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Description of key information

Substance half-life for hydrolysis: pH 5: t1/2: ca. 24 hours; pH 7: t1/2: ca. 24 hours; pH 8.5: t1/2: ca. 24 hours, at  40 °C, 1 atm, eq. or similar to OECD 111, Firmenich SA 2011

Key value for chemical safety assessment

Additional information

Eq. or similar to OECD TG 111 - preliminary screening study, 2011 - The hydrolytic stability of the test item was investigated using a method similar or equivalent to OECD TG 111 (hydrolysis as a function of pH) and EU Method A.7. The test media are standard aqueous buffers at pH 2, pH 5, pH 7, pH 8.5 and pH 12 containing 1% of non-ionic surfactant (Arkopal N 150). The tests are done in accelerated conditions at 40°C for approximately one month (28d). 200 – 300 ppm of test substance are dissolved in the pH buffer containing the surfactant and put into storage in an oven at 40°C. Commercial reference grades of buffer are utilised as listed in documented literature sources. Small aliquots of the test solution are extracted with an organic solvent (typically cyclohexane or ethyl acetate) containing a hydrocarbon standard (typically C12, C17 or C20) on a regular basis throughout the test (typically at time = 0, 0.25, 1, 2, 4, 7, 15, 21 and 28 days). The extracts are analysed by GC-FID. Under the analytical conditions employed (1) all isomers of methyl linolenate eluted together and (2) methyl oleate and the results were then plotted with time to show the degradation curves of the substance. For the isomers of methyl linolenate at pH 7 there is 50% degradation at 24 hours and complete degradation (> 90%) by 5d. At pH 8.5 the substance is degraded by 50% within 24 hours and there is complete degradation within 48 hours. At mildly acidic pH there is 50% degradation at < 72 hours and maximum degradation (> 80 %) at 15 days. For methyl oleate at pH 7 and 8.5 there is complete degradation (> 90%) within 5 days and with 50% degradation at between 72-96 hours. At pH 2 and 5 maximum degradation (ca. 80%) during the period of the test is seen at approximately 8 days. Applicant expert assessment indicates that it can be concluded that > 80% of the reaction mass of the test item looks to be degraded within 5 days. Assessment of the data on methyl linoleate isomers indicates: the substance follows first-order kinetics at acidic (t0.5 = ca. 72h) and for neutral pH and in alkali pH (t0.5 = approximately 24d). A change in mechanism moving from neutral pH to acidic conditions (with second-order kinetics) may be occurring however this is not conclusive. Under the conditions of the test the substance is not hydrolytically stable as defined in the OECD TG 111 for hydrolysis as a function of pH.