3-(diethylamino)-7-imino-7H-[1]benzopyrano[3',2':3,4]pyrido[1,2-a]benzimidazole-6-carbonitrile

Water solubility

Link to relevant study record(s)

Reference

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

December 20, 2017 - April 06, 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method A.6 (Water Solubility)

Deviations:

no

GLP compliance:

no

Type of method:

column elution method

Key result

Water solubility:

11 µg/L

Conc. based on:

test mat.

Loading of aqueous phase:

1.03 g/L

Temp.:

20 °C

pH:

> 5.6 - < 5.9

Preliminary    test

In a stepwise procedure, increasing volumes of demineralized water were added at room temperature to a defined amount of the test item. After each addition of an amount of water the mixture was treated with ultrasound for 10 minutes and visually checked for any undissolved particles.

Table4: Results of the preliminary test

Amount of test item / mg	Added volume of demineralized water / mL	Total volume of demineralized water / mL	Appearance of mixture
102.7	0.1	0.1	Dry red powder, not dissolved
	0.4	0.5	Cloudy solution, particles, not dissolved
	0.5	1.0	not dissolved
	1.0	2	not dissolved
	8.0	10	not dissolved

Three additional preliminary tests were carried out with specified amounts of the test item and 100 mL and 500 mL demineralized water, respectively. After each addition of an amount of water, the mixture was stirred for at least 24 hours, and visually checked for any undissolved particles.

Table5: Results of the preliminary test

Amount of test item / mg	Total volume of demineralized water / mL	Appearance of mixture
11.7	100	Red coloured solution with particles
10.5	500	Particles stuck at the agitator and swam on surface
3.0	500	Particles stuck at the agitator and swam on surface

The preliminary test showed that the water solubility of the test item is < 10 mg/L. According to the preliminary test the water solubility was determined by the column elution method in the main test.

Column elution method

103.0 mg of the test item were dissolved in 100 mL tetrahydrofuran using the ultrasonic bath. For charging the columns in each case 25 mL of the test item solution was added to about 3 g of sea sand and the mixtures were shaken. The solvent was then removed under reduced pressure using a rotary evaporator (40 °C, approx. 30 mbar). The dry residues were placed into the columns of the test apparatus, which have afterwards been filled with water (test temperature: 20 °C; water pH at 23 °C: 5.5). After a swelling time of 2 h pumps were started to rinse the test item coated sand with demineralized water. At the end of the study it was confirmed that residual test item remained on the columns. The residual test item was eluted with 50 mL THF. As blank value the used demineralized water was tested. No signal was detected in the range of the retention time of the test item. The concentration of the test item was quantified by HPLC. Refer to Table6 to Table8 for results.

Column 1:

Rotation period of the fraction collector:                 90 min per fraction

Duration of sampling:                                             about 71 h (47 fractions)

Table6: Column elution method, column 1 (approximately 12.5 mL/h)

Fraction no.	V / mL	pH	water solubility /µg/L
40	19.0	5.6	12.99
41	19.0	5.7	13.80
42	19.0	5.8	9.16
43	19.5	5.9	9.00
44	19.5	5.7	9.88

The water solubility was found to be 11.00 µg/L.

Column 2:

Rotation period of the fraction collector:       45 min per fraction

Duration of sampling:                                    about 66 h (88 fractions)

Table7: Column elution method, column 2 (approximately 25.0 mL/h)

Fraction no.	V / mL	pH	water solubility /µg/L
83	17.3	5.8	10.14
84	16.7	5.6	10.74
85	16.7	5.9	12.30
86	16.0	5.9	12.22
87	15.3	5.9	10.25

The water solubility was found to be 11.1 µg/L.

In the second column the concentration of five consecutive fractions was constant within ± 30 %. No increasing or decreasing tendency was observed. The first column showed a variation of the measured concentration of 35%. As for column 1, seven additional analyzed fractions (fraction 22-27) were also in the range of 9.5 mg/L to 14.6 mg/L, the variation of >30% had no influence on the final results of the water solubility experiment. The results of the first and second column were in the same order of magnitude.

Coating check:

Table8: Coating check

	Amount of test item used for coating / mg	Measured concentration of test item in eluate / mg/L	Amount of test item eluted / mg
Column 12.5 mL/h	25.8	0.360 / 0.361	18.0
Column 25.0 mL/h		0.344 / 0.344	17.2

The coating check was successful. Enough test item remained on the columns.

The water solubility c_S of the test item Disperse Red 277 was 11.1 µg/L (mean value of the columns).

Executive summary:

The water solubility c_S of the test item Disperse Red 277 at a temperature of 20 °C was determined according to the column elution method. It was found to

c_S = 0.011 mg/L

Description of key information

The water solubility c_S of the test item Disperse Red 277 at a temperature of 20 °C was determined according to the column elution method. It was found to

c_S = 0.011 mg/L

Key value for chemical safety assessment

Water solubility:

0.011 mg/L

at the temperature of:

20 °C