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Vapour pressure

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Description of key information

experimental value: 0.00011 Pa at 20 °C (OECD 104, Grain-Watson estimation method)
experimental value: 0.0000031 Pa at 20 °C (based on boiling point measurements at different pressures)
estimated by calculation (based on modified Grain method, weight-averaged value): 0.0001333 Pa at 20 °C (EPIsuite v4.10)

Key value for chemical safety assessment

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

Additional information

The vapour pressure of substance Octadecan-1-ol, ethoxylated, < 2.5 EO (CAS 9005-00-9) was determined experimentally using boiling point measurements at different pressures and estimated by calculation based on the Grain-Watson Method (according to OECD 104) or the modified Grain method (EPIsuite v4.10).


The experimental value was considered to be not reliable, as it fell outside the recommended range for DSC-based vapour pressure deduction (range: 1-1000 mbar). Alternatively, the Grain-Watson estimation procedure according the OECD Method 104 was applied, which takes into account melting point and boiling point data. 


Additionally, the vapour pressures of possible individual constituents of the substance were calculated using EPIsuite v 4.10 (MPBPVP v 1.43). In order to derive a vapour pressure value for the whole substance, weighting based on normalized composition was applied to the individual data. Since the resulting weighted value of is below 0.0001333 Pa (1E-6 mmHg), below which the estimation error increase significantly, therefore the limit value of 0.0001333 Pa is taken as a vapour pressure of the whole substance obtained with MPBPVP v 1.43.


In view of the low vapour pressure values obtained from the calculations, simple average of two estimations 0.00011 Pa and 0.000133 Pa are used to derive the key value of 0.0001215 Pa at 20 °C for chemical safety assessment.