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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:
03 October 2016 to 04 October 2016
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)
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:
< 1
Temp.:
25 °C
Remarks on result:
other: pH was not measured.
Details on results:
The three calibration series and three test item series were measured alternately. The partition coefficient Pow was determined based on a calibration curve using 6 reference substances.
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 = 0.347 × log Pow - 0.621 (Rsq = 0.948)

Retention time measured for the test material (1.38 min) was lower than the first eluting standard, Acetanilide (2.97 min). This result shows that log Pow of the test material is beyond the calibrated range. The estimated log Pow is < 1.0.

Table 1: Measured and calculated data of the reference substances

Chemical name

log Pow

Retention

time (min)

log k

Repeatability

Δ log Pow

log unit

Accuracy

log unit

log Pow

OECD 117

Calculated

Calculated

Thiourea

-

2.10

for determination of dead time

2.11

2.11

2.10

2.10

2.10

Mean

2.10

CV %

0.2

Acetanilide

1.0

2.97

-0.385

0.03

0.3

0.7

2.97

-0.385

0.7

2.96

-0.390

0.7

2.97

-0.385

0.7

2.98

-0.380

0.7

2.96

-0.390

0.7

Mean

2.97

-0.386

0.7

CV %

0.3

-

-

Benzonitrile

1.6

4.22

0.003

0.01

0.2

1.8

4.22

0.003

1.8

4.23

0.005

1.8

4.21

0.001

1.8

4.22

0.003

1.8

4.22

0.003

1.8

Mean

4.22

0.003

1.8

CV %

0.1

-

-

Methyl benzoate

2.1

5.25

0.175

0.00

0.2

2.3

5.24

0.174

2.3

5.25

0.175

2.3

5.24

0.174

2.3

5.25

0.175

2.3

5.25

0.175

2.3

Mean

5.25

0.174

2.3

CV %

0.1

-

-

Ethyl benzoate

2.6

6.85

0.353

0.01

0.2

2.8

6.85

0.353

2.8

6.84

0.353

2.8

6.86

0.354

2.8

6.85

0.353

2.8

6.85

0.353

2.8

Mean

6.85

0.353

2.8

CV %

0.1

-

-

Benzophenone

3.2

7.88

0.439

0.00

0.1

3.1

7.88

0.439

3.1

7.87

0.438

3.1

7.87

0.438

3.1

7.88

0.439

3.1

7.88

0.439

3.1

Mean

7.88

0.439

3.1

CV %

0.1

-

-

Naphthalene

3.6

10.12

0.581

0.00

0.1

3.5

10.11

0.581

3.5

10.11

0.581

3.5

10.11

0.581

3.5

10.11

0.581

3.5

10.11

0.581

3.5

Mean

10.11

0.581

3.5

CV %

0.0

-

-

Conclusions:
Under the conditionds of the study, the estimated log Pow of the test material is < 1.0.
Executive summary:

The partition coefficient of the test material was investigated in a GLP study in accordance with the standardised guidelines OECD 117 and EU Method A.8.

The partition coefficient of the test material was assessed using HPLC. Six chemicals for which log Pow has been reported were used to calibrate the elution time in units of log k. Reference substances were dissolved in acetonitrile. Concentration of these stock solutions was about 1 mg/mL.

Test item was dissolved in mobile phase. The concentration of the solution was about 0.5 mg/mL. The stock solution was diluted with mobile phase by 100 fold. Three series of the reference solutions were measured with two parallel injections, each. The retention times were determined. The three calibration series and three test item series were measured alternately. For the determination of t0 (t0 = retention time of the un-retarded component) thiourea solution was injected three times. The test was conducted at 25 °C.

The retention time measured for the test material (1.38 min) is lower than the first eluting standard, Acetanilide (2.97 min). This result shows that log Pow of the test material is beyond the calibrated range.

Under the conditions of the study, the estimated log Pow of the test material is < 1.0.

Description of key information

Under the conditions of the study, the estimated log Pow of the test material is < 1.0.

Key value for chemical safety assessment

at the temperature of:
25 °C

Additional information

The partition coefficient of the test material was investigated in a GLP study in accordance with the standardised guidelines OECD 117 and EU Method A.8. The study was assigned a reliability score of 1 in accordance with the criteria for assessing data quality set forth by Klimisch et al. (1997).

The partition coefficient of the test material was assessed using HPLC. Six chemicals for which log Pow has been reported were used to calibrate the elution time in units of log k. Reference substances were dissolved in acetonitrile. Concentration of these stock solutions was about 1 mg/mL.

Test item was dissolved in mobile phase. The concentration of the solution was about 0.5 mg/mL. The stock solution was diluted with mobile phase by 100 fold. Three series of the reference solutions were measured with two parallel injections, each. The retention times were determined. The three calibration series and three test item series were measured alternately. For the determination of t0 (t0 = retention time of the un-retarded component) thiourea solution was injected three times. The test was conducted at 25 °C.

The retention time measured for the test material (1.38 min) is lower than the first eluting standard, Acetanilide (2.97 min). This result shows that log Pow of the test material is beyond the calibrated range.

Under the conditions of the study, the estimated log Pow of the test material is < 1.0.