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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:
08 January 1996 to 07 February 1996
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 117 (Partition Coefficient (n-octanol / water), HPLC Method)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method A.8 (Partition Coefficient)
Deviations:
no
GLP compliance:
yes
Type of method:
HPLC method
Partition coefficient type:
octanol-water
Analytical method:
high-performance liquid chromatography
Key result
Type:
log Pow
Partition coefficient:
2.4
Temp.:
25 °C
Remarks on result:
other: pH not applicable

Table 1. Reference Material Results

Reference Material

log Pow

tR1

tR2

tRm

k

Log k

Thiourea

 -

1.38

1.40

1.39

 -

Aniline

0.9

2.13

2.15

2.14

0.538

-0.269

Acetophenone

1.7

2.55

2.59

2.57

0.846

-0.073

Benzophenone

3.2

4.71

4.72

4.71

2.386

0.378

Naphthalene

3.6

5.67

5.66

5.67

3.070

0.487

1,2,4-trichlorobenzene

4.2

9.09

9.07

9.08

5.520

0.742

n-butylbenzene

4.6

11.57

11.56

11.57

7.308

0.864

Triphenylamine

5.7

20.26

20.26

20.26

13.555

1.132

tR1, tR2, tRm = retention times (1st calibration, 2nd calibration, average)

Test material results

tR1 = 3.319

tR2 = 3.343

tRm = 3.331

k = 1.393

log k = 0.144

Log Pow = 2.4

Conclusions:
Under the conditions of this study, the n-octanol/water partition coefficient (log Pow) was calculated to be 2.4 at 25 °C.
Executive summary:

The n-octanol/water partition coefficient (log Pow) of the test material was determined in accordance with the standardised guidelines OECD 117 and EU method A.8 under GLP conditions using the HPLC method.

Reverse phase HPLC on octadecyl-modified stationary silica was used. From relationships between the measured retention times and the known octanol/water partition coefficients of a number of reference materials, the partition coefficient of the test material was calculated. Seven substances were chosen, having log Pow values ranging from 0.9 to 5.7; thiourea was used to determine the "dead time" (t0).

The test material was prepared at a concentration of 50 mg/L in the mobile phase (acetonitrile/water 60:40 v:v). Retention times (tR) were measured, averaged and the decimal logarithms of the capacity factors (k) calculated. The linear regression parameters were calculated from the data obtained with the standard solutions and log Pow of the test material was determined from its measured capacity factor.

Under the conditions of this study, the n-octanol/water partition coefficient (log Pow) was calculated to be 2.4 at 25 °C.

Description of key information

The n-octanol/water partition coefficient (log Pow) was calculated to be 2.4.

Key value for chemical safety assessment

Log Kow (Log Pow):
2.4
at the temperature of:
25 °C

Additional information

The n-octanol/water partition coefficient (log Pow) of the test material was determined in accordance with the standardised guidelines OECD 117 and EU method A.8 under GLP conditions using the HPLC method. 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).

Reverse phase HPLC on octadecyl-modified stationary silica was used. From relationships between the measured retention times and the known octanol/water partition coefficients of a number of reference materials, the partition coefficient of the test material was calculated. Seven substances were chosen, having log Pow values ranging from 0.9 to 5.7; thiourea was used to determine the "dead time" (t0).

The test material was prepared at a concentration of 50 mg/L in the mobile phase (acetonitrile/water 60:40 v:v). Retention times (tR) were measured, averaged and the decimal logarithms of the capacity factors (k) calculated. The linear regression parameters were calculated from the data obtained with the standard solutions and log Pow of the test material was determined from its measured capacity factor.

Under the conditions of this study, the n-octanol/water partition coefficient (log Pow) was calculated to be 2.4 at 25 °C.