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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:
2019-10-10 to 2020-05-18
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
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:
no
Type of method:
HPLC method
Partition coefficient type:
octanol-water
Analytical method:
high-performance liquid chromatography
Type:
log Pow
Partition coefficient:
3.47
Temp.:
30 °C
pH:
7
Type:
Pow
Partition coefficient:
2 951
Temp.:
30 °C
pH:
7

Preliminary estimate

A preliminary assessment of the partition coefficient was made based on the KOWWIN calculation method (Epiwin® v4.10, for Microsoft Windows c/William Meylan, 1994,1995) using the structure of the test item.

 

HPLC method

The mean void time (t0) was not reported but was accounted for within the report.

The calibration curves of the log k of the reference substances as function of log Pow had a regression line represented by the equation:

log Pow = 2.880 × log k + 1.1881 (r2 = 0.9689, n = 6).

 

Table 2. Reference items

Reference Item

CAS Number

Log Pow

 

 

 

Anisole

100-66-3

2.1

Ethylbenzoate

93-89-0

2.6

Toluene

108-88-3

2.7

Ethylbenzene

100-41-4

3.2

Isopropylbenzene

98-82-8

3.7

Biphenyl

92-52-4

4.0

 

 

 

 

Test item: one chromatographic peak reported

Mean log Pow: 3.47

Partition coefficient: Pow: 2951

Conclusions:
The partition coefficient of the test item was determined to be Pow = 245 and log Pow = 3.47 at 30 °C and pH ca. 7
Executive summary:

The n-octanol-water partition coefficient was determined using the HPLC method of OECD TG 117 and EU Method A.8. The test was performed with a concentration of up to 2000 mg test item/L in 75 % methanol : 25 % HPLC water. Samples of the test item were analysed via HPLC on a C18 column with refractive index detection. Calibration was performed using six reference items with known log Pow values (given by the guidelines). The void time of the HPLC system was determined with either thiourea or uracil.The mean void time (t0) was not reported but was accounted for within the report. The calibration curves of the log k of the reference substances as function of log Pow had an regression line represented by the equation: log Pow = 2.880 × log k + 1.1881 (r2 = 0.9689, n = 6).The partition coefficient of the test item was determined to be Pow = 2951 and log Pow = 3.47 at 30 °C and pH ca. 7.

Description of key information

Weight of evidence: substance contains constituents with Log Pow = 3.3 at 25°C and pH 7, 2020

Key data:

n-octanol/water: Pow = 1995 and log Pow = 3.3 at 25 ± 1°C and pH ca. 5.8, OECD TG 117 – HPLC method, GLP, 2020a

Supporting information:

n-octanol/water: Pow = 2951 and log Pow = 3.47 at 30°C and pH ca. 7, OECD TG 117 – HPLC method, non-GLP, 2020b

Key value for chemical safety assessment

Log Kow (Log Pow):
3.3
at the temperature of:
25 °C

Additional information

Key study : OECD TG 117, 2020a : The n-octanol/water partition coefficient was determined using the HPLC method within OECD TG 117 and Japanese guideline “Method for Testing the Partition Coefficient (n-octanol/water) under GLP. The n-octanol-water partition coefficient was determined using the HPLC method of OECD TG 117 and EU Method A.8. The test was performed with a concentration of up to 103 mg test item/L in 75 % methanol : 25 % HPLC water. Samples of the test item were analysed via HPLC on a commercial C18 column (L-column 3 C18, 250 mm x 2.1 mm ID and particle size 5 microns) with UV/visible spectrophotometric detection. Calibration was performed using six reference items with known log Pow values (given by the guidelines). The void time of the HPLC system was determined with either thiourea. The mean void time (t0) was 6.34 minutes. The calibration curves of the log k of the reference substances as function of log Pow had a combined regression line represented by the equation: log Pow =2.705 × log k + 2.113(r = 0.966, n = 6). The partition coefficient of the test item was determined to be Pow = 1995 and log Pow = 3.3 at 25 ± 1°C and pH ca. 5.8.

 

Key study : OECD TG 117, 2020b : The n-octanol-water partition coefficient was determined using the HPLC method of OECD TG 117 and EU Method A.8. The test was performed with a concentration of up to 2000 mg test item/L in 75 % methanol : 25 % HPLC water. Samples of the test item were analysed via HPLC on a C18 column with refractive index detection. Calibration was performed using six reference items with known log Pow values (given by the guidelines). The void time of the HPLC system was determined with either thiourea or uracil. The mean void time (t0) was not reported but was accounted for within the report. The calibration curves of the log k of the reference substances as function of log Pow had an regression line represented by the equation: log Pow = 2.880 × log k + 1.1881 (r2 = 0.9689, n = 6).The partition coefficient of the test item was determined to be Pow = 2951 and log Pow = 3.47 at 30 °C and pH ca. 7.