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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:
July-2016 - October 2016
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
Study conducted to standard guidelines and with GLP. Report well documented.
Qualifier:
according to guideline
Guideline:
OECD Guideline 107 (Partition Coefficient (n-octanol / water), Shake Flask Method)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method A.8 (Partition Coefficient - Shake Flask Method)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Type of method:
flask method
Partition coefficient type:
octanol-water
Specific details on test material used for the study:
Identification: Rosin dimers, calcium, zinc salt
Appearance/Physical state: Pale brown crystalline solid
Batch: 179449
Purity: 100% (as UVCB)
Expiry date: 24 March 2017
Storage conditions: Approximately 4 °C, under nitrogen, in the dark
Analytical method:
high-performance liquid chromatography
Key result
Type:
log Pow
Partition coefficient:
3.38
Temp.:
22 °C
pH:
5
Details on results:
Validation
The linearity of the detector response with respect to concentration was assessed over the nominal concentration range of 25 to 500 mg/L (n = 8). The results were satisfactory with a first order correlation coefficient (r) of 0.9995 being obtained. A second evaluation of the linearity of the detector response with respect to concentration was performed over the nominal concentration range of 2.5 to 300 mg/L (n = 11). The results were again satisfactory with a correlation coefficient (r) of 0.9996 being obtained. The recovery of analysis of the extraction procedure used for the aqueous phase samples was assessed and proved adequate for the test. At a fortified concentration of 0.65 mg/L, a mean percentage recovery of 81.8% was obtained (n = 3, range 75.8 to 90.8%, relative standard
deviation 9.73%). Reported sample solution concentrations for the aqueous phases have not been corrected for recovery of analysis.

The partition coefficient of salts is required by the shake-flask method at the pH within the environmentally relevant pH range of 5 to 9 at which solubility in n-octanol is maximized and thus the value of partition coefficient is maximized for risk assessment. Based on the presence of the acidic carboxylic acid functional groups on all components of the test item, the definitive test was performed at pH 5.0.

It was noted that a significant instrument response was achieved for the matrix blank solution on analysis, originating from the gradient elution method required for analysis of the test item and the partial UV absorbance of tetrahydrofuran at the analytical wavelength needed to monitor the test item. This had no impact on the integrity of the results reported, since incorporating the matrix blank solution into the relevant calibration plots automatically corrects for the blank response.

The partition coefficient of the test item has been determined to be 2.43 x 10^3 at pH 5.0 and 22.0 ± 0.5 °C, log10 Pow 3.38.

Table 3. The total weights (mg) and analyzed concentration (mg/L) of the respective phases.

Sample number

Total Weight (mg)*

 

Organic Phase

Aqueous Phase

 

Recovery (%)

Analyzed

Concentration

(mg/l)

Weight

(mg)

Analyzed

Concentration (mg/l)

Weight

(mg)

pH

1

28.5

1.04 x 103

29.2

0.605

8.47 x 10-2

5.00

103

2

29.5

1.02 x 103

29.6

0.478

6.92 x 10-2

5.01

101

3

12.2

1.02 x 103

12.3

0.363

4.35 x 10-2

5.02

101

4

16.3

1.03 x 103

16.5

0.438

7.01 x 10-2

5.01

102

5

8.13

1.04 x 103

8.29

0.416

6.66 x 10-2

4.99

103

6

8.13

1.04 x 103

8.32

0.340

5.45 x 10-2

4.99

103

* From analysis of the stock solution.

† From analysis of the respective phase.

Table 4. The partition coefficient determined for each sample.

Sample number

Organic/Aqueous Volume Ratio

Partition coefficient

Log10 Pow

Mean Partition Coefficient

1

1:5

1.73 x 103

3.24

1.93 x 103

2

2.14 x 103

3.33

3

1:10

2.82 x 103

3.45

2.59 x 103

4

2.35 x 103

3.37

5

1:20

2.49 x 103

3.40

2.77 x 103

Mean Pow:  2.43 x 103 

Standard deviation: 477    

Mean log10 Pow:  3.38

Conclusions:
The partition coefficient of the test item has been determined to be 2.43 x 10^3 at pH 5.0 and 22.0 ± 0.5 °C, log10 Pow 3.38.
Executive summary:

The octanol-water partition coeefficient for calcium zinc salts of oligomers of rosin was determined using the shake-flask method and according to OECD guideline 107. The partition coefficient of the test item has been determined to be 2.43 x 10^3 at pH 5.0 and 22.0 ± 0.5 °C, log10 Pow 3.38.

Description of key information

The octanol-water partition coeefficient for calcium zinc salts of oligomers of rosin was determined using the shake-flask method and according to OECD guideline 107. The partition coefficient of the test item has been determined to be 2.43 x 10^3 at pH 5.0 and 22.0 ± 0.5 °C, log10 Pow 3.38.

Key value for chemical safety assessment

Log Kow (Log Pow):
3.38
at the temperature of:
22 °C

Additional information