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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 November 20, 2017 to January 11, 2018
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
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

2.56878

3.95238

4.16481

1.38360

Knudsen-cell 2

2.54534

3.94470

4.12747

1.39936

Knudsen-cell 3

2.54331

3.99460

4.19162

1.45129

Knudsen-cell 4

2.56527

4.18662

4.40666

1.62135

 

Measurement data:

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

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

4.16481

4.04783

4.02926

4.01333

Knudsen-cell 2

4.12747

4.03247

3.96959

3.96063

Knudsen-cell 3

4.19162

3.84714

3.78225

3.77800

Knudsen-cell 4

4.40666

3.95082

3.89328

3.88680

  

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

4.01333

3.94012

3.92259

3.91676

Knudsen-cell 2

3.96063

3.95215

3.94765

3.94688

Knudsen-cell 3

3.77800

3.77519

3.77369

3.77370

Knudsen-cell 4

3.88680

3.88234

3.88058

3.88060

*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

3.91676

3.90665

3.90099

3.89796

Knudsen-cell 2

3.94688

3.94466

3.94354

3.94238

Knudsen-cell 3

3.77370

3.77340

3.77290

3.77204

Knudsen-cell 4

3.88060

3.88010

3.87952

3.87884

   

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

3.89796

3.89205

3.88834

3.88687

Knudsen-cell 2

3.94238

3.94200

3.94039

3.94022

Knudsen-cell 3

3.77204

3.77192

3.77034

3.77035

Knudsen-cell 4

3.87884

3.87880

3.87720

3.87714

 

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

3.88687

3.88424

3.88288

3.88199

Knudsen-cell 2

3.94022

3.93877

3.93780

3.93729

Knudsen-cell 3

3.77035

3.76910

3.76824

3.76774

Knudsen-cell 4

3.87714

3.87563

3.87465

3.87390

*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

3.88199

3.87633

3.86972

3.86331

Knudsen-cell 2

3.93729

3.93183

3.92582

3.91925

Knudsen-cell 3

3.76774

3.76310

3.75764

3.75213

Knudsen-cell 4

3.87390

3.86835

3.86166

3.85532

*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

3.86331

3.83537

3.82093

3.81191

Knudsen-cell 2

3.91925

3.89067

3.87364

3.86227

Knudsen-cell 3

3.75213

3.72966

3.71244

3.70214

Knudsen-cell 4

3.85532

3.83095

3.80962

3.79998

*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

3.81191

3.79720

3.78858

3.78493

Knudsen-cell 2

3.86227

3.84449

3.83462

3.83112

Knudsen-cell 3

3.70214

3.68645

3.67777

3.67483

Knudsen-cell 4

3.79998

3.78327

3.77450

3.77165

 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.

30°C at the second measurement of experiment 1, 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.

45°C at the first measurement of experiment 2, 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 first measurement of experiment 5, cell 1was 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, 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.

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.


Calculation of results

Equation: The vapour pressure was calculation using equation:

Equation parameters

Parameter

Explanation

Source/Value

p

vapour pressure in Pa

to be calculated

m

weight loss in kg

value given in tables is divided by 1000

t

time in s

as given in tables

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

M

molecular weight in kg/Mol

0.663

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 (nominal temperature 30 – 75 and 135 °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

0.00263

no

 

0.00136

yes

3.78E-03

0.00089

yes

2.60E-03

Knudsen-cell 2

0.00145

yes

4.27E-03

0.00097

yes

2.70E-03

0.00051

yes

1.49E-03

Knudsen-cell 3

0.00125

yes

3.68E-03

0.00086

yes

2.39E-03

0.00050

yes

1.46E-03

Knudsen-cell 4

0.00151

yes

4.45E-03

0.00098

yes

2.73E-03

0.00075

yes

2.19E-03

Mean

 

yes

4.14E-03

 

yes

2.90E-03

 

no

 

Standard deviation:

 

 

4.01E-04

 

 

6.08E-04

 

 

 

Mean of measured values:

 

3.518E-03

 

 

 

 

 

 

Standard deviation:

 

8.744E-04

RSD:

24.9%

 

 

 

 

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

0.00566

yes

1.58E-02

0.00661

yes

1.94E-02

0.00641

yes

1.84E-02

Knudsen-cell 2

0.00546

yes

1.53E-02

0.00601

yes

1.77E-02

0.00657

yes

1.88E-02

Knudsen-cell 3

0.00464

yes

1.30E-02

0.00546

yes

1.61E-02

0.00551

yes

1.58E-02

Knudsen-cell 4

0.00555

yes

1.55E-02

0.00669

yes

1.97E-02

0.00634

yes

1.82E-02

Mean

 

yes

1.49E-02

 

yes

1.82E-02

 

yes

1.78E-02

Standard deviation:

 

 

1.30E-03

 

 

1.69E-03

 

 

1.36E-03

Mean of measured values:

 

1.698E-02

 

 

 

 

 

 

Standard deviation:

 

1.802E-03

RSD:

10.6%

 

 

 

 

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

0.02794

yes

7.81E-02

0.01444

yes

4.77E-02

0.00902

yes

2.64E-02

Knudsen-cell 2

0.02858

yes

7.99E-02

0.01703

yes

5.62E-02

0.01137

yes

3.33E-02

Knudsen-cell 3

0.02247

yes

6.28E-02

0.01722

yes

5.68E-02

0.01030

yes

3.01E-02

Knudsen-cell 4

0.02437

yes

6.81E-02

0.02133

yes

7.04E-02

0.00964

yes

2.82E-02

Mean

 

yes

7.22E-02

 

yes

5.78E-02

 

no

 

Standard deviation:

 

 

8.14E-03

 

 

9.40E-03

 

 

 

Mean of measured values:

 

6.500E-02

 

 

 

 

 

 

Standard deviation:

 

1.022E-02

RSD:

15.7%

 

 

 

 

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

3.52E-03

2.7533E-03

-2.4537

378.2

1.70E-02

2.6441E-03

-1.7701

393.2

6.50E-02

2.5432E-03

-1.1871

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

 

Results

TestSubstance: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

3.52E-03

8.74E-04

24.9%

105.0

378.2

1.70E-02

1.80E-03

10.6%

120.0

393.2

6.50E-02

1.02E-02

15.7%

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

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

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

Results Test Substance

Vapour pressure at 20°C:

3.85 * 10-07Pa

Vapour pressure at 25°C:

8.52 * 10-07Pa

The linear regression of log p vs. 1/T gave a correlation coefficient r of - 0.9997, 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 3.87E-07 Pa and 8.52E10-07 Pa at 20°C and 25°C respectively.
Executive summary:

A study was conducted to determine the vapour pressure of the substance, Quaternary ammonium compounds, N,N,N'-tris(hydroxyethyl)-N,N'-dimethyl-N'-tallow alkyltrimethylenedi-, bis(Me sulfates) (salts), according to the 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 and 135 °C) according to effusion method (weight loss). Experiment 1-4 and 8 (nominal temperature 30 – 75 and 135 °C) showed only a poor 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 25 % (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 3.87E-07 Pa and 8.52E10-07 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