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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:
2014
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 111 (Hydrolysis as a Function of pH)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.7 (Degradation: Abiotic Degradation: Hydrolysis as a Function of pH)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Radiolabelling:
no
Analytical monitoring:
not specified
Details on sampling:
The test item solutions were prepared by adding 1 mL of a 4016 mg/L spike solution into an 100 mL volumetric flask and accurately filled up with the buffer solutions. Under argon atmosphere about 4.0 mL of the test item solutions were given into several crimped vials. The concentration did not
exceed half saturation concentration.
Buffers:
The test was carried out at three different pH values: 4.0, 7.0 and 9.0. For this purpose, buffer solutions were prepared using reagent grade chemicals and deionized water. Applicable buffer systems are described in the Appendix of OECD guideline 111 or BBA Merkblatt Nr.55, Teil I. The citrate buffer pH 4, the phosphate buffer pH 7 and the borate buffer pH 9 were prepared in a concentration of 0.05 M on the basis of the undissociated acids. The pH value of the buffer solutions used during the test were determined with a calibrated pH meter at the selected temperature with a precision of 0.1 pH units.

Details on test conditions:
The test was carried out using a thermostatically controlled water bath at +/- 0.5 °C of the chosen temperature. The temperature was kept and measured to within +/- 0.1 °C. Photolytic interference was avoided. All suitable precautions were taken to exclude dissolved oxygen (bubbling the buffer with argon for five minutes before preparing the test solution).
Duration:
120 h
pH:
4
Temp.:
50 °C
Initial conc. measured:
>= 20.3 - <= 21.4 mg/L
Duration:
120 h
pH:
7
Temp.:
50 °C
Initial conc. measured:
>= 40.2 - <= 42.4 mg/L
Duration:
120 h
pH:
9
Temp.:
50 °C
Initial conc. measured:
>= 40.6 - <= 44.1 mg/L
Number of replicates:
4 at each pH-value
Positive controls:
not specified
Negative controls:
not specified
Preliminary study:
A preliminary test was performed at 50 +/- 0.5 °C at three pH values: 4.0, 7.0 and 9.0. A sufficient number of measurements were made, in order to be able to estimate whether for each pH value and at 50 °C, the half-life time (t1/2) is less than 10 % of hydrolysis after 120 hours. These values correspond to a half-life time higher than one year under conditions more representative of those of the environment (25 °C).
Transformation products:
not measured
% Recovery:
>= 92.4 - <= 93.2
pH:
4
Temp.:
50 °C
Duration:
120 h
% Recovery:
>= 97.7 - 99
pH:
7
Temp.:
50 °C
Duration:
120 h
% Recovery:
>= 101 - <= 102
pH:
9
Temp.:
50 °C
Duration:
120 h
pH:
4
Temp.:
25 °C
DT50:
> 1 yr
Type:
(pseudo-)first order (= half-life)
pH:
7
Temp.:
25 °C
DT50:
> 1 yr
Type:
(pseudo-)first order (= half-life)
pH:
9
Temp.:
25 °C
DT50:
> 1 yr
Type:
(pseudo-)first order (= half-life)
Details on results:
No significant changes of the content in the samples were observed. At pH 4, 7 and 9 less than 10 % of the test item were hydrolysed within 120 hours at 50 °C.

Table 1: Time course of FAT 40045/Z TE concentration at pH 4 at 50 °C (analysis at 342 nm)

Time

Determined content

of FAT 40045/Z TE in sample

Actual concentration

[h]

[mg/L]

in % of initial conc.

0

21.4

100

120

19.8

92.4

Table 2: Time course of FAT 40045/Z TE concentration at pH 4 at 50 °C (analysis at 668 nm)

Time

Determined content

of FAT 40045/Z TE in sample

Actual concentration

[h]

[mg/L]

in % of initial conc.

0

20.3

100

120

18.9

93.2

Table 3: Time course of FAT 40045/Z TE concentration at pH 7 at 50 °C (analysis at 342 nm)

Time

Determined content

of FAT 40045/Z TE in sample

Actual concentration

[h]

[mg/L]

in % of initial conc.

0

42.4

100

120

42.0

99.0

Table 4: Time course of FAT 40045/Z TE concentration at pH 7 at 50 °C (analysis at 668 nm)

Time

Determined content

of FAT 40045/Z TE in sample

Actual concentration

[h]

[mg/L]

in % of initial conc.

0

40.2

100

120

39.2

97.7

Table 5: Time course of FAT 40045/Z TE concentration at pH 9 at 50 °C (analysis at 342 nm)

Time

Determined content

of FAT 40045/Z TE in sample

Actual concentration

[h]

[mg/L]

in % of initial conc.

0

40.6

100

120

41.4

102

Table 6: Time course of FAT 40045/Z TE concentration at pH 9 at 50 °C (analysis at 668 nm)

Time

Determined content

of FAT 40045/Z TE in sample

Actual concentration

[h]

[mg/L]

in % of initial conc.

0

44.1

100

120

44.6

101

Validity criteria fulfilled:
yes
Conclusions:
It can be assumed that the degradation of FAT 40045/Z TE was less than 10 % at pH 4, pH 7, pH 9 at 50 °C over a period of 120 hours. Therefore the corresponding half-life time at 25 °C can be estimated to be longer than one year.
Executive summary:

A study was performed to measure the abiotic degradation of FAT 40045/Z TE as a function of pH in aqueous solution according to OECD guideline 111 and EC method C.7(440/2008). It was shown that the hydrolysis of FAT 40045/Z TE is negligible within the pH range relevant for natural environments (pH 4 to pH 9). The half-life times at pH 4,7 and 9 are expected to be above one year at 25 °C in each case. Because the test item is stable to hydrolysis no further hydrolysis tests are necessary. The degradation of FAT 40045/Z TE was less than 10 % at pH 4, pH 7, pH 9 at 50 °C over a period of 120 hours. Therefore the corresponding half-life time at 25 °C can be estimated to be longer than one year.

Description of key information

A study was performed to measure the abiotic degradation of FAT 40045/Z TE as a function of pH in aqueous solution according to OECD guideline 111 and EC method C.7(440/2008). It was shown that the hydrolysis of FAT 40045/Z TE is negligible within the pH range relevant for natural environments (pH 4 to pH 9). The half-life times at pH 4,7 and 9 are expected to be above one year at 25 °C in each case. Because the test item is stable to hydrolysis no further hydrolysis tests are necessary. The degradation of FAT 40045/Z TE was less than 10 % at pH 4, pH 7, pH 9 at 50 °C over a period of 120 hours. Therefore, the corresponding half-life time at 25 °C can be estimated to be longer than one year.

Key value for chemical safety assessment

Half-life for hydrolysis:
1 yr
at the temperature of:
25 °C

Additional information