Disodium 4,5-dihydroxybenzene-1,3-disulphonate

Water solubility

Administrative data

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

11 Jun - 14 Jun 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2018

Report date:

2018

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Deviations:

yes

Remarks:

Loading of 2500 g/L was used instead of 5000 g/L (5-fold excess).

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method A.6 (Water Solubility)

Deviations:

yes

Remarks:

Loading of 2500 g/L was used instead of 5000 g/L (5-fold excess).

GLP compliance:

yes (incl. QA statement)

Remarks:

Landesmat für Umwelt Rheinland Pfalz, Mainz, Germany

Type of method:

flask method

Test material

Test material information

Constituent 1

Reference substance name:

Disodium 4,5-dihydroxybenzene-1,3-disulphonate

EC Number:

205-741-5

EC Name:

Disodium 4,5-dihydroxybenzene-1,3-disulphonate

Cas Number:

149-45-1

Molecular formula:

C6H6O8S2.2Na

IUPAC Name:

disodium 4,5-dihydroxybenzene-1,3-disulphonate

Test material form:

solid: particulate/powder

Results and discussion

Water solubility

Water solubility:

337.5 g/L

Conc. based on:

test mat.

Loading of aqueous phase:

2 500 g/L

Incubation duration:

22.3 h

Temp.:

20 °C

pH:

>= 1 - <= 2

Any other information on results incl. tables

Results

Measurements during Equilibration-

The data which was acquired during equilibration time (flask 1A-C, days 1 – 3) is presented in the following table:

Time [h](flask)	Temperature   [°C]	pH*	Dilution factor	Peak area   [mAU*min]	Measured values [g/L]	Difference to previous sample [%]
22.3 (1A)	20.1	1-2	500000	3.3860	327.80	-
				3.4993
46.1 (1B)	20.0	1-2	500000	3.3800	321.15	-2.0
				3.3615
70.2 (1C)	20.0	1-2	500000	3.3820	319.94	-0.4
				3.3335

* pH during equilibration phase was tested using indicator paper

As no rising tendency was observed between samplings at 22.3 h and 70.2 h (flask 1 - C), the plateau was considered reached and sampling of flasks 2-6 was performed.

Measurements at Plateau-

Flask	Temperature[°C]	pH*	Dilution factor	Peak area[mAU*min]	Measured values [g/L]
Blank	20.2	5-6	-	n.c.	<LOQ
				n.c.
2	20.0	1-2	500000	3.5140	336.07
				3.5502
3	19.9	1-2	500000	3.4828	332.15
				3.4967
4	20.0	1-2	500000	3.4402	330.51
				3.5039
5	20.1	1-2	500000	3.6183	342.14
				3.5772
6	20.0	1-2	500000	3.6814	346.84
				3.6159

* The pH value was measured with indicator pH paper, because there was too little filtered solution to measure it with the pH meter.

Results-

The measurements of flasks 2-6 were used for the calculation of the mean.

Flask	Concentration[g/L]	Total Mean[g/L]	Total Standard Deviation [g/L](Relative standard deviation[%])
2	336.1	337.5	6.9 (2.0)
3	332.2
4	330.5
5	342.1
6	346.8

*RSD = relative standard deviation

Mean at the plateau is 337.5 ± 6.9 g/L.

Results Discussion

The solubility of AF-378U in water was determined from the measured test item concentrations in the filtrated test solutions. Equilibration time can be considered as approx. 1 day (22.3 h), as the difference of less than 15 % in the concentrations and no upward tendency between the flasks 1A – 1C was observed. The test was finished on day 3. All replicates showed good correspondence. Standard deviation of the five flasks which were used for the calculation of water solubility (at the plateau) was 6.9 g/L, corresponding to a relative standard deviation of 2.0 %. The pH value was 1-2 in all five flasks, the test temperature was in the acceptable range with 19.9 – 20.1 °C over the test duration (measured in the liquid at sampling time points).

 

The water solubility of AF-378U was determined as:

337.5 ± 6.9 g/L at 20.0 °C  

(mean value ± standard deviation of five individual vessels)

 

No observations arousing doubts concerning the accuracy of the results and the validity of the study were made.

Deviations from the Study Plan

The following deviations from the study plan were documented:

(a) Instead of 10 mL of the solutions as provided in the study plan, only 5 mL solution was prepared in each case. Uncritical as the volume was sufficient to measure solubility.

(b) Flasks 2 - 6 were measured with the pH paper instead of pH meter. Uncritical, because in the guidelines the measurement is specified with pH paper and not with the pH meter.

 

Deviations from the Guideline

The following deviation from the Guideline was documented:

(a) Instead of the 5-fold excess of the test item specified in the guideline (here 5000 g/L), as described in the study plan, an initial sample weight of 2500 g/L was used. Uncritical as experience has shown that a sample quantity > 2500 g/L leads to suspensions which cannot be adequately shaken. Furthermore, the solubility of 337.5 g/L was far below that of 2500 g/L.