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Partition coefficient

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Endpoint:
partition coefficient
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2012-10-30 to 2012-11-17
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
The study was conducted according to an internationally recognised method, and under GLP. No deviation was reported. The substance is considered to be adequately characterised with its purity. Therefore full validation applies.
Reason / purpose:
reference to other study
Reason / purpose:
reference to other study
Qualifier:
according to
Guideline:
OECD Guideline 123 (Partition Coefficient (1-Octanol / Water), Slow-Stirring Method)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Remarks:
Inspected on 10July 2012 / Signed on 30 November 2012
Type of method:
slow-stirring method
Partition coefficient type:
octanol-water
Analytical method:
gas chromatography
Type:
log Pow
Partition coefficient:
5.09
Temp.:
25 °C
pH:
>= 6.4 - <= 7.3
Details on results:
The linearity of the detector response with respect to concentration was assessed over the nominal concentration ranges of 10 to 100 mg/L and 0.2 to 10 mg /L (n = 8 and n = 6 respectively). These were satisfactory with both having a correlation coefficient of 1.000 being obtained.

Recovery of analysis of the sample procedure was assessed and proved adequate for the test.
At a nominal test item concentration of 0.5 mg/L, a mean percentage recovery of 120 % was obtained (range 117 to 123 %). Aqueous sample concentrations have been corrected for recovery of analysis.

The mean stock solution concentration on analysis was 2.00 x 10E4 mg/L.
The mass balance based on the average of the 12 samples results used for the overall result gave a value of 98.5 % of the stock solution as weighed in.

Between 91 and 192 hours, 8 samples were collected for each phase in vessel 1. Four samples were collected for each phase in vessels 2 and 3 between 162 and 192 hours.

Individual results are available in the experimental reports.

Equilibrium was evident from at least 91 hours stirring. Taking the last four sets of analytical data for each vessel, the slope of the correlation was tested statistically to ensure it did not differ significantly from zero. This was performed using the t test and a probability value of P = 0.05 (critical value = 4.30 for 2 degrees of freedom).

As equilibrium was confirmed, the mean log10 partition coefficient value, the standard deviation and variance was calculated for each vessel, taking the last four sets of analytical data for each vessel. This then allowed the final weighted average and standard deviation to be calculated as the definitive result for the test. The results are shown in the following table:

 

Vessel 1

Vessel 2

Vessel 3

Mean Log10Pow

5.09

5.09

5.08

Standard Deviation

1.10 x 10-2

1.94 x 10-2

1.38 x 10-2

Variance

1.20 x 10-4

3.77 x 10 -4

1.90 x 10-4

 

Weighted average Log10Pow:                       5.09

Variance weighted standard deviation:       3.71 x 10-3

Conclusions:
The substance has potential to bioaccumulate in the environment, according to CLP classification criteria for aquatic chronic toxicity (log Kow >4).
Executive summary:

The partition coefficient of the test substance was measured under GLP according OECD 123 guideline, slow-stirring method.

Three vessels were prepared, and four samples were taken in each phase after equilibration at 25°C, between 162 and 192 hours. The overall average was calculated weighted for the variance.

Log Kow = 5.09 at 25°C

Endpoint:
partition coefficient
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
1. HYPOTHESIS FOR THE ANALOGUE APPROACH

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)

3. ANALOGUE APPROACH JUSTIFICATION

4. DATA MATRIX

See attached justification document, included in IUCLID Section 13.
Reason / purpose:
read-across source
Reason / purpose:
read-across: supporting information
Remarks:
Read-across justification document
Key result
Type:
log Pow
Partition coefficient:
5.09
Temp.:
25 °C
pH:
>= 6.4 - <= 7.3
Conclusions:
(from analogue) The substance has potential to bioaccumulate in the environment, according to CLP classification criteria for aquatic chronic toxicity (log Kow >4).
Executive summary:

The partition coefficient of the analogue test substance was measured under GLP according OECD 123 guideline, slow-stirring method.

Three vessels were prepared, and four samples were taken in each phase after equilibration at 25°C, between 162 and 192 hours. The overall average was calculated weighted for the variance.

The derived Log Kow for the target substance is 5.09.

Endpoint:
partition coefficient
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
2012
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Remarks:
The study was conducted according to an internationally recognised method. The substance is considered to be adequately characterised with its isomers composition. Validation applies, with technical restrictions limiting accuracy.
Qualifier:
according to
Guideline:
OECD Guideline 117 (Partition Coefficient (n-octanol / water), HPLC Method)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method A.8 (Partition Coefficient)
Deviations:
yes
Remarks:
log Kow value for reference substance DDT
GLP compliance:
no
Type of method:
HPLC method
Partition coefficient type:
octanol-water
Type:
log Pow
Partition coefficient:
7.04
Temp.:
30 °C
pH:
5.5

Preliminary estimate: log Kow = 4.76

Standards

 Component  Mean retention time (min)  log Kow
 injection peak (dead time = t0)  2.87  ---
 Isopropylbenzene  6.31  3.7
 Biphenyl  6.70  4.0
 n-Butylbenzene  8.06  4.5
 2,6-diphenylpyridine  8.49  4.9
 Triphénylamine  10.71  5.7
 DDT  11.23  6.5

slope = 6.5646

intercept = 3.0733

correlation coefficient (r) = 0.9728

Sample

 Component  Mean retention time (min)  log Kow
 injection peak (dead time = t0)  2.87  ---
Test substance 14.40  7.04
Executive summary:

The partition coefficient of the test substance was measured according to the OECD 117/EU A8 guideline, HPLC method.

The system was calibrated with 6 reference substances, between 3.7 and 6.5, and the result for the sample was extrapolated from the linear regression.

Partition coefficient (log Kow) = 7.0 at 30°C (extrapolated).

Endpoint:
partition coefficient
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
supporting study
Justification for type of information:
1. HYPOTHESIS FOR THE ANALOGUE APPROACH

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)

3. ANALOGUE APPROACH JUSTIFICATION

4. DATA MATRIX

See attached justification document, included in IUCLID Section 13.
Reason / purpose:
read-across source
Reason / purpose:
read-across: supporting information
Remarks:
Read-across justification document
Key result
Type:
log Pow
Partition coefficient:
7.04
Temp.:
30 °C
pH:
5.5
Executive summary:

The partition coefficient of the analogue test substance was measured according OECD 117/EU A8 guideline, HPLC method.

The system was calibrated with 6 reference substances, between 3.7 and 6.5, and the result for the sample was extrapolated from the linear regression.

The derived Log Kow for the target substance is 7.0 at 30°C.

Endpoint:
partition coefficient
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
From 03/07/2012 to 24/07/2012
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Remarks:
The study was conducted according to an internationally recognised method, and under GLP. Substance ID is adequately specified with purity. Validation applies, with technical restrictions limiting accuracy.
Qualifier:
according to
Guideline:
OECD Guideline 117 (Partition Coefficient (n-octanol / water), HPLC Method)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method A.8 (Partition Coefficient)
Deviations:
yes
Remarks:
log Kow value for reference substance DDT
GLP compliance:
yes (incl. certificate)
Remarks:
inspection 15-16/11/2011, decision 12/03/2012, signature 01/05/2012
Type of method:
HPLC method
Partition coefficient type:
octanol-water
Specific details on test material used for the study:
Storage condition of test material: Refrigerator (between 0 and 10°C under nitrogen)
Analytical method:
high-performance liquid chromatography
Type:
log Pow
Partition coefficient:
6.97
Temp.:
30 °C
pH:
5.5

Preliminary estimate: log Kow = 4.76

Standards

 Component  Retention time (min)  log Kow
 injection peak (dead time = t0)  2.98  ---
 Isopropylbenzene  6.45  3.7
 Biphenyl  6.85  4.0
 n-Butylbenzene  8.30  4.5
 2,6-diphenylpyridine  8.75  4.9
 Triphénylamine  11.14  5.7
 DDT  11.75  6.5

slope = 6.2904

intercept = 3.1830

correlation coefficient (r) = 0.9739

Sample

 Component  Retention time (min)  log Kow
 injection peak (dead time = t0)  2.98  ---
 Test substance 14.90  6.97
Executive summary:

The partition coefficient of the test substance was measured according to the OECD 117/EU A8 guideline, HPLC method.

The system was calibrated with 6 reference substances, between 3.7 and 6.5, and the result for the sample was extrapolated from the linear regression.

Partition coefficient (log Kow) = 7.0 at 30°C (extrapolated).

Description of key information

(from analogue) The substance has potential to bioaccumulate in the environment, according to CLP classification criteria for aquatic chronic toxicity (log Kow >4).

Key value for chemical safety assessment

Log Kow (Log Pow):
5.09
at the temperature of:
25 °C

Additional information

Three reliable experimental studies, conducted according to recognized OECD/EC methods, are available:

- one study (Harlan, 2013), conducted with the slow-stir method, on an analogue substance mainly composed of the 9bR* isomers, while the present dossier is for the 9bS* isomers;

- one study (Firmenich, 2012), conducted with the HPLC method, on the parent substance (9bS* isomer): log Kow = 7.0,

- one study (Firmenich, 2012b), conducted with the HPLC method, on a supporting substance which is a reaction mass of the 9bR* stereoisomers and the 9bS* isomers: no significant difference is observed between these isomers, from elution as a single peak, at log Kow = 7.0,

The slow-stir study is of high quality, and no significant difference is anticipated between stereoisomers from the HPLC studies.

However, considering that, using HPLC method, the determinations are out of the applicability range (extrapolated values), and probably overestimated due to the polycyclic structure, the read-across from the slow-stir study will be preferred (key study), and the result is retained as key value.