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Vapour pressure

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Reference
Endpoint:
vapour pressure
Type of information:
experimental study
Adequacy of study:
key study
Study period:
From 15 april 2010 to 28 october 2010
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP study, OECD 104 compliant
Qualifier:
according to guideline
Guideline:
OECD Guideline 104 (Vapour Pressure Curve)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Type of method:
effusion method: by loss of weight or by trapping vaporisate
Temp.:
20 °C
Vapour pressure:
12.1 Pa
Remarks on result:
other: extrapolated value.

Results

1. Observations

The mass of sample weighed was16.18 mg for the first assay. The sample was placed in a Knudsen effusion cell with an aperture size of A = 178 µm. Then the cell was placed in the apparatus.

 

           The mass of sample weighed was 21.33 mg for the second assay.

 

           The mass of sample weighed was 21.41mg for the third assay.

 

           Temperature steps at 27°C, 29°C and 31°C were made. The loss of mass was very quick.

 

           The whole test item was evaporated after the experimentation.

 

2. Vapour pressure results

The vapour pressure of the test item was calculated by the “Knudsen software”. The calculation results are summarized in table 1.

 

Table1: Summary of the calculation of vapour pressure of the test item

 

Test temperature

t(°C)

Test temperature

T (K)

1/T(K-1)

Experimental vapour pressure P(Pa)

Log P

(Pa)

Knudsen effusion cell size(µm)

27

300.15

3.332E-03

22.38

1.350

178

29

302.15

3.310E-03

26.57

1.424

31

304.15

3.288E-03

31.41

1.497

 

The molecular weight of guetol (pure substance) is 138.17 g/mol.

 

The graph log P = f (1/T) was then plotted to extrapolate the vapour pressure at 20°C

Conclusions:
The vapour pressure of Guetol extrapolated at 20 °C is 12.1 Pa.
Executive summary:

The objective of this study is to determine the vapour pressure of GUETOL following the Commission Directive 92/69/EC – Council Regulation (EC) No. 761/2009- EC A4 method (2009) and OECD Guideline No. 104 (2006).

The method used in this study is the Knudsen cell effusion method coupled to a micro-balance.

 

The quantity of substance leaving a cell per time unit through an aperture of known size is determined under vacuum conditions such that return of substance into the cell is negligible.

The mass of effused vapour is obtained by determining the loss of mass of the Knudsen cell.

 

As the logarithm of the vapour pressure of a pure substance is a linear function of the inverse of the temperature, the vapour pressure is determined in a limited temperature range.

 

The vapour pressure of GUETOL extrapolated at 20 °C is P = 12.1 Pa.

Description of key information

The vapour pressure of GUETOL extrapolated at 20 °C is 12.1 Pa.

Key value for chemical safety assessment

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

Additional information

Only one study was available (Defitraces, 2010), and was selected as key study. It is of reliability 1 according to Klimisch scale, since conducted according to OECD 104 guideline and GLP.

The vapour pressure of GUETOL extrapolated at 20°C is 12.1 Pa.