Hydrogen [4-[4-(p-ethoxyanilino)-4'-[ethyl(m-sulphonatobenzyl)amino]-2'-methylbenzhydrylene]-3-methylcyclohexa-2,5-dien-1-ylidene](ethyl)(m-sulphonatobenzyl)ammonium, monosodium salt

Partition coefficient

Link to relevant study record(s)

Reference

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2014

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method A.8 (Partition Coefficient)

Deviations:

no

GLP compliance:

no

Type of method:

flask method

Partition coefficient type:

octanol-water

Analytical method:

other: UV vis

Key result

Type:

log Pow

Partition coefficient:

-2.55

Temp.:

20 °C

Remarks on result:

other: pH is not available

Key result

Type:

Pow

Partition coefficient:

0.003

Temp.:

20 °C

Remarks on result:

other: pH not specified

Details on results:

None

Individual Results

Preliminary Visual Estimation of the n-octanol solubility

10 mg of the test item were stirred with different amounts of n-octanol at room temperature and visually checked for any undissolved particles.

Table: Appearance of the test mixtures

Amount of test item in mg	Volume in ml	Total volume in ml	Stirring time	Appearance of mixture
10	10	10	60 min	undissolved
10	20	20	60 min	dissolved
10	30	30	60 min	dissolved

According to this preliminary test the solubility of the test item in n-octanol is above 500 mg/l (without correction of the purity).

Calculation of the partition coefficient log Pow from the preliminary tests

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

P ow = cs octanol /cs water

s= saturation

With the data obtained from the experiments (cs > 500 mg/l) and in the preliminary test (water solubility: cs = 171 g/l) the partition coefficient was calculated as log POW < -2.5.

Due to the fact, that the n-octanol solubility is nearly the LoQ, the partition coefficient n-octanol/water has to be estimated from the individual solubilities in water and n-octanol.

Determination of the solubility in the n-Octanol phase: Flask Methods

Table: Solubility of the test item –experiments A to D

Experiment	A	B	C	D (blank)
Amount of test item (mg)	1000	1000	1000	-
Stirring time at 30°C (h)	24	48	72	72
Aliquot of the flasks (ml)	0.025	0.025	0.025	0.025
End volume (ml)	10	10	10	10
Measured concentration (μg/ml)	1.1	1.4	1.1	-
Solubility (mg/l)	440	560	440	-

Average: 480 mg/l

Table: Concentrations of the standards for recheck:

Standard	Measured concentration (μg/ml)	% Recovery
Standard 2 (c= 0.60 μg/ml)	0.62	103.3
Standard 3 (c= 0.90 μg/ml)	0.93	103.3
Standard 5 (c= 1.50 μg/ml)	1.49	99.3

Recovery range from 99.3 % to 103.3 % indicates a sufficient accuracy of the analytical method.

Calculation of the partition coefficient log Pow from the individual solubilities

By means of the flask method, the saturation concentration of the test item in n-octanol was determined to: 480 mg/l.

By means of the flask method, the saturation concentration of the test item in water was determined to: 171 g/l

Based on the above findings, the partition coefficent n-octanol/water of the test item at 20°C, from the individual solubilities in water and n-octanol, was determined to:

log P ow = - 2.55, Pow = 0.002807

Conclusions:

The n-octanol/water partition coefficient was determined to be: log Pow = - 2.55.

Executive summary:

The partition coefficient n-octanol/water of the test item was evaluated in a study conducted according to OECD Guideline 107 and OECD 117, as well as EU method A.8. Based on the individual solubilities of the test item in n-octanol and water at 20 °C, the n-octanol/water partition coefficient was determined to be: log Pow = - 2.55.

Description of key information

The partition coefficient n-octanol/water of the test item at 20 °C, calculated from the individual solubility in water and n-octanol, was determined to: log Pow = - 2.55.

Key value for chemical safety assessment

Log Kow (Log Pow):

-2.55

at the temperature of:

20 °C

Additional information

The partition coefficient n-octanol/water of the test item was evaluated in a study conducted according to OECD Guideline 107 and OECD 117, as well as EU method A.8. Based on the individual solubility of the test item in n-octanol and water at 20 °C, the n-octanol/water partition coefficient was determined to be: log Pow = -2.55.