Vinyl chloroacetate

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

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)

Deviations:

no

GLP compliance:

no

Remarks:

The data contained in the report has been generated in a laboratory holding a current statement of GLP Compliance, issued by the UK GLP Monitoring Authority, MHRA, but not as part of a formal GLP study.

Radiolabelling:

no

Analytical monitoring:

yes

Details on sampling:

- Sampling intervals for the parent/transformation products: every 15 minutes at pH 7; every 1 hour at pH 4
- Sampling method: at each appropriate time point a vial was removed and 5.0 mL of chloroform was added to the vial and shaken to aid extraction. After settling the lower organic layer was removed and placed into an autosampler vial ready for analysis. Hydrolysis solutions and extract blanks were analysed alongside linearity and check standard solutions and chloroform blanks using GC-MS.
- Sampling intervals/times for pH measurements: every 15 minutes at pH 7; every 1 hour at pH 4
- Sample storage conditions before analysis: 20 °C incubator

Buffers:

pH 4 Buffer Solution
- pH: 4.08 (measured)
- Composition of buffer: 164 mL of 0.2M glacial acetic acid solution was added to 36 mL of 0.2M sodium acetate solution and diluted to 1 litre with distilled deionised water.

pH 7 Buffer Solution
- pH: 7.08 (measured)
- Composition of buffer: 296 mL of 0.1M sodium hydroxide solution was added to 500 mL of 0.1M monopotassium phosphate solution and diluted to 1 litre with distilled deionised water.

pH 8 Buffer Solution
- pH: 8.04 (measured)
- Composition of buffer: 468 mL of 0.1M sodium hydroxide solution was added to 500 mL of 0.1M monopotassium phosphate solution and diluted to 1 litre with distilled deionised water.

Details on test conditions:

TEST SYSTEM
- Type, material and volume of test flasks, other equipment used: 100 mg test item weighed into a 100 mL volumetric flask and made to volume with chloroform

TEST MEDIUM
Approx 0.1 g of test item was weighed, in duplicate, into 100 mL digitubes. Then pH 7.0 or pH 4.0 buffer was added to make to 100 mL mark, the tube was capped and shaken well to dissolve. 5.0 mL aliquots of the resultant solution were dispensed into a series of 12 mL reaction vials. The vials were capped and immediately placed into the 20 °C incubator, leaving 1 vial for t = 0 timepoint. The remaining bulk solution was also placed into the incubator after pH measurement; this bulk solution was used for all pH measurements. At each time point a vial was removed from the incubator and the pH of the bulk solution was measured. 5.0 mL of chloroform was added to the vial and shaken to aid extraction. After settling the lower organic layer was removed and placed into an autosampler vial ready for analysis.

Duration:

300 min

pH:

7

Temp.:

20 °C

Initial conc. measured:

0.01 g/L

Duration:

10 h

pH:

4

Temp.:

20 °C

Initial conc. measured:

0.01 g/L

Number of replicates:

2

Positive controls:

yes

Remarks:

acetaldehyde

Negative controls:

no

Statistical methods:

- pH 7: % RSD of 6 injections of Standard-1 200 mg/L = 2.01 % i.e. within <= 5% nominal acceptance criteria and is therefore acceptable. r value of linearity = 0.9996 i.e. within > 0.99 nominal acceptance criteria and is therefore acceptable. Standard recoveries throughout the sequence are all within 100 % +/- 28 % (suitable criteria for a volatile species being analysed by direct injection GC) and are therefore acceptable.

- pH 4: % RSD of 6 injections of Standard-1 200 mg/L = 1.16 % i.e. within <= 5% nominal acceptance criteria and is therefore acceptable. r value of linearity = 0.9998 i.e. within > 0.99 nominal acceptance criteria and is therefore acceptable. Standard recoveries throughout the sequence are all within 100 % +/- 28 % (suitable criteria for a volatile species being analysed by direct injection GC) and are therefore acceptable.

Preliminary study:

- Hydrolysis feasibility study: Approximately 25 mg of the test item was weighed in duplicate into 25.0 mL volumetric flasks. One of the weighings was dissolved and made to volume with pH 7 buffer and shaken well to mix, while the other was made to volume with pH 8 buffer. 10 mL of each solution was pipetted into separate 28 mL glass vials and 10 mL of chloroform was added. The vial was then shaken for 1 min to aid extraction and the layers allowed to separate prior to the lower organic layer being removed and transferred to autosampler vial for analysis. A blank extraction was carried out for each pH buffer as above. The extraction procedure was repeated after 4 hours for the test item in pH 8 buffer and after 24 hours for the test item in pH 7 buffer. The extracted solutions and blank extracts were analysed by GC-MS.
- Results: The results show that all VCA present in the test solution has undergone hydrolysis at pH 7 after 24 hours, and at pH 8 after 4 hours.

- Additional hydrolysis feasibility: After assessment of initial hydrolysis feasibility it was apparent that hydrolysis at pH 8 occurs much faster than expected. Therefore hydrolysis at pH 4 was performed. It is also apparent that hydrolysis at pH 7 occurs faster than expected as no VCA was observed after 24 hours, therefore a shorter timepoint was performed.
- Results: At pH 7, the timepoint at t = 4 hours showed that 3.7 % of the initial VCA remained and at t = 8 hours no VCA remained. Therefore timepoints up to 5 hours were performed for pH 7. At pH 4, the timepoint t = 4 hours showed that 45.4% of the initial VCA remained and at t = 8 hours 19.9 % of the initial VCA remained. Therefore timepoints up to ten hours were performed for pH 4.

Transformation products:

yes

No.:

#1

No.:

#2

Key result

pH:

7

Temp.:

20 °C

DT50:

1.22 h

Key result

pH:

4

Temp.:

20 °C

DT50:

3.92 h

Details on results:

TEST CONDITIONS
- pH, sterility, temperature, and other experimental conditions maintained throughout the study: Yes
- Anomalies or problems encountered (if yes): High recoveries for Std-1 200 mg/L injections throughout sample analysis were seen for both acetaldehyde and VCA. The reason for this is unknown; however the same effect was not observed for the pH 7 analysis and therefore may be due to a matrix effect from the extraction of an acid solution into chloroform. Due to the high recoveries Test-2 concentrations were calculated using the peak area of the injection of Std-1 200 mg/L immediately prior to Test-2 injections, as the drift corrected standard recoveries were within 100 % +/- 28 % then this is not considered to have has a significant impact on results obtained.

Validity criteria fulfilled:

yes

Conclusions:

The results show that at pH 4 the half-life = 3.92 hrs whereas at pH 7 the half-life = 1.22 hrs. A trend was observed indicating that the half-life decreases when the pH increases. Chloroacetic Acid (CAS 79-11-8 / EC 201-178-4) and Acetaldehyde (CAS 75-07-0 / EC 200-836-8) were identified as the degradation products of the substance.

Executive summary:

Hydrolysis of VCA as a function of pH was determined in a study carried out in accordance with the OECD Guideline 111. Preliminary feasibility assessments were conducted and it was decided to perform the main study at pH 4 and pH 7 with short timepoints.

 

The results of the final hydrolysis test show that at pH 4 the half-life of VCA = 3.92 hrs, whereas at pH 7 the half-life = 1.22 hrs. A trend was observed indicating that the half-life decreases when the pH increases. Chloroacetic Acid (CAS 79-11-8 / EC 201-178-4) and Acetaldehyde (CAS 75-07-0 / EC 200-836-8) were identified as the degradation products of VCA.

Description of key information

Hydrolysis of VCA as a function of pH was determined in a study carried out in accordance with the OECD Guideline 111. Preliminary feasibility assessments were conducted and it was decided to perform the main study at pH 4 and pH 7 with short timepoints.

 

The results of the final hydrolysis test show that at pH 4 the half-life of VCA = 3.92 hrs, whereas at pH 7 the half-life = 1.22 hrs. A trend was observed indicating that the half-life decreases when the pH increases. Chloroacetic Acid (CAS 79-11-8 / EC 201-178-4) and Acetaldehyde (CAS 75-07-0 / EC 200-836-8) were identified as the degradation products of VCA.

Key value for chemical safety assessment

Half-life for hydrolysis:

3.92 h

at the temperature of:

20 °C