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Environmental fate & pathways

Hydrolysis

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Description of key information

The hydrolysis rate of the test substance (diflufenzopyr) was determined at 1 ppm concentration in pH 5.0, pH 7.0, and pH 9.0 buffered aqueous solutions at 25 °C. The hydrolysis rate was 0.0538 ± 0.0038 day-1 at pH 5.0, 0.0290 ± 0.0011 day-1 at pH 7.0 and 0.0270 ± 0.0015 day-1 at pH 9.0. Thus the half-life of the test substance's hydrolysis was determined to be 12.9 days at pH 5.0, 23.9 days at pH 7.0 and 25.6 days at pH 9.0.

Key value for chemical safety assessment

Half-life for hydrolysis:
23.9 d
at the temperature of:
25 °C

Additional information

The hydrolysis rate of the test substance (diflufenzopyr) was determined at 1 ppm concentration in pH 5.0, pH 7.0, and pH 9.0 buffered aqueous solutions at 25 °C (duration 30 days) according to EPA Pesticide Assessment Guidelines, Subdivision N, Chemistry: Environmental Fate, Section 161-1, October 18, 1982. The test substance hydrolyzed more rapidly in pH 5 buffer solution; about 17 % remained unchanged at day 31. The hydrolysis rate decreased in pH 7 buffered solution; approximetely 37 % remaining unchanged at day 31. The hydrolysis rate of the test substance in pH 7 and pH 9 buffered solution were similar with approximately 40 % of test substance remaining unchanged in pH 9 buffer solution at day 31.

The hydrolysis rate was 0.0538 ± 0.0038 day-1 at pH 5.0, 0.0290 ± 0.0011 day-1 at pH 7.0 and 0.0270 ± 0.0015 day-1 at pH 9.0. Thus the half-life of hydrolysis was determined to be 12.9 days at pH 5.0, 23.9 days at pH 7.0 and 25.6 days at pH 9.0.

TLC analysis detected a total of 8 radiocarbon spots (hydrolysis degradation products). These were compared to model degradation products for identification purposes via HPLC/MS analysis.