Sodium [[α,α'-(ethylenediimino)bis[2-hydroxybenzene-1-acetato]](4-)]ferrate(1-)

Phototransformation in water

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

phototransformation in water

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reason / purpose for cross-reference:

read-across source

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
- Name of test material (as cited in study report): FeEDDHMANa
- Physical state: red, brown powder
- Storage condition of test material: At room temperature, dry in the dark

Radiolabelling:

no

Analytical method:

high-performance liquid chromatography

Details on sampling:

Samples of <= 2 mL were taken. Each test solution was diluted 50 times with 15/85/0.4 (v/v/w) methanol/Milli-Q water/ammonium acetate, prior to analysis.

Buffers:

A 0.05 M phosphate buffer pH7 of potassium dihydrogenphosphate/sodium hydroxide was prepared in double distilled water. To exclude oxygen, nitrogen gas was bubbled through the buffer solution for approx. 10 min.

Light source:

Xenon lamp

Light spectrum: wavelength in nm:

> 290 - < 500

Details on light source:

The determination of the absolute distribution of the light intensity entering the reaction cell was based on an actinometric measurement using the potassium ferrioxalate actinometer. This actinometer system has a quantum yield of 1.211 molecules ferric(II) formed per photon absorbed, which can be considered to be constant in the wavelength range of 290 to 500 nm and independent of temperature and light intensity. The actinometric measurement was performed in the same reaction vessel and under the same conditions as the test solution. After a lightning period of exactly 1 minute, the formed amount of ferrous(II) ion was determined via the spectrophotometric determination of its phenantroline complex at 510 nm. The ferric(III) ion apparently forms only a weak complex with phenantroline which is transparent at 510 nm. The formed ferrous(II) in the photo reactor (ΔN in molecules per second) gave the number of photons absorbed per second in the actinometer solution i.e. the number of photons emitted per second by the test apparatus in the wavelength range of 290 - 500 nm going through the quartz top and actually reaching the test sample.

Details on test conditions:

No further details are reported.

Duration:

98.7 h

Temp.:

25 °C

Initial conc. measured:

0.87 g/L

Reference substance:

no

Dark controls:

yes

Computational methods:

Not applicable.

Preliminary study:

Not applicable.

Test performance:

Neither unusual observations during test nor deviations from test procedure or any other information affecting results are reported.

DT50:

40.66 h

Test condition:

for component A (retention time 6.5)

DT50:

35.4 h

Test condition:

for component B (retention time 19.9)

Predicted environmental photolytic half-life:

No prediction reported.

Transformation products:

not specified

Details on results:

No further details are available.

Results with reference substance:

Not applicable.

Validity criteria fulfilled:

yes

Remarks:

Basic scientific validity criteria are met.

Conclusions:

The half-life time for phototransformation of the analogue substance FeEDDHMANa at 25 +/- 3 °C is determined to be 40.66 and 35.4 hours for the two major compartments of this UVCB substance, at a light intensity of 4.86E20 photons/second in the wavelength range of 290 - 500 nm.The same result is expected for the target substance because the core chemical structures of EDDHA-moiety-containing constituents are the same in the source and in the target substance. Thus the same phototransformation rates are expected.

Executive summary:

The degradation of FeEDDHMANa in water as a result of direct photo-transformation (photolysis) was investigated according to the OECD Draft Guidance document: "Direct Phototransformation of Chemicals in water". Chemical analysis of FeEDDHMANa resulted in 4 peaks: 2 major peaks at approximately t = 6.5 and t = 19.9 minutes, respectively and two minor peaks at approximately t = 5.5 and t = 18.9 minutes, respectively. So probably, the test substance consists of at least 4 components. For practical reasons, the photochemic degradation of the 2 major components (component A and B) was determined. The half-life time for phototransformation of FeEDDHMANa at 25 +/- 3 °C is determined to be 40.66 and 35.4 hours for the two major compartments of this UVCB substance, at a light intensity of 4.86E20 photons/second in the wavelength range of 290 - 500 nm.

Reference 2

Endpoint:

phototransformation in water

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

supporting study

Reason / purpose for cross-reference:

read-across source

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
- Name of test substance: Ethylenediamine-N,N´-bis(2-hydroxyphenylacetic) acid; EDDHA/Fe3+

Radiolabelling:

no

Analytical method:

high-performance liquid chromatography

other: LI-COR Lightmeter (Sun radiation measurement)

Details on sampling:

- Sampling time: 0, 1, 3, 7, 15 and 30 days exposure
- Measurement for sun radiation: 9.00 am, 12.00 am, 2.00 pm and 5.00 pm

Buffers:

No buffer composition described.

Light source:

sunlight

Light spectrum: wavelength in nm:

400 - 700

Details on light source:

- Type: Natural sunlight

Details on test conditions:

1) Influence of exposure time to sunlight and solution concentration on EDDHA/Fe3+ photodecomposition:
17.9 mmol/L EDDHA/Fe3+ standard solution was prepared and the pH was adjusted to 7.0. The solution was left overnight in the dark to allow excess Fe to precipitate. Filtration was done through a 0.45 µm Millipore membrane and made up to volume with water. Dilutions were made in order to obtain Fe concentrations of 0.18, 0.89, 1.79, 8.90 and 17.9 mmol/L of Fe as EDDHA/Fe3+. Three replicates of each concentration were exposed to sunlight in glass tubes and three were maintained in the dark. Samples were analysed by High Performance Liquid Chromatography (HPLC) and sun radiation measurement.

2) Effect of the photodegradation products on soybean growth
Soybean seeds (Glycine max L. cv. Oshumi) were germinated at 28 °C on paper moistened with 1 mmol/L CaSO4 in the dark for 3 days. The seedlings were placed in 10 L containers filled with a 1/5 diluted EDTA-buffered nutrient solution and grown for 7 days. On the 8th day, chlorosis was induced by transferring the seedlings into 12 L polypropylene buckets with full-strength EDTA-buffered nutrient solution without Fe source. Plants were grown for 6 days (since chlorosis symptoms occurred) and then placed in 2 L pots covered with black plastic (to avoid light exposure) and the following treatments were performed:
T1) 5 µmol/L o,o-EDDHA/Fe3+ (dark)
T2) 5 µmol/L o,o-EDDHA/Fe3+ (light)
T3) 5 µmol/L o,o-EDDHA/Fe3+ + 2.5 µmol/L salicyclic acid (dark)
T4) 5 µmol/L o,o-EDDHA/Fe3+ + 2.5 µmol/L Salicyaldehyde ethylenediamine diimine (dark)
T5) 5 µmol/L o,o-EDDHA/Fe3+ + 2.5 µmol/L salicylaldehide (dark)
Plants were grown for 14 days in a growth chamber with fluorescent and soldium vapour lamps with a 16 h/30 °C and 50 % humidity day regime and 8 h/25 °C and 70 % humidity night regime. Water was added every 2 days and the solution was renewed weekly. The treatments were replicated four times and the plants were harvested after 14 days.
Salicyladehide, salicyclic acid and Salicylaldehydeethylenediamine diimine were introduced. SPAD (Soil Plant Analysis Development) readings were perfomed during the experiment with a chlorophyll meter (Minolta SPAD-502).
At the end, the shoots and roots were weighed and washed with a Tween-HCl mixture (Tween 0.1 % (v/v) and 0.1 mol/L HCl) and deionized water. The plant material was dried at 70 °C.
Concentrations of Zn, Mn, Cu and Fe in dried plant material samples were measured by atomic absorption spectrometry (ASS) after mineralization of the samples at 480 °C for 4 h and dissolving ashes in 2 % HCl at 80 °C for 30 min.

Reference substance:

no

Remarks:

Information by former studies were taken into account.

Dark controls:

yes

Remarks:

Treatments were performed in light and in the dark.

Computational methods:

Not applicable.

Preliminary study:

Not applicable.

Test performance:

Neither unusual observations during the test nor any other information affecting results are reported.

Parameter:

other: Radiation mean value

Value:

28.8 other: µmol/s/m

Remarks:

9.00 am

Parameter:

other: Radiation mean value

Value:

183.8 other: µmol/s/m

Remarks:

12.00 am

Parameter:

other: Radiation mean value

Value:

363.1 other: µmol/s/m

Remarks:

2.00 pm

Parameter:

other: Radiation mean value

Value:

175.5 other: µmol/s/m

Remarks:

5.00 pm

% Degr.:

66.3

Sampling time:

30 d

Test condition:

light condition

% Degr.:

ca. 0

Sampling time:

30 d

Test condition:

in darkness

Predicted environmental photolytic half-life:

No prediction performed.

Transformation products:

yes

No.:

#1

No.:

#2

No.:

#3

Details on results:

1) Influence of exposure time to sunlight and solution concentration on EDDHA/Fe3+ photodecomposition
- The chelate was progressively degraded along the 30 day period when it was exposed to direct sunlight. Only 33.7 % remained in solution. Most of the photodecomposition was observed during the first 7 days (38 %); another 10.7 % of decomposition was obtained after 8 days and after 30 days, an additional 17.7 % degradation was recorded.
- In darkness, almost 100 % of the chelate was recovered in solution after 30 days.
- The iron chelate was found to be more stable at high pH than at low pH values.
- When the chelate was stored in the dark, only two chromatographic peaks were obtained in the HPLC: one for the racemic isomer and another for the meso isomer of ortho,ortho-EDDHA/Fe3+. Approximately 50 % of the total amout was the racemic isomer, the other 50 % were the meso isomer.
- When the chelate was exposed to sunlight, the peak areas of both meso and racemic isomers were lower and a third peak appeared; possibly related to the photodecomposition products formed.
- Salicylaldehide, salicyclic acid and Salicylaldehyde ethylenediamine diimine peaks were also identified.
- At low chelate concentrations, the degradation increased as sunlight exposure time increased. The EDDHA/Fe3+ photodecomposition was highly correlated with the concentration exposed. Perhaps, at high concentrations, the chelate molecule could act as a screen, thus protecting the remainder of the chelate from photodecomposition.

2) Effect of photodegradation products on soybean growth
- No significant differences in micronutrient concentration in leaves were observed between plants grown in a nutrient solution protected or unprotected from light.
- Plants treated with a mixture of EDDHA/Fe3+ and salicylic acid showed a significantly lower amount of iron in leaves than plants without salicylic acid addition and not exposed to light.
- Photodecomposition products did not affect biomass production since no biomass reduction was observed.

Results with reference substance:

Not applicable.

Validity criteria fulfilled:

yes

Remarks:

Scientifically validity criteria were fulfilled.

Conclusions:

The degree of photodegradation of EDDHA/Fe3+ depends upon the sunlight exposure time and on the concentration of the solution exposed. No negative effects on soybean growth by photodecomposition products were reported. The same result is expected for the target substance because the core chemical structures of EDDHA-moiety-containing constituents are the same in the source and in the target substance. Thus the same phototransformation rates are expected.

Executive summary:

Hernández-Apaolaza and Lucena (2010) evaluated the impact of sunlight exposure and how the concentration of Ethylenediamine-N,N´-bis(2-hydroxyphenylacetic) acid (EDDHA/Fe3 +) influences the photostability of the chelate at constant pH (pH 7). In the second part of the experimental procedure, the effects of the photodegradation products (Salicylaldehide, salicyclic acid and Salicylaldehyde ethylenediamine diimineon) on soybean growth was investigated. Test concentrations of 0.18, 0.89, 1.79, 8.90 and 17.9 mmol/L (three replicates each) were exposed to sunlight and controls were maintained in the dark. Samples were taken at exposure Days 0, 1, 3, 7, 15 and 30 and analysed by High Performance Liquid Chromatography (HPLC). Sun radiation measurements with a lightmeter were performed as well.

The chelate was progressively degraded along the 30 day period when it was exposed to direct sunlight. Only 33.7 % remained in solution. Most of the photodecomposition was observed during the first 7 days (38 %); another 10.7 % of decomposition was obtained after 8 days and after 30 days, an additional 17.7 % degradation was recorded. In darkness, almost 100 % of the chelate was recovered in solution after 30 days. The iron chelate was found to be more stable at high pH than at low pH values. When the chelate was stored in the dark, only two chromatographic peaks were obtained in the HPLC: one for the racemic isomer and another for the meso isomer of ortho,ortho-EDDHA/Fe3+. Approximately 50 % of the total amount was the racemic isomer, the other 50 % were the meso isomer. When the chelate was exposed to sunlight, the peak areas of both meso and racemic isomers were lower and a third peak appeared; possibly related to the photodecomposition products formed. Salicylaldehide, salicyclic acid and Salicylaldehyde ethylenediamine diimine peaks were also identified. At low chelate concentrations, the degradation increased as sunlight exposure time increased. The EDDHA/Fe3+ photodecomposition was highly correlated with the concentration exposed. Perhaps, at high concentrations, the chelate molecule could act as a screen, thus protecting the remainder of the chelate from photodecomposition.

In order to investigate the impact of the photodegradation products on soybean (Glycine max L. cv. Oshumi) growth, different treatment groups were applied to 6-day old plants and were grown for further 14 days. Afterwards, Salicyladehide, salicyclic acid and Salicylaldehydeethylenediamine diimine were introduced. SPAD (Soil Plant Analysis Development) readings were performed during the experiment with a chlorophyll meter. The treatment groups were as followed:

T1) 5 µmol/L o,o-EDDHA/Fe3+ (dark)

T2) 5 µmol/L o,o-EDDHA/Fe3+ (light)

T3) 5 µmol/L o,o-EDDHA/Fe3+ + 2.5 µmol/L salicyclic acid (dark)

T4) 5 µmol/L o,o-EDDHA/Fe3+ + 2.5 µmol/L Salicyaldehyde ethylenediamine diimine (dark)

T5) 5 µmol/L o,o-EDDHA/Fe3+ + 2.5 µmol/L salicylaldehide (dark)

After further pretreatment, the plant material was dried at 70 °C. Concentrations of Zn, Mn, Cu and Fe in dried plant material samples were measured by atomic absorption spectrometry (ASS).

No significant differences in micronutrient concentration in leaves were observed between plants grown in a nutrient solution protected or unprotected from light. Plants treated with a mixture of EDDHA/Fe3+ and salicylic acid showed a significantly lower amount of iron in leaves than plants without salicylic acid addition and not exposed to light. The photodecomposition products did not affect biomass production since no biomass reduction was observed.

Description of key information

Fe(Na)EDDHMA, phototransformation in water, OECD Draft Guideline: DT50: 40.66 and 35.4 hours for the two major components at 25 +/- 3 °C and a light intensity of 4.86E20 photons/second in the wavelength range of 290 - 500 nm.
EDDHA/Fe3+, photostability in water and impact on soybean growth by the degradation products: The chelate was progressively degraded along the 30 day period when it was exposed to direct sunlight. The degradation products did not affect biomass production of soybean plants.

Additional information

The degradation of the source substance Fe(Na)EDDHMA (for further information, please refer to the separate read-across statement) in water as a result of direct photo-transformation (photolysis) was investigated according to the OECD Draft Guidance document: "Direct Phototransformation of Chemicals in water". Chemical analysis of Fe(Na)EDDHMA resulted in 4 peaks: 2 major peaks at approximately t = 6.5 and t = 19.9 minutes, respectively and two minor peaks at approximately t = 5.5 and t = 18.9 minutes, respectively. So probably, the test substance consists of at least 4 components. For practical reasons, the photochemic degradation of the 2 major components (component A and B) was determined.The half-life time for phototransformation of Fe(Na)EDDHMA at 25 +/- 3 °C is determined to be 40.66 and 35.4 hours for the two major compartments of this UVCB substance, at a light intensity of 4.86E20 photons/second in the wavelength range of 290 - 500 nm.

Supporting information is given by Hernández-Apaolaza and Lucena (2010), who evaluated the impact of sunlight exposure and how the concentration of Ethylenediamine-N,N´-bis(2-hydroxyphenylacetic) acid (EDDHA/Fe3 +) influences the photostability of the chelate at constant pH (pH 7). In the second part of the experimental procedure, the effects of the photodegradation products (Salicylaldehide, salicyclic acid and Salicylaldehyde ethylenediamine diimineon) on soybean growth was investigated. Test concentrations of 0.18, 0.89, 1.79, 8.90 and 17.9 mmol/L (three replicates each) were exposed to sunlight and controls were maintained in the dark. Samples were taken at exposure Days 0, 1, 3, 7, 15 and 30 and analysed by High Performance Liquid Chromatography (HPLC). Sun radiation measurements with a lightmeter were performed as well.

The chelate was progressively degraded along the 30 day period when it was exposed to direct sunlight. Only 33.7 % remained in solution. Most of the photodecomposition was observed during the first 7 days (38 %); another 10.7 % of decomposition was obtained after 8 days and after 30 days, an additional 17.7 % degradation was recorded. In darkness, almost 100 % of the chelate was recovered in solution after 30 days. The iron chelate was found to be more stable at high pH than at low pH values. When the chelate was stored in the dark, only two chromatographic peaks were obtained in the HPLC: one for the racemic isomer and another for the meso isomer of ortho,ortho-EDDHA/Fe3+. Approximately 50 % of the total amout was the racemic isomer, the other 50 % were the meso isomer. When the chelate was exposed to sunlight, the peak areas of both meso and racemic isomers were lower and a third peak appeared; possibly related to the photodecomposition products formed. Salicylaldehide, salicyclic acid and Salicylaldehyde ethylenediamine diimine peaks were also identified. At low chelate concentrations, the degradation increased as sunlight exposure time increased. The EDDHA/Fe3+ photodecomposition was highly correlated with the concentration exposed. Perhaps, at high concentrations, the chelate molecule could act as a screen, thus protecting the remainder of the chelate from photodecomposition.

In order to investigate the impact of the photodegradation products on soybean (Glycine maxL. cv. Oshumi) growth, different treatment groups were applied to 6-day old plants and were grown for further 14 days. Afterwards, Salicyladehide, salicyclic acid and Salicylaldehydeethylenediamine diimine were introduced. SPAD (Soil Plant Analysis Development) readings were performed during the experiment with a chlorophyll meter. The treatment groups were as followed:

T1) 5 µmol/L o,o-EDDHA/Fe3+ (dark)

T2) 5 µmol/L o,o-EDDHA/Fe3+ (light)

T3) 5 µmol/L o,o-EDDHA/Fe3+ + 2.5 µmol/L salicyclic acid (dark)

T4) 5 µmol/L o,o-EDDHA/Fe3+ + 2.5 µmol/L Salicyaldehyde ethylenediamine diimine (dark)

T5) 5 µmol/L o,o-EDDHA/Fe3+ + 2.5 µmol/L salicylaldehide (dark)

After further pretreatment, the plant material was dried at 70 °C. Concentrations of Zn, Mn, Cu and Fe in dried plant material samples were measured by atomic absorption spectrometry (ASS).

No significant differences in micronutrient concentration in leaves were observed between plants grown in a nutrient solution protected or unprotected from light. Plants treated with a mixture of EDDHA/Fe3+ and salicylic acid showed a significantly lower amount of iron in leaves than plants without salicylic acid addition and not exposed to light. The photodecomposition products did not affect biomass production since no biomass reduction was observed.