Phosphoric acid C12-alkyl and C18-alkyl esters, potassium salts

Partition coefficient

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

partition coefficient

Type of information:

calculation (if not (Q)SAR)

Adequacy of study:

key study

Study period:

2017-12-15

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Reason / purpose for cross-reference:

reference to other study

Reason / purpose for cross-reference:

reference to other study

Qualifier:

no guideline followed

Principles of method if other than guideline:

The test item has surface-active properties as the surface tension was determined to be 36.9 mN/m.
According to the Guidance on information requirements and chemical safety assessment, chapter R.7a, pp 107, measured solubility in 1-octanol and water can be used to determine the partition coefficient. However, it is prudent to take the critical micelle concentration (CMC) as a solubility limit in water. Water solubility of the test item was measured by tensiometry, a classic method to determine the CMC of a surfactant (please refer to IUCLID section 4.8)

GLP compliance:

yes (incl. QA statement)

Type of method:

calculation method (fragments)

Partition coefficient type:

octanol-water

Analytical method:

high-performance liquid chromatography

Key result

Type:

log Pow

Partition coefficient:

0.51

Temp.:

20 °C

pH:

7

The partition coefficient of the solute was calculated with the following formula: logPow = log (solute 1-octanol / solute water).

With the previous results for water solubility of 0.055 ±0.0075 g/L and 1-octanol solubility, the logPow of the test item was determined to be log Pow = log (0.1784 g/L / 0.055 g/L) = 0.51

Conclusions:

The logPow of the test item was calculated based on the individual solubilities in octanol and water to be 0.51 at 20 °C.

Executive summary:

Due to the high surface activity of the test item studies in accordance with OECD TG 117, 107 or 123 were technically not feasible to determine the partition coefficient of the test substance. The test item has surface-active properties based on the surface tension of 36.9 mN/m. In such cases the standard methods are not suitable the surface activity of the test item affect the distribution between the two phases.. According to the Guidance on information requirements and chemical safety assessment, chapter R.7a, pp 107, in such cases measured solubility in 1-octanol and water can be used to determine the partition coefficient. In order to avoid the artefact of unrealistically low Kow values, the critical micelle concentration in water (CMC) was determined and used as solubility limit in water Water solubility of the test item was measured by tensiometry, a classic method to determine the CMC of a surfactant (please refer to IUCLID section 4.8). Based on the results for water solubility (CMC) of 0.055 ±0.0075 g/L and 1-Octanol solubility of 0.1784 g/L the logPow of the test item was calculated to be 0.51 at 20 °C.

Reference 2

Endpoint:

partition coefficient

Data waiving:

study technically not feasible

Justification for data waiving:

the study does not need to be conducted because the substance has a high surface activity

Justification for type of information:

JUSTIFICATION FOR DATA WAIVING
In accordance with REACH Annex XI section 2 and the guidance on Information Requirements and Chemical Safety Assessment the determination of the logPow was technically not feasible as the substance is a surfactant. According to the Guidance on regulatory compliant Kow determination for surfactants (pg. 79 Version 6.0 – July 2017) the logPow should be based on the individual solubility in water and n-octanol. As recommended in the ECHA guidance the critical micelle concentration was determined and used as solubility limit for the water solubility and logPow estimation.

Description of key information

Based on the results for water solubility (CMC) of 0.055 ±0.0075 g/L and 1-Octanol solubility of 0.1784 g/L the logPow of the test item was calculated to be 0.51 at 20 °C.

Key value for chemical safety assessment

Log Kow (Log Pow):

0.51

at the temperature of:

20 °C

Additional information

In accordance with REACH Annex XI section 2 and the guidance on Information Requirements and Chemical Safety Assessment the determination of the logPow was technically not feasible as the substance is a surfactant. According to the Guidance on regulatory compliant Kow determination for surfactants (pg. 79 Version 6.0 – July 2017) the logPow should be based on the individual solubility in water and n-octanol. As recommended in the ECHA guidance the critical micelle concentration was determined and used as solubility limit for the water solubility and logPow estimation.

Due to the high surface activity of the test item studies in accordance with OECD TG 117, 107 or 123 were technically not feasible to determine the partition coefficient of the test substance. The test item has surface-active properties based on the surface tension of 36.9 mN/m. In such cases the standard methods are not suitable the surface activity of the test item affect the distribution between the two phases.. According to the Guidance on information requirements and chemical safety assessment, chapter R.7a, pp 107, in such cases measured solubility in 1-octanol and water can be used to determine the partition coefficient. In order to avoid the artefact of unrealistically low Kow values, the critical micelle concentration in water (CMC) was determined and used as solubility limit in water Water solubility of the test item was measured by tensiometry, a classic method to determine the CMC of a surfactant (please refer to IUCLID section 4.8). Based on the results for water solubility (CMC) of 0.055 ±0.0075 g/L and 1-Octanol solubility of 0.1784 g/L the logPow of the test item was calculated to be 0.51 at 20 °C.