-03

RSD:

7.8%

 

 

 

 

Calculation Results Experiment 7

Experiment

7

 

 

 

 

 

 

 

 

Real Temperature in K

393.2

 

 

 

 

 

 

 

 

Real Temperature in °C

120.0

 

 

 

 

 

 

 

 

Date of Measurement

20.06.2017 11:55

21.06.2017 12:00

22.06.2017 12:00

Elapsed Time in s

88500

83400

83400

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

0.02686

yes

1.41E-01

0.02612

yes

1.46E-01

0.02612

yes

1.46E-01

Knudsen-cell 2

0.01797

yes

9.46E-02

0.01856

yes

1.04E-01

0.01887

yes

1.05E-01

Knudsen-cell 3

0.01800

yes

9.48E-02

0.01872

yes

1.05E-01

0.01882

yes

1.05E-01

Knudsen-cell 4

0.02227

yes

1.17E-01

0.02254

yes

1.26E-01

0.02216

yes

1.24E-01

Mean

 

yes

1.12E-01

 

yes

1.20E-01

 

yes

1.20E-01

Standard deviation:

 

 

2.23E-02

 

 

2.01E-02

 

 

1.93E-02

Mean of measured values:

 

1.174E-01

 

 

 

 

 

 

Standard deviation:

 

4.644E-03

RSD:

4.0%

 

 

 

 

Calculation Results Experiment 8

Experiment

8

 

 

 

 

 

 

 

 

Real Temperature in K

408.2

 

 

 

 

 

 

 

 

Real Temperature in °C

135.0

 

 

 

 

 

 

 

 

Date of Measurement

23.06.2017 12:35

27.06.2017 12:50

28.06.2017 12:10

Elapsed Time in s

85500

88800

84600

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

0.10006

yes

5.56E-01

0.05456

yes

2.92E-01

0.08235

yes

4.62E-01

Knudsen-cell 2

0.07189

yes

3.99E-01

0.04088

yes

2.19E-01

0.05959

yes

3.34E-01

Knudsen-cell 3

0.07448

yes

4.14E-01

0.04167

yes

2.23E-01

0.06041

yes

3.39E-01

Knudsen-cell 4

0.08348

yes

4.64E-01

0.05093

yes

2.72E-01

0.07209

yes

4.05E-01

Mean

 

yes

4.58E-01

 

yes

2.51E-01

 

yes

3.85E-01

Standard deviation:

 

 

7.07E-02

 

 

3.63E-02

 

 

6.06E-02

Mean of measured values:

 

3.648E-01

 

 

 

 

 

 

Standard deviation:

 

1.048E-01

RSD:

28.7%

 

 

 

 

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

6.37E-03

2.7533E-03

-2.1957

 378.2

2.58E-02

2.6441E-03

-1.5885

 393.2

1.17E-01

2.5432E-03

-0.9305

 408.2

3.65E-01

2.4498E-03

-0.4380

Parameters of Linear Regression

Parameter

Value

Slope

-5865.7

Intercept

13.9487

Correlation Coefficient r

-0.9993

Coefficient of Determination r²

0.9985

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

Experimentally determined vapour pressures

T (°C) T (K) Pressure (Pa) Stand. Dev.
Pressure (P)
RSD Pressure
90.0 363.2 6.37E-03 1.55E-03 24.4%
105.0 378.2 2.58E-02 2.01E-03 7.8%
120.0 393.2 1.17E-01 4.64E-03 4.0%
135.0 408.2 3.65E-01 1.05E-01 28.7%

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

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

For the test item the vapour pressures at 20 °C and at 25 °C were calculated from the regression equation (see results above).

The linear regression of log P vs.1/T gave a correlation coefficient r of -0.9993, showing good repeatability and precision. Therefore, the determination is considered as valid.

Conclusions:
For the test item the following vapour pressures at 20 °C and 25 °C were calculated from the regression equation:
- at 20 °C: 8.70E-7 Pa
- at 25 °C: 1.88E-6 Pa
Executive summary:

A study was performed in order to determine the vapour pressure of the test item according to OECD TG 104 and Regulation (EC) No. 440/2008, method A.4, by using the effusion method (weight loss). The vapour pressure was determined at nine different temperatures (30, 45, 60, 75, 90, 105, 120, 135 and 150 °C). The experiments 5 to 8 (temperatures 90, 105, 120 and 135 °C) showed relevant and reproducible weight loss and were used for the further calculations. These experiments showed good reproducibility, giving relative standard deviations of less than 29 % and very good correlation. Therefore, the results of the test could be considered valid. For the test item the following vapour pressures were calculated from the regression equation: 8.70xE-07 Pa at 20 °C and 1.88 x E-06 Pa at 25 °C [reference 4.6 -1].

Description of key information

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

- at 20 °C: 8.70E-7 Pa

- at 25 °C: 1.88E-6 Pa

Key value for chemical safety assessment

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

Additional information

A study was performed in order to determine the vapour pressure of the test item according to OECD TG 104 and Regulation (EC) No. 440/2008, method A.4, by using the effusion method (weight loss). The vapour pressure was determined at nine different temperatures (30, 45, 60, 75, 90, 105, 120, 135 and 150 °C). The experiments 5 to 8 (temperatures 90, 105, 120 and 135 °C) showed relevant and reproducible weight loss and were used for the further calculations. These experiments showed good reproducibility, giving relative standard deviations of less than 29 % and very good correlation. Therefore, the results of the test could be considered valid. For the test item the following vapour pressures were calculated from the regression equation: 8.70xE-07 Pa at 20 °C and 1.88 x E-06 Pa at 25 °C (reference 4.6 -1).