Benzamide, N-[[4-[(cyclopropylamino)carbonyl]phenyl]sulfonyl]-2-methoxy-

Phototransformation in water

Link to relevant study record(s)

Reference

Endpoint:

phototransformation in water

Type of information:

experimental study

Adequacy of study:

key study

Study period:

29 Sep - 23 Nov 2004

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Study type:

direct photolysis

Qualifier:

according to guideline

Guideline:

EPA Guideline Subdivision N 161-2 (Photodegradation Studies in Water)

Qualifier:

according to guideline

Guideline:

other: Journal of the European Communities, Commission Directive, 95/36/EC

GLP compliance:

yes (incl. QA statement)

Radiolabelling:

yes

Analytical method:

high-performance liquid chromatography

Details on sampling:

- Sampling intervals for the parent: 0, 4, 8, 12, 20, 24, 30, and 48 hours post treatment
- Sampling methods for the volatile compounds, if any: Volatile traps were collected at each sampling interval (0, 4, 8, 12, 20, 24, 30, and 48 hours post treatment)
- Sampling intervals/times for pH measurements: pH measurements were performed at each sampling interval (0, 4, 8, 12, 20, 24, 30, and 48 hours post treatment)
- Sampling intervals/times for sterility check: Sterility checks and pH measurements were performed at each sampling interval.
- Sample storage conditions before analysis: Samples were stored frozen until analysis, and were analyzed within 3 days after sampling.

Buffers:

- pH: pH 7
- Type and final molarity of buffer: Potassium phosphate, 0.01 M
- Composition of buffer: KH2P04 was dissolved in Milli-Q water (1 .36 g/ L) and the pH was adjusted to pH 7 by addition of 1 M potassium hydroxide.

Light source:

Xenon lamp

Light spectrum: wavelength in nm:

> 290

Details on light source:

- Emission wavelength spectrum: >290 nm
- Filters used and their purpose: Suprax® filter (DSET) filter
- Light intensity at sample and area irradiated: 680 W/cm2
- Relative light intensity based on intensity of sunlight: The photolysis experiment was conducted so that the exposure time and intensity in the
Suntest unit would approximate natural solar radiation found in Phoenix, Arizona
- Other: Nature of light source is Suntest XLS+ unit containing a Heraeus xenon-arc lamp (ATLAS; Chicago, IL)

Details on test conditions:

TEST SYSTEM
- Type, material and volume of test apparatus/vessels: Sterile quartz glass vessels and ground glass volatile traps were used for irradiated test systems. For dark control test systems, sterile amber bottles with crimp caps were used.
- Sterilisation method: 0.2 µm sterile filter
- Details of traps for volatile, if any: Soda lime, Static for Irradiated

TEST MEDIUM
- Volume used/treatment: 20 mL
- Identity and concentration of co-solvent: Acetonitrile(<0.1%)

REPLICATION
- No. of replicates (dark): 1 per interval per label
- No. of replicates (irradiated): 2 per interval per label

Duration:

48 h

Temp.:

25 °C

Initial conc. measured:

1.06 other: mg/L (Methoxybenzoyl)

Duration:

48 h

Temp.:

25 °C

Initial conc. measured:

1.03 other: mg/L (Sulfonylbenzamide)

Reference substance:

yes

Remarks:

three reference substances

Dark controls:

yes

Test performance:

The irradiation was performed continuously. The maximum period of continuous light exposure was 48 hours. The study was terminated after 48 hours as it had reached two half-lives of the parent.

DT50:

1 d

Test condition:

The first order experimental half-life values of the methoxybenzoyl label and sulfonylbenzamide label in the irradiated samples were 24.5 and 23.2 hours respectively.

DT50:

3.5 d

Test condition:

calculated for a solar summer days at Phoenix, New River Arizona (USA, latitude 33.26 N)

DT50:

5 d

Test condition:

calculated for a solar summer days in Athens (Greece, latitude 38.03 N)

Transformation products:

yes

No.:

#1

No.:

#2

Mass Balance:

Material balance for the methoxybenzoyl label, was 99.2 ± 0.6% (range = 97.6% to100.2%) and 100.2 ± 0.6% (range = 99.0% to 100.9%) of the applied activity in the irradiated and dark (non-irradiated) samples, respectively. Material balance forsulfonylbenzamide label, was 100.7 ± 0.8% (range = 98.9% to 102.5%) and 100.6 ±0.4% (range = 99.9% to 101.4%) of the applied activity in the irradiated and dark (nonirradiated) samples, respectively.

Results:

AE 0001789 degraded very rapidly via aqueous photolysis, with half lives of 24.5 and 23.2 hours for the methoxybenzoyl label and sulfonylbenzamide label, respectively. This was equivalent to a half-life of 3.5 solar days in Phoenix, Arizona (USA). The half-life values were not calculated for the dark control samples due to no degradation. The kinetics results are summarized in the table below:

Half-life, DT50 and DT90:

Label	First Order Regression			DT50 (hrs)	DT90 (hrs)
	Half-life (hrs, days)	Equation c(t) = c0 * e-kt	R²
Methoxybenzoyl	24.5, 1.02	c(t) = 100xe-0.0282 t	0.993	24.5	81.5
Sulfonylbenzamidemide	23.2, 0.97	c(t) = 100xe-0.0298 t	0.995	23.2	77.2

Formation and Decline of Transformation Products:

Two major photodegradation products were found in this study and increased during the irradiation period. In the methoxybenzoyl label, 2-methoxy benzoic acid was the major photolyte and accounted for a maximum of 30.6% of the applied activity. In the sulfonylbenzamide label AE0001789-sulfonic acid was the major photolyte and accounted for a maximum of 55.7% of applied activity. There were multiple minor products (>10% of applied activity) formed in both the labels.14CO2accounted for a maximum 2.7% (methoxybenzoyl label) and 0.1% (sulfonylbenzamide label) of the applied radioactivity at study termination.

Validity criteria fulfilled:

not applicable

Description of key information

 DT50: 1.0 – 5.0 days (under artificial light at pH 7, EPA 161-2) 

Key value for chemical safety assessment

Half-life in water:

5 d

Additional information

In the available GLP study (M-281558-01-1), the photolysis of Cyprosulfamide was studied in a sterile aqueous buffer solution at pH 7 under exposure to simulated sunlight in the laboratory with a nominal test concentration of 1 mg/L for 48 hours at 25 °C (EPA 161-2). Based on the experimental half-life of 1.0 day (24 h), the half-life of the test substance under environmental conditions is calculated to be 3.5 solar summer days at Phoenix, New River Arizona (USA, latitude 33.26 N), or 5.0 solar summer days in Athens (Greece, latitude 38.03 N).