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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:
29 March to 04 April 2016
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
The study was conducted according to an internationally recognised method, and under GLP. No deviation was reported. Test substance is adequately specified with purity. Therefore full validation applies.
Qualifier:
according to
Guideline:
OECD Guideline 123 (Partition Coefficient (1-Octanol / Water), Slow-Stirring Method)
Deviations:
no
Principles of method if other than guideline:
Not applicable
GLP compliance:
yes (incl. certificate)
Remarks:
inspected on June 3 to 5, 2013 / signed on February 01, 2016
Type of method:
slow-stirring method
Partition coefficient type:
octanol-water
Specific details on test material used for the study:
STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: 20 ± 2 °C, protected from light, in the tightly closed original container
- Stability under test conditions: Stable

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- Treatment of test material prior to testing: The test item was melted completely at 30 °C in a water bath and used after homogenization.
Analytical method:
gas chromatography
Key result
Type:
log Pow
Partition coefficient:
5.154
Temp.:
25 °C
pH:
5.41
Details on results:
The recovery rates of 98 - 104 % indicate sufficient stability of the test item in the n-octanol stock solution during the course of the study.
The mass balance for both phases (n-Octanol- and Aqueous Phase) was determined to be between 96 - 102%.

Table 4.7/1: Partition coefficient – results

 

Replicate number

Test duration (h)

Calc. conc.

Pow

Log Pow

in n-octanol (mg/L)

in aq.phase (mg/L)

Single

Mean

SD ±

CV

1

43.91

22714

0.148

153877

5.19

5.16

0.03

0.54

48.99

23370

0.152

154247

5.19

68.00

23272

0.171

136144

5.13

73.08

22567

0.161

140489

5.15

2

43.91

22536

0.155

144933

5.16

5.15

0.02

0.37

48.99

23351

0.156

149721

5.18

68.00

23204

0.169

137032

5.14

73.08

22680

0.165

137282

5.14

3

43.91

22520

0.155

145581

5.16

5.15

0.02

0.45

48.99

23160

0.157

147920

5.17

68.00

22496

0.163

137999

5.14

73.08

21976

0.167

131445

5.12

           

Log Pow, AV

5.154

 

Weighted standard deviation

0.002

Calc. conc. = Measured concentration corrected with dilution factors (1/2 for aqueous; 100000 for n-octanol samples) and weighing factor of 1.07

aq. Phase = Aqueous phase

Pow = Partition coefficient (n-octanol/ water)

Log Pow = Decadic logarithm of the partition coefficient(n-octanol/ water)

SD = Standard deviation

CV = Coefficient of variation [%]

 

Regression analysis demonstrated that the slope of the regression line of the Pow of the four successive samples in each replicate was not significantly different from zero.

 

Validity Criteria

The mean log Pow values in the equilibration time for each replicate (4 sub-samples) did fall within a range of ± 0.3 log.

Temperatures were kept constant at 25 ± 1 °C for each determination of the partition coefficient.

Conclusions:
The substance has potential to bioaccumulate in the environment, according to CLP classification criteria for aquatic chronic toxicity (log Kow >4).
Executive summary:

The partition coefficient (n-octanol/water) of the test item was measured under GLP according to the OECD 123 Guideline, slow stirring method.

 

The partition coefficient of the test item was determined employing the slow-stirring method at 25 ± 1 °C from three independent replicates (test vessels) with four sub-replicates (samples) each. The mean log Pow values for each replicate did fall within a range of ± 0.3 log units in the equilibration time. The pH-value of the aqueous phases was determined by a pH-meter at the end of the experimental phase.

 

Analytical evaluation was performed using GC-MS on a capillary analytical column using the test item for external calibration with internal standard correction. The analytical method was validated with satisfactory results regarding linearity, limit of quantification, accuracy, precision and specificity.

 

The partition coefficient (n-octanol/water) (log Pow) of test item was determined at test temperature of 25 ± 1 °C and at a mean pH value of 5.410 from three independent replicates (test vessels) with four sub-replicates (samples) to be 5.154 ± 0.002.

Description of key information

The data is relevant for classification in aquatic chronic toxicity hazard class, according to CLP criteria.

The substance has potential to bioaccumulate in the environment (log Kow >4).

Key value for chemical safety assessment

Log Kow (Log Pow):
5.15
at the temperature of:
25 °C

Additional information

A fully reliable experimental study, conducted according to a recognized OECD method, and under GLP, is available. It is considered as a key study. The result is retained as key data.