Choline hydroxide

Partition coefficient

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

partition coefficient

Type of information:

(Q)SAR

Adequacy of study:

key study

Study period:

2017

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification

Qualifier:

no guideline required

Principles of method if other than guideline:

The partition coefficient was calculated using the OPERA calculation model.

Type:

log Pow

Partition coefficient:

-0.383

Remarks on result:

other: This is a calculation conducted using the OPERA calculation model. As such, the information on Temperature, pH can not be filled in.

Conclusions:

The logKow of pure choline hydroxide was calculated to be -0.383.

Executive summary:

The partition coefficient of pure choline hydroxide was calculated with OPERA Model calculation. The logKow was calculated to be -0.383.

Reference 2

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2013-03-21 to 2013-03-22

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Well-documented guideline study according to OECD 107. The fact that Choline hydroxide was tested as 45 % aqueous solution is not expected to influence the outcome of the partition coefficient testing.

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

OECD Guideline 107 (Partition Coefficient (n-octanol / water), Shake Flask Method)

Deviations:

no

GLP compliance:

no

Type of method:

shake-flask method to: flask method

Partition coefficient type:

octanol-water

Analytical method:

other: potentiometric titration

Type:

log Pow

Partition coefficient:

-2.25

Temp.:

25 °C

pH:

11.3

Remarks on result:

other: average out of 6 determinations

Type:

log Pow

Partition coefficient:

-2.301

Temp.:

25 °C

pH:

11.61

Remarks on result:

other: Weight of sample: 18.039 mg, ratio n-octanol:water (ml:ml) = 18:18

Type:

log Pow

Partition coefficient:

-2.523

Temp.:

25 °C

pH:

11.6

Remarks on result:

other: Weight of sample: 18.039 mg, ratio n-octanol:water (ml:ml) = 18:18

Type:

log Pow

Partition coefficient:

-2.222

Temp.:

25 °C

pH:

11.38

Remarks on result:

other: Weight of sample: 12.026 mg, ratio n-octanol:water (ml:ml) = 24:12

Type:

log Pow

Partition coefficient:

-2.097

Temp.:

25 °C

pH:

11.39

Remarks on result:

other: Weight of sample: 12.026 mg, ratio n-octanol:water (ml:ml) = 24:12

Type:

log Pow

Partition coefficient:

-2.097

Temp.:

25 °C

pH:

10.81

Remarks on result:

other: Weight of sample: 3.006 mg, ratio n-octanol:water (ml:ml) = 12:24

Type:

log Pow

Partition coefficient:

-2.398

Temp.:

25 °C

pH:

10.92

Remarks on result:

other: Weight of sample: 3.006 mg, ratio n-octanol:water (ml:ml) = 12:24

The stability of Stock Solutions 1, 2, and 3 from which the test solutions were prepared was checked alongside the sample analysis. These solutions were analysed at the end of the partition coefficient test experimental work and the concentration of test substance present was determined. These values were then compared with the theoretical concentrations of the solutions.

 

A value of 1036 mg/L was determined for Stock Solution 1. Comparison of this value with the theoretical concentration of the solution (1002.15 mg/L) indicates a 103.4 % recovery.

A value of 520 mg/L was determined for Stock Solution 2. Comparison of this value with the theoretical concentration of the solution (501.08 mg/L) indicates a 103.8 % recovery.

A value of 260 mg/L was determined for Stock Solution 3. Comparison of this value with the theoretical concentration of the solution (250.54 mg/L) indicates a 103.8 % recovery.

 

These values were deemed to show that there has been no significant degradation of the stock solutions in terms of concentration over the test period and therefore the solutions used in the test were considered to have been stable for the duration of the test. 

 

The pH of the water layers and the presaturated water blank was measured on completion of the partition coefficient shake flask test period, using a Sirius GLpH automatic pH meter which was calibrated prior to measurements being performed.

 

Table 1: Summary of Results

Calculation of Partition Coefficient (SOP 049.02)
	TEST 1A	TEST 1B	TEST 2A	TEST 2B	TEST 3A	TEST 3B
Weight of Sample mg	18.039	18.039	12.026	12.026	3.006	3.006
Volume of n-Octanol Saturated Water mLs	18	18	24	24	12	12
Volume of Water Saturated n-Octanol mLs	18	18	12	12	24	24
Dilution of n-Octanol Layers (If examined neat enter 1)	1	1	1	1	1	1
Concentration in n-Octanol phase mg/L	5	3	3	4	2	1
Concentration in n-Octanol phase x dilution mg/L	5	3	3	4	2	1
Number of mg in n-Octanol phase	0.090	0.054	0.036	0.048	0.048	0.024
Dilution of Water Layers (If examined neat enter 1)	1	1	1	1	1	1
Concentration in Water phase mg/L	1058.000	1064.000	522.000	526.000	264.000	268.000
Concentration in Water phase x dilution mg/L	1058.000	1064.000	522.000	526.000	264.000	268.000
Number of mg in Water phase	19.044	19.152	12.528	12.624	3.168	3.216
Total Number of mg recovered	19.134	19.206	12.564	12.672	3.216	3.240
p = conc in octanol/conc in water	0.005	0.003	0.006	0.008	0.008	0.004
Mean P for each test condition	0.004		0.007		0.006
Mean P for all determinations	0.006
Standard deviation of individual P from mean P	0.002
Log P	-2.301	-2.523	-2.222	-2.097	-2.097	-2.398
Log mean P for all determinations (2dp)	-2.25
pH of aqueous layer	11.61	11.66	11.38	11.39	10.81	10.92

The quality criterion in Guideline 107 for repeatability of results states that the determined values of the partition coefficient expressed as their common logarithms should fall within a range of ± 0.3 log units. All six replicates reported above meet this criterion.

Conclusions:

The partition coefficient of a 45 % aqueous solution of choline hydroxide was determined according to OECD 107 without restrictions to be -2.25 at 25 °C ± 1 °C. The quality criterion is fulfilled, i.e. the determined values of the partition coefficient of all six replicates expressed as their common logarithms fall within a range of ± 0.3 log units. Due to the ionic structure and rather small molecular weight of the substance, this result is in the scientifically expected range and can be used for further risk assessment.
In addition, the only difference between the test item and the registered substance is an additional amount of 55 % 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 hydroxide are considered be identical (-2.25).

Executive summary:

The water/octanol partition coefficient of a 45 % aqueous solution of choline hydroxide was determined according to OECD 107, shake flask method, without restrictions to be -2.25 at 25 °C ± 1 °C.

The only difference between the test item and the registered substance is an additional amount of 55 % 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 hydroxide are considered be identical (-2.25).

As such, the study was classified as Klimisch 1, fulfills the guideline requirements and the results meet the quality criterion therein.

Description of key information

Partition coefficient: -2.25 at 25 ± 1 °C (OECD Guideline 107 (Partition Coefficient (n-octanol / water), Shake Flask Method))

Calculated partition coefficient with OPERA Model: logKow = -0.383.

Key value for chemical safety assessment

Log Kow (Log Pow):

-2.25

at the temperature of:

25 °C

Additional information

The partition coefficient of a 45 % Choline hydroxide solution was determined according to OECD 107, shake flask method, without restrictions to be -2.25 at 25 ± 1 °C. The study was classified as Klimisch 1, fulfills the guideline requirements and the results meet the quality criterion therein, i.e. the determined values of the partition coefficient of all six replicates expressed as their common logarithms fall within a range of ± 0.3 log units. The only difference between the test item and the registered substance is an additional amount of 55 % 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 hydroxide are considered be identical (-2.25).

Due to the ionic structure and rather small molecular weight of the substance, this result is in the scientifically expected range and can be used for further risk assessment.

This negative partition has a strong impact on further risk assessment, e.g. indicates no potential of the substance for bioaccumulation or a low potential for dermal absorption per se.

The results are reasonable, within the scientifically expected ranges and can therefore be considered as reliable. Hence, the tonnage-driven data requirements under REACH are fully met, no datagaps were identified and 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 = -2.25) 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.

 

In addition, the partition coefficient of pure choline hydroxide was calculated with OPERA Model calculation. The logKow was calculated to be -0.383.