Fatty acids, C16-18, isononyl esters

Viscosity

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

viscosity

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study without detailed documentation

Qualifier:

according to guideline

Guideline:

DIN 53019 Part 1 (Viscometry - Measurement of viscosities and flow curves by means of rotational viscometers - Part 1: Principles and measuring geometry)

GLP compliance:

not specified

Type of method:

rotational viscometer (dynamic)

Temp.:

20°C

Parameter:

dynamic viscosity (in mPa s)

Value:

18.74

Temp.:

40°C

Parameter:

dynamic viscosity (in mPa s)

Value:

9.66

Reference 2

Endpoint:

viscosity

Type of information:

(Q)SAR

Adequacy of study:

supporting study

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
US EPA T.E.S.T. version 5.1.1

2. MODEL
Viscosity at 25 °C

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
See “Test material information”

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
See attached information on the model, extracted from the official documentation provided by the developer. Further information on the OECD criteria as outlined by the applicant is provided below under "Any other information of materials and methods incl. tables"

5. APPLICABILITY DOMAIN
See attached information and information as provided in "Any other information on results incl. tables".

6. ADEQUACY OF THE RESULT
See assessment of adequacy as outlined in the "Overall remarks, attachments" section.

Qualifier:

according to guideline

Guideline:

other: REACH Guidance on QSARs

Principles of method if other than guideline:

Calculation based on T.E.S.T. version v5.1, consensus method

- Software tool(s) used including version: T.E.S.T. v5.1
- Model(s) used: Viscosity at 25 °C
The model is a consensus result of five independent models built using different approaches: Hierarchical Clustering, Single Model, FDA Method, Group contribution method, and Nearest neighbor method. For the complete methods' descriptions see field 'Justification for type of information / Attached justification'.
The dataset used for the model development and for the external validation is derived from "Data Book on the Viscosity of Liquids" (Viswanath et al., Hemisphere Pub. Co., 1989) and "Organic Solvents Physical Properties and Methods of Purification, 4th ed. " (Riddick et al., Wiley, 1986), and includes 557 chemicals with viscosity values at 25 °C (experimentally determined or approximated if the temperature of determination was among 10 and 25 °C)
- Model description: see field 'Justification for type of information', 'Attached justification' and 'any other information on Material and methods'
- Justification of QSAR prediction: see field 'Justification for type of information', 'Attached justification' and/or 'overall remarks'

GLP compliance:

no

Type of method:

other: QSAR

Temp.:

other: 25 °C

Parameter:

dynamic viscosity (in mPa s)

Value:

13.27

Remarks on result:

other: The model calculates the viscosity in centipoise (cP): 1 cP = 1 mPa·s.

The results of the individual models and the consensus are reported in the table below:

Method	Predicted value
Hierarchical clustering (Log10(cP))	1.09
Single model (Log10(cP))	1.23
Group contribution (Log10(cP))	1.34
Nearest neighbor (Log10(cP))	0.84
Consensus model (Log10(cP))	1.12
Consensus model (cP)	13.27

 

The target molecule is evaluated as compliant with the applicability domain of the models (the prediction is not provided if a molecule fails the applicability domain assessment).

 

Evaluation of the Mean Absolute Error (MAE)

 

The MAE of the predictions obtained for the most similar molecules to the query molecule (similarity coefficient ≥ 0.5) from the external test set of the model is calculated and compared to the MAE obtained for the whole test set. Results are reported in the table below.

 

Chemicals	MAE*
Entire set	0.13
Similarity coefficient ≥ 0.5	0.12

*Mean absolute error in Log10(cP)

 

The MAE calculated for the subset of similar substances is lower than the one calculated for the whole test set. This increases the confidence in the value predicted for the query compound. Similarly, the MAE calculated for the subset of similar substances from the training set (0.04) is lower than the one calculated for the whole training set (0.11).

 

 

Performance on similar molecules

 

The model performance (predicted vs experimental viscosity values) on the three most similar molecules present in the model’s training set or in the model test set is presented in the table below.

CAS	From dataset	Similarity Coefficient	Experimental value (Log10(cP))	Predicted value (Log10(cP))	Performance
123-95-5	TR	0.99	0.92	0.97	Good
111-61-5	TR	0.98	0.85	0.88	Good
629-70-9	TE	0.97	0.82	0.77	Good

TR = training set; TE = test set

 

The performances of the model on the similar molecules are evaluated on the basis of the absolute differences between experimental and predicted values:

-Good if difference ≤ 0.5

-Moderate if difference ≤ 1.0

-Poor if difference > 1.0

Reference 3

Endpoint:

viscosity

Type of information:

(Q)SAR

Adequacy of study:

supporting study

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
US EPA T.E.S.T. version 5.1.1

2. MODEL
Viscosity at 25 °C

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
See “Test material information”

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
See attached information on the model, extracted from the official documentation provided by the developer. Further information on the OECD criteria as outlined by the applicant is provided below under "Any other information of materials and methods incl. tables"

5. APPLICABILITY DOMAIN
See attached information and information as provided in "Any other information on results incl. tables".

6. ADEQUACY OF THE RESULT
See assessment of adequacy as outlined in the "Overall remarks, attachments" section.

Qualifier:

according to guideline

Guideline:

other: REACH Guidance on QSARs

Principles of method if other than guideline:

Calculation based on T.E.S.T. version v5.1, consensus method

- Software tool(s) used including version: T.E.S.T. v5.1
- Model(s) used: Viscosity at 25 °C
The model is a consensus result of five independent models built using different approaches: Hierarchical Clustering, Single Model, FDA Method, Group contribution method, and Nearest neighbor method. For the complete methods' descriptions see field 'Justification for type of information / Attached justification'.
The dataset used for the model development and for the external validation is derived from "Data Book on the Viscosity of Liquids" (Viswanath et al., Hemisphere Pub. Co., 1989) and "Organic Solvents Physical Properties and Methods of Purification, 4th ed. " (Riddick et al., Wiley, 1986), and includes 557 chemicals with viscosity values at 25 °C (experimentally determined or approximated if the temperature of determination was among 10 and 25 °C)
- Model description: see field 'Justification for type of information', 'Attached justification' and 'any other information on Material and methods'
- Justification of QSAR prediction: see field 'Justification for type of information', 'Attached justification' and/or 'overall remarks'

GLP compliance:

no

Type of method:

other: QSAR

Temp.:

other: 25 °C

Parameter:

dynamic viscosity (in mPa s)

Value:

17.59

Remarks on result:

other: The model calculates the viscosity in centipoises (cP): 1 cP = 1 mPa·s.

The results of the individual models and the consensus are reported in the table below:

Method	Predicted value
Hierarchical clustering (Log10(cP))	1.27
Single model (Log10(cP))	1.34
Group contribution (Log10(cP))	1.50
Nearest neighbor (Log10(cP))	0.86
Consensus model (Log10(cP))	1.25
Consensus model (cP)	17.59

 

The target molecule is evaluated as compliant with the applicability domain of the models (the prediction is not provided if a molecule fails the applicability domain assessment).

Evaluation of the Mean Absolute Error (MAE)

The MAE of the predictions obtained for the most similar molecules to the query molecule (similarity coefficient ≥ 0.5) from the external test set of the model is calculated and compared to the MAE obtained for the whole test set. Results are reported in the table below.

Chemicals	MAE*
Entire set	0.13
Similarity coefficient ≥ 0.5	0.13

*Mean absolute error in Log10(cP)

 

The MAE calculated for the subset of similar substances is equal to the one calculated for the whole test set. In addition, the MAE calculated for the subset of similar substances from the training set (0.04) is lower than the one calculated for the whole training set (0.11). The latter increases the confidence in the value predicted for the query compound.

Performance on similar molecules

The model performance (predicted vs experimental viscosity values) on the three most similar molecules present in the model’s training set or in the model test set is presented in the table below.

CAS	From dataset	Similarity Coefficient	Experimental value (Log10(cP))	Predicted value (Log10(cP))	Performance
123-95-5	TR	0.98	0.92	0.97	Good
111-61-5	TR	0.97	0.85	0.88	Good
629-70-9	TE	0.95	0.82	0.77	Good

TR = training set; TE = test set

 

The performances of the model on the similar molecules are evaluated on the basis of the absolute differences between experimental and predicted values:

-Good if difference ≤ 0.5

-Moderate if difference ≤ 1.0

-Poor if difference > 1.0.

Description of key information

18.74 mPa s at 20 °C (DIN 53019)

9.66 mPa s at 40 °C (DIN 53019)

Key value for chemical safety assessment

Viscosity:

18.74 mPa · s (dynamic)

at the temperature of:

20 °C

Additional information

In addition, the dynamic viscosity of the substance was calculated for its main constituents C16 -isononyl ester and C18 -isononyl ester. QSAR calculations with T.E.S.T. v5.1.1 yielded 13.27 (C16) and 17.59 (C18) mPa s at 25 °C.