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Vapour pressure

Link to relevant study record(s)

Reference

Endpoint:

vapour pressure

Type of information:

(Q)SAR

Adequacy of study:

key study

Study period:

27 September 2021 to 14 December 2021

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

results derived from a valid (Q)SAR model, but not (completely) falling into its applicability domain, with adequate and reliable documentation / justification

Justification for type of information:

1. SOFTWARE
iSafeRat® – in Silico Algorithms For Environmental Risk And Toxicity

2. MODEL (incl. version number)
iSafeRat® VAP v1.5

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
See attached Study Report for further details.

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
See attached QMRF for further details.

5. APPLICABILITY DOMAIN
See attached QMRF/Study Report for further details.

6. ADEQUACY OF THE RESULT
See attached Study Report for further details.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 104 (Vapour Pressure Curve)

Deviations:

not applicable

Remarks:

QSAR model

Principles of method if other than guideline:

The VAPOUR PRESSURE was determined using the iSafeRat® VP, a validated QSPR model. The model uses a linear relationship in which validated boiling point values are plotted against the log of vapour pressure values, where the pressure is in Pascals. The comparison was made with other members of the same chemical group. The results are considered to be as accurate as those from a good quality OECD guideline 104 study.

GLP compliance:

no

Remarks:

QSAR model

Type of method:

other: QSAR model

Remarks:

In the majority of cases data for vapour pressure were obtained from the following methods described in the OECD Guideline No. 104: isoteniscope, dynamic, static, effusion (vapour pressure balance or loss of weight) and gas saturation methods (OECD, 2006)

Key result

Test no.:

#1

Temp.:

25 °C

Vapour pressure:

239 Pa

Remarks on result:

other: 95CI: 2.23E+02 – 2.56E+02 Pa

Key result

Test no.:

#1

Temp.:

25 °C

Vapour pressure:

163 Pa

Remarks on result:

other: 95CI: 1.49E+02 – 1.78E+02 Pa

Key result

Test no.:

#1

Temp.:

25 °C

Vapour pressure:

343 Pa

Remarks on result:

other: 95CI: 3.22E+02 – 3.65E+02 Pa

Key result

Test no.:

#1

Temp.:

25 °C

Vapour pressure:

181 Pa

Remarks on result:

other: 95CI: 1.66E+02 – 1.98E+02 Pa

Key result

Test no.:

#1

Temp.:

25 °C

Vapour pressure:

17 Pa

Remarks on result:

other: 95CI: 1.48E+01 – 1.96E+01 Pa

Key result

Test no.:

#1

Temp.:

25 °C

Vapour pressure:

533 Pa

Remarks on result:

other: 95CI: 5.03E+02 – 5.64E+02 Pa

Key result

Test no.:

#1

Temp.:

25 °C

Vapour pressure:

357 Pa

Remarks on result:

other: 95CI: 3.35E+02 – 3.80E+02 Pa

Key result

Test no.:

#1

Temp.:

25 °C

Vapour pressure:

21.6 Pa

Remarks on result:

other: 95CI: 1.88E+01 – 2.49E+01 Pa

Key result

Test no.:

#1

Temp.:

25 °C

Vapour pressure:

941 Pa

Remarks on result:

other: 95CI: 8.93E+02 – 9.91E+02 Pa

Key result

Test no.:

#1

Temp.:

25 °C

Vapour pressure:

47.4 Pa

Remarks on result:

other: 95CI: 4.22E+01 – 5.32E+01 Pa

Key result

Test no.:

#1

Temp.:

25 °C

Vapour pressure:

454 Pa

Remarks on result:

other: 95CI: 4.28E+02 – 4.82E+02 Pa

Key result

Test no.:

#1

Temp.:

25 °C

Vapour pressure:

27.9 Pa

Remarks on result:

other: 95CI: 2.45E+01 – 3.17E+01 Pa

Key result

Test no.:

#1

Temp.:

25 °C

Vapour pressure:

154 Pa

Remarks on result:

other: 95CI: 1.42E+02 – 1.66E+02 Pa

Key result

Test no.:

#1

Temp.:

25 °C

Vapour pressure:

157 Pa

Remarks on result:

other: 95CI: 1.43E+02 – 1.72E+02 Pa

Key result

Test no.:

#1

Temp.:

25 °C

Vapour pressure:

281 Pa

Remarks on result:

other: 95CI: 2.63E+02 – 3.00E+02 Pa

Key result

Test no.:

#1

Temp.:

25 °C

Vapour pressure:

66.5 Pa

Remarks on result:

other: 95CI: 5.83E+01 – 7.59E+01 Pa

Key result

Test no.:

#1

Temp.:

25 °C

Vapour pressure:

181 Pa

Remarks on result:

other: 95CI: 1.68E+02 – 1.95E+02 Pa

Applicability domain

 

Descriptor domain

The descriptor domain has been reported for each constituent of the test item. The results are as follows:

Constituents	descriptor domain (BP in °C)	status
const1	[26 ; 243.5]	inside domain
const2	[30.7 ; 256]	inside domain
const3	[26 ; 243.5]	inside domain
const4	[30.7 ; 256]	inside domain
const5	[30.7 ; 256]	inside domain
const6	[26 ; 243.5]	inside domain
const7	[26 ; 243.5]	inside domain
const8	[82.3 ; 303]	inside domain
const9	[26 ; 243.5]	inside domain
const10	[30.7 ; 256]	inside domain
const11	[30.7 ; 256]	inside domain
const12	[26 ; 243.5]	inside domain
const13	[30.7 ; 256]	inside domain
const14	[30.7 ; 256]	inside domain
const15	[26 ; 243.5]	inside domain
const16	[30.7 ; 256]	inside domain
const17	[26 ; 243.5]	inside domain
const18	[82.3 ; 303]	inside domain
const19	[26 ; 243.5]	inside domain

 

Structural fragment domain                                                                                                                                          

All chemical groups within the molecular structure of each constituent are taken into account by the model.

 

Mechanism domain

The model is based on different Simple Linear Regression equations (i.e. local models), selected on the basis of an initial classification about the capability of the substance to participate in intermolecular interactions, such as hydrogen bonding. iSafeRat® VP includes the following local models, ranked by increasing intermolecular attractive interactions:

• Vapour pressure local model for Non-Polar Organic compounds: for compounds which can only participate in weak Van der Waals attractive forces (g. alkanes, halides, alkenes, thiols… etc.).


• Vapour pressure local model for Oxygenated, Non-Hydroxylated compounds: for compounds which can participate in strong Van der Waals attractive forces (g. ethers, esters, ketones, aldehydes, epoxides, lactones, carbonates, (meth)acrylates).


• Vapour pressure local model for Nitrogenated compounds, which can participate in hydrogen bonds and/or strong Van der Waals attractive forces (g. amines, anilines, pyridines, pyrroles, nitriles, lactames, azoles, etc.).


• Vapour pressure local model for Oxygenated, Hydroxylated compounds (Secondary and Tertiary Alcohols and phenols), which can participate in hydrogen bonds.


• Vapour pressure local model for Oxygenated, Hydroxylated compounds (Primary Alcohols), which can participate in hydrogen bonds.


• Vapour pressure local model for Carboxylic Acids, which can participate in hydrogen bonds.

The descriptor domain has been reported for each constituent of the test item. All the constituents fell inside the mechanism domain and could be predicted using one of these local models.

Conclusions:

This QSPR model has been validated as a QSAR model to be compliant with the OECD recommendations for QSAR modeling (OECD, 2004). The constituents of the test item fall within the applicability domain of the model and were therefore reliably predicted for the VAPOUR PRESSURE. Therefore, this endpoint values can be considered valid and fit for purpose.

Executive summary:

A Quantitative Structure-Property Relationship (QSPR) model was used to calculate the VAPOUR PRESSURE of the consituents of the test item. This QSPR model has been validated as a QSAR model to be compliant with the OECD recommendations for QSAR modeling (OECD, 2004) and predicts the endpoint value which would be expected when testing the substance under experimental conditions in a laboratory following the Guideline for Testing of Chemicals No. 104, "Vapour Pressure" (OECD, 2006). The criterion predicted was the vapour pressure at 25°C in Pascals.

 

The VAPOUR PRESSURE was determined using the iSafeRat® VP, a validated QSPR model. The model uses a linear relationship in which validated boiling point values are plotted against the log of vapour pressure values, where the pressure is in Pascals. The comparison was made with other members of the same chemical group. The results are considered to be as accurate as those from a good quality OECD guideline 104 study.

 

This QSPR model has been validated as a QSAR model to be compliant with the OECD recommendations for QSAR modeling (OECD, 2004). The constituents of the test item fall within the applicability domain of the model and were therefore reliably predicted for the VAPOUR PRESSURE. Therefore, this endpoint values can be considered valid and fit for purpose.

 

The VAPOUR PRESSURE of the constituents of the test item were determined as follows:

Constituents	vapour pressure (Pa) at 25 °C	95% confidence limits (Pa)
const1	2.39E+02	2.23E+02 – 2.56E+02
const2	1.63E+02	1.49E+02 – 1.78E+02
const3	3.43E+02	3.22E+02 – 3.65E+02
const4	1.81E+02	1.66E+02 – 1.98E+02
const5	1.70E+01	1.48E+01 – 1.96E+01
const6	5.33E+02	5.03E+02 – 5.64E+02
const7	3.57E+02	3.35E+02 – 3.80E+02
const8	2.16E+01	1.88E+01 – 2.49E+01
const9	9.41E+02	8.93E+02 – 9.91E+02
const10	4.74E+01	4.22E+01 – 5.32E+01
const11	1.70E+01	1.48E+01 – 1.96E+01
const12	4.54E+02	4.28E+02 – 4.82E+02
const13	2.79E+01	2.45E+01 – 3.17E+01
const14	2.79E+01	2.45E+01 – 3.17E+01
const15	1.54E+02	1.42E+02 – 1.66E+02
const16	1.57E+02	1.43E+02 – 1.72E+02
const17	2.81E+02	2.63E+02 – 3.00E+02
const18	6.65E+01	5.83E+01 – 7.59E+01
const19	1.81E+02	1.68E+02 – 1.95E+02

 

Description of key information

The vapour pressure of the test item based on partial pressure of major contituents is estimated to be in the range between 17 and 941 Pa at 25°C.

Additional information

No study was conducted on the test chemical iself, as not relevant for an UVCB.

The vapour pressure of the test item was reliably estimated from data on its known constituents (covering the 96% of the composition). Data on the known constituents were reliably estimated by a validated QSAR. Validated boiling points of constituents, calculated or by literature, were used as input. All the constituents fall inside the applicability domain of the model. The calculated vapour pressure values of constituent are listed below:

Constituent	VP (Pa) et 25°C
Limonene L	239.0
Cineol 1,8	163.0
myrcene beta	343.0
6-methyl-5-hepten-2-one	181.0
citral cis (neral)	17.0
pinene alpha (-)	533.0
pinene beta	357.0
linalool (-)	21.6
sabinene	941.0
citronellal (R)	47.4
citral trans (geranial)	17.0
camphene	454.0
isocitral trans (isogeranial)	27.9
isocitral cis (isoneral)	27.9
terpinolene	154.0
dehydrocineole	157.0
phellandrene alpha	281.0
sulcatol	66.5
terpinene gamma	181.0

As the substance is an UVCB, the vapour pressure of the test item is estimated by the lowest and the highest vapour pressure values of constituents.