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Partition coefficient

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Reference
Endpoint:
partition coefficient
Type of information:
experimental study
Adequacy of study:
key study
Study period:
June 2016
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. Test substance is adequately specified. Therefore full validation applies.
Qualifier:
according to guideline
Guideline:
OECD Guideline 117 (Partition Coefficient (n-octanol / water), HPLC Method)
Deviations:
no
Guideline:
other:
Version / remarks:
METHODCouncil Regulation (EC) No 2016/266 of 7. December 2015, Method A.24 “Partition Coefficient (N-OCTANOL/WATER), HIGH PERFORMANCELIQUID CHRO-MATOGRAPHY (HPLC) METHOD”
Deviations:
no
Principles of method if other than guideline:
Not applicable
GLP compliance:
yes
Type of method:
HPLC method
Partition coefficient type:
octanol-water
Analytical method:
high-performance liquid chromatography
Key result
Type:
log Pow
Partition coefficient:
< 0.3
Temp.:
25 °C
pH:
ca. 6.42
Remarks on result:
other:
Remarks:
The correlation log K / log POW was used for calculation of the log POW of the test item OF14 AT. Due to the fact that the retention time of measurement 3 lay below the retention time of thiourea (log POW is not calculable), calculation of a mean and standard deviation for the test item was not possible. The other two measurements were calculated with log POWs which were very much lower than the lowest log POW of the reference items (2-Butanone with log POW 0.3). So the log POW of the test item OF14 AT is stated as < 0.3.
Details on results:
The partition coefficient (n-octanol/water) (log Pow) of test substance was determined at test temperature of 25 ± 0.5 °C and at a pH value of 6.42.

Findings and Results

Reference Items

Measured values

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

 

Table 4.7/1 Retention Times Reference Items

Compound

RT 1

RT 2

RT 3

RT 4

RT 5

RT 6

 

min.

min.

min.

min.

min.

min.

Thiourea

1.367

1.367

1.367

1.367

1.367

1.367

2-Butanone

1.817

1.817

1.817

1.825

1.825

1.817

Benzylalcohol

2.184

2.184

2.183

2.183

2.184

2.184

Acetophenone

2.709

2.709

2.708

2.708

2.709

2.709

Nitrobenzene

3.234

3.234

3.233

3.242

3.242

3.242

Benzene

4.634

4.634

4.633

4.633

4.634

4.634

Toluene

7.309

7.309

7.317

7.317

7.317

7.317

For calculation more decimal places than visible above were taken into account.

Calculated Values

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

Table 4.7/2 Capacity factors Reference Items

Compound

Retention Time
Mean

Retention Time
Stand. Dev.

Retention Time
Relative Stand. Dev.

K

 

min.

min.

%

 

Thiourea

1.367

0.000

0.006

0.0000

2-Butanone

1.820

0.004

0.235

0.3313

Benzylalcohol

2.183

0.000

0.004

0.5975

Acetophenone

2.708

0.000

0.003

0.9816

Nitrobenzene

3.238

0.005

0.141

1.3688

Benzene

4.633

0.000

0.002

2.3900

Toluene

7.314

0.004

0.058

4.3513


log POW/ log K

The values for log K and log POWof the reference items are presented in the following table:

Table 4.7/3 log K and log POWof Reference Items

Compound

log K

log POW*

2-Butanone

-0.4798

0.30

Benzylalcohol

-0.2237

1.10

Acetophenone

-0.0081

1.70

Nitrobenzene

0.1363

1.90

Benzene

0.3784

2.10

Toluene

0.6386

2.70

* log Kow as reported in the EU method A.24 and in OECD 117, 2004.

Correlation Results

Dead time is 1.367 ± 0.000 minutes, with RSD 0.006%.

 

The RSD of the retention times of the reference items lay all below 0.3 %.

 

Equation of the regression:

log K = 0.4731 * log POW– 0.6991
with a coefficient of determination r2= 0.9565
and a correlation coefficient r = 0.9780

 

The correlation coefficient of 0.9780 is > 0.9 (typically correlation coefficient according to the guideline) and is acceptable therefore.

Test Item

Measurement Data

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

Table 4.7/4    Retention Times Test Item

Measurement

RT

 

min.

Measurement 1

1.377

Measurement 2

1.367

Measurement 3

1.349

Mean

1.364

Standard deviation

0.014

 

Calculated Values

The calculated values are presented in the following table:

Table 4.7/5     Capacity Factor, log Capacity Factor, log POWTest Item

Measurement

K

log K

log POW

Measurement 1

0.00724

-2.1406

-3.047

Measurement 2

0.00004

-4.3910

-7.804

Measurement 3

-0.01337

n.c.*

n.c.*

Mean

 

 

n.c.*

Standard deviation

 

 

n.c.*

* Not calculable, because K is negative. The retention time of measurement 3 of the test item is lower than the retention time of thiourea which was used for determination of the dead time of the method. It was therefore not possible to calculate a mean and a standard deviation for the test item. Because the retention times of thiourea and the test item peak is nearly the same, small differences in reten-tion times of the test item peak result in higher differences in log POW results (measurements 1 and 2). The validity criterion range of ± 0.1 units is not fulfilled (for measurements 1 and 2), therefore. This is stated as uncritical, because the result is definite.

Result and Validity

Result

The correlation log K / log POW was used for calculation of the log POW of the test item. Due to the fact that the retention time of measurement 3 lay below the retention time of thiourea (log POW is not calculable), calculation of a mean and standard deviation for the test item was not possible. The other two measurements were calculated with log POWs which were very much lower than the lowest log POW of the reference items (2-Butanone with log POW 0.3). So the log POW of the test itemis stated as < 0.3.

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

Table 4.7/6. Validity Criteria and Results

Peak

Parameter

Criterion

Found

Assessment

1

Range (Max – Min. log POW)

< 0.1

n.c.*

n.c.*

Value withinofItems

0.3 – 3.2

n.c.*

n.c.*

* Not calculable, because K is negative. The retention time of measurement 3 of the test item is lower than the retention time of thiourea which was used for determination of the dead time of the method. It was therefore not possible to calculate a mean and a standard deviation for the test item. As the retention time of the peaks lies below the lowest retention time of the reference items (2-Butanone with log POW 0.3), the log POW of this peak is stated as < 0.3.

DISCUSSION

Variations in the retention times of reference items and test item are 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 with 0.9565.

Conclusions:
The substance has NOT potential to bioaccumulate in the environment, according to CLP classification criteria for aquatic chronic toxicity (major compounds with log Pow >4)
Executive summary:

The partition coefficient of the test substance was measured according to the OECD 117/EU A24 guideline, HPLC method. The system was calibrated with seven different references substances.

Using the correlation log K / log POW, the log POW of the component of test item was not calculable, because during one of three measurements its retention time lay below the retention time of thiourea. Nevertheless the measurement of the test item solution was very reproducible (RSD of retention time 1.0%). As the calculated log POW of the two measurements of the test item peak lay below the lowest log POW of the reference items (2-Butanone with log POW 0.3) and because the test item peak lay during all three measurements in the dead time of the method, the log POW of the test item is stated as <0.3

Description of key information

Using the correlation log K / log POW, the log POW of the component of test item was not calculable, because during one of three measurements its retention time lay below the retention time of thiourea. Nevertheless the measurement of the test item solution was very reproducible (RSD of retention time 1.0%).

As the calculated log POW of the two measurements of the test item peak lay below the lowest log POW of the reference items (2-Butanone with log POW 0.3) and because the test item peak lay during all three measurements in the dead time of the method, the log POW of the test item is stated as <0.3

Key value for chemical safety assessment

Additional information

A fully reliable experimental study, conducted according to a recognized OECD/EC method (HPLC) and under GLP, is available. It is considered as a key study.

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