N-methoxy-1-(2,4,6-trichlorophenyl)propan-2-amine

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

08 July 2015 to 22 July 2016

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)

Version / remarks:

13th April 2004

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

Tier 1:

- Sampling intervals for the parent: 0 and 5 days (triplicate samples)
- Sampling method: Entire treated samples were removed at each sampling time.
- Sampling intervals/times for pH measurements: pH was measured and adjusted if necessary immediately before incubation
- Sampling intervals/times for sterility check: Sterilty was not checked
- Sample storage conditions before analysis: All samples quantified and analysed on the day of sampling.


Tier 2:

Sampling intervals 20ºC Duplicate samples:
0, 1, 3, 7, 14, 21, 30 days (pH 4 and 7)
0, 1, 3, 14, 20, 24, 30 days (pH 9)
36°C Duplicate samples: 0, 3, 5, 7, 14, 21, 30 days
49.5ºC Duplicate samples:
0, 1, 3, 5, 7, 14, 21, 30 days (pH 4)
0, 1, 3, 5.35, 10, 16, 23, 30 days (pH 7)
0, 1, 2, 3, 5.35, 7, 10, 14, 23 days (pH 9)

- Sampling method: Entire treated samples were removed at each sampling time.
- Sampling intervals/times for pH measurements: pH was measured and adjusted if necessary immediately before incubation
- Sampling intervals/times for sterility check: Sterility was confirmed at Day 0 and at study termination for all tempertures and pH values. Sterility was confirmed using Envirocheck® Dip Slides (Merck)
- Sample storage conditions before analysis: All samples quantified and analysed on the day of sampling.

Buffers:

Hydrolysis was performed at pH 4, 7 and 9. For pH 7.0 and 9.0, available Merck-Titrisol® borate and phosphate buffers were used. For pH 4.0 an acetate buffer was used.
For Tier 1 testing, buffer solutions below were prepared using sterilised water but buffers were not filtered to 0.22 µm.

For Tier 2 testing, buffers in the table below were used:

Buffer Concentration Description
[M]
pH 4 0.01 Acetic acid/sodium acetate trihydrate prepared in ultra pure water and filtered to 0.22 µm to sterilise

pH 7 0.01 Hydrogenphoshpate/Dihydrogenphosphate prepared in ultra pure water and filtered to 0.22 µm to sterilise

pH 9 0.01 Borate prepared in ultra pure water and filtered to 0.22 µm to sterilise

Details on test conditions:

The initial Tier 1 testing was carried out at 50 ± 0.5°C at pH 4, 7 and 9.

TEST SYSTEM
- Type, material and volume of test flasks, other equipment used: 3 replicates, 1 mL vessel
- Sterilisation method: Sterilised water, no filtration
- Lighting: Dark
- If no traps were used, is the test system closed/open: Sealed vessel, no collection of volatiles
- Is there any indication of the test material adsorbing to the walls of the test apparatus? No
TEST MEDIUM
- Volume used/treatment: 1mL per vessel
- Kind and purity of water: Sterilised water
- Identity and concentration of co-solvent: Acetonitrile, final concentration of 0.8% v/v in each test solution


The Tier 2 testing was carried out at 20 ± 0.5°C, 36 ± 0.5°C and 49.5 ± 0.5°C at pH 4, 7 and 9.

TEST SYSTEM
- Type, material and volume of test flasks, other equipment used: 2 replicates, 1 mL vessel
- Sterilisation method: Filtration (0.22 µm)
- Lighting: Dark
- If no traps were used, is the test system closed/open: Sealed vessel, no collection of volatiles
- Is there any indication of the test material adsorbing to the walls of the test apparatus? No
TEST MEDIUM
- Volume used/treatment: 1mL per vessel
- Kind and purity of water: Sterilised water
- Identity and concentration of co-solvent: Acetonitrile, final concentration of 0.8% v/v in each test solution

Duration:

5 d

pH:

4

Temp.:

50 °C

Initial conc. measured:

10.41 mg/L

Remarks:

Tier 1

Duration:

5 d

pH:

7

Temp.:

50 °C

Initial conc. measured:

10.39 mg/L

Remarks:

Tier 1

Duration:

5 d

pH:

9

Temp.:

50 °C

Initial conc. measured:

10.12 mg/L

Remarks:

Tier 1

Duration:

30 d

pH:

4

Temp.:

20 °C

Initial conc. measured:

10.26 mg/L

Remarks:

Tier 2

Duration:

30 d

pH:

4

Temp.:

36 °C

Initial conc. measured:

8.92 mg/L

Remarks:

Tier 2

Duration:

30 d

pH:

4

Temp.:

49.5 °C

Initial conc. measured:

9.71 mg/L

Remarks:

Tier 2

Duration:

30 d

pH:

7

Temp.:

20 °C

Initial conc. measured:

9.56 mg/L

Remarks:

Tier 2

Duration:

30 d

pH:

7

Temp.:

36 °C

Initial conc. measured:

9.25 mg/L

Remarks:

Tier 2

Duration:

30 d

pH:

7

Temp.:

49.5 °C

Initial conc. measured:

9.1 mg/L

Remarks:

Tier 2

Duration:

30 d

pH:

9

Temp.:

20 °C

Initial conc. measured:

9.83 mg/L

Remarks:

Tier 2

Duration:

30 d

pH:

9

Temp.:

36 °C

Initial conc. measured:

9.25 mg/L

Remarks:

Tier 2

Duration:

23 d

pH:

9

Temp.:

49.5 °C

Initial conc. measured:

9.34 mg/L

Remarks:

Tier 2

Number of replicates:

3 replicates in Tier 1 experiment
2 replicates in Tier 2 experiment

Preliminary study:

At 50°C and 5 days, the concentration of CA5204A decreased from 104.2% at day 0 to 85.7% of the nominal concentration at pH 4, from 103.9 to 78.0% of the nominal concentration at pH 7, and from 101.1 to 56.4% of the nominal concentration at pH 9.

Transformation products:

no

Details on hydrolysis and appearance of transformation product(s):

CA5204A degraded relatively slowly at pH 4, 7 and 9 at 20°C, 36°C and 49.5°C. Hydrolysis was pH-dependent, with degradation increasing with increasing pH.
The degradation rate was proportionally slower at 20°C. At 20°C and after 30 days, the concentration of the parent compound decreased from 102.6% at day 0 to 95.4% of the nominal concentration at pH 4, from 95.6 to 87.7% at pH 7, and from 98.3 to 87.0% at pH 9.
At 36°C and after 30 days, the concentration of the parent compound decreased from 89.2% at day 0 to 77.7% of the nominal concentration at pH 4, from 92.5 to 71.8% at pH 7, and from 94.2 to 55.8% at pH 9. At 49.5°C and after 30 days, the concentration of the parent compound decreased from 97.1% at day 0 to 46.1% of the nominal concentration at pH 4, from 91.0 to 34.5% at pH 7, and from 93.4 to 16.1% at pH 9.

The presence of degradation products was only investigated at the environmentally relevant temperature of 20°C and no significant degradation products was observed by HPLC-UV analysis at 20 ºC pH 4, 7 and 9 over 30 days.

% Recovery:

>= 95.4 - <= 100

pH:

4

Temp.:

20 °C

Duration:

>= 0 - <= 30 d

% Recovery:

>= 87.7 - <= 95.6

pH:

7

Temp.:

20 °C

Duration:

>= 0 - <= 30 d

% Recovery:

>= 87 - <= 98.3

pH:

9

Temp.:

20 °C

Duration:

>= 0 - <= 30 d

% Recovery:

>= 77.7 - <= 89.2

pH:

4

Temp.:

36 °C

Duration:

>= 0 - <= 30 d

% Recovery:

>= 71.8 - <= 92.5

pH:

7

Temp.:

36 °C

Duration:

>= 0 - <= 30 d

% Recovery:

>= 55.8 - <= 94.2

pH:

9

Temp.:

36 °C

Duration:

>= 0 - <= 30 d

% Recovery:

>= 46.6 - <= 97.1

pH:

4

Temp.:

49.5 °C

Duration:

>= 0 - <= 30 d

% Recovery:

>= 34.5 - <= 91

pH:

7

Temp.:

49.5 °C

Duration:

>= 0 - <= 30 d

% Recovery:

>= 16.1 - <= 93.4

pH:

9

Temp.:

49.5 °C

Duration:

>= 0 - <= 23 d

pH:

4

Temp.:

20 °C

Hydrolysis rate constant:

0.002 d-1

DT50:

342 d

Type:

(pseudo-)first order (= half-life)

pH:

7

Temp.:

20 °C

Hydrolysis rate constant:

0.003 d-1

DT50:

232 d

Type:

(pseudo-)first order (= half-life)

pH:

9

Temp.:

20 °C

Hydrolysis rate constant:

0.004 d-1

DT50:

176 d

Type:

(pseudo-)first order (= half-life)

pH:

4

Temp.:

36 °C

Hydrolysis rate constant:

0.006 d-1

DT50:

123 d

Type:

(pseudo-)first order (= half-life)

pH:

7

Temp.:

36 °C

Hydrolysis rate constant:

0.009 d-1

DT50:

79.4 d

Type:

(pseudo-)first order (= half-life)

pH:

9

Temp.:

36 °C

Hydrolysis rate constant:

0.018 d-1

DT50:

39.4 d

Type:

(pseudo-)first order (= half-life)

pH:

4

Temp.:

49.5 °C

Hydrolysis rate constant:

0.025 d-1

DT50:

28 d

Type:

(pseudo-)first order (= half-life)

pH:

7

Temp.:

49.5 °C

Hydrolysis rate constant:

0.034 d-1

DT50:

20.5 d

Type:

(pseudo-)first order (= half-life)

pH:

9

Temp.:

49.5 °C

Hydrolysis rate constant:

0.07 d-1

DT50:

9.84 d

Type:

(pseudo-)first order (= half-life)

Validity criteria fulfilled:

not applicable

Conclusions:

CA2504A hydrolysis was pH-dependent, degradation increased with increasing pH. At 20°C and pH 4, 7 and 9 no significant degradation and no significant hydrolysis products were observed.

Executive summary:

An initial test at 50°C was carried out at 10 mg/L for 5 days at pH 4, 7 and 9. For each pH tested, triplicate samples were taken for analysis and the aqueous solutions were analysed for CA5204A concentration on the day of sampling by high performance liquid chromatography with UV-detection (HPLC-UV). As greater than 10% degradation occurred at all pHs during the initial investigation further testing was conducted. The hydrolysis of CA5204A was studied at 10 mg/L in the dark in sterile aqueous buffered solutions at pH 4, pH 7 and pH 9 at 20 °C, 36°C and 49.5°C for up to 30 days. In each test, duplicate samples were taken for analysis at up to 7-9 intervals, including t0, during incubation. On the day of sampling, the aqueous solutions were analysed for CA5204A concentration by high performance liquid chromatography with UV-detection after dilution with acetonitrile in a 1:1 ratio (v:v).

The temperatures remained constant throughout the incubation periods (20 ± 0.5°C, 36°C ± 0.5°C and 49.5±0.5°C) and there was no significant variation in the pH values of the buffered solutions. The incubation of the samples was performed in sterilised buffer solutions. Sterility was confirmed at beginning and at the end of incubation. During Tier 1 initial testing CA5204A appeared to degrade slowly at all pHs and 50ºC, with 85.7%, 78.0% and 56.4 % of the nominal concentration remaining after 5 days at pH 4, 7 and 9, respectively. After further testing, CA5204A degraded relatively slowly at pH 4, 7 and 9 at 20°C, 36°C and 49.5°C. Hydrolysis was pH-dependent, with degradation increasing with increasing pH. The degradation rate was proportionally slower at 20°C. At 20°C and after 30 days, the concentration of the parent compound decreased from 102.6% at day 0 to 95.4% of the nominal concentration at pH 4, from 95.6 to 87.7% at pH 7, and from 98.3 to 87.0% at pH 9. At 36°C and after 30 days, the concentration of the parent compound decreased from 89.2% at day 0 to 77.7% of the nominal concentration at pH 4, from 92.5 to 71.8% at pH 7, and from 94.2 to 55.8% at pH 9. At 49.5°C and after 30 days, the concentration of the parent compound decreased from 97.1% at day 0 to 46.1% of the nominal concentration at pH 4, from 91.0 to 34.5% at pH 7, and from 93.4 to 16.1% at pH 9.

Only small loss of parent were observed at 20°C pH 4, 7 and 9 over 30 days. At 25°C, the calculated half-lifes from the Arrhenius equation are respectively 244 days, 163 days and 108 days at pH 4, 7 and 9, respectively. The presence of degradation products was only investigated at the environmentally relevant temperature of 20°C and no significant degradation products was observed by HPLC-UV analysis at 20 ºC pH 4, 7 and 9 over 30 days.

Description of key information

CA2504A hydrolysis was pH-dependent, degradation increased with increasing pH. At 20°C and pH 4, 7 and 9 no significant degradation and no significant hydrolysis products were observed.

Key value for chemical safety assessment

Half-life for hydrolysis:

232 d

at the temperature of:

20 °C