Photodegradation of the isoxazolidine fungicide syp-z048 in aqueous solution: Kinetics and photoproducts

Article abstract of DOI:10.1021/jf3034607

Previous research has demonstrated that 3-[5-(4-chlorophenyl)-2,3-dimethyl- 3-isoxazolidinyl]pyridine (SYP-Z048), a newly developed nitrogen heterocycle substituted isoxazolidine compound, has good protective and curative activities against a wide range of fungal diseases of fruits and vegetables caused by Ascomycetes, Basidiomycetes, and Deuteromycetes. In this study, the photochemical behavior of SYP-Z048 was investigated in aqueous solution and in response to solar and low-pressure mercury ultraviolet (UV) lamp irradiation. SYP-Z048 photolysis was pH- and temperature-dependent and was described by a first-order degradation reaction. A total of 11 photoproducts were separated by high-performance liquid chromatography (HPLC) and solid-phase extraction (SPE) and were identified on the basis of ¹H and ¹³C nuclear magnetic resonance (NMR) and high-performance liquid chromatography-mass spectrometry (HPLC-MS) spectra. The photoproduct structures and kinetics suggested that the phototransformation of SYP-Z048 occurred via multiple reaction pathways that included the cleavage of the N-O bond in the isoxazolidine ring and the dechlorination of the benzene ring.

Full text of DOI:10.1021/jf3034607

Article
pubs.acs.org/JAFC
Photodegradation of the Isoxazolidine Fungicide SYP-Z048 in
Aqueous Solution: Kinetics and Photoproducts
Pengfei Liu,† Yanjun Xu,‡ Jianqiang Li,† Junli Liu,§ Yongsong Cao,† and Xili Liu*,†
†College of Agriculture and Biotechnology, and ‡College of Science, China Agricultural University, Beijing 100193, People’s Republic
of China
§Shenyang Research Institute of Chemical Industry, Shenyang 110021, People’s Republic of China
ABSTRACT: Previous research has demonstrated that 3-[5-(4-chlorophenyl)-2,3-dimethyl-3-isoxazolidinyl]pyridine (SYP-
Z048), a newly developed nitrogen heterocycle substituted isoxazolidine compound, has good protective and curative activities
against a wide range of fungal diseases of fruits and vegetables caused by Ascomycetes, Basidiomycetes, and Deuteromycetes. In
this study, the photochemical behavior of SYP-Z048 was investigated in aqueous solution and in response to solar and low-
pressure mercury ultraviolet (UV) lamp irradiation. SYP-Z048 photolysis was pH- and temperature-dependent and was described
by a first-order degradation reaction. A total of 11 photoproducts were separated by high-performance liquid chromatography
1
(HPLC) and solid-phase extraction (SPE) and were identified on the basis of H and 13C nuclear magnetic resonance (NMR)
and high-performance liquid chromatography−mass spectrometry (HPLC−MS) spectra. The photoproduct structures and
kinetics suggested that the phototransformation of SYP-Z048 occurred via multiple reaction pathways that included the cleavage
of the N−O bond in the isoxazolidine ring and the dechlorination of the benzene ring.
KEYWORDS: SYP-Z048, photodegradation kinetics, photodegradation pathway, photoproducts
can be difficult,27 however, because the structures can be
complex, are often unknown, and can occur at very low
concentrations in the environment. To determine the
degradation pathway of a new pesticide, researchers must
1. INTRODUCTION
Because chemical pesticides are effective and easy to apply, they
have been widely used to increase crop yields. Once applied,
however, the pesticides may suffer photodegradation, hydrol-
obtain sufficient photoproducts and use multiple analytic
ysis, or biodegradation,1,2 and the degradation products may be
methods, including high-performance liquid chromatography−
mass spectrometry (HPLC−MS), gas chromatography−mass
spectrometry (GC−MS), and nuclear magnetic resonance
(NMR).
Although reactions resulting in the “ring-opening” of the
heterocycle moiety during isoxazoline and isoxazolidine photo-
degradation have been described,28,29 the fate of SYP-Z048 in
the environment has not been investigated in depth. The goal
of the current study is to elucidate the photochemical behavior
of SYP-Z048 in aqueous solution. SYP-Z048 photolysis kinetics
are evaluated; a large number of photoproducts are identified;
and a detailed degradation pathway is proposed.
stable and toxic to non-target organisms.2,3 The widespread
occurrence of pesticides and their degradation products in the
environment and food commodities has concerned environ-
mentalists and food chemists.4,5
3-[5-(4-Chlorophenyl)-2,3-dimethyl-3-isoxazolidinyl]-
pyridine (SYP-Z048), an isoxazolidine class fungicide,6 was
developed by the Shenyang Research Institute of Chemical
Industry for control of tomato gray mold. Isoxazolines are a
relatively new class of chemicals and have substantial
antimicrobial activities.7 A series of agrochemicals with
isoxazoline as the functional group have been designed,
synthesized, and applied for crop protection.8,9 As one analogue
of these new chemicals, SYP-Z048 has protective and curative
activities against a wide range of fungal diseases caused by
Ascomycetes, Basidiomycetes, and Deuteromycetes in fruits
and vegetables.10,11 Like many other fungicides that inhibit
demethylation (“DMI fungicides”), SYP-Z048 is an ergosterol
synthesis inhibitor12 and has low mammalian toxicity, with no
genotoxicity or teratogenicity to rats.13,14
Pesticide photodegration products are an important type of
organic pollutant.15−17 Photolysis is a major process by which
pesticides are transformed18,19 and frequently occurs in the
atmosphere and on the surface of water, soil, and plants.20−23
The photoproducts generated by photolysis are in some cases
more toxic and damaging to the environment than their parent
compounds.24,25 As a result, researchers are now identifying
photoproducts and determining their toxicity as part of
pesticide risk assessment.26 Identification of photoproducts
2. MATERIALS AND METHODS
2.1. Chemicals and Reagents. SYP-Z048 (99.3% purity) was
obtained from the Shenyang Research Institute of Chemical Industry.
The standards, 2-methylpyridine (98.0% purity), 3-methylpyridine
(99.5% purity), 1-chloro-4-methylbenzene (98.0% purity), 4-chlor-
obenzaldehyde (97.0% purity), and 1-(4-chlorophenyl)ethanone
(97.0% purity), were purchased from Sigma-Aldrich. HPLC-grade
methanol was purchased from Fisher Scientific. Ultrapure water was
obtained with a Millipore water purification system (Milli-Q, Bedford,
MA). SYP-Z048 and photoproduct standard solutions and SYP-Z048
working solutions were prepared by dissolving SYP-Z048 in water/
Received: August 9, 2012
Revised: October 31, 2012
Accepted: November 6, 2012
Published: November 6, 2012
© 2012 American Chemical Society
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methanol (99:1, v/v). All other reagents were analytical-grade and
used as received.
from 200 to 350 nm with two characteristic bands at 212 and
223 nm and a shoulder at 261 nm (Figure 1). The absorption
spectral range above 290 nm suggested that SYP-Z048 could
degrade under solar light.
2.2. Photodegradation Experiments. The photodegradation
reactions were performed in a quartz tube. The aqueous solution was
irradiated through the wall of the quartz tube using a low-pressure
mercury lamp (250 W, λ = 254 nm) or direct sunlight. The light
intensity of the mercury lamp at 254 nm was 700 μW cm−2, as
measured with a ZDZ-1 ultraviolet (UV) irradiation photometer. The
solar irradiation experiments were performed during the summer
(from June to August, 2009) at the China Agricultural University,
Beijing, China (40° 27′ 53.73″ N, 116° 27′ 36.96″ E).
To investigate the kinetics of SYP-Z048 or its main photoproducts,
20 mL aliquots of 10.0 μg mL−1 SYP-Z048 in water/methanol (99:1,
v/v) were irradiated under a low-pressure mercury lamp or sunlight.
Samples from the solution were taken at regular intervals for HPLC−
MS analysis. The effect of pH was determined with solutions that were
buffered by 40 mM KH2PO4 and adjusted to pH 5, 7, and 9 by the
addition of NaOH. The effect of the temperature (30 and 50 °C)
under UV irradiation was also evaluated.
To acquire large amounts of photoproducts, 100.0 μg mL−1 SYP-
Z048 in non-buffered water/methanol (99:1, v/v) was irradiated for
45 min under a low-pressure mercury lamp at 50 °C. The irradiated
solution was collected for direct HPLC−MS or NMR analysis after a
further separation. Some main photoproducts were further confirmed
by analyzing standards on HPLC.
Figure 1. Absorption spectrum of SYP-Z048 in a water/methanol
(99:1) solution.
2.3. HPLC−MS Analysis. SYP-Z048 and photoproducts irritated
by an UV lamp and sunlight were analyzed by the Agilent 1100
HPLC−mass selective detector (MSD) system with an atmospheric
pressure electrospray ionization (API−ES) ion source and a diode
array detector (Agilent Technologies) equipped with a pre-column
and a VP-ODS (5 μm, 250 × 4.6 mm) column. The mobile phase
consisted of CH3OH (A) and H2O (B). The following conditions
were used: 40% B from 0 to 4 min and then from 40 to 20% B in 12
min. The injection volume was 5 μL, and the flow rate was 1 mL
min−1. The MS detection was performed using API−ES in positive
modes. A capillary potential of 100 V, a N2 drying gas flow of 10 L
min−1 at 320 °C, and a nebulizer pressure of 35 psi were maintained
for analysis. The post-column split condition was 30% mobile phase to
the MSD and 70% mobile phase to the waste bottle. The scan range
was 80−800 atomic mass units (amu), and the capillary voltage was
4000 V.
SYP-Z048 photodegradation experiments were carried out
under sunlight and UV light. To evaluate the effect of
hydrolysis during the experiments, SYP-Z048 in buffer solution
(pH 5, 7, and 9) was kept in darkness for 7 days at 30 and 50
°C. The results showed no obvious SYP-Z048 degradation
(data not shown). Within 7 days of solar irradiation,
photodegradation was 37, 76, and 75% in solutions buffered
to pH 5, 7, and 9 (Figure 2a). Photolysis was much faster with
UV irradiation than with solar radiation; with UV irradiation,
more than 82% of the SYP-Z048 was degraded in 120 min at 30
°C (Figure 2b) and in 7 min at 50 °C (Figure 2c). With either
sunlight or UV light, the SYP-Z048 concentration declined
logarithmically with irradiation time, indicating a first-order
degradation process.
2.4. Photoproduct Pretreatment and NMR Analysis. Because
exposure of SYP-Z048 in aqueous solution to light generated a mixture
of photoproducts at very low concentrations, pre-concentration and
separation steps were required before NMR analysis. For pre-
concentration, a collected sample of 1.5 L containing 100.0 μg mL−1
SYP-Z048 was extracted on a Visiprep solid-phase extraction (SPE)
vacuum manifold. The samples of photoproducts were added to
ENVI-18 SPE cartridges (SUPCO, 300 mg), which were pre-
conditioned with methanol and ultrapure water. After the pre-
concentrated analytes were held in the cartridges, the photoproducts
were eluted from the cartridges using 3 mL of methanol. SYP-Z048
photoproducts were separated by HPLC using the conditions
described in section 2.3. Each peak eluate was collected manually on
the basis of visual inspection of the chromatogram. The same fractions
were combined; the solvent was removed by passage through ENVI-18
SPE cartridges (SUPCO, 300 mg); and the fractions were then
vacuumed to dryness in a desiccator. About 1 mg of each product was
dissolved in deuterated methanol (CD3OD) for NMR analysis
(INOVA-50; tetermethylsilane was the internal standard).
An influence of solution pH on the pesticide photo-
degradation rate has been previously reported.30−32 An effect
of pH on the SYP-Z048 photodegradation rate was clearly
demonstrated in the current study (Figure 2). With solar
radiation, the photodegradation rate (k) was much greater at
pH 7 and 9 than at pH 5 (Figure 2a); the half-life (t1/2) with
solar degradation was 11.2, 5.0, and 5.3 days at pH 5, 7, and 9,
respectively. The effect of pH was smaller with UV irradiation
than with solar irradiation, but SYP-Z048 degradation with UV
radiation tended to be slower at pH 5 than at pH 7 and 9
(Figure 2b). Apparently, acidic conditions hindered degrada-
tion of SYP-Z048, and a similar observation has been reported
on ciprofloxacin.33
When the temperature was increased from 30 to 50 °C, the
half-life of SYP-Z048 under UV radiation decreased about 20
times (Figure 2b versus Figure 2c). This finding is consistent
with many reports that the rate of pesticide degradation
increases with the temperature.34,35
When a SYP-Z048 solution (with an initial concentration of
100 μg mL−1) was irradiated by UV light for 45 min at 50 °C,
11 main photoproducts and 2 isomers of SYP-Z048 were
detected by HPLC−MS (Figure 3). They were denoted with
uppercase letters A−M based on elution sequence, in which K
and L represent isomers of SYP-Z048, which are described
later. Kinetics curves (Figure 4) for photoproducts A, B, C, E,
F, G, I, and M were obtained from buffered solutions (pH 7)
2.5. Statistical Analysis. SYP-Z048 concentrations were fit to a
first-order degradation equation Ct = C0 e−kt, where Ct is the SYP-Z048
concentration at time t, C0 is the initial concentration of SYP-Z048, k
is the degradation rate, and t is the time. The half-life, t1/2, was
calculated from the equation t1/2 = 0.693/k.
3. RESULTS AND DISCUSSION
3.1. Photodegradation Kinetics. The UV−vis absorption
spectrum of SYP-Z048 in aqueous solution showed absorbance
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Figure 2. Kinetics of SYP-Z048 photodegradation in aqueous solutions (pH 5, 7, and 9) exposed to (a) solar irradiation at 30 °C, (b) UV irradiation
at 30 °C, and (c) UV irradiation at 50 °C. The initial concentration of SYP-Z048 was 10 μg mL−1. Lines represent linear regressions.
during a 220 min exposure to irradiation using the low-pressure
mercury UV lamp at 30 °C. Products D, H, and J were not
detected under this reaction condition. More than 97% of SYP-
Z048 was degraded after 220 min of irradiation, with the major
degradation products as B and F (Figure 4a). Compounds A, I,
and M accumulated quickly, early during irradiation, and then
decreased after 20 or 80 min (Figure 4b), indicating that they
might be primary products. The delayed appearance of
compound G suggested that it could be a secondary product.
Figure 3. HPLC chromatogram of a SYP-Z048 solution after 45 min
The decline in the concentration of compound G after 120 min
of high-pressure mercury lamp irradiation. Areas were determined at
suggested that was further transformed into other products.
254 nm.
During the irradiation period, compounds B, C, E, and F
accumulated in the solution without any further degradation.
Figure 4. Degradation of SYP-Z048 in pH 7 solutions at 30 °C in the dark (1) and during UV irradiation (2) and the concentrations of principal
photoproducts (indicated by uppercase letters) during the irradiation. A high-pressure mercury UV lamp was used. The initial concentration of SYP-
Z048 was 10 μg mL−1. Concentrations of SYP-Z048 and products B and F are shown in panel a. Concentrations of products A, C, E, G, I, and M are
shown in panel b.
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Table 1. 1H and 13C NMR Chemical Shifts (δ, ppm) and H,H-Coupling Constants (3JH,H, Hz) of Photoproducts B, C, E, F, G,
M, and SYP-Z048 (K, Z Isomer; L, E Isomer)
3.2. Identification of the Photoproducts. Photoproducts
The 1H and 13C NMR spectra for compound M were similar
to those of the parent compound; they differed only in some
chemical shifts. Thus, compound M was identified as 1-(4-
chlorophenyl)-3-(methylamino)-3-(pyridine-3-yl)butan-1-ol,
which might be produced by the opening of the SYP-Z048
isoxazolidine ring induced by the cleavage of the N−O bond.
The ring-opening reaction of heterocycles through cleavage of
the labile N−O bond under UV irradiation was also reported
by Mukai et al.34 and Singh et al.35 The compound M
experienced a further degradation under UV irradiation and
produced methyl pyridine (B and E) and derivatives of
chlorobenzene (C, F, and G). This conjecture is in accordance
with the kinetics of the compound.
1
B, C, E, F, G, and M were separated and identified by H and
13C NMR (Table 1), and A, D, H, I, and J were identified by
HPLC−MS (Table 2).
K and L were identified as isomers of SYP-Z048 because
their retention times, molecular ion peaks, and fragmentation
patterns were essentially the same as those of the SYP-Z048
standard. The peaks at m/z 310.9, 150.9, and 172.9 were
temporarily identified as (M + Na)+, (
+ Na)+ ions. The NMR data were basically consistent
with a previous report.6
+ H)+, and
(
According to the key resonances and their assignment
presented in Table 1, the compounds B, C, E, F, and G were
identified as 2-methylpyridine, 1-chloro-4-methylbenzene, 3-
methylpyridine, 4-chlorobenzaldehyde, and 1-(4-
chlorophenyl)ethanone, respectively. HPLC analyzing of the
five compound standards also confirmed the results.
The molecular ion peak of D was 18 mass units lower than
that of SYP-Z048, and the mass spectra of D lacked a chlorine
isotope peak. A characteristic fragment ion of the parent
compound was also evident at m/z 150.9. D, which might be
produced by the dechlorination and hydroxylation of SYP-
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Table 2. HPLC−MS Analysis of SYP-Z048 and Photoproducts after 45 min of Irradiation under the High-Pressure Mercury
Lamp in Water/Methanol Solution (99:1)
Z048, was identified as 4-(2,3-dimethyl-3-(pyridine-3-yl)-
isoxazolidin-5-yl)phenol.
compound M. Then, 4-chlorobenzaldehyde, 1-(4-
chlorophenyl)ethanone, 2-methylpyridine, and 3-methylpyri-
dine are formed by the cleaving of chlorinephenylaminopyr-
idine, and they are subsequently converted into 1-chloro-4-
methylbenzene by the demethyl reaction. The second pathway
is initiated by the dechlorination of the benzene ring at
chlorine; subsequent oxidation produces compounds D, H, and
I. Compounds D, H, and I are further degraded into
compounds J and A by the opening of the isoxazolidine ring.
Compounds J and A are finally transformed into 2-
methylpyridine and 3-methylpyridine.
For the compounds H and I, the molecular ions at m/z 255
were 35 mass units lower than those of SYP-Z048 and no
chlorine isotope peaks were evident. They were identified as
(M − Cl + H)+. The fragmentation patterns of compounds H
and I at m/z 150.9 and 172.9 were similar to those of SYP-
Z048, suggesting that the main molecular skeleton had not
changed. Consequently, compounds H and I were identified as
isomers of 2,3-dimethyl-5-phenyl-3-(pyridine-3-yl)-
isoxazolidine.
3.4. Photolysis of SYP-Z048 under Different Light
Sources. UV irradiation generated more photoproducts than
solar radiation. The main products of the two proposed
pathways were similar with both solar and UV radiation, except
that the following compounds were not produced with solar
radiation: 3-amino-3-(pyridin-3-yl)propanal (A), 2-methylpyr-
idine (C), 4-(2,3-dimethyl-3-(pyridine-3-yl)isoxazolidin-5-yl)-
phenol (D), and 2,3-dimethyl-5-phenyl-3-(pyridine-3-yl) (H).
Overall, these results suggest that the proposed photolysis
pathways may occur in the natural environment.
3.5. Toxicity of SYP-Z048 Photoproducts. The acute
aquatic toxicity criterion was described by The Globally
Harmonized System of Classification and Labeling of
Chemicals (GHS). According to the acute toxicity data
(which were generated with fish) from the Sigma-Aldrich
Safety Data Sheet,36 the SYP-Z048 photoproducts identified
here have different potentials for harming aquatic organisms.
The compound 4-chlorobenzaldehyde (F) is assigned to GHS
Acute Category II; 2-methylpyridine (B) and 1-(4-
chlorophenyl)ethanone (G) are assigned to GHS Acute
The fragment ions of compound J were quite different from
those of compounds H and I, although the molecular ion was
also at m/z 255. The fragments of compound J at m/z 136 and
120 are probably (
+ H)+ and (
+ H)+ ions. On the
basis of mass information, compound J might result from a
cleavage in the N−O bond of compounds H or I, which would
induce the opening of the isoxazolidine ring and produce 3-
(merhylamino)-1-phenyl-3-(pyridine-3-yl)butan-1-one.
Compound A had molecular ion peaks at m/z 150.9 (M +
H)+ and m/z 172.9 (M + Na)+, indicating that it had the same
fragment ions as the parent compound. Compound A was
identified as 3-amino-3-(pyridin-3-yl)propanal and might be
produced by demethylation and benzene ring reduction of
compound J.
3.3. Proposed Degradation Pathway. On the basis of
the degradation products and kinetics, two possible pathways
for the photodegradation of SYP-Z048 in aqueous solution are
proposed in Figure 5. The first pathway is initiated by the
opening of the isoxazolidine ring at bond N−O to yield
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Figure 5. Presumed pathways for SYP-Z048 photodegradation by UV irradiation.
(2) Gupta, B.; Rani, M.; Kumar, R.; Dureja, P. Decay profile and
metabolic pathways of quinalphos in water, soil and plants.
Chemosphere 2011, 85 (5), 710−716.
Category III; and 3-methylpyridine (E) has no acute aquatic
toxicity. However, the toxicities of the other products of SYP-
Z048 photolysis are unclear. Additional research is needed
regarding the toxicity of SYP-Z048 photoproducts to non-target
organisms in the natural environment.
́
(3) Boudina, A.; Emmelin., C.; Baaliouamer, A.; Païsse, O.;
Chovelon, J. M. Photochemical transformation of azoxystrobin in
aqueous solutions. Chemosphere 2007, 68 (7), 1280−1288.
(4) Yang, R. Q.; Lv, A. H.; Shi, J. B.; Jiang, G. B. The levels and
distribution of organochlorine pesticides (OCPs) in sediments from
the Haihe River, China. Chemosphere 2005, 61 (3), 347−354.
(5) Allaoui, A.; Malouki, M. A.; Wong-Wah-Chung, P. Efficient
degradation of methabenzthiazuron photoinduced by decatungstate
anion in water: Kinetics and mechanistic studies. Chemosphere 2011,
85 (4), 558−564.
(6) Shaber, S. H; Zhang, L. X.; Szapacs, E. M.; Quinn, J. A.
Heterocyclic substituted isoxazolidines and their use as fungicides. U.S.
Patent 6,313,147.B1, 2001.
(7) Milinkevich, K. A.; Yoo, C. L.; Sparks, T. C.; Lorsbach, B. A.;
Kurth, M. J. Synthesis and biological activity of 2-(4,5-dihydroisoxazol-
5-yl)-1,3,4-oxadiazoles. Bioorg. Med. Chem. Lett. 2009, 19 (19), 5796−
5798.
(8) Rajanarendar, E.; Nagi Reddy, M.; Rama Krishna, S.; Rama
Murthy, K.; Reddy, Y. N.; Rajam, M. V. Design, synthesis,
antimicrobial, anti-inflammatory and analgesic activity of novel
isoxazolyl pyrimido[4,5-b]quinolines and isoxazolyl chromeno[2,3-
d]pyrimidin-4-ones. Eur. J. Med. Chem. 2012, 55, 273−283.
(9) Weinig, H.-G.; Passacantilli, P.; Colapietro, M.; Piancatelli, G.
Glycal-mediated synthesis of enantiomerically pure 5-substituted
isoxazoles containing a differentially O-benzylated glycerol moiety.
Tetrahedron Lett. 2002, 43 (26), 4613−4615.
AUTHOR INFORMATION
■
Corresponding Author
*Telephone/Fax: +86-10-62731013. E-mail: seedling@cau.edu.
cn.
Funding
We gratefully acknowledge the National Natural Science
Foundation of China (31000866) for financial support.
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
We are grateful to Jibo Lin, Mingan Wang, and Yanhong Dong
for advice and assistance in the HPLC−MS and NMR analyses.
We also thank the Chinese Academy of Medical Sciences for
their NMR analysis.
REFERENCES
■
(1) Tixier, C.; Sancelme, M.; Aït-Aïssa, S.; Widehem, P.; Bonnemoy,
F.; Cuer, A.; Truffaut, N.; Veschambre, H. Biotransformation of
phenylurea herbicides by a soil bacterial strain, Arthrobacter sp. N2:
Structure, ecotoxicity and fate of diuron metabolite with soil fungi.
Chemosphere 2002, 46 (4), 519−526.
(10) Liu, J. L.; Si, N. G.; Chen, L.; Zhang, D. M.; Zhang, Z. J.
Biological activity against tomato leaf mold and application of a novel
fungicide, SYP-Z048(III). Chin. J. Pestic. 2004, 43 (3), 103−105.
11662
dx.doi.org/10.1021/jf3034607 | J. Agric. Food Chem. 2012, 60, 11657−11663

Journal of Agricultural and Food Chemistry
Article
(11) Si, N. G.; Zhang, Z. J.; Liu, J. L.; Li, Z. N.; Zhang, D. M.; Chen,
L.; Wang, L. Z. Biological activity and application of a novel fungicide:
SYP-Z048(I). Chin. J. Pestic. 2004, 43 (1), 16−18.
(30) Cao, Y. S.; Chen, J. X.; Huang, L.; Wang, Y. L.; Hou, Y.; Lu, Y.
T. Photocatalytic degradation of chlorfenapyr in aqueous suspension
of TiO2. J. Mol. Catal. A: Chem. 2005, 233 (1−2), 61−66.
(31) Liu, W.; Chen, S. F.; Zhao, W.; Zhang, S. J. Titanium dioxide
mediated photocatalytic degradation of methamidophos in aqueous
phase. J. Hazard. Mater. 2009, 164 (1), 154−160.
(12) Han, P.; Liu, X. L.; Liu, P. F.; Si, N. G. Effect of novel fungicide
5-(4-chloro pheny1)-2,3-dimethyl-3-(pyridine-3)-oxazoline on ergo-
sterol biosynthesis in Botrytis cinerea by high performance liquid
chromatography. Chin. J. Anal. Chem. 2006, 34 (10), 1467−1470.
(13) Tan, J.; Shan, Y. X.; Su, L. Evaluation of SYP-Z048 genotoxicity.
Agrochemicals 2006, 45 (4), 269−274.
(14) Yan, W. J.; Li, Z. G.; Zou, L. Y.; Wu, Y. L. Teratogenicity of
SYP-Z048 in rats. Agrochemicals 2008, 47 (9), 665−667.
́ ́
(15) Durand, G.; Barcelo, D.; Albaiges, J.; Mansour, M. Utilisation of
̌
́ ́ ́
(32) Abramovic, B. F.; Banic, N. D.; Sojic, D. V. Degradation of
thiacloprid in aqueous solution by UV and UV/H2O2 treatments.
Chemosphere 2010, 81 (1), 114−119.
(33) Torniainen, K.; Tammilehto, S.; Ulvi, V. The effect of pH, buffer
type and drug concentration on the photodegradation of ciprofloxacin.
Int. J. Pharm. 1996, 132 (1−2), 53−61.
(34) Evgenidou, E.; Fytianos, K.; Poulios, I. Photocatalytic oxidation
of dimethoate in aqueous solutions. J. Photochem. Photobiol., A 2005,
175 (1), 29−38.
liquid chromatography in aquatic photodegradation studies of
pesticides: A comparison between distilled water and seawater.
Chromatographia 1990, 29 (3−4), 120−124.
́ ́
(35) Zapata, A.; Oller, I.; Bizani, E.; Sanchez-Perez, J. A.; Maldonado,
(16) Espín, S.; Martínez-Lop
́ ́
ez, E.; Gomez-Ramírez, P.; María-
M. I.; Malato, S. Evaluation of operational parameters involved in solar
photo-Fenton degradation of a commercial pesticide mixture. Catal.
Today 2009, 144 (1−2), 94−99.
Mojica, P.; García-Fernandez, A. J. Assessment of organochlorine
́
pesticide exposure in a wintering population of razorbills (Alca torda)
from the southwestern Mediterranean. Chemosphere 2010, 80 (10),
1190−1198.
(36) http://www.sigmaaldrich.com/china-mainland.html.
(17) Bempah, C. K.; Buah-Kwofie, A.; Enimil, E.; Blewub, B.; Agyei-
Martey, G. Residues of organochlorine pesticides in vegetables
marketed in Greater Accra Region of Ghana. Food Control 2012, 25
(2), 537−542.
(18) Burrows, H. D.; Canle, L. M.; Santaballa, J. A.; Steenken, S.
Reaction pathways and mechanisms of photodegradation of pesticides.
J. Photochem. Photobiol., B 2002, 67 (2), 71−108.
(19) Lin, Y. J.; Karuppiah, M.; Shaw, A.; Gupta, G. Effect of simulated
sunlight on atrazine and metolachlor toxicity of surface waters.
Ecotoxicol. Environ. Saf. 1999, 43 (1), 35−37.
(20) Escalada, J. P.; Pajares, A.; Gianotti, J.; Biasutti, A.; Criado, S.;
Molina, P.; Massad, W.; Amat-Guerri, F.; García, N. A. Photosensitized
degradation in water of the phenolic pesticides bromoxynil and
dichlorophen in the presence of riboflavin, as a model of their natural
photodecomposition in the environment. J. Hazard. Mater. 2011, 186
(1), 466−472.
(21) Banerjee, K.; Dureja, P. Phototransformation of quinalphos on
clay surfaces. Toxicol. Environ. Chem. 1998, 68, 475−480.
(22) Zhang, L. H.; Xu, C. B.; Chen, Z. L.; Li, X. M.; Li, P. J.
Photodegradation of pyrene on soil surfaces under UV light
irradiation. J. Hazard. Mater. 2010, 173 (1−3), 168−172.
(23) Scholz, K.; Reinhard, F. Photolysis of imidacloprid (NTN
33893) on the leaf surface of tomato plants. Pestic. Sci. 1999, 55 (6),
652−654.
́
(24) Bonnemoy, F.; Lavedrine, B.; Boulkamh, A. Influence of UV
irradiation on the toxicity of phenylurea herbicides using Microtox®
test. Chemosphere 2004, 54 (8), 1183−1187.
(25) Dimou, A. D.; Sakkas, V. A.; Albanis, T. A. Metolachlor
photodegradation study in a aqueous media under natural and
simulated solar irradiation. J. Agric. Food Chem. 2005, 53 (3), 694−
701.
(26) Boesten, J. J.; Kopp, H.; Adriaanse, P. I.; Brock, T. C.; Forbes, V.
̈
E. Conceptual model for improving the link between exposure and
effects in the aquatic risk assessment of pesticides. Ecotoxicol. Environ.
Saf. 2007, 66 (3), 291−308.
́
(27) Sevilla-Moran, B.; Sandín-Espana, P.; Vicente-Arana, M. J.;
̃
Alonso-Prados, J. L.; García-Baudín, J. M. Study of alloxydim
photodegradation in the presence of natural substances: Elucidation
of transformation products. J. Photochem. Photobiol., A 2008, 198 (2−
3), 162−168.
(28) Mukai, T.; Kumagal, T.; Saiki, H.; Kawamura, Y. Photochemical
behaviour of cyclic imino ethers: The N−O bond fission, syn−anti
isomerization and cycloaddition reactions in the C−N−O chromo-
phore. J. Photochem. 1981, 17 (2), 365−368.
(29) Singh, R.; Singh, G.; Ishar, M. P. S. Facile ketone sensitized
photochemical ring opening of isoxazolidines to β-enaminocarbonyl
compounds. Indian J. Chem. 2010, 49B (2), 234−240.
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