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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:
30.09.05 - 10.01.06
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)
Version / remarks:
92/69/EEC
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method A.8 (Partition Coefficient - HPLC Method)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Type of method:
HPLC method
Partition coefficient type:
octanol-water
Analytical method:
high-performance liquid chromatography
Key result
Type:
log Pow
Partition coefficient:
8
Temp.:
25 °C
pH:
ca. 7.7

Pre-estimation of the partition coefficient of the test item using a calculation method The program KOWWIN (part of EPI Suite) was used for calculating the log Pow of the test item. The calculated value was 6.61

Therefore, according to the guidelines, the partition coefficient n-octanol/water of the test item at room temperature was determined by the HPLC method.

 

HPLC method

The results from the HPLC method are summarized in Table 1 to Table 5.

 

Table 1: Determination of the dead time t0

Dead time marker

tR/min

1stinjection

tR/min

2ndinjection

tR/min

3rdinjection

Formamide

2.14

2.15

2.14

 

Table 2: Calibration data 1stinjection

Calibration substance

tR/min

k

Log k

Log Pow

Acetophenone

2.760

0.2877

-0.5410

1.7

Methylbenzoate

3.057

0.4261

-0.3705

2.1

Phenylbenzoate

3.830

0.7869

-0.1041

3.6

Biphenyl

4.740

1.2115

0.0833

4.0

Phenanthrene

6.090

1.8414

0.2651

4.5

Triphenylamine

7.810

2.6439

0.4222

5.7

 

Regression: logPow= a+ b · log k

Parameters: a=-0.9191, b= 0.2440, r2=0.987

 

Table 3: Log Powof the test item 1stinjection

 

tR/min

k

Log k

Log Pow

Test item

25.01

10.6687

1.0281

7.98

* via extrapolation

 

Table 4: Calibration data 2ndinjection

Acetophenone

2.767

0.2908

-0.5364

1.7

Methylbenzoate

3.063

0.4292

-0.3673

2.1

Phenylbenzoate

3.837

0.7900

-0.1023

3.6

Biphenyl

4.747

1.2146

0.0844

4.0

Phenanthrene

6.097

1.8445

0.2659

4.5

Triphenylamine

7.820

2.6485

0.4230

5.7

 

Regression: logPow= a+ b · log k

Parameters: a =-0.9136, b =0.243, r2=0.987

 

Table 5: Log Powof the test item 2ndinjection

 

tR/min

k

Log k

Log Pow

Test item

25.043

10.6843

1.0287

7.99

* via extrapolation

 

Within two injections, the partition coefficient Pow of the test item was determined to be:

log Pow=>8.0

Conclusions:
The partition coefficient n-octanol/water of the test item was determined according to the HPLC method. It was found to be: log Pow = 8.0
Executive summary:

A study was conducted in accordance with OECD TG 117 and Regulation (EC) No 440/2008 method A.8 to determine the partition coefficient of the test substance using the HPLCmethod. The n-octanol/water partition coefficient of the test substance was derived from its retention time and the calibration graph. The retention time of the test item was above the retention time of the highest calibration standard (logPow 5.7) and thus out of the calibration range. Therefore, the partition coefficient n-octanol/water of the test substance was determined to be above 5.7 and estimated to be logPow 8.0

Description of key information

Key value for chemical safety assessment

Log Kow (Log Pow):
8
at the temperature of:
20 °C

Additional information

The partition coefficient n-octanol/water of the test item was determined according to the HPLC method. It was found to be: log Pow 8.0