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Environmental fate & pathways

Hydrolysis

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Description of key information

The half-life of MDIPA-Esterquat C16-18 and C18 unsatd. at 20 (measured/extrapolated), 25 (extrapolated), 50 (measured) and 60 (measured) °C was determined to be

for pH4: >30 / 64.5, 41.3, 4.5, 1.8 days

for pH7: >30 / 28.5, 10.1, 3.4, 1.7 days

for pH9: 84/46.5, 31.2, 4.2, 1.9 days

Key value for chemical safety assessment

Half-life for hydrolysis:
28.5 d
at the temperature of:
20 °C

Additional information

The hydrolysis of MDIPA-Esterquat C16-18 and C18 unsatd. was tested according to OECD Guideline 111. Hydrolysis was examined by measurement of the concentration decrease of the test substance by HPLC-MS with mass-spectroscopic determination of the mixed C16/C18 esterquat cation.

For pH 4 and 20, 50 and 60 °C the half-life is reported to be > 30, 4.5, 1.8 days (calculated directly from measurement at the corresponding temperature).

For pH 7 and 20, 50 and 60 °C the half-life is reported to be > 30, 3.4, 1.7 days (calculated directly from measurement at the corresponding temperature).

For pH 9 and 20, 50 and 60 °C the half-life is reported to be 84, 4.2, 1.9 days (calculated directly from measurement at the corresponding temperature).

For 20 °C but not for 50 and 60 °, the measurements have a high statistical variance. The calculated rate constants resp. the slopes for the pseudo-first order curve correlate well with measurements for 50 and 60 °C but not for 20 °C: coefficients of correlation for 20 °C for pH 4, 7, 9 are 0.0330, 0.518, 0.339 whereas for 50 and 60 ° these coefficients of correlation are in the range of 0.835 to 0.984.

For measurements at 20 °C pH 4 and 7, the calculated rate constants suggests an increase of test substance. To bypass statistically questionable numbers for the half-life from measurements at 20 °C, the Arrhenius equation is used to calculate these numbers from measurements at 50 and 60 °C:

pH 4, 20 and 25 °C, half-lifes 64.5 and 41.3 days

pH 7, 20 and 25 °C, half-lifes 28.5 and 20.1 days

pH 9, 20 and 25 °C, half-lifes 46.5 and 31.2 days.