Registration Dossier

Environmental fate & pathways

Hydrolysis

Currently viewing:

Administrative data

Link to relevant study record(s)

Reference
Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2015-09-04 to 2015-10-14
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)
Qualifier:
according to
Guideline:
EU Method C.7 (Degradation: Abiotic Degradation: Hydrolysis as a Function of pH)
GLP compliance:
yes (incl. certificate)
Analytical monitoring:
yes
Details on sampling:
- Solvent for sample stabilization: acidified acetonitrile (1% H3PO4 v/v)- At each sampling time 2.0 mL acetonitrile acidified with 1 % phosphoric acid were added to the sample with a Hamilton syringe (dilution factor = 2) and the sample was homogenized.- Sampling time: Tier 1 Test: at the beginning, after 2.4 hours and after 120 hours; Tier 2 Test: pH 7 at 20°C: 0, 48, 166, 268, 433, 602, 720 hours, pH 9 at 20°C: 0, 48, 95, 166, 268, 337, 433, 602 hours, pH 7 at 35°C: 0, 48, 166, 268, 337, 433, 602, 720 hours, pH 9 at 35°C: 0, 28, 48, 69, 95, 166, 214 hours, pH 7 at 50°C: 0, 44, 69, 95, 166, 214, 337 hours, pH 9 at 50°C: 0, 4, 20, 28, 44, 48, 53, 69 hours
Buffers:
- Type and final molarity of buffer: citrate buffer (pH 4), phosphate buffer (pH 7) and borate buffer (pH 9); concentration of each 0.05 M
- Composition of buffer:
Citrate buffer: 10.519 g citric acid monohydrate were dissolved in 500 mL deionised water. 59 mL of the sodium hydroxide (1M) solution was added and the flask was brought to a total volume of 1 L with deionised water. The pH value of the buffer solution was determined to be 4.00.
Phosphate buffer: 6.810 g Potassium dihydrogenphosphate were dissolved in 500 mL deionised water. 30 mL of the sodium hydroxide (1M) solution was added and the flask was brought to a total volume of 1 L with deionised water.
Borate buffer: 3.747 g potassium chloride and 3.098 g boric acid were dissolved in 500 mL deionised water. 20 mL of the sodium hydroxide (1M) solution was added and the flask was brought to a total volume of 1 L with deionised water.
Details on test conditions:
TEST SYSTEM
- Type, material and volume of test flasks, other equipment used: normal laboratory glassware and instrumentation; 100 mL (250 mL for Tier 2) volumetric flask; 6 mL glass vials; pH meter (WTW Germany); Water bath; Min.-max.-thermometer and data logger; Climate cabinet, Mass balance; Flat bed shaker
- Measures taken to avoid photolytic effects: photolytic interference was avoided; method not specified
- Measures to exclude oxygen: degassing the buffers with argon for at least five minutes and purging the vessels with argon before preparing the test solution.
- If no traps were used, is the test system closed
- Is there any indication of the test material adsorbing to the walls of the test apparatus? no
Number of replicates:
- Tier 2 Test: Individual replicate test samples (a minimum of duplicate samples contained in separate reaction vessels) were removed and the contents were analysed at each of at least six sampling times (for a minimum of twelve replicate data points).
Positive controls:
no
Negative controls:
no
Transformation products:
not specified
Key result
pH:
7
Temp.:
20 °C
DT50:
163 d
Type:
(pseudo-)first order (= half-life)
pH:
9
Temp.:
20 °C
DT50:
14 d
Type:
(pseudo-)first order (= half-life)
pH:
7
Temp.:
35 °C
DT50:
33.3 d
Type:
(pseudo-)first order (= half-life)
pH:
9
Temp.:
35 °C
DT50:
3.4 d
Type:
(pseudo-)first order (= half-life)
pH:
7
Temp.:
50 °C
DT50:
7.58 d
Type:
(pseudo-)first order (= half-life)
pH:
9
Temp.:
50 °C
DT50:
0.96 d
Type:
(pseudo-)first order (= half-life)

Tier 1 Test:

The hydrolysis of the test item was negligible at pH 4. The degradation of Scopolamine was less than 10% at pH 4 at 50°C over a period of 120 hours. Therefore the corresponding half-life time at pH 4 can be estimated to be longer than one year at 25°C.

The hydrolysis of the test item was more than 10% at pH 7 and pH 9 at 50°C over a period of 120 hours. Based on this results a Tier 2 test at 20°C, 35°C and 50°C was performed at pH 7 and pH 9.

Table 1: Summarized degradation half-life values (Tier 2 Test)

Test-temperature

pH value

Kinetic model

Slope a

[h^-1]

Y-axis intercept b

DT50

[h]

DT50

[d]

20°C

pH 7

SFO

-7.85 x 10^-5

6.50 x 10^-3

3918

163

pH 9

SFO

-9.05 x 10^-4

6.10 x 10^-3

339

14

35°C

pH 7

SFO

-3.83 x 10^-4

4.44 x 10^-3

798

33.3

pH 9

SFO

-3.73 x 10^-3

3.07 x 10^-4

81

3.4

50°C

pH 7

SFO

-1.67 x 10^-3

2.28 x 10^-3

182

7.58

pH 9

SFO

-1.32 x 10^-2

2.01 x 10^-3

23

0.96

SFO = Single First Order

Validity criteria fulfilled:
yes
Conclusions:
The half-life time at pH 4 can be estimated to be longer than one year at 25°C. For pH 7 and pH 9 a half-life of 163 and 14 days at 20°C was determined, respectively.

Description of key information

The hydrolysis of the test item was negligible at pH 4. The degradation of Scopolamine was less than 10% at pH 4 at 50°C over a period of 120 hours. Therefore the corresponding half-life time at pH 4 can be estimated to be longer than one year at 25°C.

At 35°C a half-life of 33.3 days for pH 7 and 3.4 days for pH 9 were determined. At 50°C a half-life of 7.58 days for pH 7 and 0.96 days for pH 9 were determined.

At 20 °C, half-lives of 163 days at pH 7 and 14 days at pH 9 were determined.

Key value for chemical safety assessment

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

Additional information