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Physical & Chemical properties

Partition coefficient

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Reference
Endpoint:
partition coefficient
Type of information:
experimental study
Adequacy of study:
key study
Study period:
Experimental start date: 23 December 2015, Experimental completion date: 04 January 2016
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)
Version / remarks:
2004
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method A.8 (Partition Coefficient)
Version / remarks:
Commission Regulation (EC) No 440/2008, dated May 30, 2008
Deviations:
no
GLP compliance:
no
Remarks:
However, the study was performed in a test facility which has been certified to be in compliance with the principles of GLP.
Type of method:
HPLC method
Partition coefficient type:
octanol-water
Analytical method:
high-performance liquid chromatography
Type:
log Pow
Partition coefficient:
>= 1.09 - <= 2.08
Temp.:
20 °C
pH:
9
Remarks on result:
other: The test item eluted at a column temperature of 30 °C in 4 peaks corresponding to log Pow values of 1.09, 1.59, 2.02 and 2.08.
Type:
Pow
Partition coefficient:
>= 12.4 - <= 119
Temp.:
20 °C
pH:
9
Remarks on result:
other: The test item eluted at a column temperature of 30 °C in 4 peaks corresponding to Pow values of 12.4, 38.9, 105 and 119.
Details on results:
- Dead time: t0 = 1.312 min (mean of 2 measurements with thiourea)
- Retention time of the test item: tr = 55.65
- Capacity factor k' of the test item: The test item eluted in four peaks. The mean of the two injections made revealed the following capacity factors.
Peak 1: k' = 0.656 and 0.648, arithmetic mean 0.652
Peak 2: k' = 1.185 and 1.178, arithmetic mean 1.1815
Peak 3: k' = 1.985 and 1.982, arithmetic mean 1.9835
Peak 4: k' = 2.137 and 2.130, arithmetic mean 4.26772
- Intercept of the calibration curve: A = -0.7577
- Slope of the calibration curve: B = 0.5234
- Coefficient of determination of the calibration curve: R² = 0.9835

Table 3: retention times, capacity factors and Log Pow values determined for the sample

 Peak no.  Injection  Retention Time [min]  Capacity Factor (k')  Log k' Log Pow   Mean Log Pow
 1     1  2.172 0.656 -0.183 1.10 1.09
 2  2.162 0.648  -0.188 1.09
 2     1  2.867 1.185  0.0738 1.59 1.59
 2  2.857 1.178  0.0711 1.58
 3     1  3.916 1.985  0.298 2.02 2.02
 2  3.912 1.982  0.297 2.02
 4     1  4.116 2.137  0.330 2.08 2.08
 2  4.106 2.130  0.328 2.08

Table 4: Test item sample solution percentage area normalization data

Peak no.

Percentage Area Normalization

Injection 1

Injection 1

Mean

1

16.18

16.12

16.15

2

81.29

81.36

81.33

3

1.81

1.84

1.83

4

0.72

0.68

0.70
Conclusions:
In a valid, conclusive and reliable study according to OECD TG 117 (2004), the partition coefficient (n-octanol / water) of the test item was determined to be in the range 12.4 to 119, log10 Pow range 1.09 to 2.08, at pH 9.0.
Executive summary:

The n-octanol/water partition coefficient of the test item was determined in a non-GLP study using the HPLC method according to the OECD TG 117 (2004) and EU A.8 (Commission Regulation (EC) No 440/2008) protocols. The experiment is considered relevant, adequate and conclusive.

2-Butanone, benzyl alcohol, benzonitrile, benzene, toluene and naphthalene were used as standard references. The correlation of fit of the established calibration curve (R²) was 0.9835 demonstrating the reliability of the method in the calibration range from Log Pow 0.3 to 3.6. The column temperature was 30 °C and the injection solution pH was buffed to pH 9.

The test item eluted in four peaks within the calibration range. It can be concluded that the partition coefficient of the test item is in the range of 12.4 to 119 corresponding to the Log Pow range of 1.09 to 2.08 at pH 9.0.

Description of key information

In a valid, conclusive and reliable study according to OECD TG 117 (2004), the partition coefficient (n-octanol / water) of the test item was determined to be in the range 12.4 to 119, log10 Pow range 1.09 to 2.08, at pH 9.0.

Key value for chemical safety assessment

Additional information

The UVCB substance is a complex mixture mainly of dimethyl- and methylpyridines. Therefore, a range of log Kow values has been determined in the available study. The highest experimental log Kow value of 2.08 will be used in the chemical safety assessment of the substance.