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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:
2018
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:
1. SOFTWARE
EPI Suite

2. MODEL (incl. version number)
Mpbpwin Version 1.43

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
O=P(OCCCCCCCC)(OCCCCCCCC)O
O=P(OCCCCCCCC)(O)O
OP(O)(O)=O
OP(O)(=O)OP(O)(O)=O
CCCCCCCCOP(=O)(OCCCCCCCC)OCCCCCCCC
OCCCCCCCC

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
- Defined endpoint: Vapour pressure
- Unambiguous algorithm: Mean of Antoine and Grain methods.These methods calculate the boiling of the compound (if experimental value is not available) and used this parameter to calculate the vapour pressure.
- Defined domain of applicability: Molecular weight range of the training set compounds
- Appropriate measures of goodness-of-fit and robustness and predictivity: the coefficient of correlation is 0.914 (r²)
- Mechanistic interpretation: No information available

5. APPLICABILITY DOMAIN
- Descriptor domain: Molecular weight of the test item is included in the molecular weight range of the training set compounds.
- Structural and mechanistic domains: No information available
- Similarity with analogues in the training set: No information available

6. ADEQUACY OF THE RESULT
The test item is a reaction mass composed by 6 constituents. The methods (described in the OECD 104 guideline) are not adapted for substance with a large number of constituents. Therefore, QSAR estimations have been performed on all the constituents. The highest value obtained is chosen as the key value of vapour pressure test item as a worst case approach.
Qualifier:
according to guideline
Guideline:
other: REACH Guidance on QSARs R.6
GLP compliance:
not specified
Type of method:
other: QSAR estimation
Test no.:
#1
Temp.:
25 °C
Vapour pressure:
0.381 Pa
Remarks on result:
other: QSAR result obtained for Dioctyl hydrogen phosphate
Test no.:
#2
Temp.:
25 °C
Vapour pressure:
0.234 Pa
Remarks on result:
other: QSAR result obtained for Octyl dihydrogen phosphate
Test no.:
#3
Temp.:
25 °C
Vapour pressure:
0.144 Pa
Remarks on result:
other: QSAR value obtained for Orthophosphoric acid
Test no.:
#4
Temp.:
25 °C
Vapour pressure:
0.144 Pa
Remarks on result:
other: QSAR value obtained for Pyrophosphoric acid
Test no.:
#5
Temp.:
25 °C
Vapour pressure:
3.26 Pa
Remarks on result:
other: QSAR value obtained for Tri-octylphosphate
Test no.:
#6
Temp.:
25 °C
Vapour pressure:
0.381 Pa
Remarks on result:
other: QSAR value obtained for 1-octanol

Detailed results obtained with Mpbpwin:

Vapour pressure Antoine (Pa) at 25°C Vapour pressure Grain (Pa) at 25°C Vapour pressure Mackay (Pa) at 25°C Selected Vapour pressure (Pa)
Dioctyl hydrogen phosphate 0,39 0,372 5,67 0,381
Octyl dihydrogen phosphate 0,24 0,228 5,67 0,234
Orthophosphoric acid 0,147 0,14 5,67 0,144
Pyrophosphoric acid 0,147 0,14 5,67 0,144
Tri-octylphosphate 3,32 3,2 5,67 3,26
1-octanol 0,39 0,372 5,67 0,381

The selected vapour pressure was calculated as the average of the Antoine and Grain vapour pressure. For the risk assessment, the average of the selected values for octyl hydrogen phosphate and dioctyl hydrogen phosphate was selected.

Conclusions:
The estimated vapour pressure of the test item at 25°C is 0,307 Pa
Executive summary:

The vapour pressure of the test item was estimated with a recognised QSAR program according to REACH Guidance on QSARs R.6. (May 2008). The Antoine and modified Grain method were used to calculate the vapour pressure. The mean obtained with these two methods is selected as the vapour pressure.

QSAR estimations have been performed on all the constituents of the test item. Indeed, the experimental methods described in the recognised guidelines are not adapted for such type of test item (reaction mass).

The average of the two main constituents is chosen as the key value for the test item as a worst case approach. The estimated vapour pressure of the test item at 25°C is 0,307 Pa. Based on this value, the test item is not considered as volatile at 25°C.

Description of key information

The vapour pressure of the test item was determined in a key study of Klimisch validity two.

Key value for chemical safety assessment

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

Additional information

The test item is a reaction mass composed by 6 constituents. The methods (described in the OECD 104 guideline) are not adapted for substance with a large number of constituents. Therefore, QSAR estimations have been performed on all the constituents. The average value of the two main constituents is chosen as the key value of vapour pressure test item as a worst case approach.

Based on the key value for chemical safety assessment, the test item is not considered to be volatile at 25°C.

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