Pentasodium 2,2'-((2,4-diamino-5-(4-methoxy-2-sulfophenylazo)-1,3-phenylene)bis(azo))bis(5-(2-(sulfonatooxyethyl)sulfonyl)benzenesulfonate

Partition coefficient

Link to relevant study record(s)

Reference

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From June 29, 2006 to July 07, 2006

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:

yes (incl. QA statement)

Type of method:

shake-flask method to: flask method

Partition coefficient type:

octanol-water

Analytical method:

high-performance liquid chromatography

Key result

Type:

log Pow

Partition coefficient:

< -7.3

Temp.:

20 °C

Remarks on result:

other: pH not determined

Details on results:

Octanol solubility of the test substance (average of three experiment and without correction of purity): <8.23 µg/L
The saturation concentration of the test substance in water was determined by means of the flask method in project '20060234.02' to 145.8 g/L (without correction for the purity).
From the individual solubilities the log Pow was calculated to be <-7.3.

Preliminary Visual Estimation of the n-Octanol Solubility

An amount of the test substance was stirred with increasing amounts of n-octanol at room temperature.

 

Table: Appearance of the test mixtures 

Amount of the test substance in mg	Total volume in mL	Stirring time (h)	Appearance of mixture	Solubility (mg/L)
11.07	100	0.83	undissolved
	200	1.17	undissolved
	300	0.58	undissolved
	500	0.5	undissolved
	750	0.5	undissolved
	1000	17.42	undissolved	< 11.07

 

The solubility of the test item in n-octanol was below 11.07 mg/L(without correction for the purity).

 

Calculation of the Partition Coefficient log Pow from the preliminary tests

The partition coefficient was calculated as log Pow lower than -4.12. Due to this fact the partition coefficient n-octanol/water of the test substance at ambient temperature had to be estimated by the flask method (individual solubilities).

 

Calculation of the Partition Coefficient log Pow from the individual solubilities

Table: Octanol solubility of the test substance - experiments A to D  

Experiment	A	B	C	D (blank)
Amount of test substance (mg)	3.27	2.98	3.69	-
Stirring time at 20°C (h)	24	24	24	24
Aliquot (mL)	10	10	10	10
End volume (mL)	2	2	2	2
Measured concentration (µg/L)	<41.131 <41.13	<41.131 <41.13	<41.131 <41.13	-
Mean concentration (µg/L)	<41.13	<41.13	<41.13	-
Octanol solubility (µg/L)	<8.23	<8.23	<8.23	-

  

Average experiments A to C (without correction for the purity): <8.23µg/L

The saturation concentration of the test substance in water was determined by means of the flask method in project '20060234.02' to 145.8 g/L (without correction for the purity).

From the individual solubilities the log Pow was calculated to be <-7.3.

 

Concentrations of standards for recheck

 

Standard	Measured concentration (Mg/L)	%Recovery
Standard J (c=41.13 µg/L)	39.86/139.52	96.5
Standard K (c=122 µg/L)	117.0/115.4	94.6

 

Recoveries of the standards ranged from 94.6% to 96.5%, indicating a good accuracy of the analytical method.

Conclusions:

Under the study conditions, the partition coefficient n-octanol/water of the test substance at room temperature, performed according to the flask method (individual solubilities in water and n-octanol), was determined to be <-7.3.

Executive summary:

The partition coefficient of the test substance was determined according to the flask-shaking method. Samples were prepared in aqueous and n-octanol phases. After sample preparation, the concentration of the test substance was determined by HPLC.

The saturation concentration of the test substance in water was determined to be 145.8 g/L and the octanol solubility (µg/L) was found to be <8.23. Under the study conditions, the partition coefficient n-octanol/water of the test substance at room temperature, performed according to the

flask method (individual solubilities in water and n-octanol), was determined to be <-7.3.

Description of key information

The partition coefficient n-octanol/water of the test substance at room temperature was determined to be <-7.3 (Moller, 2006).

Key value for chemical safety assessment

Log Kow (Log Pow):

-7.3

at the temperature of:

20 °C