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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:
14 June 2016 to 04 October 2016
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 123 (Partition Coefficient (1-Octanol / Water), Slow-Stirring Method)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method A.23 Partition Coefficient (1-Octanol/Water): Slow-Stirring Method
Deviations:
no
GLP compliance:
yes (incl. certificate)
Type of method:
slow-stirring method
Partition coefficient type:
octanol-water
Analytical method:
other: HPLC-MS
Key result
Type:
log Pow
Partition coefficient:
4.94
Temp.:
25 °C
pH:
>= 4.84 - <= 5.02
Remarks on result:
other: cationic components
Key result
Type:
log Pow
Partition coefficient:
4.15
Temp.:
25 °C
pH:
>= 4.11 - <= 4.19
Remarks on result:
other: anionic components
Details on results:
RESULTS
- The sampling times, analysed concentration (mg/L) of the respective phases, aqueous phase pH and resulting partition coefficient values (as Log10 Pow) for the equilibration assessment are shown in Table 16 (attached). The mean stock solution concentration on analysis was 5.78 x 10E04 mg/L (cationic component) and 4.88 x 10E04 mg/L (anionic component).
- The mass balance based on the average of the 4 samples results used for the equilibration assessment result gave a value of 91.6% (cationic component) and 96.3% (anionic component) of the analysed stock solution.
- The sampling times, analysed concentration (mg/L) of the respective phases, aqueous phase pH and resulting partition coefficient values (as Log10 Pow) for the definitive samples are shown in Tables 17, 18 and 19 (attached). The mean stock solution concentration on analysis was 4.91 x 10E04 mg/L (cationic component) and 4.99 x 10E04 mg/L (anionic component).
- The mass balance based on the average of the sample results used for the overall result gave a value of 90.3% (cationic component) and 95.4% (anionic component) of the analysed stock solution.
- Examples of calibration curves from which the sample concentrations were interpolated are presented in Figure 11 , Figure 12 , Figure 13 and Figure 14 (attached).
- For the cationic component: The relationship between equilibration time and log10 Pow for Vessel 1, Vessel 2 and Vessel 3 is shown in Figure 3, Figure 4 and Figure 5 respectively (attached).
- For the anionic component: The relationship between equilibration time and log10 Pow for Vessel 1, Vessel 2 and Vessel 3 is shown in Figure 6, Figure 7 and Figure 8 respectively (attached).
- For each of the three test vessels, the slope of the correlation was tested statistically to ensure it did not differ significantly from zero. This was performed using the t test and a probability value of P = 0.05 (critical value of 4.303 for 2 degrees of freedom). The results are summarised in Table 20 (attached).
- As equilibrium was confirmed, the mean Log10 Pow value, the standard deviation and variance was calculated for each vessel. This then allowed the final variance weighted average and standard deviation to be calculated as the definitive result for the test. The results are summarised in Table 21 (attached).
Conclusions:
The slow stirring method was used to determine partition coefficients for cationic and anionic components because the test item was an organic salt. Weighted average Log10 Pow values were reported as 4.94 (cationic components) and 4.15 (anionic components) at a nominal 25 °C.
Executive summary:

GUIDELINE

The determination of partition coefficient was carried out by the slow-stirring method, using a procedure designed to be compatible with Method A.23, 24 January 2014, and Method 123 of the OECD Guidelines for Testing of Chemicals, 23 March 2006.

 

RESULTS

The partition coefficient of the cationic and anionic components was determined because the test item was an organic salt. Weighted average Log10 Pow values were reported as 4.94 (cationic components) and 4.15 (anionic components) at a nominal 25 °C.

Description of key information

The slow stirring method was used to determine partition coefficients for cationic and anionic components because the test item was an organic salt. Weighted average Log10 Pow values were reported as 4.94 (cationic components) and 4.15 (anionic components) at a nominal 25 °C (OECD 123 and EU Method A.23).

Key value for chemical safety assessment

Log Kow (Log Pow):
4.94
at the temperature of:
25 °C

Additional information

GUIDELINE

The determination of partition coefficient was carried out by the slow-stirring method, using a procedure designed to be compatible with Method A.23, 24 January 2014, and Method 123 of the OECD Guidelines for Testing of Chemicals, 23 March 2006.

 

RESULTS

The partition coefficient of the cationic and anionic components was determined because the test item was an organic salt. Weighted average Log10 Pow values were reported as 4.94 (cationic components) and 4.15 (anionic components) at a nominal 25 °C.