2-Naphthalenesulfonic acid, 7-amino-4-hydroxy-3,8-bis[[4-[[2-(sulfooxy)ethyl]sulfonyl]phenyl]azo]-, trisodium salt

Water solubility

Link to relevant study record(s)

Reference

Endpoint:

water solubility

Type of information:

experimental study

Remarks:

ordered in 2017

Adequacy of study:

key study

Study period:

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:

yes (incl. QA statement)

Remarks:

GLP certificat is included with the study report

Type of method:

flask method

Key result

Water solubility:

298 g/L

Conc. based on:

test mat.

Loading of aqueous phase:

500 g/L

Incubation duration:

> 48 - <= 72 h

Temp.:

20 °C

Remarks on result:

completely miscible

Findings:

1.1     Measurements during Equilibration

The data which was acquired during equilibration time (flask 1A-C, days 1 – 4) is presented in the following table:

Table‎8.1‑a      Equilibration

Day	Flask	pH*	Temperature [°C]	Peak area [mAU*min]	Dilution factor	Concentration [g/L]**	Difference to previous sample
1	1A	5.00	19.6	141.6410	5000	291.80
				141.6734
2	1B	5.03	19.8	140.6670	5000	289.88	-0.7
				140.7380
3	1C	5.01	19.7	148.1563	5000	305.40	5.4
				148.6467

*Measurement with pH Paper is not possible because the solutions were too colour-intensive for this reason the pH meter was used. Moreover, due to the high viscosity and the small volume of filtrate only the pH-measurement of the diluted sample (1/100) was possible. 

**From the measurements of the freshly prepared QC sample a sensitivity correction factor of 95.8% was applied.

1.1     Measurements at Plateau

The test item concentration was determined from the twofold measurements of flasks 2 - 6. All measured values are shown in‎6.6.2. A mean solubility of 297.89 g/L with standard deviation of 6.10 g/L was measured (relative standard deviation of 2.0 %).

 

Table‎8.2‑a      Plateau

Flask	2	3	4	5	6
pH*	5.05	5.19	5.14	5.13	5.00
Temperature	19.7	19.7	19.8	19.6	19.8
Measured values (Peak area in [mAU*min])	145.1113	149.1348	144.2313	142.9925	141.3605
	145.6700	149.4914	144.3442	143.4356	140.9762
Dilution factor	5000
Test item Concentration [g/L**]	299.33	307.24	297.11	294.94	290.82

*Due to the high viscosity and the small volume of filtrate only the pH-measurement of the diluted sample (1/100) was possible. 

**From the measurements of the freshly prepared QC sample a sensitivity correction factor of 95.8% were applied

Conclusions:

The solubility of the test item Blendazol Red Blendwell in water was determined by measurement of Blendazol Red Blendwell concentration in the filtrated test solutions using HPLC method, the test substance blendazol Red is soluble in water
The concentration of Blendazol Red Blendwell in water had reached 298,89 g/L with a standard deviation of 6.10 g/L at at 20.0 ± 0.4 °C

Executive summary:

According to the guideline, the flask method was used for the determination of the solubility of the test item in water.

The sameloading rate 500 g/L was chosen for all flasks.

Three flasks 1A - C were used during equilibration.

Seven vessels (flasks blank, 1C (for the sampling point 72 h) and 2 – 6) were set onto the shaking apparatus immediately. After 24 ± 2 hours, flask 1B (for the sampling point 48 h) and after 48 ± 2 hours, flask 1A (for the sampling point 24 h) were set on the shaker and all flasks were shaken for further 24 ± 2 hours at room temperature (20.0 ± 0.5 °C). Then, flasks 1A - 1C were taken from the shaker, samples were taken, centrifuged, membrane filtered and analysed. No rising tendency in the test item concentration of the solutions were observed. Equilibrium was considered as reached at least after 1 d after test start.

Tyndall effect (i.e. a laser beam was scattered when transmitted through the liquid) could not be tested because the solutions were too colour-intensive.

At the plateau, the concentration ofBlendazol Red Blendwellin water had reached

 

297.89 ± 6.10 g/L at 20.0 ± 0.4 °C

= 297.89 ± 6.10  kg/m³(SI units)

 

(mean value ± standard deviation of five individual vessels)

 

Description of key information

The concentrations of Blendazol Red Blendwell were determined with a HPLC method. Method and sample preparation are fully described in Validation Report VB17031402G926.

see analytical methods

1.1     Results

1.1.1   Table

All measurements of flasks 2 – 6 were included in the calculation of the mean.

Table‎8.3‑a      Measurements used for Calculation of Solubility

Day	Flask	Concentration [g/L]	Total Mean [g/L]	Total Standard Deviation [g/L] (RSD* [%])
3	2	299.33	297.89	6.10 (2.0)
3	3	307.24
3	4	297.11
3	5	294.94
3	6	290.82

*RSD = relative standard deviation

 

Mean at the plateau is 297.89 g/L±6.10 g/L

Key value for chemical safety assessment

Water solubility:

298 g/L

at the temperature of:

20 °C

Additional information

Findings and Results:

 The solubility of the test itemBlendazol Red Blendwellin water was determined by measurement ofBlendazol Red Blendwellconcentration in the filtrated test solutions using HPLC method.

In the pre-test solubility was estimated to lie in the range 100 – 200 g/L. Therefore flasks with nominal concentrations 500 g/L and 1000 g/L were prepared and shaken at room temperature. The mixture with 1000 g/L was not filterable. For this reason a Flask with nominal load 715 g/l was prepared. The mixtures with 500 and 715 g/L were shaken for
1 d and measured forBlendazol Redafter centrifugation, membrane filtration (0.45 µm, nylon) and dilution. The flasks showed concentrations329.7and259.4g/L. Because the higher nominal load showed a lower concentration in the filtrate, low filterability or incomplete wetting of the mixture with nominal load 715 g/L was assumed.

Therefore a pre-test for wettability and filterability of the test item – water mixtures was performed. 500 g/L was the highest possible load.A nominal load corresponding to at least 5fold excess, as proposed in the guideline, could not be applied.

No further tests for dependency of solubility on amount of the test item (nominal load) were performed because of the low wettability and poor filterability of the test item. The highest possible nominal load was chosen for the main test.

According to the guideline, the flask method was used for the determination of the solubility of the test item in water.

The sameloading rate 500 g/L was chosen for all flasks.

Three flasks 1A - C were used during equilibration.

Seven vessels (flasks blank, 1C (for the sampling point 72 h) and 2 – 6) were set onto the shaking apparatus immediately. After 24 ± 2 hours, flask 1B (for the sampling point 48 h) and after 48 ± 2 hours, flask 1A (for the sampling point 24 h) were set on the shaker and all flasks were shaken for further 24 ± 2 hours at room temperature (20.0 ± 0.5 °C). Then, flasks 1A - 1C were taken from the shaker, samples were taken, centrifuged, membrane filtered and analysed. No rising tendency in the test item concentration of the solutions were observed. Equilibrium was considered as reached at least after 1 d after test start.

Tyndall effect (i.e. a laser beam was scattered when transmitted through the liquid) could not be tested because the solutions were too colour-intensive.

At the plateau, the concentration ofBlendazol Red Blendwellin water had reached

 

297.89 ± 6.10 g/L at 20.0 ± 0.4 °C

= 297.89 ± 6.10  kg/m³(SI units)

 

(mean value ± standard deviation of five individual vessels)