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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:
24 April 2009 to 22 May 2009
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:
2004
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:
Pow
Partition coefficient:
>= 35 800 - <= 3 160 000
Remarks on result:
other: Temperature and pH not specified
Key result
Type:
Pow
Partition coefficient:
> 3 160 000
Remarks on result:
other: Temperature and pH not specified
Key result
Type:
log Pow
Partition coefficient:
> 6.5
Remarks on result:
other: Temperature and pH not specified
Key result
Type:
log Pow
Partition coefficient:
>= 4.55 - <= 6.5
Remarks on result:
other: Temperature and pH not specified
Details on results:
PRELIMINARY ESTIMATE
- Solubility in n-octanol: > 49.9 % w/w
- Solubility in water: < 1.12 x 10^-3 % w/w
- Estimated Pow: > 4.46 x 10^4
- Estimated Log10 Pow: > 4.65

DEFINITIVE TEST
- Log10 Pow range: 4.55 to > 6.50
- Partition coefficient range: 3.58 x 10^4 to > 3.16 x 10^6

DISCUSSION
- A solvent blank chromatogram was subtracted from the sample chromatograms to remove the baseline drift caused by the mobile phase gradient. This allowed easier and more accurate integration of the test material peaks and therefore benefited the calculations of percentage area normalisation.
- Although there appeared to be some peaks that eluted near the dead time; these were not integrated or results calculated for. It was considered that the peaks integrated represented the majority of the test material. Peaks eluting at the deadtime were possibly water soluble impurities and/or starting products.
- Peak 20 in both sample chromatograms was a combination of peaks which was integrated as one for chromatogram clarity. All individual peaks would have had a retention time greater than that of DDT and hence, a log10 Pow of > 6.50.

Table 1: Retention Times, Capacity Factors, Log10 Pow Values and UV Detector Percentage Area Normalisation Data

Peak No.

Injection

Retention Time (mins)

Capacity Factor (k)

Log10k

Log10 Pow

Mean Log10 pow

Mean Percentage Area (%)

1

1

10.435

3.19

0.504

4.55

4.55

0.112

2

10.459

3.20

0.505

4.56

2

1

10.897

3.38

0.529

4.65

4.66

<0.100

2

10.999

3.42

0.534

4.67

3

1

11.540

3.64

0.561

4.77

4.77

0.156

2

11.550

3.64

0.561

4.77

4

1

12.082

3.85

0.586

4.87

4.87

0.561

2

12.099

3.86

0.587

4.87

5

1

12.794

4.14

0.617

4.99

4.99

0.686

2

12.808

4.15

0.618

4.99

6

1

14.171

4.69

0.671

5.20

5.20

1.06

2

14.190

4.70

0.672

5.20

7

1

14.806

4.95

0.694

5.29

5.29

2.37

2

14.821

4.95

0.695

5.29

8

1

16.499

5.63

0.750

5.50

5.50

1.05

2

16.523

5.64

0.751

5.50

9

1

17.527

6.04

0.781

5.62

5.62

1.53

2

17.544

6.05

0.782

5.62

10

1

19.448

6.81

0.833

5.82

5.82

1.19

2

19.472

6.82

0.834

5.82

11

1

20.347

7.17

0.856

5.91

5.91

1.42

2

20.382

7.19

0.857

5.91

12

1

21.025

7.45

0.872

5.97

5.97

0.986

2

21.078

7.47

0.873

5.97

13

1

22.836

8.17

0.912

6.13

6.13

0.915

2

22.857

8.18

0.913

6.13

14

1

24.422

8.81

0.945

6.25

6.25

1.41

2

24.454

8.82

0.946

6.25

15

1

27.109

9.89

0.995

6.44

6.45

1.20

2

27.162

9.91

0.996

6.45

16 -20

1

28.439 -38.208

10.4- > 10.6

1.02- > 1.03

> 6.50

> 6.50

85.3

2

28.480 -38.116

10.4- > 10.6

1.02- > 1.03

> 6.50

Conclusions:
Under the conditions of this study, the partition coefficient of the test material has been determined to be in the range from 3.58 x10^4 to > 3.16 x10^6, log10 Pow from 4.55 to > 6.50. By percentage area normalisation, approximately 85.3 % of the test material had a log10Pow value > 6.50.
Executive summary:

The partition coefficient of the test material was determined in accordance with the standardised guideline OECD 117, under GLP conditions.

A preliminary estimate was made using visual assessment and then the determination was carried out using the HPLC method.

A solvent blank chromatogram was subtracted from the sample chromatograms to remove the baseline drift caused by the mobile phase gradient. This allowed easier and more accurate integration of the test material peaks and therefore benefited the calculations of percentage area normalisation. Although there appeared to be some peaks that eluted near the dead time; these were not integrated or results calculated for. It was considered that the peaks integrated represented the majority of the test material. Peaks eluting at the deadtime were possibly water soluble impurities and/or starting products. Peak 20 in both sample chromatograms was a combination of peaks which was integrated as one for chromatogram clarity. All individual peaks would have had a retention time greater than that of DDT and hence, a log10 Pow of > 6.50.

Under the conditions of this study, the partition coefficient of the test material has been determined to be in the range from 3.58 x10^4 to > 3.16 x10^6, log10 Pow from 4.55 to > 6.50. By percentage area normalisation, approximately 85.3 % of the test material had a log10Pow value > 6.50.

Description of key information

Under the conditions of this study, the partition coefficient of the test material has been determined to be in the range from 3.58 x10^4 to > 3.16 x10^6, log10 Pow from 4.55 to > 6.50. By percentage area normalisation, approximately 85.3 % of the test material had a log10Pow value > 6.50.

Key value for chemical safety assessment

Additional information

The partition coefficient of the test material was determined in accordance with the standardised guideline OECD 117, under GLP conditions. The study was awarded a reliability score of 1 in accordance with the criteria set forth by Klimisch et al. (1997).

A preliminary estimate was made using visual assessment and then the determination was carried out using the HPLC method.

A solvent blank chromatogram was subtracted from the sample chromatograms to remove the baseline drift caused by the mobile phase gradient. This allowed easier and more accurate integration of the test material peaks and therefore benefited the calculations of percentage area normalisation. Although there appeared to be some peaks that eluted near the dead time; these were not integrated or results calculated for. It was considered that the peaks integrated represented the majority of the test material. Peaks eluting at the deadtime were possibly water soluble impurities and/or starting products. Peak 20 in both sample chromatograms was a combination of peaks which was integrated as one for chromatogram clarity. All individual peaks would have had a retention time greater than that of DDT and hence, a log10 Pow of > 6.50.

Under the conditions of this study, the partition coefficient of the test material has been determined to be in the range from 3.58 x10^4 to > 3.16 x10^6, log10 Pow from 4.55 to > 6.50. By percentage area normalisation, approximately 85.3 % of the test material had a log10Pow value > 6.50.

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