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Partition coefficient

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Endpoint:
partition coefficient
Type of information:
experimental study
Adequacy of study:
key study
Study period:
27-03-2018 to 05-09-2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Guideline study performed under GLP. All relevant validity criteria were met.
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)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Remarks:
inspected: June 2016 ; signature: January 2017
Type of method:
HPLC method
Partition coefficient type:
octanol-water
Analytical method:
high-performance liquid chromatography
photometric method
Type:
log Pow
Partition coefficient:
4.38
Temp.:
22.2 °C
pH:
ca. 7

HPLC method

The mean void time (t0) was determined to be 0.537 minutes.

The results of the HPLC method are given in the Table 3. The calibration curves of the log k of the reference substances as function of log Pow had an regression line represented by the equations:

Calibration 1: log Pow = 2.9820 × log k + 0.8043 (r = 0.9861, n = 14 and r2 = 0.9930).

Calibration 2: log Pow = 2.9867 × log k + 0.7981 (r = 0.9861, n = 14 and r2 = 0.9930).

 

Table 2. Calibration data

Reference item

log POW

1st Calibration

2nd Calibration

tR1
[min]

k

log k

tR2
[min]

k

log k

Benzonitrile

1.6

  1.385

  1.58

0.198

  1.389

  1.59

0.200

Nitrobenzene

1.9

  1.815

  2.38

0.377

  1.820

  2.39

0.378

Toluene

2.7

  3.247

  5.05

0.703

  3.254

  5.06

0.704

Ethylbenzene

3.2

  4.411

  7.21

0.858

  4.419

  7.23

0.859

Isopropylbenzene

3.7

  5.787

  9.78

0.990

  5.796

  9.79

0.991

1,2,4-Trichlorobenzene

4.2

  7.816

13.6 

1.13 

  7.816

13.6 

1.13 

n-Butylbenzene

4.6

10.074

17.8 

1.25 

10.067

17.7 

1.25 

Dibenzyl

4.8

10.998

19.5 

1.29 

10.998

19.5 

1.29 

tR1: Retention time 1. Injection

tR2: Retention time 2. Injection

log k: Common logarithm of the Capacity factor reference item

log POW: Common logarithm of the Partition Coefficient (n-octanol / water)

 

Table 3. Test item determination

Test Item

tR
[min]

k

log k

log POW

1st Calibration

2nd Calibration

9.139

16.0

1.20

4.38 ± 0.07
4.20 to 4.56 (95 % CI)

4.38 ± 0.07
4.20 to 4.56 (95 % CI)

9.133

16.0

1.20

 

Mean

9.136

16.0

1.20

4.38

tR : Retention time

k : Capacity factor test item

POW : Partition Coefficient (n-octanol / water)

CI : Confidence Interval

Conclusions:
The partition coefficient of the test item was determined to be log Pow = 4.38 at 22.2 °C and ca. pH 7.0
Executive summary:

The n-octanol-water partition coefficient was determined using theHPLC method of OECD Method 117 and EU Method A.8 under GLP. The test was performed with a concentration of 100 mg test item/L in 75 % methanol : 35 % HPLC water. Samples of the test item were analysed via HPLC on a C18 column with diode array detection. Calibration was performed using eight reference items with known log Pow values (given by the guidelines). The reference items were measured twice, once before and once after the measurement of the test item, for which one replicate was double injected. The void time of the HPLC system was determined with sodium nitrate. Two individual log Pow values for each of the single chromatographic resolved test item signals were derived under consideration of the first and second calibration. Finally, a mean value was calculated from these individual log Pow values. The log Pow was 4.38 ± 0.07. The partition coefficient of the test item was determined to be log Pow = 4.38 at mean temperature 22.2 °C and approximately neutral pH.

Endpoint:
partition coefficient
Type of information:
experimental study
Adequacy of study:
key study
Study period:
08-07-2020 to 21-09-2020
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Guideline study performed under GLP. All relevant validity criteria were met.
Qualifier:
according to guideline
Guideline:
OECD Guideline 117 (Partition Coefficient (n-octanol / water), HPLC Method)
Deviations:
yes
Remarks:
Calibration reference substances were injected singularly rather than simultaneously. Expert judgement indicates this is not a significant deviation in that the standards retention times should not be impacted.
Qualifier:
according to guideline
Guideline:
EU Method A.8 (Partition Coefficient)
Deviations:
yes
Remarks:
see above
GLP compliance:
yes
Type of method:
HPLC method
Partition coefficient type:
octanol-water
Analytical method:
high-performance liquid chromatography
Type:
log Pow
Partition coefficient:
4.39
Temp.:
22 °C
pH:
ca. 7
Remarks on result:
other: mean log Pow; (n=2)

HPLC method

The mean void time (t0) was determined to be 0.648 minutes.

The results of the HPLC method are given in the Table 3. The calibration curves of the log k’ of the reference substances as function of log Pow had a regression line represented by the equations:

Calibration: log k’ = 0.3362 × log Pow – 0.3797 (n = 8 and r2 = 0.9843).

 

Table 2. Calibration data

Reference Item

CAS Number

Retention Time (min)

Capacity Factor (k')

Log10 k'

Log10 Pow

Injection 1

Injection 2

Mean

Benzonitrile

100-47-0

1.409

1.419

1.414

1.183

0.07307

1.6

Nitrobenzene

98-95-3

1.842

1.842

1.842

1.844

0.26577

1.9

Toluene

108-88-3

3.212

3.207

3.210

3.955

0.59720

2.7

Ethylbenzene

100-41-4

4.315

4.320

4.318

5.666

0.75329

3.2

Isopropylbenzene

98-82-8

5.646

5.641

5.644

7.714

0.88726

3.7

1,2,4-Trichlorobenzene

120-82-1

7.527

7.536

7.536

10.629

1.02648

4.2

n-Butylbenzene

104-51-8

9.708

9.723

9.716

14.001

1.14615

4.6

Dibenzyl

103-29-7

10.690

10.709

10.700

15.520

1.19089

4.8

 

 

 

 

 

 

 

 

 

Table 3. Test item determination

Peak

Injection

Retention Time (min)

Capacity Factor (k')

Log10 k'

Log10 Pow

Mean
Log10 Pow

1

1

8.712

12.451

1.0952

4.39

4.39

1

2

8.717

12.459

1.0955

4.39

 

 

 

 

 

 

 

Conclusions:
The partition coefficient of the test item was determined to be log Pow = 4.39 at 22°C and ca. pH 7.0
Executive summary:

The n-octanol/water partition coefficient was determined using the HPLC method within OECD TG 117 and EU Method A.8 in accordance with GLP. The test was performed with a nominal concentration of 50 mg test item/L injected at 5 µL with a mobile phase of 75% methanol : 25% HPLC water. Samples of the test item were analysed via HPLC on a C18 column with variable wavelength detector. Calibration was performed using eight reference items with known log POW values (given by the guidelines). The dead time of the HPLC system was determined with sodium nitrite. The dead time and the reference items were measured in duplicate. The test item was injected and measured in duplicate. One individual partition coefficient value of the resolved chromatographic test item signals was derived for each injection. A mean value was calculated from the individual log Pow values. The partition coefficient of the test item was determined to be log Pow 4.39 at a mean temperature 22°C and approximately neutral pH.

Description of key information

Log Pow = 4.39, at 22 ±0.8 °C and ca. pH 7.0, HPLC method, OECD TG 117, 2020

Supporting data:

Log Pow = 4.38 ± 0.07 at 22.2 °C and ca. pH 7.0, HPLC method, OECD TG 117, 2018

Key value for chemical safety assessment

Log Kow (Log Pow):
4.39
at the temperature of:
22 °C

Additional information

Key study : OECD TG 117, 2018 : The n-octanol-water partition coefficient was determined using theHPLC method of OECD Method 117 and EU Method A.8 under GLP. The test was performed with a concentration of 100 mg test item/L in 75 % methanol : 35 % HPLC water. Samples of the test item were analysed via HPLC on a C18 column with diode array detection. Calibration was performed using eight reference items with known log Pow values (given by the guidelines). The reference items were measured twice, once before and once after the measurement of the test item, for which one replicate was double injected. The void time of the HPLC system was determined with sodium nitrate. Two individual log Pow values for each of the single chromatographic resolved test item signals were derived under consideration of the first and second calibration. Finally, a mean value was calculated from these individual log Pow values. The log Pow was 4.38 ± 0.07. The partition coefficient of the test item was determined to be log Pow = 4.38 at mean temperature 22.2 °C and approximately neutral pH.

Key study : OECD TG 117, 2020 : The n-octanol/water partition coefficient was determined using the HPLC method within OECD TG 117 and EU Method A.8 in accordance with GLP. The test was performed with a nominal concentration of 50 mg test item/L injected at 5 µL with a mobile phase of 75% methanol : 25% HPLC water. Samples of the test item were analysed via HPLC on a C18 column with variable wavelength detector. Calibration was performed using eight reference items with known log POW values (given by the guidelines). The dead time of the HPLC system was determined with sodium nitrite. The dead time and the reference items were measured in duplicate. The test item was injected and measured in duplicate. One individual partition coefficient value of the resolved chromatographic test item signals was derived for each injection. A mean value was calculated from the individual log Pow values. The partition coefficient of the test item was determined to be log Pow 4.39 at a mean temperature 22°C and approximately neutral pH.