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Environmental fate & pathways

Hydrolysis

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Reference
Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Study period:
from 2001-01-05 to 2001-11-27
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
test procedure in accordance with national standard methods with acceptable restrictions
Qualifier:
according to guideline
Guideline:
other: BBA Guideline Part IV Sect 5.1 - Degradation and Fate in a Water Sediment System
Version / remarks:
Dec 1990
Deviations:
not specified
Qualifier:
according to guideline
Guideline:
other: Commission Directive 95/36/EC 7.1.1.1.2 & 7.1.1.2.1
Version / remarks:
July 1995
Deviations:
not specified
Qualifier:
according to guideline
Guideline:
other: SETAC Procedures for Assessing the Environmental Fate and Ectoxicolgy of Pesticides
Version / remarks:
March 1995
Deviations:
not specified
GLP compliance:
yes
Specific details on test material used for the study:
Ring labelled 14C MCPP-P 2-EHE, radiochemical purity 100 %.
Batch No.: NXG 3087/3
Radiolabelling:
yes
Analytical monitoring:
yes
Details on sampling:
All samples were processed as soon as they were taken and were not stored prior to analysis.
At each sampling occasion, a single flask was removed from the constant temperature room and the pH, redox and oxygen content of the water was measured. The volume of the water was measured and aliquots taken for determination of radioactivity by LSC. The water was acidified (ca. pH 2) with hydrochloric acid and the resulting solution was partitioned against ethyl acetate. The volume of the ethyl acetate and the water phase was measured and aliquots were taken for determination of radioactivity by LSC. The stability of MCPP-P 2-EHE to acidification and partitioning with ethyl acetate was assessed and the compound was found to be stable.
Due to the low level of radioactivity present in the samples they were concentrated by rotary evaporation prior to analysis by HPLC.
Duration:
7 d
pH:
7.38
Temp.:
20 °C
Initial conc. measured:
0.19 µg/L
Positive controls:
not specified
Negative controls:
not specified
Transformation products:
yes
No.:
#1
No.:
#1
No.:
#1
% Recovery:
31.75
pH:
7.38
Temp.:
20 °C
Duration:
3.8 h
% Recovery:
16.41
pH:
7.38
Temp.:
20 °C
Duration:
16.9 h
% Recovery:
0
pH:
7.38
Temp.:
20 °C
Duration:
24.6 h
Key result
pH:
7.38
Temp.:
20 °C
DT50:
4.34 h
Type:
(pseudo-)first order (= half-life)

Measurements showed that the water in the flasks remained aerobic with an oxygen content > 60 % throughout the study. Throughout the study the overall recovery of radioactivity ranged from 101.45 % to 123.38 % with an overall mean of 111.3 %. It is important to note that due to the low level of radioactivity present in the whole sample (ca. 11000 dpm) small variations in the measured radioactivity had a significant effect on the percentage values. The recoveries on concentration of the ethyl acetate extracts ranged from 78 to 90 % of the applied radioactivity.

HPLC analysis of the extracts showed that degradation of MCPP-P 2-EHE started as soon as it was added to the natural water and by 24 hours all the MCPP-P 2-EHE was converted to MCPP-P acid.

Validity criteria fulfilled:
not specified
Remarks:
expected to be a valid source
Conclusions:
MCPP-P 2-EHE has a DT50 of 4.34 h and a DT90 of 9.99 h in natural water, and, therefore, is not stable and is unlikely to be persistent in natural water.
Executive summary:

In order to determine the hydrolysis of MCPP-P 2-EHE the behaviour of the substance in natural river water was investigated with radio labelled material. Water from a river in the UK was taken. Aqueous samples were taken over a 7 day period and following acidification, partitioning with ethyl acetate and concentration the samples were analysed by reverse phase HPLC. HPLC analysis of the extracts showed that MCPP-P 2-EHE was rapidly degraded in natural water to MCPP-P acid. The determined half-life of MCPP-P 2-EHE was 4.34 hours at pH 7.38 and 20 °C and, thus, it is not stable and unlikely that MCPP-P 2-EHE will be persistent in water.

Description of key information

MCPP-P 2-EHE has a DT50 of 4.34 h and a DT90 of 9.99 h in natural water, and, therefore, is unlikely to be persistent in natural water.

Key value for chemical safety assessment

Half-life for hydrolysis:
4.34 h
at the temperature of:
20 °C

Additional information

In order to determine the hydrolysis of MCPP-P 2-EHE the behaviour of the substance in natural river water was investigated with radio-labeled material [McGhee, 2001]. Water from a river in the UK was taken. Aqueous samples were taken over a 7 day period and following acidification, partitioning with ethyl acetate and concentration the samples were analysed by reverse phase HPLC. HPLC analysis of the extracts showed that MCPP-P 2-EHE was rapidly degraded in natural water to MCPP-P acid. The determined half-life of MCPP-P 2-EHE was 4.34 hours at pH 7.38 and 20 °C and, thus, it is not stable and unlikely that MCPP-P 2-EHE will be persistent in water.