cyproconazole (ISO); (2RS,3RS;2RS,3SR)-2-(4-chlorophenyl)-3-cyclopropyl-1-(1H-1,2,4-triazol-1-yl)butan-2-ol

Phototransformation in water

Link to relevant study record(s)

Reference

Endpoint:

phototransformation in water

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

Apr 2002

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Study type:

direct photolysis

Qualifier:

according to guideline

Guideline:

other: OECD Guidelines for the Testing of Chemicals, Phototransformation of Chemicals in Water

Version / remarks:

2000

Deviations:

yes

Remarks:

See section on "Any other information on materials and methods incl. tables"

Qualifier:

according to guideline

Guideline:

other: OECD TG 101; LN-Visible Absorption Spectra

Version / remarks:

May 1981

Deviations:

yes

Remarks:

See section on "Any other information on materials and methods incl. tables"

GLP compliance:

yes (incl. QA statement)

Radiolabelling:

yes

Analytical method:

high-performance liquid chromatography

Light source:

not specified

Light spectrum: wavelength in nm:

>= 190 - <= 820

Temp.:

25 °C

Initial conc. measured:

22.02 mg/L

Temp.:

25 °C

Initial conc. measured:

44.04 mg/L

Temp.:

25 °C

Initial conc. measured:

1 384 mg/L

Temp.:

25 °C

Initial conc. measured:

3 608 mg/L

Reference substance:

no

Dark controls:

yes

Remarks on result:

not measured/tested

Remarks on result:

not measured/tested

Transformation products:

not measured

FINDINGS

The molar absorption coefficients were calculated from the UV-Visible spectra of the test substance in methanol and methanol/buffer using the Beer-Lambert law, εi = Ai/C·d
where εi = the molar absorption coefficient at wavelength i, Ai = the sample absorbance at wavelength i, C = the molar concentration of the test substance solution and d = the solution cell path length (1.000 cm). Due to the low solubility of the test substance in the buffer medium, data are also presented for the test substance in methanol. The molar absorption coefficients for the test substance in methanol at 290 nm are low. The spectra obtained for the test substance in the buffered solution (methanolic) showed no absorbance above the baseline in the region 290-800 nm.

 

Table 1. UV-Visible spectrum of the test substance (4.746E-03 mol/L) in methanol.

Molar concentration (M)	4.746E-03
Wavelength/nm	259.4	266.0	274.6	290.0
Absorbance	0.974	1.119	0.734	0.016
Molar absorption coefficient (L mol cm)	205	236	155	3.37

 

Table 2. UV-Visible spectrum of the test substance (1.236E-02 mol/L) in methanol.

Molar concentration (M)	1.236E-02
Wavelength/nm	259.4	266	274.6	290
Absorbance	2.485	0.818	1.862	0.020
Molar absorption coefficient (L/mol/cm)	201	228	151	1.62

 

Table 3. UV-Visible spectrum of the test substance in 5 % methanol/buffer.

Molar concentration (M)	7.546E-05
Wavelength/nm	242.5	265.6	290
Absorbance	0.04	0.015	0.00
Molar absorption coefficient (L/mol/cm)	53.0	199	---

 

Table 4. UV-Visible spectrum of the test substance in 10 % methanol/buffer.

Molar concentration (M)	1.509E-04
Wavelength/nm	242.5	265.4	290.0
Absorbance	0.018	0.041	0.005
Molar absorption coefficient (L/mol/cm)	119	272	**

**Below the detection limit of the instrument.

Validity criteria fulfilled:

not specified

Conclusions:

In a study conducted according to OECD TG 101, an OECD draft guideline and following GLP, the molar absorption coefficients ε are < 10 L/mol/cm at wavelengths ≥ 290 nm. Therefore, the test substance is expected to be stable to photolysis under environmentally relevant conditions.

Executive summary:

The photolysis of the 14C–Triazole labelled test substance in water was studied according to OECD TG 101, an OECD draft guideline and following GLP. The UV-Visible spectra of the test substance was obtained in buffered aqueous solutions of pH 7.02 (with up to 10 % methanol added as co-solvent) and in neat methanol at 25 °C. The initial concentrations of the test substance were 22.02, 44.04, 1384 and 3608 mg/L. From the spectra, the molar absorption coefficients were determined to estimate the photolysis of the test substance.

Spectra were measured from 190 - 820 nm at a scan speed of 240 nm/min. The molar absorption coefficients for the test substance in methanol at 290 nm were low. No significant absorbance was detected in the region 290 - 800 nm. Since the molar absorption coefficients were ≤ 10 L/mol/cm at wavelengths ≥ 290 nm, no further studies concerning the direct phototransformation in sunlight are required.

Based on the findings, it is concluded that the test substance is stable to photolysis under environmentally relevant conditions.

Description of key information

Stable to photolysis under environmentally relevant conditions, irradiation with continuous light by UV-Visible spectra (measured wavelength: 190-800 nm), 25 °C, OECD TG 101 and an OECD draft guideline, Oliver & Hurt 2002

Additional information

Only one study is available for this endpoint. The 14C–Triazole labelled test substance was studied according to OECD TG 101 and OECD draft guideline and following GLP (Oliver & Hurt 2002, Reliability 2). The UV-Visible spectra (measured wavelength: 190-820 nm) of the test substance was obtained in buffered aqueous solutions of pH 7.02 (with up to 10 % methanol added as co-solvent) and in neat methanol at 25 °C. The initial concentrations of the test substance were 22.02, 44.04, 1384 and 3608 mg/L. From the spectra, the molar absorption coefficients were determined to estimate the photolysis of the test substance. The molar absorption coefficients are ≤ 10 L/mol/cm at wavelengths ≥ 290 nm. It is concluded that the test substance is stable to photolysis under environmentally relevant conditions.