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Environmental fate & pathways

Hydrolysis

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Description of key information

In a study according to OECD test guideline 111 under GLP, the registered substance was slightly hydrolytically instable with a half life of 352 days at 20°C and pH 7. Adjusting to an average EU outdoor temperature of 12°C, the half-life was calculated to be 453 days at pH 7 (mean half-life from three temperatures). 

Key value for chemical safety assessment

Half-life for hydrolysis:
453 d
at the temperature of:
12 °C

Additional information

Hydrolysis as a function of pH was determined according to OECD Guideline No. 111 and Council Regulation (EC) No. 440/2008, Method C.7 for the registered substance (batch number: S700040031) from 2010-05-26 to 2010-07-14 atDr.U.Noack-Laboratorien, Sarstedt, Germany.

For pH 4, 7 and 9 a 5 day (preliminary) testing at 50 °C was performed. During this testing no hydrolysis was observed for the pH 4 samples. With respect to the guideline a half life of > 1 year could be assumed for the test item at pH 4 and environmental typical temperatures. For the other pH values the definitive testing was performed. The definitive testing was conducted with a test item concentration of 10 mg/L in buffer solutions of pH 7 and 9 at temperatures of 20, 30 and 50 °C, respectively. For pH 7 and 9 samples were taken at test start (0 h) and at least 8 spaced points until end. Buffer solutions were analysed at test start and test end and there was no analytical interference with the test item.

Analyses of the test item were performed via LC-MS on a reversed phase column for the formain components (2 EO, 3 EO, 4 EO and 5 EO). The method was validated with satisfactory results in regard to linearity, repeatability of injection, accuracy and specificity.

Reaction rate constants and half lives were calculated from the analysed concentrations and are presented in Table 1. The registered substance is seen to be slightly hydrolytically instable at pH 7, 20 °C and 30 °C and hydrolytically instable at pH 7, 50°C and pH 9, with increasing instability to higher pH and higher temperature. The slope of the regression graphs for the pH 7, 20 °C test conditions was not significantly different from zero, thus these results should be treated with respect to the high uncertainty of the evaluated data.

Reaction Rate Constants and Half Lives

pH4 pH 7 pH9

preliminary test
 50 °C


20 °C


30 °C


50 °C


20 °C


30 °C


50 °C

Reaction rate constantkobs
[1/s]

Stable,
half life of > 1 year
at environmental typical temperatures

2.28 x
10-8

7.10 x
10-8

8.25 x
10-7

1.77 x
10-6

6.65 x
10-6

4.78 x
10-5

Half lifeT½[h]

8454

2711

233

109

28.9

4.03

Half lifeT½[d]

352

113

9.72

4.54

1.20

0.17