Bis(acetato-O)hydroxyaluminium

Partition coefficient

Link to relevant study record(s)

Reference

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

from 2015-05-27 to 2015-12-07

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EU Method A.8 (Partition Coefficient - Shake Flask Method)

Deviations:

no

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

flask method

Partition coefficient type:

octanol-water

Analytical method:

other: Inductively coupled plasma optical emission spectrometry (ICP-OES)

Key result

Type:

log Pow

Partition coefficient:

-0.6

Temp.:

30 °C

pH:

4.7

Details on results:

The program KOWWIN (part of EPI Suite) was used for calculating the log Pow of the test item. The calculated value was -0.6. This value is only valid for Aluminiumhydroxidacetat-Hydrat.

Preliminary visual estimation of the n-octanol solubility:

Defined amounts of the test item were stirred with increasing volumes of n-octanol at room temperature and visually checked for any undissolved parts.

 

Table 1: Results of the preliminary visual estimation of the n-octanol solubility

Amount of test item / mg	Added volume of n-octanol /mL	Total volume of n-octanol /mL	Stirring time / h	Appearance of mixture
7.1	10	10	2	undissolved
	90	100	~ 19	undissolved

 According to this preliminary test the solubility of the test item in n-octanol was below 71 mg/L (without correction for the purity).

Calculation of the partition coefficient log P_ow from the preliminary test:

The program KOWWIN (part of EPI Suite) was used for calculating the log P_ow of the test item. The calculated value was -0.6. This value is only valid for Aluminiumhydroxidacetat-Hydrat.

Determination of the solubility in n-octanol: Flask method:

The test item is a complex substance. As a representative parameter for the solubility of the complete test item, the concentration (c_s) of aluminum formed at equilibrium under a defined set of conditions (temperature, loading rate, stirring time) was determined.

After the equilibration time precipitate was observed in the flasks of the experiments excluding the blank experiment. After the equilibration time of the flask method, aliquots of the mixtures were taken and centrifuged (30 minutes with 15000 rpm at 20 °C). The concentration of aluminium in the water extracts of the test item was determined by means of ICP-OES.

 

Table 2: n-Octanol solubility experiments of the test item

Experiment	24 h experiment	48 h experiment	72 h experiment	Blank experiment (72 h)
Amount of test item / mg	18.9	17.4	17.6	-
Amount of distilled water / mL	100	100	100	100
Stirring time at 30 °C / h	24	48	72	72
Measured aluminium concentration / mg/L	3.1	7.5	6.9	<0.1

 

Mean aluminium concentration of the experiments with a loading rate of approx. 0.2 g/L : 6 mg/L

 

Calculation of the partition coefficient log P_ow from the individual solubilities:

The study for the determination of the water solubility showed in a first main test highly differing results and in a second main test an influence of the initial weight on the resulting water solubility. As the test item is a complex substance and in analogy to the water solubility, it can be assumed that the components of the test item would also show different solubilities in n-octanol depending on the initial concentration. Therefore, an estimation of the partition coefficient using the single solubilities of the test item in water and n-octanol was not possible and not sensible as well.

Conclusions:

It was not possible to determine the partition coefficient using the individual solubilities of the test item in water and n-octanol. The program KOWWIN (part of EPI Suite) was used for calculating the log Pow of the test item. The calculated value was -0.6. This value is only valid for Aluminiumhydroxidacetat-Hydrat.

Executive summary:

A study was conducted in accordance with OECD TG 107 and Regulation (EC) No 440/2008 method A.8 to determine the partition coefficient of the test substance using the flask method. Two solutions of the test substance was prepared in n-octanol (7.1 mg in 10 and 100 mL) as a preliminary test. In both solutions the test substance was not dissolved. A determination of the solubility of the test substance in n-octanol was measured with flask method according to the OECD guideline 105. Three paralel experiments with the test substance and one blank experiment were performed for 24, 48 and 72 h (blank only 72 h). After equilibration, aliquotes of the mixtures were taken and centrifuged for 30 minutes with 15000 rpm at 20 °C and the aluminium content in the water extracts was determined by means of ICP-OES. As the test item is a complex substance and in analogy to the water solubility, it can be assumed that the components of the test item would also show different solubilities in n-octanol depending on the initial concentration. Therefore, an estimation of the partition coefficient using the single solubilities of the test item in water and n-octanol was not possible and not sensible as well. Hence, the partition coefficient log Pow of the test item was calculated with KOWWIN to be log P_ow = -0.6. This value is only valid for Aluminiumhydroxidacetat-Hydrat.

Description of key information

It was not possible to determine experimentally the partition coefficient using the individual solubilities of the test item in water and n-octanol. The program KOWWIN (part of EPI Suite) was used for calculating the log Pow of the test item. The calculated value was -0.63.

Key value for chemical safety assessment

Log Kow (Log Pow):

-0.63

at the temperature of:

25 °C

Additional information

Using KOWWIN v1.68 the logPow of the test item was calculated to be -0.63 at 25 °C. The substance is not within the applicability domain of the model. Thus, the estimation may be less accurate (reference 4.7-1).

A study was conducted in accordance with OECD TG 107 and Regulation (EC) No 440/2008 method A.8 to determine the partition coefficient of the test substance using the flask method (reference 4.7-2). Two solutions of the test substance was prepared in n-octanol (7.1 mg in 10 and 100 mL) as a preliminary test. In both solutions the test substance was not dissolved. A determination of the solubility of the test substance in n-octanol was measured with flask method according to the OECD guideline 105. Three parallel experiments with the test substance and one blank experiment were performed for 24, 48 and 72 h (blank only 72 h). After equilibration, aliquotes of the mixtures were taken and centrifuged for 30 minutes with 15000 rpm at 20 °C and the aluminium content in the water extracts was determined by means of ICP-OES. As the test item is a complex substance and in analogy to the water solubility, it can be assumed that the components of the test item would also show different solubilities in n-octanol depending on the initial concentration. Therefore, an estimation of the partition coefficient using the single solubilities of the test item in water and n-octanol was not possible. Hence, the partition coefficient log Pow of the test item was calculated with KOWWIN to be log Pow = -0.63.