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Vapour pressure

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Reference
Endpoint:
vapour pressure
Type of information:
experimental study
Adequacy of study:
key study
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
Specific details on test material used for the study:
Batch No.: WD0066442; EINECS-No.: 927-957-5; Purity: 100 % (UVCB); Appearance: amber liquid; Homogeneity: homogeneous; Molecular weight: 400 - 10000 g/mol
Key result
Test no.:
#1
Temp.:
20 °C
Vapour pressure:
0 Pa
Remarks on result:
other: 400 g/mol - lowest molecular mass present in the UVCB sub.
Key result
Test no.:
#2
Temp.:
25 °C
Vapour pressure:
0 Pa
Remarks on result:
other: 400 g/mol - lowest molecular mass present in the UVCB sub.
Key result
Test no.:
#3
Temp.:
20 °C
Vapour pressure:
0 Pa
Remarks on result:
other: 3000 g/mol - av. molecular mass based on different constituents
Key result
Test no.:
#4
Temp.:
25 °C
Vapour pressure:
0 Pa
Remarks on result:
other: 3000 g/mol - av. molecular mass based on different constituents

The following vapour pressures were determined experimentally and considered as valid

Vapour Pressures (Effusion Method) molecular mass 400 g/mol:

 

Experiment

T

Mean p

Stand. Dev. p

RSD p

No.

K

Pa

Pa

%

4

348.2

3.09E-03

7.00E-04

22.6%

5

363.2

6.21E-03

1.20E-03

19.3%

6

378.2

2.10E-02

9.95E-04

4.7%

7

393.2

2.94E-02

5.88E-03

20.0%

 

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

 

Vapour Pressures (Effusion Method) molecular mass 3000 g/mol:

 

Experiment

T

Mean p

Stand. Dev. p

RSD p

No.

K

Pa

Pa

%

4

348.2

1.13E-03

2.55E-04

22.6%

5

363.2

2.27E-03

4.38E-04

19.3%

6

378.2

7.65E-03

3.63E-04

4.7%

7

393.2

1.08E-02

2.15E-03

20.0%

 

Both graphs 1/T vs. log (p) show a straight line with a correlation coefficient of –0.9830.

Conclusions:
Under the study conditions, the vapour pressures at 20 °C and at 25 °C were calculated from the regression equation. For the molecular mass of 400 g/mol the vapour pressure was established at 5.93-E5 Pa (20 °C) and at 9.00-E5 Pa (25 °C). For the molecular mass of 3000 g/mol the vapour pressure was established at 2.16-E5 Pa (20 °C) and at 3.29-E5 Pa (25 °C).
Executive summary:

A study was conducted to determine the vapour pressure of the test substance according to OECD Guideline 104 and EU Method A.4 using the effusion method (Knudsen Cell), in compliance with GLP. Two different molecular mass (400 and 3000 g/mol) were used for calculation. The vapour pressure of the test substance was determined at seven different temperatures (30, 45, 60, 75, 90, 105 and 120 °C). Experiment 1-3 (nominal temperature 30, 45 and 60 °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. Four 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 23 % (limit value from the guideline 30 %) and good correlation. Therefore, the result of the test can be considered valid. For the calculation a molecular mass of 400 and 3000 g/mol was used. 400 g/mol represents the worst case calculation (lowest molecular mass of the UVCB substance), 3000 g/mol represents the average molecular mass based of the different constituents obtained in GPC and LC/MS analysis. Under the study conditions, the vapour pressures at 20 °C and at 25 °C were calculated from the regression equation. For the molecular mass of 400 g/mol the vapour pressure was established at 5.93-E5 Pa (20 °C) and at 9.00-E5 Pa (25 °C). For the molecular mass of 3000 g/mol the vapour pressure was established at 2.16-E5 Pa (20 °C) and at 3.29-E5 Pa (25 °C) (Muckle, 2018).

Description of key information

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

Key value for chemical safety assessment

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

Additional information

Molecular mass 400 g/mol (lowest MW present in the UVCB substance):

Vp at 20 °C: 5.93-E5 Pa

Vp at 25 °C: 9.00-E5 Pa

 

Molecular mass 3000 g/mol (av. MW based of the different constituents):

Vp at 20 °C: 2.16-E5 Pa

Vp at 25 °C: 3.29-E5 Pa