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Hydrolysis

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Description of key information

Hydrolytically unstable as per OECD 111. The half-life time of the substance is < 10 minutes at pH 7 and pH 9, and < 5 minutes at pH 4 @ 25 deg. C.

Key value for chemical safety assessment

Half-life for hydrolysis:
10 min
at the temperature of:
25 °C

Additional information

Study was performed by using OECD 111 in accordance with GLP. However, as the substance is hydrolytically unstable it was not possible to perform the test as outlined in the guidelines. In order to obtain as much information on hydrolysis as possible, an alternative test was designed. The hydrolytic stability was tested in buffered aqueous solutions at pH 4.0, 7.0, and 9.0 at 25 °C for 40 minutes. The progress of the hydrolysis was followed by monitoring alcohol, the main degradation product; octyl alcohol isomers. Additionally, the formation of a white precipitation was observed during the hydrolysis study. This is most likely due to the formation of the insoluble titanium oxides. No other degradation products were identified.

The response of the hydrolysis productoctyl alcohol isomers was > 99% (area).In the chromatograms, small additional peaks were observed at 12.03 minutes (at pH 4) and 12.13 minutes, all 1% at the specific mass fragments monitored. The additional peaks might derive from impurities in the test substance and/or hydrolysis products.

To achieve sufficient sensitivity for the analysis of the identified hydrolysis product, selected ion monitoring was used as detection method. Therefore it was not possible to obtain accurate information on the mass fraction of the unknown peaks or to record their entire mass spectrum, and hence it was not possible to identify these additional peaks.

The hydrolysis half -life time for the substance was < 5 minutes at 25 deg. c and at pH 4, and < 10 minutes at pH 7 and 9, respectively.

The results of this study are considered reliable to be used for C&L purposes to conclude this substance to be hydrolytically unstable releasing only octyl alcohol isomers (Exxal 8; alcohols, C7-9-iso, C8-rich) and hydrated titanium dioxide when in contact with water. Based on the results this substance can be considered as rapidly degradable.

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