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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:
from 2009-09-01 to 2009-11-04
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
The study is regarded as reliable without restrctions because it was conducted in accordance with GLP regulation and guideline.
Qualifier:
according to guideline
Guideline:
EU Method A.8 (Partition Coefficient)
Version / remarks:
440/2008/EC; May 2008
Deviations:
no
Qualifier:
according to guideline
Guideline:
OECD Guideline 117 (Partition Coefficient (n-octanol / water), HPLC Method)
Version / remarks:
13 April 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:
log Pow
Partition coefficient:
2.33
Temp.:
25 °C
pH:
ca. 10
Details on results:
log Pow based on last eluting peak: < 2.33 ± 0.011 (95 % confidence interval)

Result

The three calibration series and three test item series were measured alternately. The partition coefficient Pow was estimated based on a calibration curve using 6 reference items.

The capacity factors k’ were calculated from the dead time and retention times of the reference substances. The log k’ data of the reference substances were plotted against their log Pow values. The equation of the curve fitted to the calibration points is as follows:

log k = 0.648 * log Pow – 0.450         (Rsq = 0.976)

The capacity factors k and log Pow for the test item were calculated based on the calibration data obtained with the reference substances (see Table 2 and 3).

Table 2.: Measured and calculated data of last eluting peak (> 5 area%)

Chemical name

Retention time (min)

log k'

log Pow

Pow

Accuracy log unit

Calculated data

Test item

4.36

0.228

1.05

11

0.02

4.36

0.228

1.05

11

4.40

0.235

1.06

11

4.41

0.236

1.06

11

4.43

0.239

1.06

12

4.44

0.241

1.07

12

Mean

4.40

0.235

1.06

11

Conf. (95 %)

-

-

0.013

0.3

CV%

0.8

-

-

-

 

Table 3.:  Measured and calculated data of last eluting peak

Chemical name

Retention time (min)

log k'

log Pow

Pow

Accuracy log unit

Calculated data

Test item

20.05

1.056

2.32

211

0.02

20.06

1.056

2.32

211

20.27

1.061

2.33

215

20.31

1.062

2.33

215

20.46

1.066

2.34

218

20.51

1.067

2.34

219

Mean

20.28

1.061

2.33

215

Conf. (95 %)

-

-

0.011

5.5

CV%

1.0

-

-

-

 

Quality criteria were met, as values of log p derived from individual measurements fell within a range of ± 0.1 log units.

The determined log Pow: based on last eluting peak (> 5 area%): < 1.06 ± 0.013 (95 % confidence interval)

The estimated Pow: based on last eluting peak (> 5 area%): < 11 ± 0.3 (95 % confidence interval) 

The determined log Pow: based on last eluting peak: < 2.33 ± 0.011 (95 % confidence interval)

The estimated Pow: based on last eluting peak: < 215 ± 5.5 (95 % confidence interval)

Conclusions:
Components of the test item eluted in a wide range, from t=0 until 20.3 minutes. Main components (> 5%) eluted from t=0 to 4.4 minutes. Based on this experiment the estimated log Pow of the test item is 2.3 considering the last eluating peak.
Executive summary:

A study according to OECD 117 and EU Method A.8 was performed to determine the partition coefficinet of the test item. The partition coefficient Pow of the test item was determined based on a calibration curve using six reference items. The log Pow value was calculated, using the measured regression coefficients and the capacity factor of the test item. Components of the test item eluted in a wide range, from t = 0 until t = 20.3 minutes. Main components (> 5 %) eluted from t = 0 to t = 4.4 minutes. Based on this experiment the log Pow of the test item is 2.3 considering the main components.

The determined logPow : based on last eluting peak: < 2.33 ± 0.011 (95 % confidence interval)

The estimated Pow         : based on last eluting peak: < 215 ± 5.5 (95 % confidence interval)

Description of key information

The partition coefficient was determined according to EU Method A.8, resulting in a log Pow of 2.3 for the test item.

Key value for chemical safety assessment

Log Kow (Log Pow):
2.3
at the temperature of:
20 °C

Additional information

A study according to OECD 117 and EU Method A.8 was performed to determine the partition coefficinet of the test item. The partition coefficient Pow of the test item was determined based on a calibration curve using six reference items. The log Pow value was calculated, using the measured regression coefficients and the capacity factor of the test item. Components of the test item eluted in a wide range, from t = 0 until t = 20.3 minutes. Main components (> 5%) eluted from t = 0 to t = 4.4 minutes. Based on this experiment the log Pow of the test item is 2.3 considering the main components.

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