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Vapour pressure

Link to relevant study record(s)

Reference

Endpoint:

vapour pressure

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2017

Reliability:

1 (reliable without restriction)

Qualifier:

according to guideline

Guideline:

EU Method A.4 (Vapour Pressure)

GLP compliance:

yes (incl. QA statement)

Type of method:

effusion method: vapour pressure balance

Temp.:

20 °C

Vapour pressure:

< 0 hPa

Temp.:

25 °C

Vapour pressure:

< 0 hPa

Temp.:

50 °C

Vapour pressure:

< 0 hPa

1.1     Individual results

The vapour pressure was measured in the temperature range 95 °C to 120 °C. Additionally the heating phase was evaluated to get more information about the vapour pressure at temperatures of 52 °C and 81 °C[1]. Due to the fact that the test item had a melting point of 79.4 °C the vapour pressures at temperatures≥81 °C were measured of the melted test item. The measured vapour pressures at the corresponding temperatures are listed inTable 1.After the measurement a mass loss of approx. 2.5 % (w/w) was determined.

Table1: Measured vapour pressures and corresponding temperatures

Temperature / °C	Vapour pressure / hPa
95	8.6 × 10^-5
100	5.3 × 10^-5
105	3.2 × 10^-5
110	3.2 × 10^-5
115	3.6 × 10^-5
120	4.1 × 10^-5
52 (heating phase)	3.1 × 10^-5
81 (heating phase)	3.4 × 10^-4

Figure1on page8gives the vapour pressure (logarithmic scale) as a function of the inverse temperature (1/T, T in Kelvin). Only for better readability the temperature is also reported in a centigrade scale.

In the temperature range 81 °C to 105 °C the measured vapour pressure decreased with increasing temperatures. At higher temperatures the measured vapour pressure increased with increasing temperatures. The vapour pressure at 52 °C was considerably lower than at 81 °C.

The difference between the vapour pressures at 52 °C and 81 °C was caused by the melting of the test item (melting point 79.4 °C). The decreasing values starting at 81 °C could have been caused by the evaporation of higher volatile components of the test item. The test item was a mixture containing a lot of different chain lengths. After the higher volatile components were removed from the test item the vapour pressure of the remaining test item showed a slightly increasing tendency.

Since the test item showed an ambiguous behaviour the values for 20, 25 and 50 °C could not be extrapolated. Assuming a normal behaviour of the solid test item and under consideration of the value at 52 °C it can be presumed that the vapour pressure for 20, 25 and 50 °C is <10^-4hPa.

Table2: Estimated vapour pressure at 20, 25 and 50 °C

T / °C	p / hPa	p / Pa
20	< 10^-4	< 10^-2
25	< 10^-4	< 10^-2
50	< 10^-4	< 10^-2

 

 

2            Final results

Based on the measured vapour pressure at 52 °C (vapour pressure balance), the vapour pressure values for the test item were estimated:

T / °C	p / hPa	p / Pa
20	< 10^-4	< 10^-2
25	< 10^-4	< 10^-2
50	< 10^-4	< 10^-2

 

[1]  The heating phase was not planned to be used in the evaluation. Therefore considerably less data points were recorded at these temperatures.

Conclusions:

The extrapolated vapor pressure of the substance at 20°C is < 0.0001 hPa.

Executive summary:

The extrapolated vapor pressure of the substance at 20°C is < 0.0001 hPa.

Description of key information

The extrapolated vapor pressure of the substance at 20°C is < 0.0001 hPa.

Key value for chemical safety assessment

Vapour pressure:

0 hPa

at the temperature of:

20 °C