Reaction mass of disodium 2-({4-methyl-2-[(4-{[5-methyl-1-(2-sulfonatophenyl)hexan-3-yl]amino}-9,10-dioxo-9,10-dihydroanthracen-1-yl)methyl]pentyl}amino)benzene-1-sulfonate,disodium 4-{5-methyl-3-[(4-{[5-methyl-1-(4-sulfonatophenyl)hexan-3-yl]amino}-9,10-dioxo-9,10-dihydroanthracen-1-yl)amino]hexyl}benzene-1-sulfonate anddisodium 4-{5-methyl-3-[(4-{[5-methyl-1-(2-sulfonatophenyl)hexan-3-yl]amino}-9,10-dioxo-9,10-dihydroanthracen-1-yl)amino]hexyl}benzene-1-sulfonate

Partition coefficient

Link to relevant study record(s)

Reference

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

key study

Study period:

February 08, 2018 - February 23, 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

equivalent or similar to guideline

Guideline:

other: OECD 105

Deviations:

no

Principles of method if other than guideline:

OECD 105

GLP compliance:

no

Type of method:

flask method

Partition coefficient type:

octanol-water

Analytical method:

high-performance liquid chromatography

Key result

Type:

log Pow

Partition coefficient:

ca. -2.5

Temp.:

20 °C

Remarks on result:

other: pH not determined

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.

Table3: 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
4.1	100	100	~18	dissolved
50.1	10	10	~4	not dissolved
	40	50	1	not dissolved
	50	100	~17	not dissolved

According to this preliminary test the solubility of the test item in n-octanol was between 41 mg/L and 501 mg/L (without correction for the purity).

Calculation of the partition coefficient log P_OW from the preliminary test

The partition coefficient P_OW may be estimated from the saturation concentrations in n-octanol and water. The estimated partition coefficient was calculated with the water solubility data determined in project 20170230.04 (c_S ≥ 242 g/L). It was calculated to be: log P_OW < -2.7.

Due to the calculations the partition coefficient was estimated based on the ratio of the solubilities in water and n-octanol. The n-octanol solubility was determined using the flask method. The shake flask method and the HPLC method were not applicable due to the estimated low log P_OW and due to the salt content of the test item (see copy of the certificate of the test item).

Determination of the solubility in n-octanol: Flask method

The individual saturation solubility of the test item in n-octanol was performed within this study. After that, the partition coefficient was estimated based on the ratio of the test item solubility in n-octanol and water. The flask method was performed as described above. The data for the evaluation are given in Table4. The n-octanol solubility was calculated from the measured and unrounded concentration values and not from the rounded values given in Table4.

Table4: n-Octanol solubility experiments of the test item

Experiment	24 h experiment	48 h experiment	72 h experiment	168 h experiment	Blank experiment (72 h)
Amount of test item / mg	50.3	52.7	50.9	50.8	--
Amount of n-octanol / ml	20	20	20	20	20
Stirring time at 30 °C / h	24	48	72	168	72
Dilution factor	20	20	20	20	20
Measured concentration / mg/L	36.73 / 36.74	94.24 / 94.27	33.56 / 33.56	25.19 / 25.19	0.16 / 0.16
Mean concentration / mg/L	36.73	94.25	33.56	25.19	0.16
n-Octanol solubility/ g/L	0.74	(1.89)^[1]	0.67	0.51	0.003

[1]       According to the sample preparation for each experimentaliquots of the n-octanol phase were sampled after the corresponding stirring time and filtered over a 0.2 µm HPLC syringe filter. Except for the 48 h experiment the filtered solutions were coloured slightly blue. The filtrate of the 48 h experiment was coloured dark blue. Therefore the 48 h experiment is declared as a single outlier and is not taken into account for the results of the n-octanol solubility.

The solubility experiments showed a decreasing amount of the test item at increasing stirring time. This may result from instability of the test item in n-octanol. Therefore, as conservative approach the highest measured concentration was taken into account. Hence, the n-octanol solubility of the test item at 20 °C was determined to be ≥ 74 mg/L without correction of the purity.

Calculation of the partition coefficient log P_OWfrom the individual solubilities

In the project PS20170230-4 the water solubility of the test item at 20 °C was determined to be ≥ 242 g/L without correction of the purity. Within this project the n-octanol solubility of the test item at 20 °C was determined to be ≥ 74 mg/L. Although for different reasons but for both the water solubility and the n-octanol solubility of the test item only a range could be given as final result. Nevertheless the individual solubilities in water and n-octanol were in different orders of magnitude. Therefore the partition coefficient P_OW of the test item was determined to be approximately:

log P_OW ~ -2.5

Executive summary:

The partition coefficient (n-octanol/water) of the test item was estimated based on the ratio of the individual solubilities of the test item in water and n-octanol. The solubilities were determined according to the flask method.The shake flask method and the HPLC method were not applicable due to the low log P_OW and due to the salt content of the test item.

It was found to be approximately:

 

log P_OW ~ -2.5

Description of key information

The partition coefficient (n-octanol/water) of the test item was estimated based on the ratio of the individual solubilities of the test item in water and n-octanol. The solubilities were determined according to the flask method. The shake flask method and the HPLC method were not applicable due to the low log P_OW and due to the salt content of the test item.

It was found to be approximately: 

log P_OW ~ -2.5

Key value for chemical safety assessment

Log Kow (Log Pow):

-2.5

at the temperature of:

20 °C