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Environmental fate & pathways

Hydrolysis

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Description of key information

Hydrolysis, as a function of pH, EU Method C.7: hydrolytically stable compound (at pH 4, 7 and 9) and the half-life at 25 °C will be greater than 1 year 

Key value for chemical safety assessment

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

Additional information

The potential of the test substance to hydrolyse under environmental conditions was investigated according to OECD Guideline 111 under certificated GLP compliance (Tarran, 2012). The test substance was dissolved in an aqueous solution at pH 4, 7 and 9 and incubated in the dark at 50 +/- 0.5 °C. The concentration of the test item is determined as a function of time. The estimation of the half-life at 25 °C for any single pH was determined by the use of the Arrhenius relationship. The test substance was diluted to 25 mL with acetonitrile (MeCN). This solution was diluted by a factor of 100 in pH 4, 7 and 9 buffers, resulting in a concentration of 501 mg/L. Concerning pH 4 and 7, the preliminary experiment over a period of 5 days was sufficient to conclude, that the substance is stable at ambient temperature, since the half-lifes will be greater than 1 year, respectively. A further test was required at pH 9, since approximately 10 % hydrolysis after 5 days occurred at 50 °C, however, variability in the results from the 24 and 48 h timepoints indicated higher hydrolysis rates. In the Tier 2 testing, the sample solutions (diluted to 10 mL with MeCN, concentration of 506 mg/L) were maintained at the same temperature for a period of 7 days. Since less than 10 % hydrolysis was observed after this testing period, also at pH 9 the substance can be regarded as hydrolytically stable at ambient temperature. As less than 10 % hydrolysis occurred after five days, no further testing to determine the rate constants was performed.