2-chloro-N-[[[4-(trifluoromethoxy)phenyl]amino]carbonyl]benzamide

Phototransformation in water

Administrative data

Endpoint:

phototransformation in water

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

23.08.1991 to 18.09.1991

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

This study was conducted to GLP

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1991

Report date:

1991

Materials and methods

Study type:

direct photolysis

Test guideline

Qualifier:

according to guideline

Guideline:

other: Phototransformation of Chemicals in Water, Part A: Direct Phototransformation, UBA,

Version / remarks:

1990

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

1

Reference substance name:

2-chloro-N-[[[4-(trifluoromethoxy)phenyl]amino]carbonyl]benzamide

EC Number:

264-980-3

EC Name:

2-chloro-N-[[[4-(trifluoromethoxy)phenyl]amino]carbonyl]benzamide

Cas Number:

64628-44-0

Molecular formula:

C15H10ClF3N2O3

IUPAC Name:

3-(2-chlorobenzoyl)-1-[4-(trifluoromethoxy)phenyl]urea

Study design

Radiolabelling:

no

Analytical method:

high-performance liquid chromatography

Light source:

other: mercury immersion lamp - polychromatic light

Light spectrum: wavelength in nm:

295 - <= 490

Details on light source:

The degradation experiment was conducted in a merrygo-round irradiation apparatus, fitted with a mercury immersion lamp. Higher-energy UV-rays below 295 nm were quantitatively absorbed by the incorporation of a filter tube.

Details on test conditions:

The quantum yield of the direct photodegradation of triflumuron in aqueous solution was determined in polychromatic light according to the ECETOC-method. The degradation experiment was conducted in a merrygo-round irradiation apparatus, fitted with a mercury immersion lamp. Higher-energy UV-rays below 295 nm were quantitatively absorbed by the incorporation of a filter tube. The quantum yield was calculated by means of the computer program QUANT. Besides the quantum yield, the absorption of the compound in the range of the tropospheric sunlight spectrum and the geographic, climatic, seasonal and matrix-specific marginal conditions are important factors influencing the degradation of the substance by direct photodegradation. The so-called environmental half-life for different marginal conditions can be assessed by means of arithmetic models (GC-Solar computer model by Zepp & Cline3 (1977) and the computer program according to Frank and Klöpffer4 (1985).

Preparation of solutions:
Experiments without using solvents are very problematic (adsorption effects) due to the extremely low water solubility of triflumuron. Usually the highly pure acetonitrile used remains neutral in photodegradation experiments.

Stock solution:
An amount of 21.0 mg test substance was dissolved in 100 ml acetonitrile. An aliquot of 2.5 mL of this stock solution was diluted with 47.5 ml acetonitrile and 50 mL water to a standard solution containing 5.25 mg active ingredient per liter water/acetonitrile 1:1 (v:v). The purity of the substance was checked by HPLC.

Solutions for the UV-absorption spectra:
Solutions in different solvents were used for recording UV-absorption spectra. The UV-absorption spectrum of a solution of 5.25 mg triflumuron/1 water/acetonitrile (1:1, v:v) was used for the calculation of the quantum yield.

Solutions for the photodegradation experiments:
The stock solution was diluted with water/acetonitrile (1:1;v:v). The evaluation of the HPLC analyses on the basis of external standard yielded 5.73 and 5.64 mg triflumuron per 1 water/acetonitrile (1:1; v:v), resp., as initial concentration for the two degradation experiments.

Performance of the photodegradation experiment:
The merry-go-round irradiation apparatus was started about 30 min. before beginning the exposure of the samples in order to guarantee a constant radiation of the light source as well as a constant sample temperature (room temperature) already at the beginning of the experiment. Subsequently only the merry-go-round but not the lamp or the cycle cooling was switched off for entering or removing of samples.
After the equilibration phase of the system, 2 measuring cuvettes with 3.0 mL (A) each were first entered and exposed for 10.0 min. After that the measuring cuvettes containing 3.0 mL test solution (5.1.3) each were swiftly placed onto the 10 positions of the merry-go-round. Scattered over a period of 7.5 hours, 1 sample each was removed and clearly marked (study-number, duration of exposure, test number).
Towards the end of the test period two actinometer samples were placed on positions of the merry-go-round meanwhile having become unoccupied and these were exposed for 10 min.

Results and discussion

Quantum yield (for direct photolysis):

0.009

Dissipation half-life of parent compound

Dissipation half-life of parent compound 1

Key result

DT50:

8.45 h

Test condition:

Experiment 1

Dissipation half-life of parent compound 2

Key result

DT50:

9.52 h

Test condition:

Experiment 2

Transformation products:

yes

Remarks:

2-chlorobenzamide was formed during photochemical degradation.

Details on results:

The UV-absorption spectrum showed a main maximum at 200 nm. From the UV absorption data and the kinetic results of two photodegradation experiments in a merry-go-round irradiation apparatus the quantum yield was calculated to be 0.0095.
The resulting quantum yield and UV absorption data in aqueous solution were used to estimate the environmental half-life of triflumuron concerning direct photodegradation in water by two different simulation models The results of modelling indicate that direct photodegradation in aqueous solution contributes to the overall elimination of triflumuron in the environment to low extent only and that the environmental half-lives concerning direct photodegradation ranges from two months to more than one year, for the period of main use.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Remarks:

The study is acceptable

Conclusions:

This study investigated the photodegradation of triflumuron in water. The quantum yield was calculated to be 0.0095. DT50 values of 8.45-9.52 hours were calculated.