Leucophor 1111X

Endpoint summary

Additional information

APPEARANCE AND STATE

Leucophor 1111X is a pale-yellow powder at 20 °C and 1013 hPa; it is primarily manufactured/used as an aqueous solution, therefore the particle size is not relevant for Chemical Safety Assessment.

Melting and boiling point were investigated using the Differential Scanning Calorimetry (DSC) and Capillary methods. During DSC analysis, in the temperature range of 25 - 350 °C, a small endothermic effect was observed between 30 - 120 °C, which corresponds to a release of water of 4.5 %. A second endothermic signal is observed from 230 °C which corresponds to the decomposition of the test item. After the measurement the test item changed from yellow powder to brown powder. In the capillary analysis the test item did not show melting point under atmospheric pressure (1013 hPa). A change of visual aspect start at 230 °C, which confirm the decomposition temperature observed with DSC (Hasemann, 2016).

The density of Leucophor 1111 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 in the range of 2.8 E-042 to 9.4 E-050 mmHg, 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 1111X in water was determined by measurement of the test item concentration in the filtrated test solutions using photometry. In the pre-test, the solubility could be limited to the range of 10 – 50 g/l (visually observation). The main test was performed two times. In the first main test, the measured concentration of the test item in the solutions was approximately 110 g/l, therefore, the test was aborted as the test item was completely dissolved in water. A new test was performed with the highest possible nominal load of the test item in water 550 g/l. All filtrated test solutions showed a slight Tyndall effect (i.e. a laser beam was slightly scattered when transmitted through the liquid). At the plateau, the concentration of test item in water had reached 382.28 ± 58.75 g/l at 20.0 ± 0.5 °C and pH 8.68 -9. A reason for the difference between the results of the pre-test (range 10 - 50 g/l, visual observation) and the main test may be the secondary components in the test item which could have caused a false negative solubility of the test item (Affolter, 2016).

Leucophor 1111X 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 1111X.

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).

Leucophor 1111X is expected to be completely dissociated in the aquatic compartment and that the ionic species are stable. In acid pH conditions, the diethanolamine/ethanolamine functional groups on triazine rings are expected to be protonated.

PHYSICAL HAZARDS

Leucophor 11111X 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.