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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:
20170801-20171124
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 111 (Hydrolysis as a Function of pH)
Qualifier:
according to guideline
Guideline:
EU Method C.7 (Degradation: Abiotic Degradation: Hydrolysis as a Function of pH)
GLP compliance:
no
Remarks:
conducted at the company internal.
Analytical monitoring:
yes
Remarks:
Digital Electronic Indictors + S.S.R. with PID automatic calculation capability
Buffers:
- Acetate buffer pH 4, 0.1 M: solution of 0.1 M acetic acid adjusted to pH 4 using 10 N sodium hydroxide. The buffer contains 0.002% (w/v) PREVENTAL BIT 20.
- Phosphate buffer pH 7, 0.1 M: solution of 0.1 M potassium dihydrogenphosphate adjusted to pH 7 using 10 N sodium hydroxide. The buffer contains 0.002% (w/v) PREVENTAL BIT 20.
- Borate buffer pH 9, 0.1 M: solution of 0.1 M boric acid and 0.1 M potassium chloride adjusted to pH 9 using 10 N sodium hydroxide. The buffer contains 0.002% (w/v) PREVENTAL BIT 20.
Duration:
168 h
pH:
4
Temp.:
20 °C
Initial conc. measured:
ca. 70 mg/L
Remarks:
HPLC test
Duration:
168 h
pH:
4
Temp.:
50 °C
Initial conc. measured:
ca. 70 mg/L
Remarks:
HPLC test
Duration:
168 h
pH:
7
Temp.:
20 °C
Initial conc. measured:
ca. 50 mg/L
Remarks:
UV test
Duration:
168 h
pH:
7
Temp.:
50 °C
Initial conc. measured:
ca. 65 mg/L
Remarks:
UV test
Duration:
168 h
pH:
9
Temp.:
20 °C
Initial conc. measured:
ca. 55 mg/L
Remarks:
HPLC test
Duration:
168 h
pH:
9
Temp.:
50 °C
Initial conc. measured:
ca. 60 mg/L
Remarks:
HPLC test
Number of replicates:
two
Positive controls:
yes
Negative controls:
yes
Statistical methods:
System control, data acquisition and data processing were performed using the following programme: Empower version 5.00 (Waters, Milford, MA, USA)
Transformation products:
no
% Recovery:
ca. 121
pH:
4
Temp.:
20 °C
Duration:
168 h
Remarks on result:
other: HPLC test
% Recovery:
ca. 123
pH:
4
Temp.:
50 °C
Duration:
168 h
Remarks on result:
other: HPLC test
% Recovery:
ca. 97.3
pH:
7
Temp.:
20 °C
Duration:
168 h
Remarks on result:
other: UVA test
% Recovery:
ca. 102
pH:
7
Temp.:
50 °C
Duration:
168 h
Remarks on result:
other: UVA test
% Recovery:
ca. 113
pH:
9
Temp.:
20 °C
Duration:
168 h
Remarks on result:
other: HPLC test
% Recovery:
103
pH:
9
Temp.:
50 °C
Duration:
168 h
Remarks on result:
other: HPLC test
pH:
4
Temp.:
20 °C
Hydrolysis rate constant:
-0 h-1
DT50:
443 d
Remarks on result:
other: HPLC test
pH:
4
Temp.:
50 °C
Hydrolysis rate constant:
-0 h-1
DT50:
361 d
Remarks on result:
other: HPLC test
pH:
7
Temp.:
20 °C
Hydrolysis rate constant:
-0 h-1
DT50:
117 d
Remarks on result:
other: UVA test
pH:
7
Temp.:
50 °C
Hydrolysis rate constant:
-0 h-1
DT50:
65 d
Remarks on result:
other: UV test
pH:
9
Temp.:
20 °C
Hydrolysis rate constant:
-0 h-1
DT50:
37.7 d
Remarks on result:
other: HPLC test
pH:
9
Temp.:
50 °C
Hydrolysis rate constant:
-0.001 h-1
DT50:
10 d
Remarks on result:
other: HPLC test

The result of pH 7 from HPLC is not reasonable due to the significant tailing effect. So recheck with UV test (SHIMADZU UV-2700,λ=429nm).


The mean recoveries of the buffer solutions at t=0 fell within the criterion range of 80-110%. It demonstrated that the analytical method was adequate to support the hydrolysis study on the test substance.

Validity criteria fulfilled:
yes
Conclusions:
According to OECD 111 and EC C.7 test method, the half-life time of Everlan SL65 at 20°C are 443 days, 117 days and 37.7 days respectively at pH=4, pH=7 and pH=9.
Executive summary:

This test using the procedures outlined in the Everlight Study Plan for 170302-09, OECD 111 (OECD, 2004) and EC C.7 (EC no. 440/2008).

 

In Main study, the mean recoveries of the buffer solutions at pH=4 and t=0 fell within the criterion range of 80 -120%. It demonstrated that the analytical method was adequate to support the hydrolysis study on the test substance. At pH=7, the mean recoveries of the buffer solutions at t=0 fell within the criterion range of 80-110%. At pH=9, the mean recovery of the buffer solutions at t=0 fell within the criterion range of 4.7 -110%. For testing of pseudo-first order kinetics the mean logarithms of the relative concentrations between 10% and 90% were plotted against time. At all temperatures linear relationships were obtained. The half-life times of the test substance were determined according to the model for pseudo-first order reactions. All logarithms of the relative concentrations were correlated with time using linear regression analysis. The rate constant (kobs) and half-life time of the test substance at each temperature was obtained and the Arrhenius equation was used to determine the rate constant and half-life time at 20°C.

 

According to OECD 111 and EC C.7 test method, the half-life time of Everlan SL65 at 20°C are 443 days, 117 days and 37.7 days respectively at pH=4, pH=7 and pH=9.

Description of key information

According to OECD 111 and EC C.7 test method, the half-life time of Everlan SL65 at 20°C are 443 days, 117 days and 37.7 days respectively at pH=4, pH=7 and pH=9.

Key value for chemical safety assessment

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

Additional information

This test using the procedures outlined in the Everlight Study Plan for 170302-09, OECD 111 (OECD, 2004) and EC C.7 (EC no. 440/2008).

 

In Main study, the mean recoveries of the buffer solutions at pH=4 and t=0 fell within the criterion range of 80 -120%. It demonstrated that the analytical method was adequate to support the hydrolysis study on the test substance. At pH=7, the mean recoveries of the buffer solutions at t=0 fell within the criterion range of 80-110%. At pH=9, the mean recovery of the buffer solutions at t=0 fell within the criterion range of 4.7 -110%. For testing of pseudo-first order kinetics the mean logarithms of the relative concentrations between 10% and 90% were plotted against time. At all temperatures linear relationships were obtained. The half-life times of the test substance were determined according to the model for pseudo-first order reactions. All logarithms of the relative concentrations were correlated with time using linear regression analysis. The rate constant (kobs) and half-life time of the test substance at each temperature was obtained and the Arrhenius equation was used to determine the rate constant and half-life time at 20°C.

 

According to OECD 111 and EC C.7 test method, the half-life time of Everlan SL65 at 20°C are 443 days, 117 days and 37.7 days respectively at pH=4, pH=7 and pH=9.