Z-85

Hydrolysis

Description of key information

In accordance with Annex VIII Column 2 specific rules for adaptation from Column 1,the assessment of hydrolytic stability was not performed due to the low water solubility of the test substance (0.26 mg/L) in addition to the substance being readily biodegradable. A substance specific method able to detect a decrease of 10% in concentration at approximately half the water solubility saturation could not be developed.

Additional information

No determination was carried using Method C7 of Commission Directive 92/69/EEC and Method 111 of the OECD Guidelines for Testing of Chemicals, 13 April 2004 for the following reasons:

 

1. The test material is essentially insoluble in water.  Although a value of less than 0.260 mg/l was obtained, this value was deemed to be a significant overestimate (see the water solubility section of this report). Methods C7 and 111 state that they are only applicable to water soluble substances. A calculated value of water solubility gave a result of less than 4.197 x 10-6 mg/l. Testing at half this value is deemed unfeasible. At the levels which the test would be undertaken, it would not be possible to detect down to 10% material remaining due to the high limits of detection.
2.  The test material is a mixture. Methods C7 and 111 are not really applicable to mixtures as the monitoring of individual components may prove difficult.
3. Recoveries of analyses could not be performed at any concentration less than 0.1 mg/l. With a concentration step, this level was deemed the limit of detection. If testing was performed, it would have to be at an increased level than that specified in the guidelines. Any results obtained may therefore be inaccurate.
4. The only suitable recovery of analysis procedure was by freeze-drying. The problem with freeze-drying with this test material is that high volumes are required. Freeze-drying is a relatively slow process. If the test material did undergo hydrolysis, it is likely that the degradation would continue throughout sample treatment thus giving erroneous results based on the speed of the freeze-drying process.
5. The test material contains ester functionalities. Although testing was deemed inapplicable, it was deemed appropriate to include an estimate of hydrolytic stability using specialist chemical estimation software. Using HYDROWIN version 1.67, © 2000 U.S. Environmental Protection Agency, the half-life was predicted to be 15.8 days at pH 8 and 158 days at pH 7.