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Hydrolysis

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Reference
Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
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)
Version / remarks:
OECD Guidelines for the Testing of Chemicals no. 111: “Hydrolysis as a Function of pH", April 13, 2004;
Deviations:
yes
Remarks:
Any deviations from standard operating procedures (SOPs) were evaluated and filed in the study file. There were no deviations from SOPs that affected the integrity of the study.
Principles of method if other than guideline:
List of study plan deviations
1. During the hydrolysis main study at pH 4 and pH 7 (20°C), the variation in temperature was 0.7°C which exceeds the criterion of 0.5°C. As the plot of the logarithm of the relative concentration as a function of time yielded a linear line, this was considered acceptable.
2. During the hydrolysis main study at pH 4 and pH 7 at 20°C, samples were taken within the hydrolysis range of 10% and 90% but samples proved not stable during storage in the freezer. As a results, stored samples had to be excluded for determination of hydrolysis rate and half-life time. Sufficient results however remained to calculate hydrolysis rate and halflife time accurately.
3. During the hydrolysis main study at pH 9 at 40°C, less than six sampling points (i.e. four points) were taken within the hydrolysis range of 10% and 90%. This was due to rapid hydrolysis. The runtime of the analytical method is 4.5 minutes (including time needed for injection and needle wash), thus the analysis of a duplicate sample takes 9 minutes. This limited the sampling rate.
4. The mean accuracy of the storage stability of the samples was 112% for the low concentration and 113% for the high concentration. This was only slightly outside the criterion of 70-110%. The mean accuracies were even slightly higher than for the freshly analysed samples. Based on this, it was safely concluded that samples are stable in the freezer.
The study integrity was not adversely affected by the deviations.
GLP compliance:
yes
Remarks:
All phases of the study performed by the test facility were conducted in compliance with OECD Principles of GLP. Exception: The test item characterization information supplied by the sponsor was produced under the sponsor's quality system.
Specific details on test material used for the study:
Test item storage: At room temperature
Stable under storage conditions: until 16 September 2017 (expiry date)
Batch No.: 0900243308
Radiolabelling:
no
Analytical monitoring:
yes
Buffers:
Acetate buffer pH 4, 0.1 M: solution of 16.7% 0.1 M sodium acetate in water and 83.3% 0.1 M acetic acid in water. The buffer contains 0.0009% (w/v) sodium azide.
Phosphate buffer pH 7, 0.1 M: solution of 0.1 M potassium di-hydrogenphosphate in water adjusted to pH 7 using 10 N sodium hydroxide. The buffer contains 0.0009% (w/v) sodium azide.
Borate buffer pH 9, 0.1 M: solution of 0.1 M boric acid in water and 0.1 M potassium chloride in water adjusted to pH 9 using 10 N sodium hydroxide. The buffer contains 0.0009% (w/v) sodium azide.
Details on test conditions:
pH 4
Temperature I: 20.1°C +/- 0.7°C
Temperature II: 50.3°C +/- 0.2°C
Temperature III: 60.2°C +/- 0.2°C
pH 7
Temperature I: 20.1°C +/- 0.7°C
Temperature II: 40.2°C +/- 0.2°C
Temperature III: 50.3°C +/- 0.0°C
pH 9
Temperature I: 20.2°C +/- 0.2°C
Temperature II: 30.2°C +/- 0.1°C
Temperature III: 40.1°C +/- 0.0°C
Duration:
264.45 h
pH:
4
Temp.:
20 °C
Initial conc. measured:
9.92 mg/L
Remarks:
Test 1
Duration:
792.05 h
pH:
4
Temp.:
20 °C
Initial conc. measured:
10.7 mg/L
Remarks:
Test 2
Duration:
458.17 h
pH:
4
Temp.:
50 °C
Initial conc. measured:
9.99 mg/L
Duration:
191.12 h
pH:
4
Temp.:
60 °C
Initial conc. measured:
9.81 mg/L
Duration:
213.38 h
pH:
7
Temp.:
20 °C
Initial conc. measured:
10.9 mg/L
Remarks:
Test 1
Duration:
791.7 h
pH:
7
Temp.:
20 °C
Initial conc. measured:
10.7 mg/L
Remarks:
Test 2
Duration:
48.12 h
pH:
7
Temp.:
40 °C
Initial conc. measured:
11 mg/L
Duration:
21.52 h
pH:
7
Temp.:
50 °C
Initial conc. measured:
10.9 mg/L
Duration:
21.98 h
pH:
9
Temp.:
20 °C
Initial conc. measured:
10.5 mg/L
Duration:
2.68 h
pH:
9
Temp.:
30 °C
Initial conc. measured:
9.84 mg/L
Duration:
0.97 h
pH:
9
Temp.:
40 °C
Initial conc. measured:
9.18 mg/L
Number of replicates:
For determination of the hydrolysis rate at 20°C at pH 4 and pH 7, a first test had to stopped after 429.60 hours (pH 4) and 333.13 hours (pH 7) since temperature dropped significantly. Therefore a second test was performed and the results of Test 1 till the temperature dropped and of Test 2 were combined.
Statistical methods:
Calibration curve
The calibration line was constructed using all data points. There was a linear relationship between response and test item concentration in the range of 0.100 – 12.0 mg/L (in end solution). Since the coefficient of correlation (r) was > 0.99 and the back calculated accuracies of the data points were in the range 85-115% the calibration line was accepted.
Preliminary study:
The results of the preliminary test showed that the test item was much more stable at pH 4 than at pH 7 and pH 9.
Transformation products:
no
Remarks:
Research to investigate the identity or nature and rates of formation and decline of hydrolysis products was not required since the studies were conducted according to the testing guidelines provided in Annex VIII (volume 10-100 tons/year).
% Recovery:
99
pH:
4
Temp.:
20 °C
Duration:
264.45 h
Remarks on result:
other: Test 1
% Recovery:
107
pH:
4
Temp.:
20 °C
Duration:
792.05 h
Remarks on result:
other: Test 2
% Recovery:
100
pH:
4
Temp.:
50 °C
Duration:
458.17 h
% Recovery:
98
pH:
4
Temp.:
60 °C
Duration:
191.12 h
% Recovery:
110
pH:
7
Temp.:
20 °C
Duration:
213.38 h
Remarks on result:
other: Test 1
% Recovery:
106
pH:
7
Temp.:
20 °C
Duration:
791.7 h
Remarks on result:
other: Test 2
% Recovery:
110
pH:
7
Temp.:
40 °C
Duration:
48.12 h
% Recovery:
109
pH:
7
Temp.:
50 °C
Duration:
21.52 h
% Recovery:
105
pH:
9
Temp.:
20 °C
Duration:
21.98 h
% Recovery:
98
pH:
9
Temp.:
30 °C
Duration:
2.68 h
% Recovery:
92
pH:
9
Temp.:
40 °C
Duration:
0.97 h
pH:
4
Temp.:
20 °C
Hydrolysis rate constant:
0.001 h-1
DT50:
32 d
Type:
(pseudo-)first order (= half-life)
Remarks on result:
other: All logarithms of the relative concentrations were correlated with time using linear regression analysis.
pH:
4
Temp.:
25 °C
Hydrolysis rate constant:
0.001 h-1
DT50:
22 d
Type:
(pseudo-)first order (= half-life)
Remarks on result:
other: All logarithms of the relative concentrations were correlated with time using linear regression analysis and the Arrhenius equation was used to determine the rate constant and half-life time at 25°C.
pH:
4
Temp.:
50 °C
Hydrolysis rate constant:
0.007 h-1
DT50:
4.2 d
Type:
(pseudo-)first order (= half-life)
Remarks on result:
other: All logarithms of the relative concentrations were correlated with time using linear regression analysis.
pH:
4
Temp.:
60
Hydrolysis rate constant:
0.013 h-1
DT50:
2.2 d
Type:
(pseudo-)first order (= half-life)
Remarks on result:
other: All logarithms of the relative concentrations were correlated with time using linear regression analysis.
pH:
7
Temp.:
20 °C
Hydrolysis rate constant:
0.008 h-1
DT50:
83 h
Type:
(pseudo-)first order (= half-life)
Remarks on result:
other: For testing of pseudo-first order kinetics the mean logarithms of the relative concentrations between 10% and 90% were plotted against time. All logarithms of the relative concentrations were correlated with time using linear regression analysis.
pH:
7
Temp.:
25 °C
Hydrolysis rate constant:
0.014 h-1
DT50:
50 h
Type:
(pseudo-)first order (= half-life)
Remarks on result:
other: All logarithms of the relative concentrations were correlated with time using linear regression analysis. The Arrhenius equation was used to determine the rate constant and half-life time at 25°C
pH:
7
Temp.:
40 °C
Hydrolysis rate constant:
0.057 h-1
DT50:
12 h
Type:
(pseudo-)first order (= half-life)
Remarks on result:
other: For testing of pseudo-first order kinetics the mean logarithms of the relative concentrations between 10% and 90% were plotted against time. All logarithms of the relative concentrations were correlated with time using linear regression analysis.
pH:
7
Temp.:
50 °C
Hydrolysis rate constant:
0.157 h-1
DT50:
4.4 h
Type:
(pseudo-)first order (= half-life)
Remarks on result:
other: For testing of pseudo-first order kinetics the mean logarithms of the relative concentrations between 10% and 90% were plotted against time. All logarithms of the relative concentrations were correlated with time using linear regression analysis.
pH:
9
Temp.:
20 °C
Hydrolysis rate constant:
0.314 h-1
DT50:
2.2 h
Type:
(pseudo-)first order (= half-life)
Remarks on result:
other: For testing of pseudo-first order kinetics the mean logarithms of the relative concentrations between 10% and 90% were plotted against time. All logarithms of the relative concentrations were correlated with time using linear regression analysis.
pH:
9
Temp.:
25
Hydrolysis rate constant:
0.557 h-1
DT50:
1.2 h
Type:
(pseudo-)first order (= half-life)
Remarks on result:
other: All logarithms of the relative concentrations were correlated with time using linear regression analysis. The Arrhenius equation was used to determine the rate constant and half-life time at 25°C.
pH:
9
Temp.:
30
Hydrolysis rate constant:
0.971 h-1
DT50:
0.71 h
Type:
(pseudo-)first order (= half-life)
Remarks on result:
other: For testing of pseudo-first order kinetics the mean logarithms of the relative concentrations between 10% and 90% were plotted against time. All logarithms of the relative concentrations were correlated with time using linear regression analysis.
pH:
9
Temp.:
40
Hydrolysis rate constant:
2.79 h-1
DT50:
0.25 h
Type:
(pseudo-)first order (= half-life)
Remarks on result:
other: For testing of pseudo-first order kinetics the mean logarithms of the relative concentrations between 10% and 90% were plotted against time. All logarithms of the relative concentrations were correlated with time using linear regression analysis.
Validity criteria fulfilled:
yes
Remarks:
The analytical method was validated for the following parameters: Specificity: specific Calibration curve: r = 0.9998 Accuracy: 103 and 105% Repeatability: 0.62 and 0.79% Limit of quantification: 0.5 mg/L
Conclusions:
The study was performed to determine hydrolysis of Resorcinol diacetate at different temperatures and as a function of pH values in the environment (pH 4, 7 and 9).
Executive summary:

The purpose of the study was to determine hydrolysis as a function of pH for Resorcinol diacetate. The rate of hydrolysis of the test item as a function of pH was determined at pH values normally found in the environment (pH 4-9). An ultra performance liquid chromatographic method with spectrophotometric detection (UPLC-UV) for the quantitative analysis of the test item in water was developed. The study was based on OECD Guideline for the Testing of Chemicals no. 111.

The half-life times of the Resorcinol diacetate were:

 Parameter  Guideline  Result
 Analytical method  SANCO 3029  validated
 Hydrolysis at pH 4  OECD 111   t1/2 = 32 days at 20°C
      t1/2 = 22 days at 25°C
      t1/2 = 4.2 days at 50°C
      t1/2 = 2.2 days at 60°C
 Hydrolysis at pH 7  OECD 111   t1/2 = 83 hours at 20°C
      t1/2 = 50 hours at 25°C
      t1/2 = 12 hours at 40°C
      t1/2 = 4.4 hours at 50°C
 Hydrolysis at pH 9  OECD 111   t1/2 = 2.2 hours at 20°C
      t1/2 = 1.2 hours at 25°C
      t1/2 = 0.71 hours at 30°C
      t1/2 = 0.25 hours at 40°C

Description of key information

The purpose of the study was to determine hydrolysis as a function of pH for Resorcinol diacetate. The rate of hydrolysis of the test item as a function of pH was determined at pH values normally found in the environment (pH 4-9). An ultra performance liquid chromatographic method with spectrophotometric detection (UPLC-UV) for the quantitative analysis of the test item in water was developed. The study was based on OECD Guideline for the Testing of Chemicals no. 111.

The half-life times of the Resorcinol diacetate were:

 Parameter  Guideline  Result
 Analytical method  SANCO 3029  validated
 Hydrolysis at pH 4  OECD 111   t1/2 = 32 days at 20°C
      t1/2 = 22 days at 25°C
      t1/2 = 4.2 days at 50°C
      t1/2 = 2.2 days at 60°C
 Hydrolysis at pH 7  OECD 111   t1/2 = 83 hours at 20°C
      t1/2 = 50 hours at 25°C
      t1/2 = 12 hours at 40°C
      t1/2 = 4.4 hours at 50°C
 Hydrolysis at pH 9  OECD 111   t1/2 = 2.2 hours at 20°C
      t1/2 = 1.2 hours at 25°C
      t1/2 = 0.71 hours at 30°C
      t1/2 = 0.25 hours at 40°C

Key value for chemical safety assessment

Additional information