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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:
20 Jul 2017
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Reference:
Composition 0
Qualifier:
according to
Guideline:
OECD Guideline 117 (Partition Coefficient (n-octanol / water), HPLC Method)
Version / remarks:
2004
Qualifier:
according to
Guideline:
EU Method A.8 (Partition Coefficient - HPLC Method)
GLP compliance:
yes (incl. certificate)
Remarks:
Staatliches Gewerbeaufsichtsamt Hildesheim, Germany
Type of method:
HPLC method
Partition coefficient type:
octanol-water
Test material information:
Composition 1
Key result
Type:
log Pow
Partition coefficient:
3.59
Temp.:
23.9 °C
Remarks on result:
other: No pH value was measured for this mobile phase, because it is neutral. Furthermore the test item does not have functional groups with influence on the pH value of the mobile phase.
Remarks:
weighted mean of two test item signals.
Type:
log Pow
Partition coefficient:
>= 3.46 - <= 3.6
Temp.:
23.9 °C
Remarks on result:
other: No pH value was measured for this mobile phase, because it is neutral. Furthermore the test item does not have functional groups with influence on the pH value of the mobile phase.
Remarks:
range based on two test item signals.

Calibration

The retention time data of the reference items used for calibration are given in the following table.

Reference item

log POW

1st Calibration

2nd Calibration

tR1

[min]

k

log k

tR2

[min]

k

log k

Nitrobenzene

1.9

2.130

2.76

0.441

2.138

2.78

0.444

Toluene

2.7

4.246

6.50

0.813

4.271

6.55

0.816

Ethylbenzene

3.2

6.175

9.91

0.996

6.198

9.95

0.998

Isopropylbenzene

3.7

8.616

14.2

1.15

8.646

14.3

1.16

1,2,4-T richlorobenzene

4.2

11.923

20.1

1.30

11.952

20.1

1.30

n-Butylbenzene

4.6

16.405

28.0

1.45

16.439

28.0

1.45

Dibenzyl

4.8

18.682

32.0

1.51

18.661

32.0

1.51

tR1: Retention time of 1st Injection

tR2: Retention time of 2nd Injection

k: Capacity factor reference item

log POW: Decadic logarithm of the Partition Coefficient (n-octanol / water)

 

The calculated slope, Y-intercept and correlation coefficient for the first and second calibration of the reference items are shown in the following table. The correlation coefficient r for both calibrations was > 0.9.

 

1st Calibration

2nd Calibration

slope

2.774

2.781

Y-intercept

3.6020

3.5940

r2

0.9928

0.9923

r

0.9964

0.9961

r: Correlation Coefficient

r2: Coefficient of determination

 

Results of Test Item Analysis

For each test item signal, two individual log POWvalues were derived under consideration of the first and second calibration and a mean value was calculated from these individual log POWvalues. The results are summarized in the following table.

 

tR

[min]

k

log k

log POW

1st Calibration

2nd Calibration

Signal 1

6.898

11.2

1.05

3.46 ± 0.04

3.37 to 3.56 (95 % Cl)

3.46 ± 0.04

3.36 to 3.56 (95 % Cl)

6.908

11.2

1.05

Mean

6.903

11.2

1.05

3.46

Signal 2

7.617

12.5

1.10

3.60 ± 0.04

3.51 to 3.70 (95 % Cl)

3.59 ± 0.04

3.50 to 3.69 (95 % Cl)

7.627

12.5

1.10

Mean

7.622

12.5

1.10

3.60

tr: Retention time

k: Capacity factor test item

POW: Partition Coefficient (n-octanol / water)

CI: Confidence Interval

 

The summarized results and weighted average mean are reported in the following table

 

log POW

Area

[%]

 

1st Calibration

2nd Calibration

Mean

Signal 1

3.46 ± 0.04

3.37 to 3.56 (95 % Cl)

3.46 ± 0.04

3.36 to 3.56 (95 % Cl)

3.46

8.1

Signal 2

(main signal)

3.60 ± 0.04

3.51 to 3.70 (95 % Cl)

3.59 ± 0.04

3.50 to 3.69 (95 % Cl)

3.60

91.9

Weighted Mean

3.59

 

 

 

Conclusion

For each of the two test item signals, two individual log POW values were derived under consideration of the first and second calibration and a mean value was calculated from these individual log POW values. Finally, a weighted average mean value based on the peak area of the respective signals was calculated.

The mean column temperature was determined to be 23.9 °C during the course of the study.

The log POW of the test item was determined to be 3.46 for the first signal as well as 3.60 for the second (main) signal, with a weighted average mean value of 3.59.

Conclusions:
A partition coefficient of 3.59 (at 23.9 °C) was determined for the test substance according to OECD 117.
Executive summary:

According to OECD 117 (2004) and GLP, Log Kow of the test item was determined to be 3.59 at 23.9 °C via HPLC-method. The experiment resulted in a range of 3.46 -3.60 and a weighted average mean was obtained on the basis of the ratio of signals of the isomers.

Description of key information

Log POW: 3.59 at 23.9 °C (OECD 117, HPLC Method)

Key value for chemical safety assessment

Log Kow (Log Pow):
3.59
at the temperature of:
23.9 °C

Additional information

According to OECD 117 (2004) and GLP, Log Kow of the test item was determined to be 3.59 at 23.9 °C via HPLC-method. The experiment resulted in a range of 3.46 -3.60 and a weighted average mean was obtained on the basis of the ratio of signals of the isomers.