Determination of 2,4-D and dicamba in food crops by MEKC

The determination of 2,4-D (2,4-dichlorophenoxyacetic acid) and Dicamba (2-methoxy-3,6-dichlorobenzoic acid) residues in sugar cane, rice and corn was performed by a supercritical fluid extraction (SFE) method using CO2/acetone as extraction mix and an SFE apparatus developed in our laboratory. The extracts were cleaned up after extraction by both liquid- liquid partition and a Florisil column. Micellar electrokinetic capillary chromatography (MEKC) coupled with ultraviolet on-column detection was used for the analysis of these pesticides. The detection limits were improved by the preparation of a special detection cell with an increased pathlength that gave detection limits of ca. 0.6 pg for 2,4-D and Dicamba. Our results demonstrated that capillary electrophoresis can be a powerful new analytical tool for pesticide residue analysis.

Breve revisão de métodos de determinação de resíduos do herbicida á cido 2,4-diclorofenoxiacético (2,4-D)

This paper supplies a revision about the main techniques of extraction, clean-up and pre-concentration of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) in water and soil samples, as well as chromatographic methods and immune assays for its identification and quantification.

Absorption and translocation of 2,4-D in plants of Memora peregrina

The objective of this work was to evaluate absorption and translocation of the herbicide 2,4-D in plants of Memora peregrina. The herbicide 2,4-D was used alone with the formulation DMA 806 BR and associated with the herbicide picloram in the commercial product Padron. Levels of radioactivity on the treated leaves were determined in sample obtained after washing them with methanol and chloroform at different times after the application of the radiolabelled formulation (1, 2, 4, 8, 24, and 48 h). Translocation was evaluated by cutting plants between stem and root. The parts obtained were: root, stem, leaf treated, leaves above the leaf treated, leaves below the leaf treated, and leaf opposite of the leaf treated. These parts were weighted, dried, ground, burnt, and radioactivity in the samples was determined. The results suggest that the translocation of the radioactive herbicide 2,4-D was insignificant in plants of M. peregrina in the two treatments evaluated. Absorption of 14C 2,4-D in the treatment with DMA 806 BR and the mixture of DMA 806 BR plus Padron had the same behavior. These observations explain the inefficient control obtained with this herbicide in plant species under study.

Biomimetic sensor based on 5,10,15,20-tetrakis(pentafluorophenyl)-21H,23H- porphyrin iron (III) chloride and MWCNT for selective detection of 2,4-D

Exploitation of the electronic properties of carbon nanotubes for the development of voltammetric and amperometric sensors to monitor analytes of environmental relevance has increased in recent years. This work reports the development of a biomimetic sensor based on a carbon paste modified with 5,10,15,20-tetrakis(pentafluorophenyl)-21H,23H-porphyrin iron (III) chloride (a biomimetic catalyst of the P450 enzyme) and multi-wall carbon nanotubes (MWCNT), for the sensitive and selective detection of the herbicide 2,4- dichlorophenoxyacetic acid (2,4-D). The sensor was evaluated using cyclic voltammetry and amperometry, for electrochemical characterization and quantification purposes, respectively. Amperometric analyses were carried out at -100 mV vs. Ag/AgCl(KClsat), using a 0.1 mol L-1 phosphate buffer solution at pH 6.0 as the support electrolyte. Under these optimized analytical conditions, the sensor showed a linear response between 9.9 × 10-6 and 1.4 × 10-4 mol L-1, a sensitivity of 1.8 × 104 (±429) μA L mol -1, and limits of detection and quantification of 2.1 × 10 -6 and 6.8 × 10-6 mol L-1, respectively. The incorporation of functionalized MWCNT in the carbon paste resulted in a 10-fold increase in the response, compared to that of the biomimetic sensor without MWCNT. In addition, the low applied potential (-100 mV) used to obtain high sensitivity also contributed to the excellent selectivity of the proposed sensor. The viability of the application of this sensor for analysis of soil samples was confirmed by satisfactory recovery values, with a mean of 96% and RSD of 2.1% (n = 3). © 2013 Elsevier B.V.

Identificação de microrganismos resistentes ao herbicida ácido 2,4-diclorofenóxiacético (2,4-D) em solos de Rondônia, Brasil

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Investigação da toxicidade e da capacidade de recuperação do herbicida 2,4-D comercial (2,4-diclorofenoxiacético) empregando brânquias de tilápias, Oreochromis niloticus, como biomarcador

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Investigação da toxicidade, citotoxicidade e genotoxicidade de uma formulação comercial de 2,4-D (Diclorofenoxiacético) utilizando os organismos testes Allium cepa e Tradescantia pallida

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Crescimento e produtividade do algodoeiro em função da aplicação de subdoses de 2,4-d e cloreto de mepiquat

Pós-graduação em Agronomia - FEIS

Análise histopatológica de fígado de tilápias (Oreochromis Niloticus) expostas ao herbicida 2,4-D comercial

The action of man has led, over the years, major impacts on the environment, especially in aquatic ecosystems, leading to an impairment of water quality, considered one of the essential factors for the maintenance of vital functions and consequently the life of the planet. Among the activities considered a risk for the environment are linked to pollution from many sources and even entire watersheds, whether by industrial waste, sewage, or for substances used in agriculture, such as pesticides, herbicides and fertilizers. The (2,4-D) 2,4- dichlorophenoxyacetic acid is used worldwide, and the fact that its genotoxicity is proven by several studies and by its long persistence in soil, which enables the leaching and percolation of compounds affecting water bodies, toxicity studies are relevant and justifiable. Thus, this study aimed to evaluate the toxicity of 2,4-D by examining the liver of the fish Oreochromis niloticus exposed to different dilutions. Portions of liver were collected and fixed for histological and histochemical techniques to detect total proteins, polysaccharides and lipids. lipids. Treatment with 2,4-D herbicide apparently did not alter the lipid profiles, the accumulation of polysaccharides, and the presence of total proteins. The 2.5 and 5.0% were lethal to fish. These mortalities are probably of high toxic and cytotoxic potential of 2,4-D herbicide results. Several histopathological changes were found, such as: loss of cytoplasmic integrity, loss of cell limit, nuclear deformation, vacuolated cytoplasm, tissue disorganization and hydropic degeneration. Statistically significant changes were: hydropic degeneration and vacuolated cytoplasm. It is concluded, therefore, that the qualitative morphological analysis is an important method for observing changes in liver toxicology studies. As the O. niloticus species is an efficient biological indicator of water pollution by 2,4-D

Análise histopatológica de fígado de tilápias (Oreochromis Niloticus) expostas ao herbicida 2,4-D comercial

The action of man has led, over the years, major impacts on the environment, especially in aquatic ecosystems, leading to an impairment of water quality, considered one of the essential factors for the maintenance of vital functions and consequently the life of the planet. Among the activities considered a risk for the environment are linked to pollution from many sources and even entire watersheds, whether by industrial waste, sewage, or for substances used in agriculture, such as pesticides, herbicides and fertilizers. The (2,4-D) 2,4- dichlorophenoxyacetic acid is used worldwide, and the fact that its genotoxicity is proven by several studies and by its long persistence in soil, which enables the leaching and percolation of compounds affecting water bodies, toxicity studies are relevant and justifiable. Thus, this study aimed to evaluate the toxicity of 2,4-D by examining the liver of the fish Oreochromis niloticus exposed to different dilutions. Portions of liver were collected and fixed for histological and histochemical techniques to detect total proteins, polysaccharides and lipids. lipids. Treatment with 2,4-D herbicide apparently did not alter the lipid profiles, the accumulation of polysaccharides, and the presence of total proteins. The 2.5 and 5.0% were lethal to fish. These mortalities are probably of high toxic and cytotoxic potential of 2,4-D herbicide results. Several histopathological changes were found, such as: loss of cytoplasmic integrity, loss of cell limit, nuclear deformation, vacuolated cytoplasm, tissue disorganization and hydropic degeneration. Statistically significant changes were: hydropic degeneration and vacuolated cytoplasm. It is concluded, therefore, that the qualitative morphological analysis is an important method for observing changes in liver toxicology studies. As the O. niloticus species is an efficient biological indicator of water pollution by 2,4-D

Photo-Fenton oxidation of phenol and organochlorides (2,4-DCP and 2,4-D) in aqueous alkaline medium with high chloride concentration

A highly concentrated aqueous saline-containing solution of phenol, 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4-dichlorophenol (2.4-DCP) was treated by the photo-Fenton process in a system composed of an annular reactor with a quartz immersion well and a medium-pressure mercury lamp (450 W). The study was conducted under special conditions to minimize the costs of acidification and neutralization, which are usual steps in this type of process. Photochemical reactions were carried out to investigate the influence of some process variables such as the initial concentration of Fe2+ ([Fe2+](0)) from 1.0 up to 2.5 mM, the rate in mmol of H2O2 fed into the system (F-H2O2,F-in) from 3.67 up to 7.33 mmol of H2O2/min during 120 min of reaction time, and the initial pH (pH(0)) from 3.0 up to 9.0 in the presence and absence of NaCl (60.0 g/L). Although the optimum pH for the photo-Fenton process is about 3.0, this particular system performed well in experimental conditions starting at alkaline and neutral pH. The results obtained here are promising for industrial applications, particularly in view of the high concentration of chloride, a known hydroxyl radical scavenger and the main oxidant present in photo-Fenton processes. (C) 2012 Elsevier Ltd. All rights reserved.

Expression of Ornithine Decarboxylase Is Transiently Increased by Pollination, 2,4-Dichlorophenoxyacetic Acid, and Gibberellic Acid in Tomato Ovaries1

A cDNA encoding for a functional ornithine decarboxylase has been isolated from a cDNA library of carpels of tomato (Lycopersicon esculentum Mill.). Ornithine decarboxylase in tomato is represented by a single-copy gene that we show to be up-regulated during early fruit growth induced by 2,4-dichlorophenoxyacetic acid and gibberellic acid.

A soil-based microbial biofilm exposed to 2,4-D: bacterial community development and establishment of conjugative plasmid pJP4

A soil suspension was used as a source to initiate the development of microbial communities in flow cells irrigated with 2,4-dichlorophenoxyacetic acid (2,4-D) (25 mu g ml(-1)). Culturable bacterial members of the community were identified by 16S rRNA gene sequencing and found to be members of the genera Pseudomonas, Burkholderia, Collimonas and Rhodococcus. A 2,4-D degrading donor strain, Pseudomonas putida SM 1443 (pJP4::gfp), was inoculated into flow cell chambers containing 2-day old biofilm communities. Transfer of pJP4::gfp from the donor to the bacterial community was detectable as GFP fluorescing cells and images were captured using confocal scanning laser microscopy (GFP fluorescence was repressed in the donor due to the presence of a chromosomally located lacl(q) repressor gene). Approximately 5-10 transconjugant microcolonies, 20-40 mu m in diameter, could be seen to develop in each chamber. A 2,4-D degrading transconjugant strain was isolated from the flow cell system belonging to the genus Burkholderia.

Rhizodeposits of Trifolium pratense and Lolium perenne: Their comparative effects on 2,4-D mineralization in two contrasting soils

Rhizosphere enhanced biodegradation of organic pollutants has been reported frequently and a stimulatory role for specific components of rhizodeposits postulated. As rhizodeposit composition is a function of plant species and soil type, we compared the effect of Lolium perenne and Trifolium pratense grown in two different soils (a sandy silt loam: pH 4, 2.8% OC, no previous 2,4-D exposure and a silt loam: pH 6.5, 4.3% OC, previous 2,4-D exposure) on the mineralization of the herbicide 2,4-D (2,4-dichlorophenoxyacetic acid). We investigated the relationship of mineralization kinetics to dehydrogenase activity, most probable number of 2,4-D degraders (MPN2,4-D) and 2,4-D degrader composition (using sequence analysis of the gene encoding alpha-ketoglutarate/2,4-D dioxygenase (tfdA)). There were significant (P < 0.01) plant-soil interaction effects on MPN2,4-D and 2,4-D mineralization kinetics (e.g. T pratense rhizodeposits enhanced the maximum mineralization rate by 30% in the acid sandy silt loam soil, but not in the neutral silt loam soil). Differences in mineralization kinetics could not be ascribed to 2,4-D degrader composition as both soils had tfdA sequences which clustered with tfdAs representative of two distinct classes of 2,4-D degrader: canonical R. eutropha JMP134-like and oligotrophic alpha-proteobacterial-like. Other explanations for the differential rhizodeposit effect between soils and plants (e.g. nutrient competition effects) are discussed. Our findings stress that complexity of soil-plant-microbe interactions in the rhizosphere make the occurrence and extent of rhizosphere-enhanced xenobiotic degradation difficult to predict.

Crystal structure of the magnesium salt of the herbicide 2,4-D: pentaaqua[(2,4-dichlorophenoxy)acetato-kO]magnesium (2,4-dichlorophenoxy)acetate hemihydrate

In the structure of the title magnesium complex with the phenoxy herbicide (2,4-dichlorophenoxy)acetic acid (2,4-D), [Mg(H2O)5(C8H5Cl2O3)]+ C8H5Cl2O3)- . 0.5H2O, the discrete cationic MgO6 complex units comprise a carboxyl O-donor from a monodentate 2,4-D cationic ligand and five water molecules in a slightly distorted octahedral coordination. The 2,4-D anions are linked to the complex units through duplex water O-H...O(carboxyl) hydrogen bonds through the coordinated water molecules. In the crystal inter-unit O-H...O hydrogen-bonding interactions involving coordinated water molecules as well as the hemi-hydrate solvate molecule with carboxyl O-atom acceptors, give a two-dimensional layered structure lying parallel (001), in which pi-pi ligand-cation interactions [minimum ring centroid separation, 3.6405(17)A] and a short O-H...Cl interaction [3.345(2)A] are also found.