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Vapour pressure

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Reference
Endpoint:
vapour pressure
Type of information:
(Q)SAR
Adequacy of study:
key study
Study period:
2012
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification
Justification for type of information:
Accepted calculation method
Guideline:
other: REACH guidance on QSARs R.6, May 2008
Principles of method if other than guideline:
The Estimation Program Interface (EPI) Suite v4.1 includes the model MPBPWIN for estimating the vapour pressure of organic compounds. The Estimation Programs Interface was developed by the US Environmental Agency's Office of Pollution Prevention and Toxics and Syracuse Research Corporation (SRC). © 2000 - 2011 U.S. Environmental Protection Agency for EPI SuiteTM. Published online in January 2011.
GLP compliance:
no
Type of method:
other: QSAR
Temp.:
25 °C
Vapour pressure:
0 Pa
Remarks on result:
other: 1.Constituent Pentaerythrite (modified Grain method)
Temp.:
25 °C
Vapour pressure:
0 Pa
Remarks on result:
other: 2.Constituent reaction product: adipic acid ester consisting 2 pentaerythrite (modified Grain method)
Temp.:
25 °C
Vapour pressure:
0 Pa
Remarks on result:
other: 3.Constituent molecular homologues consisting of 1 fatty acid ester with pentaerythrite (modified Grain method)
Temp.:
25 °C
Vapour pressure:
< 0 Pa
Remarks on result:
other: 4.Constituent molecular homologues consisting of 2 fatty acid esters with pentaerythrite (modified Grain method) value: 2.36E-18 Pa
Temp.:
25 °C
Vapour pressure:
< 0 Pa
Remarks on result:
other: 5.Constituent molecular homologues consisting of 3 fatty acid esters with pentaerythrite (modified Grain method) value: 9.17E-24 Pa
Temp.:
25 °C
Vapour pressure:
0 Pa
Remarks on result:
other: total vapour pressure

 Validity of the model:

1. Defined Endpoint: Vapour pressure

2. Unambigous algorithm: The modified Grain method was used for calculation.

The calculated vapour pressure of each constituent is regarded as partial pressure and is proportionately calculated based on the results of the examination on the material balance. Adding up the proportionated partial pressures, a calculated total pressure of the substance is obtained.

a. Constituent Pentaerythrite: the vapour pressure was estimated to be 3.6E-06 Pa at 25 °C. The substance refers to the molecular weight fraction of 0.6 % of the total material balance. The proportionately vapour pressure is 2.16E-08 Pa at 25 °C.

b. Constituent reaction product: adipic acid ester consisting 2 pentaerythrite: the vapour pressure was estimated to be 1.28E-13 Pa at 25 °C. The substance refers to the molecular weight fraction of 1.4 % of the total material balance. The proportionately vapour pressure is 1.79E-15 Pa at 25 °C.

c. Constituent molecular homologues consisting of 1 fatty acid ester with pentaerythrite: the vapour pressure was estimated to be 4.58E-12 Pa at 25 °C. The substance refers to the molecular weight fraction of 1.4 % of the total material balance. The proportionately vapour pressure is 6.41E-14 Pa at 25 °C.

d. Constituentmolecular homologues consisting of 2 fatty acid esters with pentaerythrite: the vapour pressure was estimated to be 2.36E-18 Pa at 25 °C. The substance refers to the molecular weight fraction of 7.5 % of the total material balance. The proportionately vapour pressure is 1.77E-19 Pa at 25 °C.

e. Constituentmolecular homologues consisting of 3 fatty acid esters with pentaerythrite: the vapour pressure was estimated to be 9.17E-24 Pa at 25 °C. The substance refers to the molecular weight fraction of 7.5 % of the total material balance. The proportionately vapour pressure is 6.88E-25 Pa at 25 °C.

Adding up the proportionated partial pressures, a calculated total pressure of 2.19E-08 Pa at 25 °C for the substance is obtained.

3. Applicability domain: With a molecular weight of 136.15 to 929.51 g/mole the representative constituents of the substance are within the range of the training set (16 - 943).

4. Statistical characteristics: Correlation coefficient of the total test set is r2= 0.914.

The representative constituents of the substance are not highly complex and the rules applied for the substance appears appropriate. An individual uncertainty for the investigated substance is not available. It is considered that estimated values for vapour pressure can be subjected to great uncertainty if the computed pressure is lower than 1 Pa, especially when the boiling point has not been experimentally determined.

Nevertheless, for this mixture of constituents the calculated vapour pressure value represents the constituent with the highest vapour pressure.

5. Mechanistic interpretation: The vapour pressure is related to fugacity models describing the distribution of the substance in the environment.

Adequacy of prediction: The results for the representative constituents of the substance fall within the applicability domain described above and the estimation rules applied appears appropriate. Therefore the predicted value can be considered reliable yielding a useful result for further assessment.

Conclusions:
The QSAR determination of the vapour pressure of representative constituents of the substance using the model MPBPWIN included in the Estimation Program Interface (EPI) Suite v4.1 revealed a total vapour pressure value of 2.19E-08 Pa at 25 °C. The predicted value can be considered reliable yielding a useful result for further assessment.
Executive summary:

The substance is a complex mixture and assessed as UVCB substance. In order to present a more specified value of the vapour pressure for the substance, calculations on vapour pressure were performed for representative constituents of the substance using the Estimation Program Interface EPI-Suite version 4.1.

The total vapour pressure of the substance was predicted using the QSAR calculation of the Estimation Programm Interface EPI-Suite v4.1. Calculations were carried out for 5 representative constituents of the substance. The calculated vapour pressure of each constituent is regarded as partial pressure and is proportionately calculated based on the results of the examination on the material balance. Adding up the proportionated partial pressures, a calculated total pressure of 2.19E-08 Pa at 25 °C for the substance is obtained. The predicted value can be considered reliable yielding a useful result for further assessment.

 

Description of key information

The QSAR determination of the vapour pressure of representative constituents of the substance using the model MPBPWIN included in the Estimation Program Interface (EPI) Suite v4.1 revealed a total vapour pressure value of 2.19E-08 Pa at 25 °C.

Key value for chemical safety assessment

Vapour pressure:
0 Pa
at the temperature of:
25 °C

Additional information

In a study on the determination of the vapour pressure of the substance, conducted according to the OECD TG 104, static method, it was found that the value for the vapour pressure of the substance was below the limit of quantification (< 20 Pa).

The substance is a complex mixture and assessed as UVCB substance. In order to present a more specified value of the vapour pressure for the substance, calculations on vapour pressure were performed for representative constituents of the substance using the Estimation Program Interface EPI-Suite version 4.1.

Calculations were carried out for 5 representative constituents of the substance. The calculated vapour pressure of each constituent is regarded as partial pressure and is proportionately calculated based on the results of the examination on the material balance. Adding up the proportionated partial pressures, a calculated total pressure of 2.19E-08 Pa at 25 °C for the substance is obtained. The predicted value can be considered reliable yielding a useful result for further assessment.