Characterisation by high-performance liquid chromatography–multiple mass spectrometry of intermediate compounds formed from mepanipyrim photoinduced degradation

Calza, Paola; Medana, Claudio; Baiocchi, Claudio; Branca, Paolo Luigi; Pelizzetti, Ezio

doi:10.1016/j.chroma.2004.07.055

Cited by 8 publications

(9 citation statements)

References 22 publications

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“…This behaviour is rather unexpected and in confinal mineralization of several organic compounds, [10][11][12][13] but also for acquiring information on naturally occurring transformations. Specific examples of the applicability of this method are represented by reactions occurring in the environment [14,15] and in living organisms. [16,17] In both cases, some of the intermediates identified through a photocatalytic process have been found in soil samples [14,15] and in the animal liver.…”

Section: Introductionmentioning

confidence: 99%

“…Specific examples of the applicability of this method are represented by reactions occurring in the environment [14,15] and in living organisms. [16,17] In both cases, some of the intermediates identified through a photocatalytic process have been found in soil samples [14,15] and in the animal liver. [16,17] Nevertheless, despite its extensive applications, several mechanistic aspects are still unexplained.…”

Section: Introductionmentioning

confidence: 99%

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Light‐Induced Transformation of Alkylurea Derivatives in Aqueous TiO₂ Dispersion

Calza

Medana

Baiocchi

et al. 2006

Chemistry A European J

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The light-induced degradation of alkylurea derivatives under simulated solar irradiation has been investigated in aqueous solutions containing TiO(2) as a photocatalyst. Herein, we will focus on how the presence of one or more methyl (or ethyl) groups on urea modifies the kinetics of disappearance and influences both the ratio and the extent of the inorganic nitrogen formation caused by different degradation pathways. In the present work, we have elucidated a mechanism for the formation of transformation products of the alkyl derivatives by combining several analytical and spectroscopic procedures and the theoretical simulation of ab initio calculations. In all cases, N-demethylation represents only a secondary pathway, while the main transformation proceeds through an unexpected cyclization, involving (m)ethyl- and di(m)ethylureas with the formation of (methyl)amino-2,3-dihydro-1,2,4-oxadiazol-3-one as the principal intermediate of the reaction (with a yield of 60 %). This behaviour is rather unexpected and in contrast with the typical photocatalyzed transformation pathways, which proceed through the formation of more simple structures.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Light‐Induced Transformation of Alkylurea Derivatives in Aqueous TiO₂ Dispersion

Calza

Medana

Baiocchi

et al. 2006

Chemistry A European J

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“…The main steps involved are normally hydroxylation in various positions followed by further oxidation leading to ring-openings and to the formation of aldehydes and alcohols. In some cases, mass spectra of degradation products look simpler than those of parent compounds because of the introduction of OH [55].…”

Section: Lc-ms Determination Of the Artificial Degradation Of Pesticidesmentioning

confidence: 98%

“…Photocatalysis has been used to study the transformation products of fairly hydrophobic molecules: imidacloprid [100], tebuconazole [18], thiabendazole [105] and mepanipyrim [55]. The main steps involved are normally hydroxylation in various positions followed by further oxidation leading to ring-openings and to the formation of aldehydes and alcohols.…”

Section: Lc-ms Determination Of the Artificial Degradation Of Pesticidesmentioning

confidence: 99%

Liquid Chromatography Tandem Mass Spectrometry as a Tool to Investigate Pesticides and Their Degradation Products

Medana¹,

Calza²,

Baiocchi³

et al. 2005

COC

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The analytical determination of organic structures is a fundamental need in environmental, food and medicinal chemistry, and the chemistry of pesticide compounds is closely involved in this determination because of the environmental and biological transformations that can occur to these molecules. Degradation products often possess higher toxicity than parent substances but unknown structures, and aqueous milieu produce hard-to-solve instrumental problems. The need to analyze low concentrations in polar solutions means that methods in which liquid chromatography is hyphenated to mass spectrometry have a large playing field, which combines trace determination and structural elucidation. An important area of study comprises degradation-simulating models, such as titanium dioxide mediated photocatalytic attacks on different organic structures. HPLC-mass spectrometric studies on pesticides, their metabolites and their degradation products are reviewed.

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“…Studies on the degradation of fungicides of different chemical classes in aqueous solutions as models for the identification of possible degradation pathways are also reported 5–11. In particular, photochemical processes have been shown to play an important role in the elimination of fungicides and derived pollutants.…”

Section: Introductionmentioning

confidence: 99%

Degradation of anilinopyrimidine fungicides photoinduced by iron(III)–polycarboxylate complexes

Anfossi

Sales

Vanni

2006

Pest Management Science

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The photoinduced degradation of three anilinopyrimidine fungicides (cyprodinil, pyrimethanil and mepanipyrim) by Fe(III)-polycarboxylate complexes in aqueous solution was investigated. A photochemical redox reaction of Fe(III) complexes of oxalate and citrate occurs during irradiation (simulating sunlight) and is an important source of Fe(II) and a series of oxidants such as H2O2 and O radicals. The mechanism involves the formation of polycarboxylate radicals and/or carbon-centred radicals derived from decarboxylation, whereas the contribution of Fe(OH)2+ to O radical formation is negligible. The attack of O radicals on the fungicide molecules produces numerous photodegradation products, which were identified by means of LC-ES-MS and turned out to be mono- or dihydroxylated derivatives of the active ingredients, except for 2-amino-4,6-dimethylpyrimidine, which is only formed by pyrimethanil. The half-lives of the active ingredients, when submitted to irradiation in the presence of iron(III)-polycarboxylate complexes, were estimated to vary between 28 and 79 min (photodegradation rates in the same conditions: mepanipyrim > cyprodinil > pyrimethanil), and photodegradation is slower in citrate than in oxalate solutions. Photoproducts and their kinetics of formation are very similar for the three fungicides. The OH substitution involves the aromatic and the heterocyclic ring and the nitrogen bridge between the two rings, except for mepanipyrim when the hydroxylation also involves the propynylic side chain.

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Characterisation by high-performance liquid chromatography–multiple mass spectrometry of intermediate compounds formed from mepanipyrim photoinduced degradation

Cited by 8 publications

References 22 publications

Light‐Induced Transformation of Alkylurea Derivatives in Aqueous TiO₂ Dispersion

Light‐Induced Transformation of Alkylurea Derivatives in Aqueous TiO₂ Dispersion

Liquid Chromatography Tandem Mass Spectrometry as a Tool to Investigate Pesticides and Their Degradation Products

Degradation of anilinopyrimidine fungicides photoinduced by iron(III)–polycarboxylate complexes

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Characterisation by high-performance liquid chromatography–multiple mass spectrometry of intermediate compounds formed from mepanipyrim photoinduced degradation

Cited by 8 publications

References 22 publications

Light‐Induced Transformation of Alkylurea Derivatives in Aqueous TiO2 Dispersion

Light‐Induced Transformation of Alkylurea Derivatives in Aqueous TiO2 Dispersion

Liquid Chromatography Tandem Mass Spectrometry as a Tool to Investigate Pesticides and Their Degradation Products

Degradation of anilinopyrimidine fungicides photoinduced by iron(III)–polycarboxylate complexes

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Light‐Induced Transformation of Alkylurea Derivatives in Aqueous TiO₂ Dispersion

Light‐Induced Transformation of Alkylurea Derivatives in Aqueous TiO₂ Dispersion