thiacloprid (ISO);(Z)-3-(6-chloro-3-pyridylmethyl)-1,3-thiazolidin-2-ylidenecyanamide;{(2Z)-3-[(6-chloropyridin-3-yl)methyl]-1,3-thiazolidin-2-ylidene}cyanamide

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Oct 1994 - Dec 1994

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EPA Guideline Subdivision N 161-1 (Hydrolysis)

Version / remarks:

1982

GLP compliance:

yes (incl. QA statement)

Radiolabelling:

yes

Analytical monitoring:

yes

Details on sampling:

- Sampling intervals for the parent/transformation products: The solutions were incubated for a maximum period of 30 days under sterile conditions in the dark at 25 °C, and the sampling intervals were 0, 2, 7, 13, 20, 27 and 30 days.
- Sampling method: Duplicate samples were analyzed at each sampling.
- Sampling intervals/times for pH measurements: At initiation of the test (day 0) and after 7, 20 and 30 days of incubation a subsample of each test solution was subjected to pH measurement.
- Sampling intervals/times for sterility check: At initiation of the test (day 0) and after 7, 20 and 30 days of incubation a subsample of each test solution was subjected to sterility check.
- Sample storage conditions before analysis: Samples were stored in the refrigerator at about -2 to 7 °C until analysis.
- Other observation, if any (e.g.: precipitation, color change etc.): During the test the incubation temperature shown on the display of the thermostat was recorded on a daily basis (work days).

Buffers:

- pH 5: 125 mL of 0.04 M sodium acetate solution (5.44 g CH3COONa x H2O/L) are brought to a volume of 250 mL with water. The pH of this solution is measured with a glass electrode and then adjusted to pH 5.0 at the respective test temperature (25 ± 2 °C) using 0.04 M sodium hydroxide solution (1.6 g NaOH/L) or acetic acid.
- pH 7: 50 mL of a 0.1 M tris(hydroxymethyl)aminomethane solution (12.1 g/L) are mixed with 45 mL of an 0.1 N hydrochloric acid solution (3.65 g HCI/L). The pH of this solution is measured with a glass electrode and then adjusted to pH 7.0 at the respective test temperature (25±1 °C) using 0.1 N hydrochloric acid solution and 0.1 N sodium hydroxide solution, respectively.
- pH 9: 0.04 moles boric acid (2.48 g H3BO3) are dissolved in 1 L of a 0.04 M potassium chloride solution (2.98 g KCI/L). To 125 mL of this solution add 53 ml of a 0.04 M sodium hydroxide solution (1.6 g NaOH/L) and dilute with water to a volume of 250 mL. The pH of this solution is measured with a glass electrode and then adjusted to pH 9.0 at the respective test temperature (25 ± 2 °C) using 0.04 M sodium hydroxide solution or boric acid.
- Type and final molarity of buffer: The buffer stock solutions were diluted to the desired molarity of 0.01 with purified water and subsequently sterilized.

Details on test conditions:

TEST SYSTEM
- Type, material and volume of test flasks, other equipment used: The test solutions were prepared with radiolabelled parent compound at a concentration of about 0.35 mg a.i./L. After preparation of the radioactively labelled test substance application solutions five mL portions of the solutions S (pH 5), N (pH 7) and B (pH 9) were pipetted into 20 crimp-top vials under sterile conditions. Three vessels were used as time zero samples for sterility check and measurement of pH and radioactivity concentration
- Sterilisation method: Buffer solutions and all glass ware used for preparation of solutions and sampling procedure was sterilized by steam pressure sterilization before application of the test substance.

- Measures taken to avoid photolytic effects: Samples were closed using crimp caps with Teflon-faced septa and incubated in the dark at 25 ±1 °C in a temperature controlled water bath (thermostat).
- Measures to exclude oxygen: Samples were closed using crimp caps with Teflon-faced septa.
- Other: Volatilization of radioactivity from the solutions was not to be expected. This finally could be confirmed by the material balances calculated for each sampling interval.

Transformation products:

not specified

Remarks:

Two transformation products were detected but not further identified. The transformation products did not exceed 2% of the applied radioactivity.

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

- Two transformation products were detected in the pH 9 treatment, but not further identified.
- The transformation products did not exceed 2% of the applied radioactivity.

pH:

5

Temp.:

25 °C

DT50:

> 1 yr

Remarks on result:

other:

Remarks:

Calculation of half-lives was not possible due to the constant levels of the parent test substance in solutions.

pH:

7

Temp.:

25 °C

DT50:

> 1 yr

Remarks on result:

other:

Remarks:

Calculation of half-lives was not possible due to the constant levels of the parent test substance in solutions.

pH:

9

Temp.:

25 °C

DT50:

> 1 yr

Remarks on result:

other:

Remarks:

Calculation of half-lives was not possible due to the constant levels of the parent test substance in solutions.

Details on results:

TEST CONDITIONS
- pH, sterility, temperature, and other experimental conditions maintained throughout the study: Yes. Sterility: The sterility of the test solutions was checked in subsamples (samples no. 1,6, 11, 16 and 17 of solution S, N and B) taken after 0, 7, 20 and 30 days of incubation. The sterility tests demonstrated that sterile conditions could be maintained throughout the test period. No contamination was observed in the test solutions checked after 0, 7, 20 and 30 days of incubation.
Temperature: The recorded daily temperatures showed that incubation temperature was maintained constant at 25 ± 1 °C throughout the study.
pH: The pH of the test solutions was measured in subsamples (samples no. 1,6, 11, 16 and 17 of solution S, N and B) taken after 0, 7, 20 and 30 days of incubation. It is shown that the pH levels were kept constant at the set up values.

MAJOR TRANSFORMATION PRODUCTS
- Under the conditions of pH 5 and 7 no formation of degradation products was observed at any time of sampling. About 98% of the recovered radioactivity was representing the unchanged parent compound according to TLC analysis of the samples.
- There was no tendency of decrease of the concentration of the test substance in the test solutions during the incubation period. Therefore the test substance has to be regarded as stable under conditions of pH 5, 7 and 9.
- The calculation of half-lives was not possible due to the constant levels of the test substance in solutions.

MINOR TRANSFORMATION PRODUCTS
- Under conditions of pH 9 throughout the experiment two minor degradates were detected, each of them representing constantly less than 2% of the applied radioactivity.

VOLATILIZATION (at end of study)
- Total volatile organics in % of the applied: The total recovery of radioactivity was calculated to be on average (± standard deviation) 100.0 ±0.6% (pH 5), 101.7 ±1.1 % (pH 7) and 101.3 ±2.3% (pH 9) of the applied amount during the incubation period of 30 days. The complete material balances found at all samplings demonstrate that no radioactivity dissipated from the solutions by means of volatilization.

Validity criteria fulfilled:

not applicable

Conclusions:

(Z)-3-(6-chloro-3-pyridylmethyl)-1,3-thiazolidin-2-ylidenecyanamide has to be regarded as resistant to hydrolysis under acidic (pH 5), neutral and alkaline (pH 9) conditions since the test substance was recovered from solution at constant levels throughout the experiment (95-98%). In the pH range tested (pH 5 to 9) formation of hydrolysis products was only observed at pH 9 at amounts less than 2% of the applied radioactivity. It is concluded from this study that hydrolysis will be of no relevance for the degradation of the test substance in the environment.

Description of key information

DT50 = > 1 year

 

(Z)-3-(6-chloro-3-pyridylmethyl)-1,3-thiazolidin-2-ylidenecyanamide is not hydrolytically degraded at 25 °C and pH 5, 7 or 9.

Key value for chemical safety assessment

Half-life for hydrolysis:

1 yr

at the temperature of:

25 °C

Additional information

(Z)-3-(6-chloro-3-pyridylmethyl)-1,3-thiazolidin-2-ylidenecyanamide has to be regarded as resistant to hydrolysis under acidic (pH 5), neutral (pH 7) and alkaline (pH 9) conditions since the test substance was recovered from solution at constant levels throughout the experiment (95-98%). The DT50 of the test substance is estimated to be > 1 year at 25°C. It is concluded from this study that hydrolysis will be of no relevance for the degradation of the test substance in the environment.