Registration Dossier
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EC number: 635-476-4 | CAS number: 88349-88-6
Hydrolysis
Administrative data
Link to relevant study record(s)
Description of key information
The hydrolytic stability of [14C]-cloquintocet acid was studied in buffered aqueous solution, under sterile conditions, at pH values of 4, 7 and 9. Solutions of aqueous buffers were prepared at pH 4, 7 and 9 at ca 50 °C and were sterilised by autoclaving. [14C]-cloquintocet acid (in acetonitrile ca 16 µL) was applied to glass vials containing buffer (3 mL) to achieve final concentrations of ca 2 μg/mL.
Duplicate incubation units were analysed immediately after treatment (0 DAT) and 5 days after treatment (5 DAT).
Radioactivity present in the test solution at each pH and sampling interval was determined by liquid scintillation counting (LSC). All samples were analysed for [14C]-cloquintocet acid by high performance liquid chromatography (HPLC) and selected samples were also analysed by LC-MS to confirm the identity of cloquintocet acid. The potential for adsorption of the test substance to glassware from buffer solutions was assessed prior to studying the hydrolytic stability.
Additional vials, treated with non-radiolabelled cloquintocet acid, were incubated concurrently with the test samples and were used to confirm pH and sterility at the end the incubation. Sterile conditions were maintained throughout the in-life phase of the incubation.
The recovery of radioactivity in buffer solutions in the adsorption test was 103 to 106% therefore there was no significant adsorption of cloquintocet acid to the vials.
Mean recovery of applied radioactivity in solution was 97 - 104% at each sampling interval.
At 50 °C, cloquintocet acid was hydrolytically stable at pH 4, 7 and 9 after incubation for 5 days with > 95% of applied radioactivity recovered as unchanged cloquintocet acid. There were minor degradation products detected at each pH (maximum 4%). Cloquintocet acid was hydrolytically stable for 5 days at 50 °C at pH values of 4, 7, and 9. In accordance with the guideline 10% hydrolysis at 50 °C over 5 days corresponds to a DT-50 of more than a year at 25 °C and for substances that hydrolyse less than this, no further testing is required.
Key value for chemical safety assessment
- Half-life for hydrolysis:
- 1 yr
- at the temperature of:
- 25 °C
Additional information
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