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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:
15 to 16 May 2013
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
EU Method A.8 (Partition Coefficient - HPLC Method)
Qualifier:
according to
Guideline:
OECD Guideline 117 (Partition Coefficient (n-octanol / water), HPLC Method)
GLP compliance:
yes (incl. certificate)
Remarks:
Hess. Ministerium für Umwelt, Energie, Landwirtschaft und Verbraucherschutz, Wiesbaden, Germany
Type of method:
HPLC method
Partition coefficient type:
octanol-water
Analytical method:
high-performance liquid chromatography
Key result
Type:
log Pow
Partition coefficient:
2.6
Temp.:
25 °C
pH:
4
Key result
Type:
log Pow
Partition coefficient:
2.6
Temp.:
25 °C
pH:
7
Key result
Type:
log Pow
Partition coefficient:
1.9
Temp.:
25 °C
pH:
9

Determination of the dead time (t0)

The mean values of the t0substance retention time for each run and pH are reported in the following table.

 

pH

Run

Retention time (min)

4

Run 1

0.489

Run 2

0.487

7

Run 1

0.489

Run 2

0.487

9

Run 1

0.485

Run 2

0.485

 

 

Determination of the parameters for log POWcalculation

 

From the calibration runs performed at different pH values, the parameters for the log POWcalculation were calculated and resulted as follow.

 

pH

Run

a

b

4

RUN 1

1.4707

2.2097

RUN 2

1.4635

2.2102

7

RUN 1

1.4696

2.2116

RUN 2

1.4592

2.2186

9

RUN 1

1.4704

2.2191

RUN 2

1.4701

2.2192

 

 

The following table report the retention time measured for the test substance and the calculated log POW.

 

pH

Run

1. Inj. tR(min)

2. Inj. tR(min)

3. Inj. tR(min)

4. Inj. tR(min)

Mean tR(min)

k'

log k'

log POW

Log POW(mean)

4

RUN 1

2.087

2.085

2.082

2.080

2.0835

3.2607

0.5133

2.60

2.6

RUN 2

2.078

2.080

2.072

2.073

2.0758

3.2623

0.5135

2.60

7

RUN 1

2.047

2.047

2.047

2.045

2.0465

3.1851

0.5031

2.58

2.6

RUN 2

2.037

2.038

2.035

2.035

2.0363

3.1812

0.5026

2.57

9

RUN 1

1.228

1.227

1.233

1.232

1.2300

1.5361

0.1864

1.88

1.9

RUN 2

1.250

1.252

1.250

1.252

1.2510

1.5794

0.1985

1.91

 

The results show that the partition coefficient of the test item is pH dependent.

Description of key information

The partition coefficient of the substance resulted pH-dependent. Three solutions were used at pH 4, 7 and 9, giving the following results (at 25 °C):

Log Pow at pH 4 = 2.6

Log Pow at pH 7 = 2.6

Log Pow at pH 9 = 1.9

(OECD guideline 117, HPLC method)

Key value for chemical safety assessment

Additional information