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Physical & Chemical properties

Partition coefficient

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Endpoint:
partition coefficient
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 117 (Partition Coefficient (n-octanol / water), HPLC Method)
Qualifier:
equivalent or similar to guideline
Guideline:
other: EU A.24 (Partition Coefficient (n-octanol / water), HPLC method)
GLP compliance:
yes (incl. QA statement)
Remarks:
Landesamt für Umwelt, Mainz, Germany
Type of method:
HPLC method
Partition coefficient type:
octanol-water
Type:
log Pow
Partition coefficient:
> 6.5
Temp.:
25 °C
pH:
ca. 4

Measurement Data

The retention times which were recorded for the reference items are presented in the following table.

Compound

RT 1

RT 2

RT 3

RT 4

RT 5

RT 6

 

min.

min.

min.

min.

min.

min.

Thiourea

1.358

1.350

1.358

1.358

1.358

1.350

Acetophenone

2.100

2.100

2.100

2.100

2.100

2.100

Naphthalene

3.642

3.650

3.642

3.642

3.642

3.650

Diphenyl ether

4.267

4.275

4.267

4.267

4.267

4.283

Phenanthrene

5.350

5.358

5.350

5.358

5.358

5.367

Fluoranthene

6.650

6.658

6.650

6.658

6.650

6.667

Triphenylamine

9.675

9.692

9.683

9.692

9.692

9.708

4,4’-DDT

12.308

12.325

12.317

12.325

12.317

12.342

 

Calculated Values

For each reference item, the calculated capacity factors are presented in the following table.

Compound

Retention Time Mean

Retention Time Standard Deviation

Retention Time Relative Standard Deviation

k

 

min.

min.

%

 

Thiourea

1.356

0.004

0.317

0

Acetophenone

2.100

0.000

0.000

0.5492

Naphthalene

3.644

0.004

0.118

1.6885

Diphenyl ether

4.271

0.007

0.163

2.1506

Phenanthrene

5.357

0.006

0.117

2.9518

Fluoranthene

6.656

0.007

0.102

3.9098

Triphenylamine

9.690

0.011

0.114

6.1486

4,4’-DDT

12.322

0.011

0.092

8.0902

 

log POW / log k

The values for log k and log POW of the reference items are presented in the following table:

Compound

log k

log POW

Acetophenone

-0.2603

1.70

Naphthalene

0.2275

3.60

Diphenyl ether

0.3326

4.20

Phenanthrene

0.4701

4.50

Fluoranthene

0.5922

5.10

Triphenylamine

0.7888

5.70

4,4’-DDT

0.9080

6.50

 

Correlation Results

Dead time is 1.356 ± 0.004 minutes, with RSD (relative standard deviation) 0.3%.

The RSD of the retention times of the reference items were all below 0.2 %.

Equation of the regression: log k = 0.2497 * log POW – 0.6796 with a coefficient of determination r2 = 0.9941

Test Item 2,6-diisopropyl naphthalene

Measurement Data

The retention times of the test item are presented in the following table:

Measurement

RT (min.)

Measurement 1

17.092

Measurement 2

17.100

Measurement 3

17.108

Mean

17.100

Standard deviation

0.008

 

Calculated Values

The calculated values are presented in the following table:

Measurement

k

log k

log POW

Measurement 1

11.6086

1.0648

6.986

Measurement 2

11.6148

1.0650

6.986

Measurement 3

11.6209

1.0652

6.987

Mean

6.986*

Relative Standard deviation

0.001

* With the calculated capacity factors for the test item, the calculated log POW had to be extrapolated, hence its validity is limited, because the calculated capacity factor was higher than the highest capac-ity factor of the used reference item 4,4’-DDT and thus outside the calibration range.

Finally, the log POW was stated as > 6.5.

log POW was calculated from the capacity factor as follows:

log POW = (log k + 0.6796) / 0.2497

 

Results and Validity

The chromatogram of the test item 2,6-diisopropyl naphthalene gave one peak with a reten-tion time of 17.100 min (mean).

Due to the fact that the retention time of the test item (17.100 min) exceeded the retention time of 4,4’-DDT (12.322 min) andwas thus outside the calibrated range, the calculated log POW had to be extrapolated.

As recommended by the OECD guideline, the log Pow of 2,6-diisopropyl naphthalene is stated as > 6.5 (highest log Pow of a reference item (4,4’-DDT)) at the temperature of 25.0 ± 1°C.

Validity

The validity criteria and results are presented in the following table:

 

Peak

Parameter

Criterion

Found

Assessment

1

Range (Max – Min. log POW)

< 0.1

0.002

valid

Value within Range of Ref. Items

2.100 - 12.322

17.100

not within range

 

DISCUSSION

Variations in the retention times of the reference items and the test item were very small. Therefore, a stable configuration of the HPLC-column can be assumed.

The correlation log k/log POW is good: the coefficient of determination r2 was calculated as 0.9941. This value was considered sufficiently high as to use the calibration function for the determination of the log POW of the test item 2,6-diisopropyl naphthalene.

The chromatogram of the test item 2,6-diisopropyl naphthalene gave one peak with a reten-tion time of 17.10 min (mean).

Due to the fact that the retention time of the test item (17.10 min) exceeded the retention time of 4,4’-DDT (12.32 min) and was thus outside the calibrated range, the calculated log POW had to be extrapolated, therefore having limited validity.

As recommended by the OECD guideline, the log POW of 2,6-diisopropyl naphthalene is stated as > 6.5 (highest log POW of a reference item (4,4’-DDT)) at the temperature of 25.0 ± 1°C.

No observations were made which might create doubts concerning the validity of the study outcome.

Endpoint:
partition coefficient
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
EPI Suite v4.11 Estimation Programs Interface Suite™ for Microsoft® Windows v 4.11. US EPA, United States Environmental Protection Agency, Washington, DC, USA.

2. MODEL (incl. version number)
KOWWIN v1.68

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 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 "Overall remarks, attachments" section.

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 R.6
Principles of method if other than guideline:
- Software tool(s) used including version: EPI Suite v4.11
- Model(s) used: KOWWIN v1.68
The octanol-water partition coefficient of organic compounds is estimated starting from the chemical structure, which is divided into fragments (atom or larger functional groups). Coefficient values of each fragment or group are summed together to yield the log P estimate. For the complete method's description see field 'Any other information on materials and methods incl. tables'.
The datasets used for the model development (2447 molecules) and for the external validation (10946 molecules) are described in the field 'Any other information on materials and methods incl. tables'.
- 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 'overall remarks'
GLP compliance:
no
Type of method:
other: QSAR
Partition coefficient type:
octanol-water
Type:
log Pow
Partition coefficient:
6.08
Remarks on result:
other: QSAR result, no information on temperature and pH available.

TYPE

NUM

LOGKOW FRAGMENT DESCRIPTION

COEFF

VALUE

Frag 

4

-CH3 [aliphatic carbon]               

0.5473

2.1892

Frag 

2

-CH [aliphatic carbon]               

0.3614

0.7228

Frag 

10

Aromatic Carbon                          

0.294

2.94

Const

    

Equation Constant                        

        

0.229

Endpoint:
partition coefficient
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, but not (completely) falling into its applicability domain, with adequate and reliable documentation / justification
Remarks:
The substance is not fully compliant with the applicability domain of the model. However, this calculation is used in a weight of evidence approach or as supporting information, in accordance to the REACh Regulation (EC) No 1907/2006, Annex XI General rules for adaptation of the standard testing regime set out in Annexes VII to X, 1.2. It is adequately documented and justified: the overall internal quality check in VEGA indicates that the prediction is reliable with a Klimisch score of 2.
Justification for type of information:
1. SOFTWARE
VEGA version 1.1.5b36

2. MODEL (incl. version number)
ALogP Model v. 1.0.0

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 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 R.6
Principles of method if other than guideline:
- Software tool(s) used including version: VEGA v1.1.5b36
- Model(s) used: ALogP Model version 1.0.0
The model is based on the Ghose-Crippen-Viswanadhan LogP (ALogP) and consists of a regression equation based on the hydrophobicity contribution of 120 atom types as described in: A.K. Ghose and G.M. Crippen, J. Comput. Chem. 1986, 7, 565-577; V.N. Viswanadhan et al., J. Comput. Chem. 1993, 14, 1019-1026; A.K. Ghose, V.N. Viswanadhan, J.J. Wendoloski, J. Phys. Chem. A 1998, 102, 3762-3772. For the purpose of applicability domain assessment, the training set of the Meylan LogP model (9961 compounds) has been considered, setting all molecules as belonging to the test set.
- 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
Partition coefficient type:
octanol-water
Type:
log Pow
Partition coefficient:
5.13
Remarks on result:
other: QSAR result, no information on temperature and pH available.

For detailed information on the results please refer to the attached report.

Endpoint:
partition coefficient
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, but not (completely) falling into its applicability domain, with adequate and reliable documentation / justification
Remarks:
The substance is not fully compliant with the applicability domain of the model. However, this calculation is used in a weight of evidence approach or as supporting information, in accordance to the REACh Regulation (EC) No 1907/2006, Annex XI General rules for adaptation of the standard testing regime set out in Annexes VII to X, 1.2. It is adequately documented and justified: the overall internal quality check in VEGA indicates that the prediction is reliable with a Klimisch score of 2.
Justification for type of information:
1. SOFTWARE
VEGA version 1.1.5b36

2. MODEL (incl. version number)
MLogP Model v. 1.0.0

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 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 R.6
Principles of method if other than guideline:
- Software tool(s) used including version: VEGA v1.1.5b36
- Model(s) used: MLogP Model version 1.0.0
The model is based on the the Moriguchi LogP (MLogP) and consists of a regression equation based on 13 structural parameters as described in: I. Moriguchi, S. Hirono, Q. Liu, I. Nakagome, and Y. Matsushita, Chem. Pharm. Bull. 1992, 40, 127-130; I. Moriguchi, S. Hirono, I. Nakagome, H. Hirano, Chem. Pharm. Bull. 1994, 42, 976-978. For the purpose of applicability domain assessment, the training set of the Meylan LogP model (9961 compounds) has been considered, setting all molecules as belonging to the test set.
- 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
Partition coefficient type:
octanol-water
Type:
log Pow
Partition coefficient:
5
Remarks on result:
other: QSAR result, no information on temperature and pH available.

For detailed information on the results please refer to the attached report.

Description of key information

In an experimental study acording to OECD 117 guideline, log Kow of 2,6-diisopropylnaphthalene is stated as > 6.5 at a temperature of 25.0 ± 1°C and pH ca. 4.

Key value for chemical safety assessment

Log Kow (Log Pow):
6.5
at the temperature of:
25 °C

Additional information

The log Kow of 2,6-diisopropylnaphthalene substance has been evaluated in supporting studies using three scientifically valid QSAR models: EPI Suite / KOWWIN, VEGA / ALogP and VEGA / MLogP; The generated results were 6.08, 5.13 and 5, respectively. Based on the applicability domain compliance, the result generated with KOWWIN has been evaluated as more reliable. It is concluded that a log Kow of ca. 6 can be considered a reliable estimation of the octanol/water partition coefficient of 2,6-diisopropylnaphthalene.