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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:
1988-07-29
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Well-performed and well documented guideline study equivalent to OECD 123. The fact that Choline chloride was tested as 75% aqueous solution is not expected to influence the outcome of the partion coefficient testing. Report only available in German, but applicant employes native speaker.
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 123 (Partition Coefficient (1-Octanol / Water), Slow-Stirring Method)
Deviations:
no
GLP compliance:
not specified
Type of method:
shake-flask method to: flask method
Partition coefficient type:
octanol-water
Analytical method:
other: ion pair chromatography
Type:
Pow
Partition coefficient:
0
Temp.:
25 °C
Remarks on result:
other: average of three independent determinations
Type:
log Pow
Partition coefficient:
-3.77
Temp.:
25 °C
Remarks on result:
other: average of three independent determinations

Results / raw data

1. Weight:

20.8978 g 1-Octanol (Water saturated)

0.2939 g Choline chloride solution

24.8850 g dest. Water (Octanol saturated)

Concentration of Choline chloride solution in octanol phase: c = 1.8 mg / L

Concentration of Choline chloride solution in water phase: c = 11.83 g / L

Pow = c (choline chloride solution in 1-Octanol phase) / c(choline chloride solution in water phase) = 1.8 mg/L / 11.83 g/L = 0.00015

2. Weight:

20.8978 g 1-Octanol (Water saturated)

0.4203 g Choline chloride solution

24.9756 g dest. Water (Octanol saturated)

Concentration of Choline chloride solution in octanol phase: c = 2.7 mg / L

Concentration of Choline chloride solution in water phase: c = 16.82 g / L

Pow = c (choline chloride solution in 1-Octanol phase) / c(choline chloride solution in water phase) = 2.7 mg/L / 16.82 g/L = 0.00016

3. Weight:

20.9077 g 1-Octanol (Water saturated)

0.6474 g Choline chloride solution

25.0927 g dest. Water (Octanol saturated)

Concentration of Choline chloride solution in octanol phase: c = ca. 5 mg / L

Concentration of Choline chloride solution in water phase: c = 25.82 g / L

Pow = c (choline chloride solution in 1-Octanol phase) / c(choline chloride solution in water phase) = 5 mg/L / 25.82 g/L = 0.00019

 

Table 1: Summary of results

 

Pow

logPow

1. Weight

0.00015

-3.82

2. Weight

0.00016

-3.79

3. Weight

0.00019

-3.71

Average

0.00017

-3.77

Conclusions:
The logPow of a 75% choline chloride solution was determined in a well-performed and well-documented study classified as Klimisch 1. Hence, the results can be considered as reliable and sufficient to cover this endpoint. The only difference between the test item and the registered substance is an additional amount of 25% water. This addition is not considered relevant as i.a. the distribution of the compound in water is measured after the establishment of the equilibrium, and hence the logPow of the test item and pure Choline chloride are considered be identical (-3.77).
The experimental result is in the scientifically expected range taking into account the ionic structure of Choline chloride and rather small molecular weight. Also, the variation between the single measurement is relatively small, which contributes to the conclusion that the determined value of logPow = -3.77 is reasonable.
Executive summary:

The water/octanol partition coefficient of a 75% aqueous solution of choline chloride was determined equivalent to OECD guideline 123. The Pow was 0.00017, which corresponds to a logPow of -3.77.

The study was classified as acceptable and satisfies the requirements of OECD 123.

Description of key information

Octanol / water partition coefficient: Pow = 0.00017, logPow = -3.77 at 25°C (equivalent to OECD 123)

Key value for chemical safety assessment

Log Kow (Log Pow):
-3.77
at the temperature of:
25 °C

Additional information

The logPow of a 75% choline chloride solution was determined in a well-performed and well-documented study classified as Klimisch 1 (BASF, 1988). Hence, the results can be considered as reliable and sufficient to cover this endpoint. The only difference between the test item and the registered substance is an additional amount of 25% water. This addition is not considered relevant as i.a. the distribution of the compound in water is measured after the establishment of the equilibrium, and hence the logPow of the test item and pure Choline chloride are considered be identical (-3.77).

The experimental result is in the scientifically expected range taking into account the ionic structure of Choline chloride and rather small molecular weight. Also, the variation between the single measurement is relatively small, which contributes to the conclusion that the determined value of logPow = -3.77 is reasonable.

So in summary, the available data from this one study (BASF, 1988) is sufficient to cover this endpoint and meets fully the tonnage-driven data requirements under REACH. Hence, no further testing is required.

In general, the logPow is a very important parameter for risk assessment. Especially a negative value like the determined one (logPow = -3.77) allows to draw relevant conclusions, for example poor dermal absorption due to the ionic structure, a not existing potential for accumulation or the impact of the accompanied high water solubility on ecotoxicity testing. These points will be discussed more intensely in the corresponding sections.