Pregn-4-ene-3,20-dione, 21-(acetyloxy)-6-fluoro-11-hydroxy-16-methyl-, (6.alpha.,11.beta.,16.alpha.)-

Vapour pressure

Link to relevant study record(s)

Reference

Endpoint:

vapour pressure

Type of information:

experimental study

Adequacy of study:

key study

Study period:

10 to 11 Apr 2001

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

EU Method A.4 (Vapour Pressure)

Deviations:

yes

Remarks:

several substances were measured together

GLP compliance:

no

Other quality assurance:

other: Not specified

Type of method:

effusion method: Knudsen cell

Key result

Temp.:

25 °C

Vapour pressure:

< 0.001 Pa

Remarks on result:

other: The vapour pressure of 0.001 Pa equals an evaporation rate of 0.014 μg/s

The measured evaporation rate of the mixture (1.5*10^-3 μg/s) at 25 °C is significantly below the calculated value. Therefore, it can be assumed that the vapour pressure of the mixture and consequently of the test substance is lower than the lower limit of the measuring range recommended by the EC Testing Guideline. In addition the mass spectra of the vapor escaping from the Knudsen cell show only masses m/e < 200 indicating that impurities with low molecular weights were evaporated from the mixture.

 

Validity criteria for the measurement of the vapour pressure:

Target condition according to guideline:	Actual condition according to the study:	Validity criteria met:
At least two vapour pressure and temperature values - and preferably three or more – are required in the range 0 to 50 °C (or 120 to 150 °C).	Temperature tested:25 °C. One measurement was performed.	No
A log p versus 1 /T curve should be stated.	Raw data is not available	With restrictions
An estimate of the vapour pressure at 20 or 25 °C should be stated.	Values 25 °C are given.	Yes

 

Conclusions:

A vapour pressure of lower than 0.001 Pa was measured at 25 °C for Fluocortolon-A-Acetat.

Executive summary:

The vapour pressure was determined using a screening method based on the detection of the evaporation rate from a Knudsen cell of a vapour pressure balance at 25 °C. Since simplified experimental conditions are also acceptable within the scope of this project, the substance was mixed with three other compounds. From all test substances low or very low vapour pressures were expected. For this reason the experiments consisted in the measurement of the evaporation rate of the mixture from a Knudsen cell at 25 °C. Since the evaporation rate of the mixture was below the value derived from the lower limit of the vapour pressure range recommended for the use of a vapour pressure balance (10^-3 Pa, EC Testing Guideline A.4) it can be assumed that the vapour pressure of the mixture is lower than 10 ^-3 Pa. Considering this fact, the vapour pressure of the single compounds in the mixture has also to be lower than 10^-3 Pa. Therefore, the vapour pressure can be estimated to be lower than 0.001 Pa at 25°C.

Description of key information

The vapour pressure of Fluocortolon-A-Acetat can be estimated to be lower than 0.001 Pa at 25 °C.

Key value for chemical safety assessment

Vapour pressure:

0.001 Pa

at the temperature of:

25 °C

Additional information

"Should read: < 0.001 Pa"

The vapour pressure was determined using a screening method based on the detection of the evaporation rate from a Knudsen cell of a vapour pressure balance at 25 °C. Fluocortolon-A-Acetat was mixed with four other compounds. Since the evaporation rate of the mixture was below the value derived from the lower limit of the vapour pressure range recommended for the use of a vapour pressure balance (10-3Pa, EC Testing Guideline A.4) it can be assumed that the vapour pressure of the mixture is lower than 10-3Pa. Considering this fact, the vapour pressure of the single compounds in the mixture has also to be lower than 10-3Pa.

The estimation of a low vapour pressure for Fluocortolon-A-Acetat is supported by QSAR calculation of the Estimation Program Interface EPI-Suite v4.11. The experimental melting point of 259.7 °C and the calculated boiling point of 487.9 °C (at 1013 hPa) were taken into account for estimation. Using the modified Grain method, the vapour pressure was estimated to be 1.58E-10 Pa at 25 °C.