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Water pollution by pesticides and other chemical contaminants is a subject of major importance due to the risk for human health and the environment. The search for remediation processes able to withdraw chemical contaminants from water and to allows water reuse is an urgent need. Herein, a simple and cheap system for pesticides removal was constructed and evaluated using water samples contaminated with two widely used herbicides (imazapic and imazethapyr, at g L−1 level). Operation parameters and process efficiency, in terms of removal rate in the reclaimed water and degradation rate of pesticides in the dry residue, were quantitatively determined. The model was tested in real-world field experiments and was able to remove more than 99.95% of both contaminants from a 10 L solution containing 4.16 ± 0.94 g of imazethapyr and 1.31 ± 0.17 g of imazapic, generating reusable water with minimum volume loss (

Brazilian environmental legislation obliges the aeroagriculture operators to treat the effluents generated after aircraft washing. This effluent commonly contains high levels of pesticides (g L−1) with potential to produce point source pollution. In the present study, we evaluated the efficiency of two systems on the removal of the fungicides epoxiconazole and pyraclostrobin from these effluents. The first system is based on ozonation and is currently suggested by regulatory authority. The second system is based on a pyramid-shaped solar still. The pesticides removal was monitored using liquid chromatography mass spectrometry to determine the mass quantity of both molecules throughout the treatment. After treatment with ozone treatment, the total mass of epoxiconazole decreased by 73% and pyraclostrobin decreased by 90.8%. The solar distillation system removed epoxiconazole and pyraclostrobin by >99.995 and 99.99%, respectively. The both systems proved to be efficient in the treatment of effluent containing residues of the fungicide Opera®, a formulation containing epoxiconazole and pyraclostrobin. The solar distillation system showed a higher degree of removal and presents the advantage of operating without energy sources, reagents or consumables.

In this work, a method was developed, validated, and applied to determination of ten pesticide residues (trifluralin, carbofuran, chlorothalonil, pendimethalin, captan, tebuconazole, pyraclostrobin, difenoconazole, deltamethrin, and azoxystrobin), from seven distinct classes, in carrot samples, employing a QuEChERS procedure for the analyte extraction and gas chromatography coupled to mass spectrometry (GC-MS) for quantification. The dispersive clean-up step was optimized using different sorbents at different concentrations and mixings. The method proved to be efficient and robust, showing recoveries in the range 72–117%, and RSD ranging from 4.9 to 16.6% (except for chlorothalonil and captan) at fortification levels of 45, 90, 180, and 450 μg kg−1 with seven replicates analyzed for each level (n = 28). Chlorothalonil and captan could not be validated due to analyte stability problems. Detection limits were between 15 and 45 μg kg−1, and the quantification limits were between 45 and 90 μg kg−1. The method was successfully applied to real samples.

An initial set of 12 kinetic experiments was carried out to remove naphthalene from an aqueous effluent by photo-Fenton involving Fe0 and Fe2+ at two different concentrations of H2O2 (150 and 300 m...

A method was developed for the analysis of 22 antiparasitic residues belonging to the benzoylurea, organophosphate, pyrimidinamine, pyrethrin and pyrethroid classes in salmon by liquid chromatography coupled with tandem mass spectrometry. Samples were extracted with acetonitrile-water as the extraction solvent with use of a vibrational shaking apparatus with a ceramic homogenizer. After extraction, the acetonitrile extracts were cleaned up by incubation at low temperature (-20 °C, 1 h) to remove fat, followed by dispersive solid-phase extraction using Z-Sep+ and primary-secondary amine as sorbents. Validation was performed following the 2002/657/EC and SANTE/11813/2017 guidelines. The trueness of the method ranged from 87% to 121% and precision ranged from 4.1% to 23.7%, with the exception of cyphenothrin, dicyclanil and azamethiphos. The method developed is particularly advantageous because the use of a vibrational shaker allows unattended extraction of samples and eliminates a laborious tissue disruption step, which increases sample throughput in the laboratory. The sample preparation and chromatographic separations can be performed in 5 and 4 h, respectively, for 36 samples. Graphical abstract.

Pressure cycling (300 s at 91.4 kPa + 300 s at 338.2 kPa per cycle) was performed to extract water-soluble compounds from ground coffee at ≈17 °C. The efficiency of solute removal (E) at equilibrium, and the extraction rate constant by dispersing the solids in the solvent (k) were examined. The obtained aqueous solution was freeze-dried at ≈2.25 Pa for 48 h and the produced instant coffee was analyzed by GC–MS to speculate about its quality. For comparison, an additional set of experiments by involving three different extraction procedures was also carried out (i: infusion at 91.4 kPa and ≈17 °C; ii: infusion at 91.4 kPa and ≈100 °C; iii: pressurized extraction at 338.2 kPa and ≈17 °C). Pressure cycling extraction presented the optimal E (79 ± 6%), and a k (2.9 × 10−3 s−1, or 1033 s to reach equilibrium) comparable to that found at 100 °C in percolator batteries of commercial extractors. The qualities of lyophilized coffee from pressure cycling extraction and from the best expected condition of extraction for the purpose of retention of coffee volatiles (i.e.; 91.4 kPa and ≈17 °C) were analogous.

The aim of this work was to investigate the kinetics of removal of clomazone herbicide from an aqueous solution by electrocoagulation. The experiments were performed in a cylindrical batch reactor with six aluminum electrodes in monopolar mode, arranged in series and connected to a digital DC power. The aqueous solution (tap water + clomazone) with initial pH close to 7.9 was always treated at ambient temperature (≈20 °C) and atmospheric pressure for 5,400 s. For a confidence level of 95% the rate constant of electrocoagulation and the efficiency of removal of clomazone at equilibrium were 2.1 × 10−3 ± 0.5 × 10−3 s−1 and 97.7 ± 2.2%, respectively. The final chemical oxygen demand was 88% lower than that measured initially, while turbidity and apparent color were totally removed from the synthetic solution at a rate close to that of formation of aluminum hydroxides. Some reaction intermediates, such as benzonitrile-2-chloro and 2-chloro-hex-2,4-diene-1,6-dioic-acid determined by gas chromatography mass spectrometry (GC-MS) analysis, explain the ratio of equilibrium to initial total organic carbon approximately between 0.6 and 0.8 at a probability of 95%.

The main aim of this manuscript was to investigate the kinetics of zero valent iron (ZVI) oxidation to produce Fe2+ in hydrogen peroxide-water solutions. The experiments were performed in a batch reactor by submerging an iron plate in agitated aqueous H2O2 at 25 °C and pH ~2–4. A shrinking core model described properly the kinetics of iron oxidation. The overall rate of this reaction was governed by the rate of transport of protons through an iron (hydr)oxide film formed over the iron plate. To validate the model, additional kinetic experiments were carried out at different surface area of ZVI, initial concentration of H2O2, and pH. The determined concentrations of total iron, Fe2+, Fe3+ and H2O2 were reproduced by a detailed kinetic model for the Fenton-like process with ZVI that comprised 14 species and 22 reactions. Tests of oxidation of chlorpyrifos confirmed the reliability of the model to describe the Fenton-like process with ZVI.

Palladium(0) nanoparticles supported on a polymeric membrane, CA/Pd(0), were found to be a highly efficient “dip catalyst” (heterogeneous catalyst) for Suzuki–Miyaura cross-coupling reactions. Iodo-, bromo- and electron-poor chloroarenes coupled with phenylboronic acid under eco-friendly conditions (i.e., phosphine-free and with water as the solvent) to give excellent yields. The CA/Pd(0) was prepared initially via the synthesis of Pd(0) by hydrogen decomposition of Pd(acac)2 dissolved in BMI·BF4 ionic liquid at 75 °C for 1.0 hour to yield a black suspension (nanoparticles with a diameter of 2.7 ± 0.4 nm). These nanoparticles were washed with acetone and dried under reduced pressure. The Pd(0) nanoparticles were subsequently added to a cellulose acetate solution with acetone to generate the CA/Pd(0) polymeric membrane. The CA/Pd(0) “dip catalyst” was characterised by X-ray diffraction (XRD), scanning electron microscopy (SEM), electron-dispersive spectroscopy (EDS) and transmission electron microscopy (TEM).

The presence of the pyrethroids residues in different samples and the impact on human health is an increasing concern due to their widespread use. So, a method to determine eighteen pyrethroids in fish samples using a modified QuEChERS was developed. The clean-up procedure was performed by freezing samples overnight followed by dispersive solid phase extraction. The combination of C18, PSA and Z-Sep+ was optimized using a mixture design approach and samples were analysed using gas chromatography mass spectrometry. The method was validated using trahira samples and a scope extension was performed for tilapia and tainha. Recoveries were within 63–129%, relative standard deviation was ≤21.5% and the quantification limits were 5 µg kg−1 or 10 µg kg−1. The applicability of the method was assessed by analysis of fourteen real samples, in which residues were detected in four samples. Such detections demonstrate the importance of this sensitive method.

A method for the determination of five sedatives and 14 β-blocker residues in swine, bovine and equine kidney was validated. Samples were extracted with acetonitrile and purified using dispersive solid phase extraction (d-SPE) with Celite 545 with subsequent analysis by LC-MS/MS. A simplified protocol was applied to validate the method scope extension to include new matrices. Parameters such as recovery, trueness, linearity (r2), relative standard deviation (RSD), decision limit (CCα) and method capability (CCβ) were measured for the bovine and equine kidney matrices. The method was applied to the analysis of more than 300 real samples and is currently included in the Brazilian National Residue Control Plan.

SiO2-TiO2 materials prepared by sol-gel method were evaluated in the photocatalytic degradation of diuron. The materials were prepared with and without surfactant cetyltrimethylammonium chloride at different temperatures (25, 50 and 100 ºC). The samples were characterized by N2 adsorption-desorption measurements, scanning electron microscopy, X-ray diffraction, ultraviolet-visible diffuse reflectance spectroscopy and infrared diffuse reflectance spectroscopy. The results showed that the materials synthesized with the surfactant had higher surface areas and band-gap values similar to anatase. All materials were more active than the commercial catalyst P-25 and better performance was achieved using the surfactant in the material synthesis.

Os herbicidas podem persistir no solo ou ser carreados para fora da área, contaminando mananciais hídricos a jusante da lavoura. Em vista disso, o presente trabalho objetivou estimar a persistência dos herbicidas imazethapyr e clomazone na lâmina de água de arroz irrigado. Para isso, foi realizado um ensaio com diferentes doses e épocas de aplicação da mistura formulada (75 g i.a. ha-1 de imazethapyr + 25 g i.a. ha-1 de imazapic) e clomazone (1.500 g i.a. ha-1). Para determinação dos produtos na água de irrigação, foram coletadas amostras de água a partir do primeiro dia até 62 dias após a inundação. Os resultados demonstraram que o período de detecção dos herbicidas na água de irrigação foi mais longo para o imazethapyr que para o clomazone. A meia-vida do imazethapyr na lâmina da água variou conforme o tratamento, com valores entre 1,6 e 6,2 dias, e a do clomazone foi de cinco dias.

A new method to evaluate the levels of residue and the dissipation of chlorothalonil fungicide in tomatoes and cucumbers grown in experimental greenhouses was developed and validated. The vegetables were submitted to a single spraying with chlorothalonil at half, equal to and double of the recommended dose. Chlorothalonil residues were extracted in Ultra-Turrax system using ethyl acetate in the presence of anhydrous sodium sulphate and determined by gas chromatography with electron capture detection. The analytical curves were linear from 0.005 to 5.0 mg L-1, with coefficient of determination higher then 0.995. The assays provide acceptable results with RSD values below 10.5% and recoveries were between 92.2 and 114.5% for tomatoes, and between 86.2 and 103.3% for cucumbers, both obtained from spiked samples at 0.028, 0.28, 2.8 and 5.0 mg kg-1 levels. Statistical interpretation of residue levels fitted to a first-order model for the dissipation behavior of chlorothalonil. The mean half-life after treatments at the recommended dose, in the two experimental years, was 8.8 days for tomatoes and 1.6 days for cucumbers. The higher decrease rate of chlorothalonil residues in cucumbers is mainly due to the higher growth rate of this vegetable relative to tomato. The developed method has proven to be efficient for the determination of chlorothalonil residues in tomatoes and cucumbers with a limit of quantification of 0.02 mg kg-1 level, permitting to evaluate the risk of consumer exposure to these residues. Desenvolveu-se e validou-se um novo método para avaliar os níveis de resíduo e a dissipação do fungicida clorotalonil em tomates e pepinos cultivados em estufas experimentais. Os vegetais foram submetidos a uma única pulverização com clorotalonil em meia dose, dose recomendada e dobro da dose. Os resíduos de clorotalonil foram extraídos em sistema Ultra-Turrax empregando acetato de etila na presença de sulfato de sódio anidro e determinados por cromatografia gasosa com detecção por captura de elétrons. As curvas analíticas foram lineares de 0,005 a 5,0 mg L-1, com coeficiente de determinação maior que 0,995. Os ensaios de precisão fornecem resultados aceitáveis com valores de RSD abaixo de 10,5% e recuperações entre 92,2 e 114,5% para tomate, e entre 86,2 e 103,3% para pepino, ambos obtidos para níveis de fortificação 0,028, 0,28, 2,8 e 5,0 mg kg-1. A interpretação estatística dos níveis de resíduo indicou um modelo de primeira ordem para o comportamento da dissipação do clorotalonil. O tempo médio de meia-vida para o tratamento na dose recomendada, nos dois anos experimentais, foram 8,8 dias para tomate e 1,6 dia para pepino. A taxa mais elevada da diminuição de resíduos de clorotalonil em pepino é devida, principalmente, à taxa de crescimento mais elevada deste vegetal com relação ao tomate. O método desenvolvido provou ser eficiente para a determinação de resíduos de clorotalonil em tomate e pepino até o nível de 0,02 mg kg-1, permitindo avaliar o risco da exposição do consumidor.

A procedure has been developed for the determination of quinclorac, bentazone, 2,4-D, clomazone, and propanil residues in surface and agriculture waters by SPE and HPLC-UV. The method was validated and was applied for levels between 0.1 and 0.5 g/L, after a 500-fold pre-concentration. Average recoveries ranged from 85.7 to 109.8% with overall relative standard deviations of 1.8 to 13.4%.

A rapid and sensitive method for the determination of metalaxyl residues in water samples has been developed. The metalaxyl residues were preconcentred from the sample by solid-phase extraction and determination by gas chromatography and nitrogen–phosphorus detection. The developed method was applied to water samples from an area under influence of highway accident in Brazil. After optimization of the extraction and detection conditions, the method was validated. Recoveries are generally better than 96.7%, with a relative standard deviation of 2.8–12.5%. The effective limit of quantification in the water samples after preconcentration step was 0.1 μg L−1.

A flow injection spectrophotometric method for the determination of propoxur with diazotized 4-aminobenzoic acid as the coupling agent was developed. The determination involves on-line hydrolysis at room temperature of the propoxur with sodium hydroxide. The resulting 2-isopropoxyphenol is coupled with diazotized 4-aminobenzoic acid in order to achieve an appropriate selectivity and sensitivity to the spectrophotometric measurements. The calibration curve is linear over the range 1–10 mg L−1 of propoxur. The proposed method has provided a detection limit of 0.15 mg L−1 of propoxur and a sample frequency of 120 injections per hour. The relative standard deviation of six independent determinations of a sample containing 5 mg L−1 propoxur was 0.74%. The suitability of the proposed procedure for the determination of propoxur in commercial pesticide formulations was studied. The procedure provides results comparable to those obtained by the liquid chromatography analysis.

The title polymeric catalyst is successfully applied to Suzuki—Miyaura reactions of aryl iodides and bromides in water as the solvent.

A procedure was developed for determination of 5 sedatives and 14 β-blockers in swine kidney and subsequent analysis by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). Three different procedures for extraction were tested, evaluated through recovery studies. The procedure using acetonitrile for extraction and cleanup with freezing at low temperature and dispersive solid phase extraction using 500 mg celite® 545 before the concentration step presented the better results. The dried samples were redissolved with methanol and analyzed using a LC-MS/MS system with electrospray ionization (ESI) operating in positive MRM mode. The recovery values for this procedure were in the 75-88% range. The robustness of the method was tested against small variations. The method was used to analyze carazolol, azaperone and azaperol in collaborative assay, obtaining results close to designed value.

A method is described for the determination of clomazone residues in surface water by high-performance liquid chromatography with UV detection. The method involves solid-phase extraction with C 18 extraction tubes. Clomazone was separated on a C 18 column with a mobile phase of methanol–water (65:35, v/v) at pH 4.0 and a flow-rate of 1.0 ml/min. After optimization of the extraction and separation conditions, the method was validated. The method developed can be used for determination of clomazone in surface water, at the limit of 0.1 μg/l set by the European Union drinking water directive, with a 400-fold preconcentration.

An efficient and sensitive method for simultaneous determination of the insecticide fipronil and its main metabolites fipronil desulfinyl, fipronil sulfide and fipronil sulfone in surface water was developed and validated. Fipronil and its metabolites were determined by gas chromatography with electron capture detection (GC-ECD) after a preconcentration step using solid phase extraction (SPE). The evaluated validation parameters included analytical curve and linearity, limit of detection (LOD) and quantification (LOQ), precision and accuracy. GC-ECD presented a good response for fipronil and its metabolites, and all analytical curves showed determination coefficients higher than 0.995. The LOD values of the method were 2.5 ng L-1 for fipronil and 2.0 ng L-1 for each metabolite. All recovery values were between 81.3 and 112.3%, with relative standard deviation (RSD) values lower than 14.2%. The proposed method was successfully applied to the analysis of water samples from flooded rice fields. Um método eficiente e sensível para a determinação simultânea do inseticida fipronil e seus principais metabólitos fipronil desulfinil, fipronil sulfeto e fipronil sulfona em águas superficiais foi desenvolvido e validado. Fipronil e seus metabolitos foram determinados por cromatografia gasosa com detecção por captura de elétrons (GC-ECD) após uma etapa de pré-concentração empregando extração em fase sólida (SPE). Os parâmetros de validação avaliados incluíram curva analítica e linearidade, limites de detecção (LOD) e de quantificação (LOQ), precisão e exatidão. GC-ECD apresentou uma boa resposta para fipronil e seus metabólitos, e todas as curvas analíticas apresentaram coeficientes de determinação superiores a 0,995. Os LODs do método foram 2,5 ng L-1 para fipronil e 2,0 ng L-1 para cada metabólito. Todos os valores de recuperação variaram de 81,3 a 112,3%, com valores de desvio padrão relativo (RSD) inferiores a 14,2%. O método proposto foi aplicado com sucesso em amostras de água de lavoura de arroz irrigado.

In this work, an analytical method based on solid phase extraction (SPE) and liquid chromatography tandem mass spectrometry (LC-APCI-MS/MS) was developed and validated for the determination and confirmation of five pharmaceuticals in water samples. The limits of detection (LOD) ranged from 0.053 to 0.53 µg L-1 and the limits of quantification (LOQ) from 0.16 to 1.6 µg L-1. Good linearity was obtained with r > 0.99 for all compounds. The recoveries of the compounds ranged from 70 to 120% with relative standard deviations (RSD) below 20% for all. Through multiple reactions monitoring (MRM) two different transitions, precursor ion-product ion, were selected for each pharmaceutical. Neste trabalho, foi desenvolvido e validado um método analítico baseado na extração em fase sólida (SPE) e cromatografia líquida acoplada a espectrometria de massas em tandem (LC-APCI-MS/MS) para a determinação e confirmação de cinco fármacos em amostras de água. Os limites de detecção (LOD) variaram de 0,053 a 0,53 µg L-1 e os limites de quantificação (LOQ) de 0,16 a 1,6 µg L-1. Foi obtida boa linearidade com r > 0,99 para todos os compostos. As recuperações dos compostos variaram de 70 a 120%, com desvios padrão relativos (RSD) menores que 20% para todos. Através do monitoramento de reações múltiplas (MRM), foram selecionadas duas transições diferentes íon precursor-íon produto para cada fármaco.

The determination of pesticide residues in water samples by Liquid Chromatography require sample preparation for extraction and enrichment of the analytes with the minimization of interferences to achieve adequate detection limits. The Solid Phase Extraction (SPE), Solid Phase Microextraction (SPME), Stir Bar Sorptive Extraction (SBSE) and Dispersive Liquid-Liquid Microextraction (DLLME) techniques have been widely used for extraction of pesticides in water. In this review, the principles of these sample preparation techniques associated with the analysis by Liquid Chromatography with Diode Array Detection (LC-DAD) or Mass Spectrometry (LC-MS) are described and an overview of several applications were presented and discussed.

Um método analítico baseado na extração em fase sólida e cromatografia líquida acoplada à espectrometria de massas tandem (LC-ESI-MS-MS) foi desenvolvido e validado para a determinação e confirmação de dezoito agrotóxicos (herbicidas, inseticidas e fungicidas) e dois metabólitos em amostras de água. Os limites de detecção variaram de 0,4 a 40,0 ng L-1 e os limites de quantificação de 4,0 a 100,0 ng L-1. Foi obtida boa linearidade, com r2 > 0,99 para todos os compostos. As recuperações, para 95% dos compostos, variaram de 70 a 120%, com RSDs menores que 21% para todos. Através do monitoramento de reações múltiplas (MRM), foram selecionadas duas diferentes transições íon precursor-íon produto para cada agrotóxico. A metodologia proposta pode ser usada para a determinação de resíduos de agrotóxicos em águas de superfície e potável, em concordância com a Lei n° 518 do Ministério da Saúde, Brasil, e com os parâmetros da União Européia para água potável (Directive 98/83/EC). An analytical method using solid-phase extraction and liquid chromatography coupled to electrospray ionization tandem mass spectrometry (LC-ESI-MS-MS) was developed and validated for the determination and confirmation of eighteen polar pesticides (herbicides, insecticides and fungicides) and two metabolites in water samples. The limits of detection varied between 0.4‑40.0 ng L-1 and the limits of quantification between 4.0-100.0 ng L-1. Good linearity with r2 > 0.99 for all compounds was obtained. The recovery for 91% of the accuracy experiments varied from 70 to 120%, with RSD below 21% for all. Through multiple reaction monitoring (MRM) two different precursor ion-product ion transitions were selected for each pesticide. The proposed methodology can be used for the convenient and effective determination of pesticide residues in surface and drinking waters in accordance with Law No. 518 of the Ministry of Health, Brazil, and the European Union Directive on drinking water quality (98/83/EC).

A new method is described for the determination of the herbicide bispyribac-sodium in surface water, especially from river and irrigated rice water samples. The method involves extraction in solid phase and quantification by high performance liquid chromatography with diode array detection (HPLC-DAD). After optimization of the extraction and separation parameters, the method was validated. The method presented average recoveries of 101.3 and 97.7%, under repeatability and intermediate precision conditions, respectively, with adequate precision (RSD from 0.9 to 7.5%). The method was applied for the determination of bispyribac-sodium in surface water samples with a limit of detection of 0.1 μg L-1.

This study evaluated the degradation of the herbicide clomazone in distilled water and from irrigated rice fields, through UV irradiation and under natural conditions. After a solid phase extraction (SPE) as preconcentration step, the remained concentration of clomazone was determined by high performance liquid chromatography with diode array detection (HPLC-DAD) and the identification of the degradation products was achieved by gas chromatography-mass spectrometry (GC-MS). Under UV irradiation, the clomazone was degraded faster in distilled water than in surface water. In irrigated rice water, under sunlight irradiation, clomazone presented a half-life time average of 3.2 days in three consecutive harvests, and after application the concentration in water remained higher than 0.1 μg L-1 for 20 days. Several by-products, like 2-chlorobenzaldehyde and 2-chlorobenzene methanol, were identified by GC-MS, which evidenced that the concentration of intermediates at the begining increase and then they also undergo degradation. Este estudo avaliou a degradação do herbicida clomazone em água destilada e de campos de arroz irrigado, através de irradiação UV e sob condições naturais. Após a etapa de pré-concentração por extração em fase sólida (SPE), a concentração remanescente foi determinada por cromatografia líquida de alta eficiência com detecção por arranjo de diodos (HPLC-DAD) e a identificação dos produtos de degradação foi efetuada por cromatografia gasosa com espectrometria de massas (GC-MS). Sob irradiação UV, o clomazone foi degradado mais rapidamente na água destilada que na água de superfície. Na água de irrigação, sob luz solar, o clomazone apresentou tempo de meia-vida médio de 3,2 dias em três safras consecutivas, e após a aplicação a concentração na água permaneceu acima de 0,1 μg L-1 por cerca de 20 dias. Diversos subprodutos, tais como 2-clorobenzaldeído e 2-clorobenzeno metanol, foram identificados por GC-MS, evidenciando que a concentração dos intermediários aumentou no início e então eles também sofreram degradação.

This study evaluates the degradation of the herbicide propanil and of its major degradation product, 3,4-dichloroaniline (3,4-DCA) in water from irrigated rice farming in the State of Rio Grande do Sul, Brazil. It also assesses the contamination risk of surrounding surface waters. After a solid phase extraction step, the concentration of both compounds was determined by high performance liquid chromatography with ultraviolet detection. Confirmation was conducted by gas chromatography-mass spectrometry. Concentrations of propanil in water samples varied from 0.1 to 3600 µg L-1. Propanil was degraded very rapidly to 3,4-DCA and high concentrations of this product were found, varying from 1.0 to 567.5 µg L-1 in water. The obtained half-life times for propanil in water under real conditions for the 2001, 2002 and 2003 harvests were 18.2, 12.5 and 12.2 h, respectively. O estudo avalia a degradação do herbicida propanil e de seu principal produto de degradação, a 3,4-dicloroanilina (3,4-DCA), em água de irrigação de lavouras de arroz irrigado no Estado do Rio Grande do Sul, Brasil. Além disso, estima, também, o risco de contaminação das águas de superfície das proximidades. Após uma etapa de extração em fase sólida, a concentração de ambos os compostos foi determinada por cromatografia líquida de alta eficiência com detecção na região do ultravioleta. A confirmação foi realizada por cromatografia gasosa-espectrometria de massas. A concentração de propanil nas amostras de água variou de 0,1 a 3600 µg L-1. O propanil degradou-se rapidamente em 3,4-DCA, sendo que altas concentrações deste produto foram encontradas, variando entre 1,0 e 567,5 µg L-1. Os tempos de meia-vida para o propanil em água sob condições reais nas safras de 2001, 2002 e 2003 foram 18,2, 12,5 e 12,2 h, respectivamente.

The effects of 2,4-D (1 or 10 mg/L) on acetylcholinesterase (AChE) and metabolic parameters were evaluated in piava ( Leporinus obtusidens ) after 96 h. AChE activity was significantly reduced in the brain at a concentration of 10 mg/L and in the muscle at both concentrations tested. Muscle glycogen and lactate were significantly reduced for both 2,4-D concentrations but no significant change was observed in liver glycogen. Muscle protein levels were enhanced after exposure at 10 mg/L, but no significant changes were observed in muscle and liver glucose. Liver lactate and protein were significantly reduced after exposure to this herbicide. 2,4-D exposure produced a decrease in blood glucose at both concentrations and enhanced lactate levels at 10 mg/L. Plasma protein increased at both concentrations tested. In conclusion, the results obtained indicate that 2,4-D affects brain and muscle AChE activity and some blood and tissue metabolic parameters of L. obtusidens. The stress generated by 2,4-D is the probable cause of alterations observed and measured parameters can be used to monitor 2,4-D fish toxicity.

The effects of the herbicide, clomazone, on acetylcholinesterase (AChE), catalase and TBARS formation in teleost fish (Rhamdia quelen) were studied. The fish were exposed to 0.5 or 1.0 mg L(-1) of clomazone for 12, 24, 48, 96 and 192 h. After 192 h of exposure period, fish were transferred to clean water and kept in the same for 192 h to study the recovery response. Same parameters as that of exposure period were assayed after 96 and 192 h of recovery period. Specific AChE activity was reduced in the brain and muscle after treatments, reaching a maximum inhibition of 47% in the brain and 45% in the muscle after 12h of exposure. Fish exposed to clomazone increased TBARS production in the liver for all exposure periods. The brain presented elevated TBARS levels after 12, 24 and 48 h, but after 96 and 192 h, these levels decreased. The decrease of TBARS levels persisted in brain tissue after 96 h of recovery and returned to the control value after 192 h in clean water. Catalase activity was reduced for all periods of exposure. Histological analysis showed vacuolation in the liver after herbicide exposure. Some of the alterations observed were completely restored after recovery period.

This article presents an evaluation of the pollution of river water by herbicides used in the culture of irrigated rice in Rio Grande do Sul State, Brazil. Firstly, a theoretical evaluation was made using the approaches suggested by EPA-USA, the "Groundwater Ubiquity Score" index and the Goss method to estimate the pollution possibilities. Afterwards, a monitoring program was established for the rivers of the area from 2001 to 2003 to investigate the presence of herbicide residues. The results indicate that the herbicides clomazone and propanil are the ones with larger presence and frequency in the analyzed samples. The theoretical forecast was confirmed by the results of the monitoring program.

Evaluation of a simple and rapid method for determination of clomazone in environmental water samples, by high-performance liquid chromatography with ultraviolet detection, is described. After solid-phase extraction with C18 extraction cartridges clomazone was separated on a C18 column with 65∶35 (v/v) methanol-water, pH 4.0, as mobile phase at a flow-rate of 1.0 mL min−1. After optimization of the extraction and separation conditions, the method was used for determination of clomazone residues in rivers and agricultural waters of the central region of the Rio Grande do Sul province. The results revealed that clomazone persists in agricultural water at least for 130 days, and was present in 90% of the river water samples analyzed.