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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:
April 23, 2010
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:
yes (incl. QA statement)
Type of method:
effusion method: by loss of weight or by trapping vaporisate
Key result
Temp.:
20 °C
Vapour pressure:
0.033 Pa

The logarithm of the evaporation rate of the reference control substance at 20°C deviated < 10% from the average value obtained during the validation test. This show the acceptability of the data of the reference substances for the determination of the vapour pressure of the test substance.

The equation of reference regression curve was found to be log P20= 1.04 X log V20+ 4.32 (r =0.993, n=10).

Extrapolation of the curve to 20°C resulted in a value of -5.60 for the log νT, 20 of the test substance and the value was fitting in the regression curve.

The plot of log VT of the test substance versus 1000/T figure 1 (in the window 'attached background material').

The results of the isothermal TGA analysis are given in table 1 below.

Table 1 Results of the isothermal TGA analysis

Temperature

(deg. C)

Weight loss (µg/min)

VT(g/cm2/h)

Log VT

110

10.58

10.10

1.26 x 10-3

1.21 x 10-3

-2.90

-2.92

120

17.17

17.23

2.05 x 10-3

2.06 x 10-3

-2.69

-2.69

130

27.27

28.25

3.31 x 10-3

3.37 x 10-3

-2.48

-2.47

140

44.22

45.17

5.28 x 10-3

5.39 x 10-3

-2.28

-2.27

Conclusions:
Under the study conditions, the vapour pressure of the test substance was determined to be 0.0328 Pa at 20°C.
Executive summary:

A study was conducted to determine the vapour pressure of the test substance according to OECD Guideline 104 and EU method A.4. 17.5 and 17.9 mg of the test substance was applied on glass plates respectively, and placed in the thermogravimetric analyzer. The weight loss of the test substance was measured continuously as a function of time from 70°C to 150°C. Benzo(ghi)perylene, chrysene, hexachlorobenzene, naphthalene and water were used as reference substances for validation. The log Vt, 20 value which was obtained by extrapolation of the evaporation rate curve, fitted in the vapour pressure regression curve. From this, it was concluded that the vapour pressure of the test substance at 20°C is 3.28 × 10-2 Pa = 2.46 × 10-4 mm Hg. Under the study conditions, the vapour pressure of the test substance was determined to be 0.0328 Pa at 20°C (Brekelmans, 2010a).

Description of key information

A study was conducted to determine the vapour pressure of the test substance according to the OECD Guideline 104 and EU Method A.4.

Key value for chemical safety assessment

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

Additional information

Vapour pressures of the test substance and other category members are as follows:

Oils, vegetable, deodoriser distillates = 0.0328 Pa

Glycerides, C16-18 and C18-unsatd., deodorizer distillates = 0.00113 Pa

Lauric fats deodorizer distillates = 0.152 Pa

Soybean oil, deodorizer distillates = 0.00312 Pa

The VP of 0.0328 Pa was selected for chemical safety assessment as this value was experimentally determined with the representative substance tested. The vapour pressure of other category members have been provided as a weight of evidence to support the experimental value.