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Description of key information

The stability of the substance was determined according to the OECD guideline 111 and the EU method, C. 7 (Currenta, 2009). Based on kinetic parameters, the following dissipation half-lives for a temperature of 25 °C were extrapolated based on the Arrhenius equation:
pH 4 (25 °C): > 1 year
pH 7 (25 °C): 573 days
pH 9 (25 °C): 15 days.

Key value for chemical safety assessment

Additional information

The hydrolysis behaviour of the substance was assessed in a study conducted to a high standard, in full compliance with all three tiers of the OECD guideline 111 and the EU method C.7. The kinetic parameters were followed using a HPLC/UV method. As the substance is a NLP containing different molecular weight fractions (= NLP-fraction) which were not completely individually identified, half-life determinations were calculated for six main NLP-fractions representing 96 % of the test item. The stability of the test item is found to decrease with increasing pH-value. At pH 4 and 50 °C the substance is found to be stable. Therefore it can be assumed that the substance is also stable at 25 °C and no half-life time and hydrolysis rate were calculated. The half-life time for the substance at pH 7 is 573 days and at pH 9 is 15 days, both at 25 °C.  

As the hydrolysis reaction of a NLP is very complex, resulting in a sum of hydrolysis products, a clear identification of the hydrolysis products is complicated. The NLP molecules having different chain lengths even at the different carboxylic acid groups within the same molecule and may hydrolyse following different reaction kinetics. Shorter chain molecules could be already part of the NLP and could also be newly built by hydrolysis of longer chain molecules. These shorter chains may hydrolyse also.