Disodium 4,4'-methylenebis[3-hydroxy-2-naphthoate]

Partition coefficient

Link to relevant study record(s)

Reference

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

key study

Study period:

21 MAR 2013 - 20 JUN 2013

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Reason / purpose for cross-reference:

reference to other study

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

European Commission Regulation (EC) No. 440/2008

Deviations:

no

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Qualifier:

according to guideline

Guideline:

OECD Guideline 117 (Partition Coefficient (n-octanol / water), HPLC Method)

Deviations:

no

GLP compliance:

no

Type of method:

estimation method (solubility ratio)

Partition coefficient type:

octanol-water

Analytical method:

high-performance liquid chromatography

Type:

log Pow

Partition coefficient:

-3.2

Temp.:

20 °C

pH:

7

Preliminary Visual Estimation of the Water Solubility

Different amounts of the test item and water were treated with ultrasound or stirred at room temperature until the mixture appeared dissolved or the water solubility could be estimated to be below 10 mg/L. Results in the following table:

Amount of test item in mg	Total volume in mL	Appearance of mixture
85.9	0.1	undissolved^1)
	0.5	undissolved^1)
	1.0	dissolved^1)

¹⁾: After adding the indicated amount of water, the solution was treated with ultrasound for 10 minutes.

According to the preliminary visual estimation the water solubility of the test item is above 86 g/L.

Preliminary Visual Estimation of the n-Octanol Solubility

A defined amount of the test item was stirred with different amounts of n-octanol at room temperature and visually checked for any undissolved parts.

Results in the following table:

Amount of test item in mg	Volume n-octanol (total volume) in mL	Stirring time in min	Appearance of mixture
18.5	10	55	undissolved
	100	58	undissolved
	300	158	undissolved

The solubility of the test item in n-octanol is < 0.062 g/L (without correction of the purity).

Calculation of the Partition Coefficient log P_ow based on preliminarey solubility tests and Estimation via EPI Suite:

The partition coefficient P_ow may be estimated from the saturation concentrations in n-octanol and water by the following equation:

P_ow = c_s^octanol / c_s^water

where: c_s^octanol < 0.062 g/L; Concentration measured in n-octanol phase at saturation

c_s^water = 86 g/L^; Concentration measured in water phase at saturation

With the mentioned data the partition coefficient was calculated as: logP_ow<-3.1.

Therefore the partition coefficient n-octanol/water of the test item at room temperature was calculated from the individual solubilities of the test item in the aqueous phase and in n-octanol. The individual solubility in n-octanol was determined by the flask-method via HPLC.

In addition the program kowwinnt (part of episuite from SRC) was used for calculating the log P_ow of the test item. The EPI (Estimation Programs Interface) Suite was developed by the EPA's Office of Pollution Prevention Toxics and Syracuse Research Corporation (SRC). The calculated value was log P_ow = 1.2 for the test item.

Determination of the solubility of the test item in water and n-octanol via HPLC and flask method:

The water solubility of the test item at 20 °C was determined to be 43 g/L (SD = 1 g/L).

The octanol solubility of the test item was determined to be 0.029 g/L.

Calculation of the Partition Coefficients log P_ow from the Individual Solubilities

Saturation concentration of the test item in n-octanol: 0.029 g/L.

Saturation concentration of the test item in the aqueous phase: 43 g/L

The partition coefficient n-octanol/aqueous phase of the test item at 20 °C was determined to be: log P_ow = -3.2

Conclusions:

The log Pow was found to be -3.2.

Executive summary:

The partition coefficient n-octanol/water of the test substance was determined according to EU Method A.8 and OECD Guideline 107 in a non-GLP study via the solubility ratio. The solubilities of the test item in water and n-octanol was determined via HPLC with the flask-method. The P_ow was found to be -3.2.

Description of key information

The partition coefficient n-octanol/water of the test substance was determined according to EU mMethod A.8 and OECD Guideline 107 in a non-GLP study via the solubility ratio. The solubilities of the test item in water and n-octanol was determined via HPLC with the flask-method. The P_owwas found to be -3.2.

Key value for chemical safety assessment

Log Kow (Log Pow):

-3.2

at the temperature of:

20 °C