N,N-dimethyldecylamine N-oxide

Hydrolysis

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2002-03-22 to 2002-06-28

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

Inconsistent results for C14 homologue.

Qualifier:

according to guideline

Guideline:

OECD Guideline 111 (Hydrolysis as a Function of pH)

Deviations:

yes

Remarks:

: (1) Proper steps were not taken to expel oxygen from the test vessels

Qualifier:

according to guideline

Guideline:

EU Method C.7 (Degradation: Abiotic Degradation: Hydrolysis as a Function of pH)

Principles of method if other than guideline:

N/A

GLP compliance:

yes (incl. QA statement)

Radiolabelling:

no

Analytical monitoring:

yes

Details on sampling:

- Sampling intervals for the parent/transformation products: immediately and after 5 days of incubation
- Sampling method: no data
- Sampling methods for the volatile compounds, if any: N/A
- Sampling intervals/times for pH measurements: immediately and after 5 days of incubation using a calibrated pH meter
- Sampling intervals/times for sterility check: sterility checks were not performed
- Sample storage conditions before analysis: no data
- Other observation, if any: no data

Buffers:

- pH: 4.00, 7.07 and 9.08
- Type and final molarity of buffer: no data
- Composition of buffer: The pH 4 buffer was prepared by adding 330 mL 0.1 M citric acid to 170 mL 0.1 M trisodium citrate and adjusting the final volume to 1000 mL with Suprapur water. The pH of the solution was 3.76, which was adjusted with trisodium citrate to pH 4. The pH 7 solution was prepared by adding 500 mL 0.1 M potassium dihydrogen phosphate to 296.5 mL 0.1 M sodium hydroxide solution and adjusting the final volume to 1000 mL with Suprapur water. The pH of the resulting solution was 7.07. The pH 9.0 buffer was prepared by adding 500 mL 0.1 M boric acid in 0.1 M potassium chloride to 213 mL 0.1 M sodium hydroxide and adjusting the final volume to 1000 mL with Suprapur water. The pH of the solution was 9.12, which was adjusted with 0.1 M boric acid in 0.1 M potassium chloride to pH 9.08.

Estimation method (if used):

N/A

Details on test conditions:

TEST SYSTEM
- Type, material and volume of test flasks, other equipment used: Glass tube equipped with a screw cap.
- Sterilisation method: no data
- Lighting: kept in the dark
- Measures taken to avoid photolytic effects: test systems and solutions were kept in the dark at all times to avoid photolysis
- Measures to exclude oxygen: purged with nitrogen
- Details on test procedure for unstable compounds: N/A
- Details of traps for volatile, if any: none
- If no traps were used, is the test system closed/open: N/A
- Is there any indication of the test material adsorbing to the walls of the test apparatus: no

TEST MEDIUM
- Volume used/treatment: 50 mL
- Kind and purity of water: Suprapur water
- Preparation of test medium: See preparations of buffer and test solutions
- Renewal of test solution: test solution not renewed
- Identity and concentration of co-solvent: N/A

OTHER TEST CONDITIONS
- Adjustment of pH: not performed
- Dissolved oxygen: no data

Duration:

5 d

Temp.:

50 °C

Initial conc. measured:

4 167 other: ug/L (nominal)

Number of replicates:

2

Positive controls:

no

Negative controls:

no

Statistical methods:

No data

Preliminary study:

- For the C12 homologue, test solutions at pH 4, 7 and 9 showed no decrease in concentration of the test substance after the incubation period.
- For the C14 homologue, no decrease in concentration was detected at pH 7 and 9. However, at pH 4, a significant of 27.5% was observed. Re-analysis of the extracts confirmed these results. No explanation could be found for this possible hydrolysis of the C14 homologue at pH 4, especially because the C12 homologue didn't show any significant decrease of concentration at pH 4. Therefore, the 5-day test at pH 4 was repeated.
- In the repeat test, the C12 homologue showed similar results to the initial test. However, the duplicate of the repeated test for the C14 homologue showed inconsistent results. One test solution (A) showed a decrease of concentration of 44.3% and the duplicate one (B) showed a decrease of 5.6% after 5 days of incubation at 50 deg C. However, after addition of the extraction solvent to solution A, a cloudy extract was obtained. This was probably the reason for this low concentration. The QC samples analyzed in the repeat test were not within specifications for the C14 homologue.

Test performance:

- As <10% hydrolysis was observed after 5 days, there was no need to extend the test to 30 days.

Transformation products:

not measured

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

N/A

% Recovery:

96

pH:

4

Temp.:

50 °C

Duration:

5 d

% Recovery:

96.6

pH:

7

Temp.:

50 °C

Duration:

5 d

% Recovery:

93.7

pH:

9

Temp.:

50 °C

Duration:

5 d

pH:

4

Temp.:

50 °C

Remarks on result:

hydrolytically stable based on preliminary test

pH:

7

Temp.:

50 °C

Remarks on result:

hydrolytically stable based on preliminary test

pH:

9

Temp.:

50 °C

Remarks on result:

hydrolytically stable based on preliminary test

Other kinetic parameters:

N/A

Details on results:

TEST CONDITIONS
- pH, sterility, temperature, and other experimental conditions maintained throughout the study: Yes/No
- Anomalies or problems encountered (if yes):

RECOVERY OF TEST SUBSTANCE
C12 homologue at pH4:
- Range of maximum concentrations in % of the applied amount and day(s) of incubation when observed: 83.6% (day 0, test 1); 100% (day 0, test 2)
- Range of maximum concentrations in % of the applied amount at end of study period: 89.4% (day 5, test 1); 88.7% (day 5, test 1, re-analysis); 103% (day 5, test 2)

C14 homologue at pH4:
- Range of maximum concentrations in % of the applied amount and day(s) of incubation when observed: 83.6% (day 0, test 1); 98.5% (day 0, test 2)
- Range of maximum concentrations in % of the applied amount at end of study period: 89.4% (day 5, test 1); 88.7% (day 5, test 1, re-analysis); 92.9% (day 5, test 2, re-analysis)

C12 homologue at pH7:
- Range of maximum concentrations in % of the applied amount and day(s) of incubation when observed: 87.4% (day 0)
- Range of maximum concentrations in % of the applied amount at end of study period: 97.1% (day 5); 96.2% (day 5, re-analysis)

C14 homologue at pH7:
- Range of maximum concentrations in % of the applied amount and day(s) of incubation when observed: 89.7% (day 0)
- Range of maximum concentrations in % of the applied amount at end of study period: 81.8% (day 5); 76.0 (day 5, re-analysis)

C12 homologue at pH9:
- Range of maximum concentrations in % of the applied amount and day(s) of incubation when observed: 85.5% (day 0)
- Range of maximum concentrations in % of the applied amount at end of study period: 93.7% (day 5)

C14 homologue at pH9:
- Range of maximum concentrations in % of the applied amount and day(s) of incubation when observed: 89.0% (day 0)
- Range of maximum concentrations in % of the applied amount at end of study period: 81.3% (day 5)

PATHWAYS OF HYDROLYSIS
- Description of pathways: no data
- Figures of chemical structures attached: No

Due to FI-MS/MS problems, the extracts at day 5 of the first hydrolysis experiment were stored in the refrigerator at approximately 4 deg C for 5 days. In order to check the stability of the extracts, test samples at pH 4, 7 and 9 were freshly prepared and stored together with the day 5 extracts. Accuracy results from this experiment were between 94% and 96% and therefore it can be stated that day 5 extracts were stable after storage in the refrigerator.

Validity criteria fulfilled:

yes

Conclusions:

C12/C14 alkyl dimethyl amine oxide (AO) is hydrolytically stable. There was no significant decrease in AO concentration in solution at pH 4, 7, and 9 after 5 days at 50 degrees C.

Executive summary:

In this study, hydrolysis of C12/C14 alkyl dimethyl amine oxide (AO) was investigated at pH 4, 7 and 9 according to OECD Test Guideline 111 and EU Method C.7. AO was tested at a nominal concentration of 4167 ug/L for 5 days at 50 C. Both the C12 and C14 homologues of the test substance were evaluated.

Analytical samples were taken at time 0 and after 5 days of incubation at 50 deg C and protected from light to prevent photolysis. Samples were analyzed by atmospheric pressure ionization interfaced with flow injection/mass spectrometry (FI-MS/MS). Internal calibration standards were prepared from deuterated test substance.

Results of the test solutions at pH 4, 7 and 9 showed no significant decrease of concentration after 5 days of incubation at 50 deg C for the C12 homologue. For the C14 homologue, the same results were obtained at pH 7 and 9. However, at pH 4 a significant decrease of concentration of 27.5% was observed. Re-analysis of the extracts confirmed these results. No explanation could be found for this possible hydrolysis of the C14 homologue at pH 4, especially because the C12 homologue didn't show any significant decrease of concentration at pH 4. Therefore, the 5-day test at pH 4 was repeated.

In the repeat test, the C12 homologue showed similar results to the initial test. However, the duplicate of the repeated test for the C14 homologue showed inconsistent results. One test solution showed a decrease of 44.3% and the duplicate showed a decrease of 5.6%. Results of the C14 homologue showed that the analytical method used for the determination of the C14 homologue was not consistent. As a result, conclusions were based on the C12 homologue results only.

The test solutions at pH 4, 7 and 9 showed no significant decrease in concentration of the C12 homologue after 5 days of incubation. Further testing at these pH levels was not required according to the EEC Directive 92/69 EEC Annex V, Part C.7 criteria; therefore, it can be stated that the test substance is hydrolytically stable. Because AO is hydrolytically stable, rate constants for hydrolysis were not calculated.

Reference 2

Endpoint:

hydrolysis

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

REPORTING FORMAT FOR THE ANALOGUE APPROACH

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
Both the target and source substances contain identical functional groups and differ only by the C-chain length and hence will have similar hydrolytic stability properties.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
Source: Amines, C12-14 (even numbered) -alkyldimethyl, N-oxides (EC 931-292-6)
Target: N,N-dimethyldecylamine N-oxide (EC 220-020-5; CAS 2605-79-0)

3. ANALOGUE APPROACH JUSTIFICATION
The target and source substances contain identical functional groups. The only difference between the two substances is the alkyl chain length (C10 in the target and mainly C12 in the source). This difference in chain length is not expected to have an effect on the rate of hydrolysis.

4. DATA MATRIX
Target: No data
Source: No hydrolysis at pH 4, 7 or 9 in the preliminary test, therefore considered to be hydrolytically stable.

Reason / purpose for cross-reference:

read-across source

Qualifier:

according to guideline

Guideline:

OECD Guideline 111 (Hydrolysis as a Function of pH)

Deviations:

yes

Remarks:

: (1) Proper steps were not taken to expel oxygen from the test vessels

Qualifier:

according to guideline

Guideline:

EU Method C.7 (Degradation: Abiotic Degradation: Hydrolysis as a Function of pH)

Transformation products:

not measured

pH:

4

Temp.:

50 °C

Remarks on result:

hydrolytically stable based on preliminary test

pH:

7

Temp.:

50 °C

Remarks on result:

hydrolytically stable based on preliminary test

pH:

9

Temp.:

50 °C

Remarks on result:

hydrolytically stable based on preliminary test

Description of key information

No studies are available for C10 AO however a study is available for C12 -14 AO. The results of this study are read across to C10 AO as any potential for hydrolysis will not be affected by the difference in alkyl chain length between the two substances.

Based on the results of the study with C12-14 AO, performed according to OECD 111, the substance is stable to hydrolysis.

Additional information

No studies are available for C10 AO, however a study is available for C12 -14 AO. The results of this study are read across to C10 AO as any potential for hydrolysis will not be affected by the difference in alkyl chain length between the two substances.

Hydrolysis of C12/C14 alkyl dimethylamine oxide (AO) was investigated at pH 4, 7 and 9 according to OECD Test Guideline 111 and EU Method C.7 [Analytico Medinet B.V. (2002)]. AO was tested at a nominal concentration of 4167 ug/L for 5 days at 50 °C.

Both the C12 and C14 homologues of the test substance were evaluated. Analytical samples were taken at time 0 and after 5 days of incubation at 50 °C and protected from light to prevent photolysis. Samples were analyzed by atmospheric pressure ionization interfaced with flow injection/mass spectrometry (FI-MS/MS). Internal calibration standards were prepared from deuterated test substance. Results of the test solutions at pH 4, 7 and 9 showed no significant decrease of concentration after 5 days of incubation at 50 °C for the C12 homologue. For the C14 homologue, the same results were obtained at pH 7 and 9. However, at pH 4 a significant decrease of concentration of 27.5% was observed. Re-analysis of the extracts confirmed these results. No explanation could be found for this possible hydrolysis of the C14 homologue at pH 4, especially because the C12 homologue didn't show any significant decrease of concentration at pH 4. Therefore, the 5-day test at pH 4 was repeated. In the repeat test, the C12 homologue showed similar results to the initial test. However, the duplicate of the repeated test for the C14 homologue showed inconsistent results. One test solution showed a decrease of 44.3% and the duplicate showed a decrease of 5.6%. Results of the C14 homologue showed that the analytical method used for the determination of the C14 homologue was not consistent. As a result, conclusions were based on the C12 homologue results only.

The test solutions at pH 4, 7 and 9 showed no significant decrease in concentration of the C12 homologue after 5 days of incubation. Further testing at these pH levels was not required according to the EEC Directive 92/69 EEC Annex V, Part C.7 criteria; therefore, it can be stated that the test substance is hydrolytically stable. Because AO is hydrolytically stable, rate constants for hydrolysis were not calculated.