Pregna-1,4-diene-3,20-dione, 6-fluoro-11-hydroxy-16-methyl-21-[(1-oxopentyl)oxy]-, (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:

21 to 22 Jun 2001

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

test procedure in accordance with national standard methods 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

Type of method:

effusion method: Knudsen cell

Key result

Temp.:

25 °C

Vapour pressure:

< 0.001 Pa

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.

 

Validity criteria for the measurement of the vapour pressure:

Target condition according to guideline:	Actual condition according to the study:	Validity criteria met:
The vapour pressure should be determined for at least two temperatures. Three or more are preferred in the range 0 to 50 °C, in order to check the linearity of the vapour pressure curve.	One temperature (25 °C) is measured.	No
A log p versus 1 /T curve should be stated.	Not found.	No
An estimate of the vapour pressure at 20 or 25 °C should be stated.	Is stated.	Yes

 

Conclusions:

A vapour pressure of <0.001 Pa was measured at 25 °C for Fluocortolon-21-Valerat.

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. Fluocortolon-21-Valerat 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 of Fluocortolon-21-Valerat can be estimated to be lower than 0.001 Pa at 25°C.

Description of key information

The vapour pressure of Fluocortolon-21-Valerat 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-21-Valerat was mixed with three 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-21-Valerat is supported by QSAR calculation of the Estimation Programm Interface EPI-Suite v4.11. The experimental melting point of 207 °C (mean value) and the calculated boiling point of 524.3°C (at 1013 hPa) were taken into account for estimation. Using the modified Grain method, the vapour pressure was estimated to be 5.3E-11 Pa at 25 °C.