Registration Dossier

Environmental fate & pathways

Hydrolysis

Currently viewing:

Administrative data

Link to relevant study record(s)

Description of key information

Determination of the Abiotic Degradation of FAT 40858/A TE (Hydrolysis as a Function of pH)

Key value for chemical safety assessment

Additional information

In a preliminary test the test item was dissolved in aqueous solutions buffered at pH 4, 7 and 9 and incubated at 50 ± 0.5 °C for maximum of 5 days.

No significant reduction of the test item concentration was observed in the samples incubated at pH 4.

In the incubated samples at pH 7 a significant reduction of the test item concentration was observed.

In the incubated samples at pH 9 the test item degraded rapidly. No test item related signal could be found in the freshly prepared samples.

A main test was performed to determine the half-life time of FAT 40858/A TE at pH 7. No main test was performed at pH 4 and pH 9.

Amain test was performed in buffered solutions at pH 7. The test item was dissolved and incubated at 23°C, 40 °C and 50 °C.The concentration of the test item was determined as a function of time. The logarithms of the concentration relation (co/ct) were plotted against the time. A pseudo first order reaction was assumed. The correlation coefficients were calculated and the reaction constants and half lifes were calculated from regression data at each temperature.

For reaction at pH 7 the Arrhenius relationship was calculated based on data generated at 23, 40 and 50 °C. Logarithm of the rate constants were plotted against the reciprocal of the absolute temperature.
Following relation was found:

pH 7: ln k = - 11866 * 1/T + 36

Degradation Products: The UV-chromatograms showed several degradation products as signal eluting prior to the test item signal. In agreement with the sponsor, no identification of the metabolites was performed.

Conclusion:

The test item is stable at pH 4.

At pH 7, the test item is degraded by hydrolysis. The half life of reaction at 23 °C was determined to be 23 h at pH 7.

At pH 9 the test item is supposed to degrade immediately.