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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 July 18, 2011 to April 23, 2012
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 107 (Partition Coefficient (n-octanol / water), Shake Flask Method)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method A.8 (Partition Coefficient)
Deviations:
no
GLP compliance:
yes
Type of method:
other: Estimation method
Partition coefficient type:
octanol-water
Specific details on test material used for the study:
- Molecular formula: Cn+9 H2n+14 N Cl (n=12-16)
- Molecular weight: 352.5
- Substance type: Solid
- Physical state: White powder with lumps (determined at NOTOX)
- Method used for analysis: LC-MS/MS and GC-MS (external standard)
- Purity test date: 20 December, 2011
- Lot/batch No.: 667S0002
- Expiration date of the lot/batch: 16 August, 2012
- Stability under test conditions: Stable
- Storage condition of test material: At room temperature in the dark in desiccator
- Study specific test substance information: Freeze dried Arquad sample 2.10-40, stored in desiccator above P2O5 and substance was handeled in nitrogen environment in glovebox
- Other:
- Chemical name: Benzyl(C12-C16-alkyl)dimethylazanium chloride
- Analytical purity: 99.24 + 0.0676 % w/w (C12-BKC: 73.803%, C14-BKC:25.300%, C16-BKC: 0.132%)
Analytical method:
not specified
Key result
Type:
Pow
Partition coefficient:
1.01
Temp.:
20 °C
Remarks on result:
other: Based on solubility in distilled water
Key result
Type:
log Pow
Partition coefficient:
0.004
Temp.:
20 °C
Remarks on result:
other: Based on solubility in distilled water
Key result
Type:
Pow
Partition coefficient:
1.03
Temp.:
20 °C
Remarks on result:
other: Based on solubility in buffer solutions
Key result
Type:
log Pow
Partition coefficient:
0.01
Temp.:
20 °C
Remarks on result:
other: Based on solubility in buffer solutions
Key result
Type:
Pow
Partition coefficient:
567
Temp.:
20 °C
Remarks on result:
other: Based on critical micelle concentration
Key result
Type:
log Pow
Partition coefficient:
2.75
Temp.:
20 °C
Remarks on result:
other: Based on critical micelle concentration

The n-octanol solubility of the test substance as the sum of the solubilities of each component was 459 g/L (determined at 20.3 ± 0.5°C). According to information supplied by the sponsor, the solubility of the test substance in distilled water was 455 g/L (determined at 20.0°C), the solubility in buffer solutions was 444 g/L (determined at 20.1 ± 0.1°C) and the critical micelle concentration was 0.81 g/L (determined at 19.7 ± 0.1°C).

Table 1. Pow and Log Pow values of the test substance

Main study - Pow values of the test substance

 

Pow

Log Pow

Based on solubility in distilled water

1.01

0.004

Based on solubility in buffer solutions

1.03

0.01

Based on critical micelle concentration

567

2.75

Conclusions:
Under the conditions of the study, the partition coefficient (Pow values) of the test substance was determined to be 1.01, 1.03 and 567 at 20°C. This corresponds to log Pow values of 0.004, 0.01 and 2.75 based on solubility in water, in buffer solutions and on critical micelle concentration, respectively.
Executive summary:

A study was conducted to determine the partition coefficient of the test substance using the estimation method according to OECD guideline 107 and EU method A.8, in compliance with GLP. The partition coefficient was calculated as the quotient of the n-octanol solubility and the water solubility. Three aliquots between 1.99 and 2.21 g of test substance were weighed into glass vessels and to each vessel, 2 mL n-octanol was added. The solutions were stirred at 20.3 ± 0.5°C for 24, 48 or 72 hours. As the blank, 2 mL n-octanol was stirred for 72 hours. After the stirring period, the n-octanol phases were two-times centrifuged at 16421g and 20°C for 5 minutes. Volumes of 50 μL of the n-octanol phases were accurately weighed into volumetric flasks of 50 mL and the flasks were filled up to the mark with methanol. Thereafter, the solutions were further diluted to obtain concentrations within the calibration range. The end solution was 85/15% (v/v) methanol/mobile phase B. Under the conditions of the study, the partition coefficient (Pow values) of the test substance was determined to be 1.01, 1.03 and 567 at 20°C. This corresponds to log Pow values of 0.004, 0.01 and 2.75 based on solubility in water, in buffer solutions and on critical micelle concentration, respectively (Brekelmans, 2012).

Description of key information

The partition coefficient was determined according to OECD Guideline 107 and EU Method A.8 (octanol/water type) (Brekelmans, 2012)

Key value for chemical safety assessment

Log Kow (Log Pow):
2.75
at the temperature of:
20 °C

Additional information

Pow values: 1.01, 1.03 and 567 at 20°C and log Pow values: 0.004, 0.01 and 2.75 based on solubility in water, in buffer solutions and on critical micelle concentration, respectively.