Oxalonitrile

Hydrolysis

Administrative data

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Data source

Reference

Title:

Unnamed

Year:

2015

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 111 (Hydrolysis as a Function of pH)

Test guideline 2

Qualifier:

according to guideline

Guideline:

other: OECD 316 (Phototransformation of Chemicals in Water – Direct Photolysis)

Test guideline 3

Guideline:

other:

Version / remarks:

This study was conducted following the United States Environmental Protection Agency (EPA) Good Laboratory Practice Standards (40 CFR Part 160), 16 October 1989, the Organisation for Economic Cooperation and Development (OECD) Principles of Good Laboratory Practice[C(97) 186/Final], 26 November 1997; and the standard operating procedures of Ajwa Analytical Laboratories, LLC, and the protocol as approved by the Sponsor with the following exceptions:
Ajwa Analytical Laboratories, LLC was not certified by the OECD. However, GLP-compliant equipment was used by GLP-trained staff from University of California-Davis and Ajwa Analytical Laboratories, LLC.
Signed and dated GLP, Quality Assurance and Data Confidentiality statements were provided.

Principles of method if other than guideline:

a) The protocol states that the amount of cyanogen to be applied to water is 1.09 mg. The experiments used 2.18 mg to achieve higher detectable concentrations.
Impact on the study: None. The amount is within the OECD Guidelines of less than 0.01M.

b) The protocol states that the three temperatures to be used were 10, 20 and 40 °C. Due to the slow degradation on cyanogen at low pH and temperature, the R2 between the three replicates for pH 4 at 10 °C was very low. Therefore, an additional temperature level (50 °C) was tested to obtain a third temperature level. Impact on the study: None. The OECD Guidelines does not specify the temperature values. This study has three valid temperature levels for pH 4.

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Oxalonitrile

EC Number:

207-306-5

EC Name:

Oxalonitrile

Cas Number:

460-19-5

Molecular formula:

C2N2

IUPAC Name:

carbononitridic cyanide

Test material form:

gas

Radiolabelling:

no

Results and discussion

Transformation products:

no

Dissipation DT50 of parent compound

Key result

pH:

7

Temp.:

23 °C

DT50:

50 min

Remarks on result:

other: hydrolysis in the dark

Applicant's summary and conclusion

Conclusions:

According to the study, ethanedinitrile half-life is 4.3 hours at 10 °C. Increase of temperature promote ethanedinitrile hydrolysis. At 23 °C, the half-life is 50 min. in pH 7.0 solution. This study showed that hydrolysis in the dark is an important route of degradation for ethanedinitrile in water.

Executive summary:

The purpose of this test is to study the hydrolysis of Cyanogen (C2N2) at different pH values at three temperatures following the OECD 111 and OECD 316 test methodologies to support registration of Cyanogen. The OECD 111 states that this “method is generally applicable to chemical substances (unlabelled or labelled) for which an analytical method with sufficient accuracy and sensitivity is available. It is applicable to slightly volatile and non-volatile compounds of sufficient solubility in water. The test should not be applied to chemicals that are highly volatile from water (e.g. fumigants, organic solvents) and thus cannot be kept in solution under the experimental conditions of this test.” However, the OECD 316 Guidelines suggest using the headspace measurement for highly volatile compounds such as fumigants. In this case, the OECD 316 Guidelines suggested using minimal head-space and adequate sealing in the photolysis cells to minimize volatile losses during the study. In this study, Cyanogen was spiked in pH 4.0 (5 mM Potassium Acid Phthalate), pH 7.0 (5 mM Potassium Phosphate Monobasic-Sodium Hydroxide), and pH 9.0 (Potassium Carbonate-Potassium Borate-Potassium) aqueous buffer solutions at a concentration of 0.42 mM and kept in the dark to determine the half-lives at 10±1, 21±1, and 40±1 °C and to find whether hydrolysis is an important degradation route from an environmental standpoint. Cyanogen is stable in pH 4.0 aqueous solution at 10 °C in the dark. Under those conditions, the half-life is 80 days. But Cyanogen becomes unstable when the solution pH increases. In pH 7.0 and pH 9.0 solutions, the half-life becomes 4.3 hours and 6 minutes at10°C, respectively. High temperatures can also promote cyanogen hydrolysis. At 23 °C, the half-life of Cyanogen is 50 min. in pH 7.0 solution compared to 4.3 hours at 10°C. This study showed that, hydrolysis in the dark will be an important route of degradation for Cyanogen in water that has neutral or basic pH. This study was conducted in accordance with the protocol, except for the following: 1)     The protocol states that the amount of cyanogen to be applied to water is 1.09 mg. The experiments used 2.18 mg to achieve higher detectable concentrations. Impact on the study: None. The amount is within the OECD Guidelines of less than 0.01M. 2)     The protocol states that the three temperatures to be used were 10, 20 and 40 °C. Due to the slow degradation on cyanogen at low pH and temperature, the R^2between the three replicates for pH 4 at 10 °C was very low. Therefore, an additional temperature level (50 °C) was tested to obtain a third temperature level. Impact on the study: None. The OECD Guidelines does not specify the temperature values. This study has three valid temperature levels for pH 4. Compliance: This study was conducted following the United States Environmental Protection Agency (EPA) Good Laboratory Practice Standards (40 CFR Part 160), 16 October 1989, the Organisation for Economic Cooperation and Development (OECD) Principles of Good Laboratory Practice[C(97) 186/Final], 26 November 1997; and the standard operating procedures of Ajwa Analytical Laboratories, LLC, and the protocol as approved by the Sponsor with the following exceptions: Ajwa Analytical Laboratories, LLC was not certified by the OECD. However, GLP-compliant equipment was used by GLP-trained staff from University of California-Davis and Ajwa Analytical Laboratories, LLC. Signed and dated GLP, Quality Assurance and Data Confidentiality statements were provided. Conclusion: According to the study, ethanedinitrile half-life is 4.3 hours at 10 °C. Increase of temperature promote ethanedinitrile hydrolysis. At 23 °C, the half-life is 50 min. in pH 7.0 solution. This study showed that hydrolysis in the dark is an important route of degradation for ethanedinitrile in water.