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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:
21 October - 30 November 2016
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
The study was conducted in accordance with international guidelines and in accordance with GLP. All relevant validity criteria were met.
Qualifier:
according to
Guideline:
EU Method A.8 (Partition Coefficient - HPLC Method)
Deviations:
no
Qualifier:
according to
Guideline:
OECD Guideline 117 (Partition Coefficient (n-octanol / water), HPLC Method)
Deviations:
no
Qualifier:
according to
Guideline:
EPA OPPTS 830.7570 (Partition Coefficient, n-octanol / H2O, Estimation by Liquid Chromatography)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Type of method:
HPLC method
Partition coefficient type:
octanol-water
Specific details on test material used for the study:
STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Room temperature
- Stability under test conditions: Assumed stable. Stability at higher temperatures not availbale.
- Solubility and stability of the test substance in the solvent/vehicle: N/A
- Reactivity of the test substance with the solvent/vehicle of the cell culture medium: N/A
Analytical method:
high-performance liquid chromatography
Key result
Type:
log Pow
Partition coefficient:
>= 3.7 - <= 4
Temp.:
35 °C
pH:
7

Prelim Test

The log Powof the test sbstance was calculated to be 3.5, using the Rekker calculation method. The pKa of the test substance was estimated to be 13.81, using the Perrin calculation method.

Main Test

The results of the HPLC method are shown in Table 1. The equation of the regression line was log k' = 0.349 x log Pow - 0.862 (r2= 0.997, n = 12).

Table 1       Powof the Test Substance

 Substance

Retention Time (First Run)

(mins) 

 Retention Time (Second Run)

(mins)

 Mean Retention Time

(mins)

 Log Pow

 Pow

 Area %

 Formamide (t0)

0.577 

0.578 

0.578 

 

 

 

 Nitrobenzene

0.921 

0.919 

 

1.9 

 

 

 Bromobenzene

1.518 

1.516 

 

3.0 

 

 

 1,4 -Dichlorobenzene

1.883 

1.882 

 

3.4 

 

 

 Biphenyl

2.522 

2.520 

 

4.0 

 

 

 1,2,4 -Trichlorobenzene

2.909 

2.906 

 

4.2 

 

 

 Dibenzyl

4.172 

4.166 

 

4.8 

 

 

 Test Substance - Isomer 1

2.153 

2.151 

2.152 

3.7

5.2 x 103 

88 

 Test Substance - Isomer 2

2.492 

2.490 

2.491 

4.0 

9.1 x 103 

12 

 

Conclusions:
The log Pow values of the for isomers of the test item at neutral pH were 3.7 and 4.0.
Executive summary:

The log Powof the test substance (both isomer forms) was determined using the HPLC method in accordance with EU Method A.8.

The partition coefficient (Pow) of the test substance isomers at neutral pH were 5.2 x 103and 9.1 x 103, corresponding to Log Powvalues of 3.7 and 4.0, respectively.

Since the test substance is a mixture, the Log Powis reported as a range i.e. 3.7 - 4.0.

Description of key information

Partition coefficient: Log Pow= 3.7 - 4.0, EU Method A.8 - HPLC method, Anon, 2017. 

Key value for chemical safety assessment

Additional information

The log Powof the test substance (both isomer forms) was determined using the HPLC method in accordance with EU Method A.8.

The partition coefficient (Pow) of the test substance isomers at neutral pH were 5.2 x 103and 9.1 x 103, corresponding to Log Powvalues of 3.7 and 4.0, respectively.

Since the test substance is a mixture, the Log Powis reported as a range i.e. 3.7 - 4.0.

The surface tension measurement of < 60 mN/m was not considered to preclude the use of OECD 117 method for partition coefficient (refer to Section 4.8).