reaction mass of Benzenesulfonic acid, 2,2'-(1,2-ethenediyl)bis[5-[[4-[bis(2- hydroxyethyl)amino]-6-(phenylamino)-1,3,5-triazin-2-yl]amino]-, disodium salt and Benzenesulfonic acid, 5-[[4-[bis(2-hydroxyethyl)amino]-6-(phenylamino)-1,3,5-triazin-2-yl]amino]-2-[2-[4-[[4-[(2-hydroxyethyl)amino]-6-(phenylamino)-1,3,5-triazin-2-yl]amino]-2-sulfophenyl]ethenyl]-, disodium salt

Endpoint summary

Additional information

APPEARANCE AND STATE

Leucophor 1501X is a yellow powder at 20 °C and 1013 hPa; it is primarily marketed/used in a non solid or granular form, therefore the particle size is not relevant for Chemical Safety Assessment.

During the DSC analysis neither melting point, nor boiling point was recorded up to 480 °C; at 95.0 ± 0.8 °C evaporation of crystal water was observed. The signal recorded at about 480 °C has been attributed to decomposition.

The density of Leucophor 1501 X is approximately 1 g/cm³ at room temperature.

Based on the physicochemical properties of the substance, the experimental measurements of properties like vapour pressure (estimated 0.000000001 Pa, at 25 °C),surface tension, flash point can be avoided, while viscosity determination is technically not feasible.

SOLUBILITY and PARTITION COEFFICIENT

The solubility of Leucophor 151X in water was determined by measurement of the test item concentration in the filtrated test solutions using photometry. The main test was performed two times. All filtrated test solutions showed no Tyndall effect (i.e. a laser beam was not scattered when transmitted through the liquid). At the plateau, the concentration of substance in water had reached 67.28 ± 4.24 g/l at 20.0 ± 0.5 °C and pH ca 9 (Affolter, 2016).

Leucophor 1501X is a Stilbene Fluorescent Whitening Agents salt, which is a class of compounds known to be water-soluble, based on the characteristically chemical structure and the functional groups. The sulphonate and the hydroxyl substituent groups contribute to the hydrophilicity of the substance.

The test item is also expected to possess a greater affinity with the water phase than the octanol one, leading to a negative partition coefficient log Kow. As many salts and as many Stilbene Fluorescent Whitening Agents, a negative partition coefficient can be considered as representative for the substance under investigation.

This conclusion can be supported by the outcomes of the partition coefficient investigation performed on the similar substance 01. The test item is very water soluble (i.e. > 608 g/l), as Leucophor 1501X.

During the preliminary test, a very good solubility in water and a poor solubility in n-octanol were found indicating a partition coefficient below -2. Hence, a main test according to testing Guidelines (either HPLC or flask shaking method) could not be applied. Therefore the partition coefficient of the test item was estimated using the solubility data in n-octanol (as obtained in the preliminary test) and in water (Weissenfeld, 2005).

Under environmental conditions, Leucophor 1501X dissociates completely in water.

PHYSICAL HAZARDS

Leucophor 1501X does not ignite and propagate combustion; the screening evaluation failed to evidence reasons of concern, on the basis of the chemical structure analysis and the thermal behaviour investigation.

It does not meet the criteria to be considered as flammable/explosive/oxidising.

READ ACROSS APPROACHES

All the substances used in a read across approach are Stilbene derivatives Fluorescent Whitening Agents salts. They display similar structural and physicochemical properties: all of them exhibit a comparable thermal behaviour; furthermore they present high degree of dissociation in water and very low octanol/water partition coefficients because to a higher affinity with water phase than the octanol one. They are all very soluble in water, due to the presence of sulphonated groups in the molecules.

The common starting compound and the similar treatment let to expect that all the analogues would be characterized by a comparable impurity profile. Residues of salification, water and by-product(s) from manufacturing process can be present in variable percentage ranges. The impurity profile is not expected to significantly impact the physicochemical properties.

The read across approach can be considered as reliable and representative; the differences occurring in the structure formulas (i.e. substituents) are expected to not significantly impact the physical and chemical characterisation.

Further details about the justification for read across approach are given in the report attached to the Section 13 of this dossier.