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Hydrolysis

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Description of key information

Hydrolysis (6h, pH 1.6, 37 °C): 94.00 %

Hydrolysis (8h, pH 1.6, 37 °C): 99.3 %

Hydrolysis (5 days, 50 °C): at pH 7 - 9.6 %; at pH 4 - 96 %; at pH 9- 98 %.

Half time at 25 °C: > 1 year (pH 7), 12 days (pH 4, pH 9)

Key value for chemical safety assessment

Half-life for hydrolysis:
1 yr
at the temperature of:
25 °C

Additional information

The hydrolysis profile of the substance was evaluated in different conditions.

The hydrolysis of the rate under pH simulated gastric conditions (pH 1.6, at 37 °C, under dark and sterile conditions) was evaluated in function of time. The aim was to evaluate the time necessary for the parent substance to be hydrolysed at least for 90% and to assess the hydrolysis’ products formation. At properly defined time (0, 0.3, 1, 1.5, 2, 4, 6, 8 h) an amount of each hydrolysis sample was collected and tested, using ad hoc developed methods, in order to determine the concentration of the parent substance and plot a kinetic curve of hydrolysis.

A quantitative analysis of the main hydrolysis products was done followed by a qualitative analysis in order to evaluate whether other substances are formed.

The parent substance was hydrolysed almost completely after 6 h (94 %), while after 8 h a hydrolysis rate of 99.3 % was found.

Half-time of the reaction (time for 50% of the compound to react): 1.126934 h

Similar substance 05 is the main degradation product, followed by Similar Substance 04 and Similar Substance 06.

The hydrolysis of the substance at pH 4, 7 and 9 was evaluated based on data on Similar Substance 01. Justification for Read Across is given in Section 13 of IUCLID.

The rate of hydrolysis of the test material was evaluated according to the OECD Guideline 111, EU method C.7 and OPPTS 835.2120. During the preliminary study the test substance solutions were prepared in the buffer solutions (pH 4, 7 and 9) and placed in the dark in a temperature-controlled environment at 49.9 °C ± 0.1 °C. The concentration of the test substance in the test samples was determined immediately after preparation (t=0) and after 5 days. Blank buffer solutions were treated similarly as the test samples and analysed at t = 0 and the pH of each of the test solutions (except for the blanks) was determined at each sampling time.

The substance was hydrolysed by 96 %, 9.6 % and 98 % at pH 4, pH 7 and pH 9 respectively. Since the substance is hydrolytically stable only in pH 7, test samples were prepared and treated similarly as during the preliminary test for the pH 4 and 9, at temperatures 20 °C, 50 °C and 60 °C. The concentrations of the test substance were determined immediately after preparation (t=0) and at several sampling points after t=0. The mean recoveries of the test substance containing buffer solutions at t=0 fell within the criterion range of 90-110 % in the preliminary and main study.

During the preliminary study a degree of hydrolysis of ≥ 10 % was observed at pH 4 and pH 9 after 5 days and < 10 % was observed at pH 7 after 5 days. It demonstrated that the half-life time of the test substance at pH 7 at 25 °C is > 1 year.

The half-time of the substance at 25 °C at pH 4 and pH 9 is 12 days.

The substance seems to hydrolyse in a great extend at pH 1.6, 4 and 9, while in a neutral pH no hydrolysis is expected.