Reaction mass of sodium 3-[[4-[(4-ethoxy-m-tolyl)azo]-1-naphthyl]azo]benzenesulphonate and sodium 3-[[4-[(4-ethoxyphenyl)azo]-1-naphthyl]azo]benzenesulphonate

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 from 02 to 21, 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:

1995

GLP compliance:

yes

Type of method:

flask method

Partition coefficient type:

octanol-water

Analytical method:

high-performance liquid chromatography

Type:

Pow

Partition coefficient:

16.68

Temp.:

24 °C

pH:

6.3 - 6.7

Type:

log Pow

Partition coefficient:

1.2

Temp.:

24 °C

pH:

6.3 - 6.7

Details on results:

PRELIMINARY TEST
The water solubility of the test item was determined in the specific study to be 0.44 g/l at 20 °C.
The preliminary test at room temperature showed that the octanol solubility of the test item was < 0.0818 g/l.
With the determined solubility in water of 0.44 g/l and 1-octanol from these preliminary tests, the partition coefficient log POW can be estimated to be between -0.077 and -1.099

MAIN TEST

To verify the accuracy of the analytical method two fresh prepared standard solutions for both phases (prepared with the test item) were measured in between the samples of the shake-flask-method. The recovery rate of the measured standard solutions was in the range from 109.2 % to 109.5 %, which shows a good accuracy of the analytical method.

Separating funnel	Total amount of test item in the separating funnel (mg)	recovery rate (%)	POW	log POW
1a	1.65	85.4	22.17	1.3
1b	1.65	85.4	20.51	1.3
2a	1.72	89.1	17.62	1.2
2b	1.72	89.3	17.00	1.2
3a	1.74	90.0	11.10	1.0
3b	1.74	90.4	11.69	1.1
mean value			16.68	1.2
standard deviation			4.12	0.1

Concentrations in the aqueous phases

Separating funnel	pH values	Measured concentration (mg/l)	Mean concentration (g/l)
1a	6.27	3.29 / 3.52	3.41
1b	6.49	3.59 / 3.74	3.66
2a	6.52	2.25 / 2.37	2.31
2b	6.62	2.34 / 2.45	2.39
3a	6.66	3.63 / 3.85	3.74
3b	6.56	3.54 / 3.62	3.58

Concentrations in the octanol phases

separating funnel	Measured concentration (mg/l)	Mean concentration (g/l)
1a	75.85 / 75.25	75.55
1b	75.20 / 75.02	75.11
2a	40.52 / 40.85	40.68
2b	40.88 / 40.53	40.71
3a	41.60 / 41.48	41.54
3b	41.73 / 41.88	41.81

Conclusions:

log Pow: 1.2 ± 0.1 at 24 °C and pH 6.3 - 6.7

Executive summary:

The partition coefficient of the test item was determined by means of the shake-flask-method, according to OECD Test Guideline 107 (1995). A preliminary test was conducted to determine the suitable method. The preliminary test at room temperature showed that the octanol solubility of the test item was < 0.0818 g/l. With the determined solubility in water of 0.44 g/l and 1-octanol from these preliminary tests, the partition coefficient log Pow can be estimated to be between -0.077 and -1.099

After adding the different amounts of stock solution, pre-saturated double distilled water and pre-saturated 1-octanol, the funnels were shaken for approx. 10 minutes in a shaking apparatus. After shaking the phases were allowed to separate in the funnels. Subsequently, 10 ml of each phase were centrifuged for 30 minutes at 20 °C and 15000 rpm. The pH values of all water phases were measured.

The partition coefficient (log Pow) of the test item was determined at 24 °C (pH 6.3 – 6.7) to be 1.2 ± 0.1.

To verify the accuracy of the analytical method two fresh prepared standard solutions for both phases (prepared with the test item) were measured in between the samples of the shake-flask-method. The recovery rate of the measured standard solutions was in the range from 109.2 to 109.5 %, which shows a good accuracy of the analytical method.

Conclusion

log Pow: 1.2 ± 0.1 at 24 °C and pH 6.3 - 6.7

Description of key information

log Pow: 1.2 ± 0.1 at 24 °C and pH 6.3 - 6.7

Key value for chemical safety assessment

Log Kow (Log Pow):

1.2

at the temperature of:

20 °C

Additional information

OECD 107 - shake-flask method