Atividade residual e carência irregular do ácido diclorofenoxiacético (2, 4-d) no desenvolvimento inicial da soja / Residual activity and irregular depletion of dichlorophenoxyactic acid (2, 4-d) in the early development of soybean / Actividad residual y carencia irregular del ácido diclorofenoxiacético (2, 4-d) en el desarrollo inicial de la soja

O 2,4-D (ácido diclorofenoxiacético) é amplamente utilizado no controle seletivo, pós-emergência, de plantas de folha estreita, como trigo, milho, arroz, entre outras. Contudo seu uso indiscriminado pode ocasionar problemas no desenvolvimento da cultura. O objetivo do trabalho foi avaliar os danos causados pelo uso inadequado do 2,4-D no desenvolvimento inicial da soja (Glycine max). Os tratamentos consistiram na combinação de cinco períodos de carência: um, quatro, oito, 12 e 15 dias antes da semeadura da soja e duas doses de aplicação: a dose recomendada e a dose duplicada (L/ha), consistindo em um esquema fatorial 5x2 com três repetições. As plantas foram cultivadas por 44 dias, e em seguida coletadas e analisadas quanto à taxa de germinação (%), número de rebrota, índice de clorofila, comprimento de raiz e parte aérea (cm), massa seca e fresca (g). A dose duplicada revelou maior efeito sobre todas as variáveis analisadas, reduzindo em 20% a porcentagem de emergência. O índice de clorofila decresceu quando comparados o menor período de carência (um dia) e o maior (15 dias), e na dose duplicada. A massa seca também foi superior na dose recomendada, assim como o comprimento da raiz e da parte aérea. Os períodos de carência de um, quatro e oito dias foram os que mais influenciaram o crescimento da raiz.

Dichlorophenoxyacetic acid (2,4-D) is widely used in the selective, post-emergence control of narrow-leaf plants such as wheat, corn, and rice, among others. However, its uncontrolled use can cause problems in the development of the crop. The purpose of this paper was to evaluate the damage caused by the inadequate use of 2,4-D in the early development of soybean (Glycine max). The treatments consisted of a combination of five grace periods: 1, 4, 8, 12 and 15 days before sowing; and two application doses: the recommended dose and a duplicate dose (L/ha), consisting of a factorial matrix of 5x2, with three replicates. The plants were cultivated for 44 days, then collected and analyzed for germination rate (%), regrowth number, chlorophyll index, root and shoot length (cm), dry and fresh mass (g). The duplicate dose showed a greater effect on all analyzed variables, reducing the emergency percentage by 20%. The chlorophyll index decreased when compared to the shortest (1 day) and longest (15 days) grace periods, and in the duplicate dose. Dry mass was also higher when using the recommended dose, as well as the root and shoot length. Grace periods of 1, 4 and 8 days were the ones that were most influenced the root growth.

El 2,4-D (ácido diclorofenoxiacético) es ampliamente utilizado en el control selectivo, pos emergencia, de plantas de hoja estrecha, como trigo, maíz, arroz, entre otras. Sin embargo, su uso indiscriminado puede ocasionar problemas en el desarrollo de la cultura. El objetivo del trabajo fue evaluar los daños causados por el uso inadecuado del 2,4-D en el desarrollo inicial de la soja (Glycine max). Los tratamientos consistieron en la combinación de cinco períodos de carencia: 1, 4, 8, 12 y 15 días antes de la siembra de la soja y dos dosis de aplicación: la dosis recomendada y la dosis duplicada (L/ha), consistente en un esquema factorial 5x2 con tres repeticiones. Las plantas fueron cultivadas por 44 días, y luego recolectadas y analizadas en cuanto a la tasa de germinación (%), número de rebrote, índice de clorofila, longitud de raíz y parte aérea (cm), masa seca y fresca (g). La dosis duplicada reveló un mayor efecto sobre todas las variables analizadas, reduciendo en un 20% el porcentaje de emergencia. El índice de clorofila disminuyó cuando se comparó el menor período de carencia (1 día) y el mayor (15 días), y en la dosis duplicada. La masa seca también fue superior en la dosis recomendada, así como la longitud de la raíz y de la parte aérea. Los períodos de carencia de 1, 4 y 8 días fueron los que más influenciaron el crecimiento de la raíz.

A review of methods for the analysis of orphan and difficult pesticides: glyphosate, glufosinate, quaternary ammonium and phenoxy acid herbicides, and dithiocarbamate and phthalimide fungicides.

This article reviews the chromatography/MS methodologies for analysis of pesticide residues of orphan and difficult chemical classes in a variety of sample matrixes including water, urine, blood, and food. The review focuses on pesticide classes that are not commonly included in multiresidue analysis methods such as highly polar or ionic herbicides including glyphosate, glufosinate, quaternary ammonium, and phenoxy acid herbicides, and some of their major degradation or metabolite products. In addition, dithiocarbamate and phthalimide fungicides, which are thermally unstable and have stability issues in some solvents or sample matrixes, are also examined due to their special needs in residue analysis.

Estimation of the validation parameters for a fast analysis of herbicide residues by LC-MS/MS.

Due to strict regulatory requirements for pesticide residue analysis, only the results of residue analysis with acceptable quality should be reported. As a consequence proper validation of the measurement method is required. In this context, accuracy, precision, specificity, limit of determination (LOQ), matrix effect, linearity, uncertainty calculation and ruggedness become increasingly important. This paper reports a description of the validation parameters of a fast method for the determination of five phenoxy acid herbicides (2,4-D, MCPA, MCPP, haloxyfop and fluazifop) in food crops. The recoveries were performed in the concentration range from 0.05 to 0.5 mg kg⁻¹ for apples, pears, carrots and celeriac with five replicates at each level. The mean recoveries ranged from 70% to 95% for all crops. The precision of the method expressed as a relative standard deviation (RSD%) was found to be in the range 3-14%. For all herbicides, the linearity response of the detector was tested by correlation coefficients (r² > 0.99) in the concentration range from 0.05 to 0.5 mg kg⁻¹. The LOQ was determined as the lowest spiked level meeting the requirement of accuracy (70-120%) and precision (RSD% < 20% according to European Union guidelines. The uncertainty and robustness were calculated. On the basis of the results, the method can be considered fast, simple and robust and is suitable to be applied to the analysis of studied herbicides in routine testing laboratories.

Combination of graphene oxide-based solid phase extraction and electro membrane extraction for the preconcentration of chlorophenoxy acid herbicides in environmental samples.

Combination of different extraction methods is an interesting and debatable work in the field of sample preparation. In the current study, for the first time, solid phase extraction combined with electro membrane extraction (SPE-EME) was developed for ultra-preconcentration and determination of chlorophenoxy acid herbicides in environmental samples using capillary electrophoresis (CE). In the mentioned method, first, a 100mL of chlorophenoxy acid herbicides (2-methyl-4-chlorophenoxyacetic acid (MCPA), 2-(2,4-dichlorophenoxy) propanoic acid (2,4-DP) and 2-(4-chloro-2-methylphenoxy) propanoic acid (MCPP)) was passed through a column of graphene oxide as a solid phase, and then the adsorbed herbicides were eluted by 4.0mL of 8% acetic acid (HOAC) in methanol. Then, the elution solvent was evaporated and the herbicides residue was dissolved in 4.0mL of double distilled water (pH 9.0). Afterwards, the herbicides in 4.0mL of the aqueous solution were transferred to an EME glass vial. In the EME step, the herbicides were extracted from the sample solution into the basic acceptor solution (pH 13.0) under electrical potential, which was held inside the lumen of the fiber with 1-octanol as the supported liquid membrane (SLM). Under the optimized conditions, high enrichment factors were obtained in the range of 1950-2000. The limits of quantification (LOQs) and method detection limits (MDLs) were obtained in the range of 1.0-1.5 and 0.3-0.5ngmL(-1), respectively. Finally, the performance of the present method was evaluated for extraction and determination of chlorophenoxy acid herbicides in environmental samples.

Combined isotope and enantiomer analysis to assess the fate of phenoxy acids in a heterogeneous geologic setting at an old landfill.

Phenoxy acid herbicides and their potential metabolites represent industrial or agricultural waste that impacts groundwater and surface waters through leaching from old landfills throughout the world. Fate assessment of dichlorprop and its putative metabolite 4-CPP (2-(4-chlorophenoxy)propionic acid) is frequently obstructed by inconclusive evidence from redox conditions, heterogeneous geologic settings (e.g. clay till) and ambiguous parent-daughter relationships (i.e. 4-CPP may be daughter product or impurity of dichlorprop). For the first time, a combination of four methods was tested to assess transformation of phenoxy acids at a contaminated landfill (Risby site): analysis of (i) parent and daughter compound concentrations, (ii) enantiomer ratios (iii) compound-specific isotope analysis and (iv) enantiomer-specific isotope analysis. Additionally, water isotopes and chloride were used as conservative tracers to delineate two distinct groundwater flow paths in the clay till. Metabolite concentrations and isotope ratios of chlorinated ethenes demonstrated dechlorination activity in the area with highest leachate concentrations (hotspot) indicating favorable conditions also for dechlorination of dichlorprop to 4-CPP and further to phenoxypropionic acid. Combined evidence from concentrations, enantiomer ratios and isotope ratios of dichlorprop and 4-CPP confirmed their dechlorination in the hotspot and gave evidence for further degradation of 4-CPP downgradient of the hotspot. A combination of 4-CPP enantiomer and isotope analysis indicated different enantioselectivity and isotope fractionation, i.e. different modes of 4-CPP degradation, at different locations. This combined information was beyond the reach of any of the methods applied alone demonstrating the power of the new combined approach.

Capillary electrophoresis-electrochemiluminescent detection of N,N-dimethyl ethanolamine and its application in impurity profiling and stability investigation of meclophenoxate.

Numerous drugs are carboxylic acid derivatives containing amino group, and hydrolysis reaction of these agents often generates toxic amines. Thus, the detection of amine impurity is of great importance in drug quality control of these amino group-containing ester and amide. A capillary electrophoresis method coupled with end-column electrochemiluminescent detection based on tris(2,2'-bipyridyl)ruthenium(II) system was proposed for the analysis of N,N-dimethyl ethanolamine (DMEA, the degradation product of meclophenoxate) in the presence of its precursor. Baseline separation of DMEA and meclophenoxate can be easily achieved under the selected conditions. DMEA can be assayed within 3 min over the concentration range of 5.0x10(-8) to 3.0x10(-6) mol L(-1) with a detection limit of 2.0x10(-8) mol L(-1) at the signal-to-noise ratio of 3. The relative standard deviations of the signal intensity and the migration time were less than 5.3 and 2.5% for a standard sample containing 1.0x10(-7) mol L(-1) DMEA (n=5), respectively. The presented method has been successfully applied for the profiling of DMEA resulting from the hydrolysis of meclophenoxate in commercial formulations. A primary stability investigation of meclophenoxate in aqueous solution was also carried out at different temperatures, and the results showed that the degradation of meclophenoxate accelerated at the higher temperature.

Selection of a support matrix for the removal of some phenoxyacetic compounds in constructed wetlands systems.

The efficiency of constructed wetlands systems in the removal of pollutants can be significantly enhanced by using a support matrix with a greater capacity to retain contaminants by sorption phenomena, ionic exchange or other physico-chemical processes. The aim of this work was to evaluate the efficiencies of 3 different materials, Light Expanded Clay Aggregates [LECA] (in two different particle sizes), Expanded Perlite and Sand, for the removal from water of one pharmaceutical compound (clofibric acid) and one pesticide (MCPA). Both belong to the class of phenoxyacetic compounds. In addition, relationships were established between the compounds' removal efficiencies and the physico-chemical properties of each material. LECA exhibited a high sorption capacity for MCPA, while the capacity for clofibric acid was more modest, but still significant. In contrast, perlite had a very limited sorption capacity while sand did not exhibit any sorption capacity for any of the compounds. LECA with smaller particle sizes showed higher efficiencies than larger grade LECA and can achieve efficiencies near 100% for the lower concentrations in the order of 1 mg l(-1). However, the use of these smaller particle media at larger scales may present problems with hydraulic conductivities. The results show that expanded clay presents important advantages in laboratory studies and could be used as a filter medium or a support matrix in constructed wetlands systems.

Occurrence of alkylphenolic substances in a Great Lakes coastal marsh, Cootes Paradise, ON, Canada.

Occurrence and fate of alkylphenols (APs), known endocrine disruptors, were investigated in a Great Lakes coastal wetland, Cootes Paradise, ON. The wetland, which receives discharges from a Wastewater Treatment Plant (WTP) and several Combined Sewer Overflows (CSOs), is an important spawning ground for fish and crucial habitat for other fauna. Elevated concentrations of nonylphenol ethoxylates (NPEs) and their degradation product nonylphenol (NP) were found in water and sediment samples near the sources. Since transfer of APs through the food chain is of concern, we compared their concentrations in invertebrates from clean and contaminated sites. The results reveal transfer of alkylphenolics from sediments to biota and their accumulation in the invertebrate tissue, particularly the highly hydrophobic 4-NP, whose concentrations ranged from 1.9 to 6.3 microg g(-1). To our knowledge, this is the first study to evaluate AP concentrations in tissue of benthic invertebrates under real environmental conditions.

Automated dynamic liquid-liquid-liquid microextraction followed by high-performance liquid chromatography-ultraviolet detection for the determination of phenoxy acid herbicides in environmental waters.

Automated dynamic liquid-liquid-liquid microextraction (D-LLLME) controlled by a programmable syringe pump and combined with HPLC-UV was investigated for the extraction and determination of 5 phenoxy acid herbicides in aqueous samples. In the extraction procedure, the acceptor phase was repeatedly withdrawn into and discharged from the hollow fiber by the syringe pump. The repetitive movement of acceptor phase into and out of the hollow fiber channel facilitated the transfer of analytes into donor phase, from the organic phase held in the pore of the fiber. Parameters such as the organic solvent, concentrations of the donor and acceptor phases, plunger movement pattern, speed of agitation and ionic strength of donor phase were evaluated. Good linearity of analytes was achieved in the range of 0.5-500 ng/ml with coefficients of determination, r2 > 0.9994. Good repeatabilities of extraction performance were obtained with relative standard deviations lower than 7.5%. The method provided up-to 490-fold enrichment within 13 min. In addition, the limits of detection (LODs) ranged from 0.1 to 0.4 ng/mL (S/N = 3). D-LLLME was successfully applied for the analysis of phenoxy acid herbicides from real environmental water samples.

Incidence rates of lymphomas and environmental measurements of phenoxy herbicides: ecological analysis and case-control study.

The authors conducted an ecological study of the distribution of malignant lymphomas in a rice-growing area in northern Italy. They considered data on concentrations of phenoxy herbicides in soil and water and found the highest incidence of non-Hodgkin's lymphoma in subjects who lived in an area where 2,4-dichlorophenoxyacetic acid and 2,4,5-trichlorophenoxyacetic acid existed in very high concentrations. During 1985-1988, the incidence of non-Hodgkin's lymphoma in males in the most-polluted municipalities was twice as high as was noted for the remaining less-polluted territories. During 1991-1993, non-Hodgkin's lymphoma was higher by 60%. The authors also conducted a population-based case-control study. They found an association between employment of women in rice-growing jobs (particularly as rice weeders) and risk of non-Hodgkin's lymphoma (odds ratio=1.9; 95% confidence interval=0.6, 6.0). Work in rice fields was correlated strongly with residence in polluted areas. The authors did not detect an association between area of residence or occupation and incidence of Hodgkin's disease.

Spectrophotometric assay of hydroxylated by-products in penicillin V fermentations and its application in screening of mutant penicillin producer strains on agar media.

A fast and sensitive spectrophotometric method has been developed to measure the level of hydroxylated by-products (p-hydroxyphenoxyacetic acid and p-hydroxypenicillin V) in penicillin V fermentations. The method is based on a color reaction of the above-mentioned phenolic by-products with nitrous acid, yielding yellow nitroso derivatives. Both the nitroso derivative of p-hydroxyphenoxyacetic acid and that of p-hydroxypenicillin V have an absorption peak at 450 nm in alkaline solution with a molar absorption of 4.00 x 10(3) M-1cm-1 for both compounds. No fermentation medium components were found to interfere considerably with the assay. On the basis of the color reaction, an agar prescreen method has been developed for isolation of nonhydroxylating Penicillium chrysogenum strains in strain-improvement programs.

Gas chromatographic measurement of volatility of herbicide esters.

The vapour pressures of eleven herbicide esters were calculated from gas chromatographic measurement of relative retention volumes (dibutyl phthalate = 1) on a non-polar SE-30 column. Measurements were made at temperatures from 72 to 182 degrees C, but by assuming that the ratio of the latent heat of vaporization of the ester to that of dibutyl phthalate was independent of temperature, values for vapour pressure could be extrapolated to 25 degrees C. Vapour pressures at 25 degrees C ranged from 2.5.10(-4) mmHg for 2,4-D ethyl ester to 1.9.10(-7) mm Hg for picloram isoocytly ester.

Chlorinated phenoxyacetic acid derivatives and tetrachlorodibenzo-p-dioxin in foliage after application of 2,4,5-trichlorophenoxyacetic acid esters.

Six reforestation areas were sprayed with 2,4,5-T esters. Leaf samples from the areas were analyzed for the esters, tetrachlorodioxin, and dehalogenated phenoxyacetic acid esters. Tetrachlorodioxin was found in one leaf sample only, but the level found, relative to the amount of 2,4,5-T ester found, was lower than in the formulation material used in the study. The concentration of the dichlorophenoxyacetic acid esters present in several leaf samples was greater, relative to the 2,4,5-T ester, which indicated a photochemical breakdown of the 2,4,5-T in the environment.

GLC determination of ticrynafen and its metabolites in urine, serum, and plasma of humans and animals.

A sensitive GLC assay for ticrynafen, a diuretic agent with uricosuric properties, and its two metabolites in urine, serum, and plasma is described. The method employs methylation of carboxylic acid groups and trimethylsilyation of the hydroxyl group on one metabolite that cannot otherwise be separated readily from ticrynafen as a simple methyl ester. Urinary output and serum or plasma levels of ticrynafen and its two metabolites were measured in specimens from human volunteers receiving one 250-mg tablet.

Gas-liquid chromatographic method with electron-capture detection for the determination of residues of some phenoxyacetic acid herbicides in water as their 2,2,2-trichloroethyl esters.

A gas-liquid chromatographic method with electron-capture detection was developed for the determination of residues of 2,4-dichlorophenoxyacetic acid (2,4-D) and 4-chloro-2-methylpenoxyacetic acid (MCPA) in water as their 2,2,2-trichloroethyl esters, and the sensitivity was compared with that for 2-chloro- and 2,2,2-trifluoroethyl esters. The residue is isolated by sorption of the phenoxy acid on Amberlite XAD-4, eluted with benzene and then esterified with 20% (v/v) 2,2,2-trichloroethanol in trifluoroacetic anhydride in the presence of sulphuric acid. The recoveries at the 0.4 ppb level are 92.1 +/- 3.4% (2,4-D) and 87.8 +/- 2.1% (MCPA) and the detection limits for a 1-1 sample of water are 0.096 ppb (2,4-D) and 0.06 ppb (MCPA).

Gas-liquid chromatographic determination of tienilic acid (SKF 62.698) in human plasma and urine.

A gas-liquid chromatographic method is described for the determination of tienilic acid (SKF 62.698), a diuretic with uricosuric properties, in human plasma and urine. The method, which is based on the methylation of the compound, is rapid, specific and sensitive. The lowest level accurately determined is about 50 ng/ml in plasma and 1 mug/ml in urine. The first results from a human volunteer are given.