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Vapour pressure

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Description of key information

Under the conditions of the study, the vapour pressure of the test material was determined to be 1.471×10^-7 Pa at 20 °C and 2.036 ×10^-7 Pa at 25 °C.

Key value for chemical safety assessment

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

Additional information

The vapour pressure of the test material was investigated in a study which was performed under GLP conditions and in accordance with the standardised guideline OECD 104. The study was assigned a reliability score of 1 in accordance with the criteria for assessing data quality set forth by Klimisch et al. (1997).

The experimental procedure followed the Knudsen cell effusion method. A small quantity of the test substance (nominally 6 - 8 mg) was placed in each of two weighed aluminium crucibles and a lid, with an orifice of a nominal 1 mm diameter (accurately measured), cold-welded on. The crucibles were weighed to an accuracy of 1 µg and placed in the apparatus, which was then evacuated to ultra-high vacuum.

At various time intervals, the apparatus was brought to atmospheric pressure, the crucibles reweighed and the loss in mass of test substance from each calculated. The vapour pressure ¿ (Pa) was calculated using the Hertz-Knudsen relationship. An initial weight loss was recorded at 53 °C, which was subsequently assumed to be due to some residual solvent, the vapour pressure after this initial loss was too low to be measured below 100 °C. Measurements between 100 and 192 °C were on the very lower limit of what can be determined by the effusion method (<1×10^-4 Pa), therefore the correlation from the Ln VP vs 1/T was not as good as would be expected at higher vapour pressures. Extrapolation of the results gave a good estimate of the vapour pressure for the test material at 20 and 25 °C, which was 1.471×10^-7 and 2.036×10^-7 Pa respectively. IR spectra from the control, tested and untested material gave the same spectrum, therefore the material was confirmed not to have under gone any chemical change.

Under the conditions of the study, the vapour pressure of the test material was determined to be 1.471×10^-7 Pa at 20 °C and 2.036 ×10^-7 Pa at 25 °C.