5-[[4-chloro-6-[(3-sulphophenyl)amino]-1,3,5-triazin-2-yl]amino]-4-hydroxy-3-[[4-[[2-(sulphooxy)ethyl]sulphonyl]phenyl]azo]naphthalene-2,7-disulphonic acid, sodium salt

Hydrolysis

Description of key information

 From the result of the pretest at pH 4 a half-life period at 25°C of ≥1 year can be estimated. From the result of the pretest at pH 9 and pH 11 a half-life period at 25°C of less than one day can be estimated.
A half-life of 6 days at 25°C was extrapolated from the results of the main test. 

Key value for chemical safety assessment

Half-life for hydrolysis:

6 d

at the temperature of:

25 °C

Additional information

The objective of this study was the determination of the abiotic degradation of the test substance (the main compound) under hydrolysis conditions according to guideline 84/449/EWG, appendix V, C. 10.;hydrolysis rate as a function of the pH-value.

The fate of the test substance at different pH (4, 7, 9, and 11) and temperatures was investigated.

From the result of the pre-test at 50°C at pH 4 a half-life period at 25°C of ≥1 year can be estimated. After 2.4 hours a slight decomposition of the ester dye was recognized; after 5 days, the degradation amounted to about 10.6% without clearly visible increase of another peak.

At pH 7 and 50°C, significant decomposition was observed. After 2.4 hours a clear increase of a peak with a retention time of 14.2 min ( SA 01 bis-vinyl) was found which was accompanied by a decrease of the ester dye in the same size. After 5 days only a main peak with a retention time of 17.4 min ( SA 01-OH) was found.

In the main test at pH 7 – at temperatures of 50, 60, and 70°C for up to 5.8, 2.5, and 0.67 hours, respectively – a half-life of 6 days was extrapolated for 25°C. The degradation of the ester dye at pH 7 and the different temperatures was accompanied by an increase of the peak with a retention time of ca. 14.5 min ( SA 01 bis-vinyl) and a slight increase of the peak with a retention time of ca. 17 min ( SA 01-OH).

The pre-test at 50°C at pH 9 and pH 11 led to a complete decomposition of the dye at both pH and time points. Due to the fact that the decomposition was higher than 50% after 2.4 hours at 50°C, no further experiments were carried out (in compliance with the test guideline) at pH 9 and pH 11. A half-life period of less than one day at 25°C was estimated based on this data.

At pH = 9.0, only one peak at a retention time of 17.4 min ( SA 01-OH) could be detected after 2.4 h. The ester dye was completely hydrolysed. After 5 days, no coloured components could be identified.

At pH = 11, at both time points only several peaks of decomposition products could be found.