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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:
2018-11-07 to 2018-12-06
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 104 (Vapour Pressure Curve)
Qualifier:
according to guideline
Guideline:
EU Method A.4 (Vapour Pressure)
GLP compliance:
no
Type of method:
effusion method: Knudsen cell
Temp.:
20 °C
Vapour pressure:
< 0.01 Pa
Temp.:
25 °C
Vapour pressure:
< 0.01 Pa
Temp.:
50 °C
Vapour pressure:
< 0.01 Pa

Individual results

The vapour pressure was measured in the temperature range of 10 °C to 70 °C. The measured vapour pressures at the corresponding temperatures are listed in Table 1. The mass of the test item was determined before (2.8192 g) and after the vapour pressure measurement (2.8102 g). After the measurement a mass loss of approx. 0.3% (w/w) was determined.

Table 1: Measured vapour pressures and corresponding temperatures

Temperature / °C

Vapour pressure / hPa

10

2.5 x 10E-5

20

8.9 x 10E-6 (*)

30

1.8 x 10E-5

40

3.2 x 10E-5

50

2.1 x 10E-5

60

n.e.

70

5.3 x 10E-5

50

6.0 x 10E-6 (*)

n.e.: not evaluable

(*): below detection limit

The measured vapour pressures did not show the expected dependency between temperatures and vapour pressures. This indicated that the vapour pressure was influenced by minor components that evaporated when the temperature was raised. A last measurement at 50 °C during cooling down showed a lower vapour pressure value (6.0 x 10E-6 hPa) compared with the measurement at 50 °C during heating up (2.1 x 10E-5 hPa). This observation supports the assumption of minor volatile components within the test item.

Additionally, the measured data points at 20 °C and 50 °C (cooling down) were under the detection limit of the effusion method (10E-5 hPa) and the remaining data points were not significantly above the detection limit.

Due to the aforementioned reasons it was concluded that the dependency between temperature and vapour pressure cannot be described with a linear regression. As a conservative approach the vapour pressures for 20, 25, and 50 °C are reported to be below 1 x 10E-4 hPa based on the measured values.

Table 2: Final upper limit values for the vapour pressure at 20, 25 and 50 °C

T / °C

p / hPa

p / Pa

20

< 1 x 10E-4

< 1 x 10E-2

25

< 1 x 10E-4

< 1 x 10E-2

50

< 1 x 10E-4

< 1 x 10E-2

Conclusions:
The vapour pressure of the test item was investigated according to OECD 104 and EU A.4. However, the measured vapour pressures did not show the expected dependency between temperatures and vapour pressures and therefore cannot be described with a linear regression. As a conservative approach the vapour pressures for 20 °C, 25 °C and 50 °C are reported to be below 1 x 10-4 hPa based on the measured values.
Executive summary:

The vapour pressure of the test item was investigated according to OECD 104 and EU A.4. However, the measured vapour pressures did not show the expected dependency between temperatures and vapour pressures and therefore cannot be described with a linear regression. As a conservative approach the vapour pressures for 20 °C, 25 °C and 50 °C are reported to be below 1 x 10-4 hPa based on the measured values.

Description of key information

The vapour pressures of the test item at 20 °C, 25 °C and 50 °C are below 1 x 10E-4 hPa.

Key value for chemical safety assessment

Additional information

The measured vapour pressures did not show the expected dependency between temperatures and vapour pressures and therefore cannot be described with a linear regression. As a conservative approach the vapour pressures for 20 °C, 25 °C and 50 °C are reported to be below 1 x 10-4 hPa based on the measured values.