Disodium [6-[(2-anilino-1-naphthyl)azo]-2,4-dinitrophenolato(2-)][3-hydroxy-4-[(2-hydroxy-1-naphthyl)azo]naphthalene-1-sulphonato(3-)]chromate(2-)

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 July 19th to August 1st, 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

adopted in 1995

GLP compliance:

yes

Type of method:

flask method

Partition coefficient type:

octanol-water

Analytical method:

high-performance liquid chromatography

Type:

log Pow

Partition coefficient:

0.2

Temp.:

26.5 °C

pH:

ca. 7.7

Details on results:

To verify the accuracy of the analytical method two fresh prepared standard solutions in double distilled water (prepared with the test item) and two in acetonitrile were measured in between the samples of the shake-flask-method; the recovery rate of the measured standard solutions was in the range from 95.8 % to 101.4 %, which shows a good accuracy of the analytical method

PRELIMINARY TEST
Considering the water solubility of 88.5 g/l at 20 °C, determined in the specific study, and the solubility in octanol between 1.6 and 2.3 g/l, determined from the preliminary test, the partition coefficient was estimated to be between -0.7 and -1.1.

Results of the shake-flask-method

separating funnel	total amount of test item in the separating funnel (mg)	recovery rate (%)	Pow	log Pow
1a	136.62	102.0	2.19	0.3
1b	134.76	100.6	2.22	0.3
2a	151.13	112.8	1.73	0.2
2b	147.05	109.7	1.64	0.2
3a	143.00	106.7	0.89	0.0
3b	148.26	110.6	0.94	0.0
mean value				0.2
standard deviation				0.2

Concentrations in the octanol phases

separating funnel	measured concentration (mg/l)	mean concentration^*(mg/l)
1a	70.9 / 71.8	3567.2
1b	70.8 / 71.0	3544.2
2a	47.4 / 48.4	2394.4
2b	45.2 / 46.2	2284.6
3a	46.2 / 45.6	2293.2
3b	48.4 / 48.3	2417.4

* under consideration of the dilution factor 5

Concentrations in the aqueous phases

separating funnel	pH values^*	measured concentration (mg/l)	mean concentration^**(mg/l)
1a	7.6	162.7 / 163.6	1631.8
1b	7.7	157.9 / 161.4	1596.9
2a	7.7	138.4 / 138.4	1384.0
2b	7.5	138.0 / 140.4	1391.6
3a	7.7	256.2 / 256.5	2563.5
3b	8.1	256.2 / 259.5	2578.5

* at temperatures of 26.3 – 27.1 °C

** under consideration of the dilution factor 10

 

Conclusions:

log Pow: 0.2 at ca 26.5 °C and pH ca 7.7

Executive summary:

The partition coefficient of the test item was determined, in accordance with the method and procedures outlined into OECD guideline 107. The concentration in the aqueous and octanol phases was determined by HPLC-UV validate method. On the basis of the preliminary assay, the value of the partition coefficient was estimated to be between -0.7 and -1.1. Three experiments were carried out applying different solvent ratios.

Test temperature was 26 ± 1 °C.

An HPLC method using UV-VIS detection has been validated for the quantification of the test item in ultra-pure water, in n-octanol.The procedure was found to be suitable for the analysis.

The partition coefficient, log Pow, of test item resulted to be 0.2 ± 0.2 at ca 26.5 °C and pH ca 7.7.

Conclusion

log Pow: 0.2 ± 0.2 at ca 26.5 °C and pH ca 7.7

Description of key information

0.2 at ca 26.5 °C and pH ca 7.7

Key value for chemical safety assessment

Log Kow (Log Pow):

0.2

at the temperature of:

26.5 °C

Additional information

OECD 107 - shake-flask method