Diethylene glycol is an extremely toxic substance to humans. Recently, cases of beer contamination in Brazil have raised awareness of the need for developing simple screening methods to evaluate this type of compound. This research developed a liquid-liquid extraction with low-temperature partitioning technique to determine diethylene glycol in beer via gas chromatography. Employing a flame-ionization detector simplifies the method, lowers its cost and therefore, it can be used as screening step to assess the possibility of contamination. A gas chromatograph coupled to a mass spectrometer would be used only for a confirmatory analysis. The optimized method was validated for the main figures of merit, and it proved to be adequate, with good values of recovery rate (94-106%), limit of detection (3.0 mg L-1), and quantification (10.0 mg L-1). Accuracy, in terms of repeatability and intermediate accuracy, showed variation coefficients lower than or equal to 20%. This method was applied to 28 samples of beers marketed in Brazil, and diethylene glycol was found above the limit of detection in three of them (10.7%). These results were confirmed by a gas chromatograph coupled to a mass spectrometer, which showed the reliability of the screening method for determining diethylene glycol in beer samples.

The liquid-liquid extraction with low-temperature partitioning technique (LLE/LTP) was miniaturized to determine the pesticides chlorpyrifos, bifenthrin, λ-cyhalothrin, and deltamethrin in a biological matrix, by gas chromatography. The method was proposed for fetal-bovine serum samples (500 μL), by using a full factorial design (23) with one center point. The evaluated factors included the volume of water added to the sample (1000 μL), volume of extraction solvent (500 μL) and stirring time (60 s) – a cleanup step was not necessary. The method was validated for the main figures of merit. The results indicated that the LLE/LTP/GC/ECD miniaturized method was efficient in extracting pesticides from blood-serum samples (75 to 115%). It showed both selectivity and sensitiveness, with limits of quantification (LOQ) ranging from 8 at 17 μg L-1;. Once validated, the method was applied to blood-serum samples of rural workers from a city in the Brazilian state of Minas Gerais. In that case, the presence of chlorpyrifos was detected in two of the samples.

Birnessite type manganese oxide (δ-MnO2) was synthesized for use in degradation of the cationic dye methylene blue in aqueous solution. The material was characterized using infrared spectroscopy, X-ray diffraction, and Brunauer-Emmett-Teller (BET) surface area calculations. The removal of the dye from aqueous solutions was evaluated considering the effects of the following variables: pH, manganese oxide concentration, contact time, and temperature. UV-Vis spectroscopy analyses indicated achievement of 99 and 95% removal of methylene blue (7 mg L-1) at pH 2.0 and 4.0, respectively, after 120 min of contact with the birnessite (100 mg L-1). At higher pH of 6.0 and 8.0, removals of around 99 and 80%, respectively, were obtained after a longer time of 1860 min. Analyses of total organic carbon (TOC) revealed that 80% reduction of organic matter was obtained at pH 4.0. The method of multivariate curve resolution-alternating least squares (MCR-ALS) was used together with UV-Vis spectroscopy to evaluate the removal process, confirming the degradation of methylene blue. Thionine (λmax = 601 nm) was identified as one of the byproducts of N-demethylation of methylene blue. The results indicated that the degradation process started with N-demethylations of the methylene blue molecule.

Clomazone exhibits high water solubility, low sorption in soil colloids, and therefore can leach and contaminate deep layers of soil profile and groundwater. In this work, the effect of the incorporation of sugarcane bagasse biochar in leaching and bioavailability of clomazone in red latosol was evaluated. Soil samples amended with 1% (m/m) biochar were placed in different depths (0-1, 0-2.5 and 0-5 cm) on the top of polyvinyl chloride (PVC) columns filled with soil. Clomazone-based herbicide was applied, and rainfall was simulated on top of the columns. A validated chromatographic method, together with a greenhouse bioassay, were used to quantify and to evaluate the mobility and availability of clomazone along the columns. The incorporation of sugarcane bagasse biochar in the superficial layers at the column tops increased herbicide sorption, reduced its leaching and bioavailability in soil and scaled down the environmental risk of clomazone avoiding contamination of underground aquifer reservoirs.

Two types of manganese oxide were investigated for the removal/degradation of Orange G (OG) dye in aqueous solution. One manganese oxide (pyrolusite) was obtained commercially and the other (birnessite) was prepared according to the polyol method by means of the oxidation of MnII hydroxide by H2O2. Both materials were characterized by X-ray diffraction (XRD), infrared spectroscopy (IR), scanning electron microscopy (SEM), and nitrogen adsorption/desorption at 77 K. The effects of agitation time, pH, and MnO2 dose on the degradation of OG by the birnessite and pyrolusite were evaluated. Approximately 90 and 99% decoloration of OG (10 mg L-1) was obtained after 30 min of stirring with 0.20 g L-1 of birnessite or pyrolusite, respectively. The decoloration and increased intensity of absorbance bands in the UV-visible spectrum were indicative of a degradation process that followed pseudo-first order kinetics. The findings demonstrated the high efficiency of different types of manganese oxides for removal of this organic pollutant from waters.

Abstract Biochar is a carbonaceous material that has excellent potential as a fertilizer and soil conditioner. However, there is a lack of information concerning the effects of the amount and particle size of this pyrogenic material on the soil sorption capacity. In this work, evaluation was made of changes in clomazone (CMZ) sorption in a Red Latosol following soil conditioning using different percentages (0.25, 0.5, and 1% w/w) of sugarcane biochar in three particle sizes (<106, 106-508, and 508-610 µm). The conditioned soils presented apparent sorption coefficients (Kd) up to 1300 times higher than that of pure soil, besides changes in the behavior of CMZ sorption. The biochar particle size and percentage influenced sorption of the herbicide as well as its retention in the amended soil during desorption processes. Both sorption and desorption Freundlich constants were linearly correlated with the external surface area of the biochar present in the soil.

Effluents from pulp mills have a high organic load and can still contain high organic bio-recalcitrant material that is harmful to the aquatic environment, even after undergoing biological treatment in effluent treatment plants. This study presents a novel treatment method tested on effluents (prior to and after biotreatment) from a Brazilian kraft pulp mill, based on hydroxyl radical production and hydrogen peroxide obtained by plasma generated by high-voltage electrolysis. These species present significant oxidation potential that could enable the complete breakdown of the organic matter. From the application of plasma to treat pulp mill effluent for a 7-hour period, it was obtained a chemical oxygen demand (COD) removal between 88.2 and 99.7%, total organic carbon (TOC) removal of 90.3 to 95.6%, and a color removal of 95.0 to 98.0%. The final pH of the treated effluent was 11.6 to 11.9. The results obtained in this study showed that the high-tension plasma treatment, applied on effluent from kraft pulp mills before and after biological treatment, can be an attractive alternative.

A new method has been developed to determine trace levels of organophosphorus pesticide parathion-methyl in water samples by using dispersive liquid-liquid microextraction (DLLME), followed by gas chromatograph coupled with electron capture detector (GC/ECD) analysis. The optimized and validated method showed high extraction recovery (101.1%), high enrichment factor (57.3), low limits of detection and quantification, 0.083 and 0.250 µg L-1, respectively. The established DLLME-GC/ECD method has been successfully applied for the evaluation of the photodegradation of the parathion-methyl by UV254nm radiation in different conditions of pH and temperature. The parathion-methyl photodegradation at pH 3 and 35 °C achieved > 99.5% after 120 min of exposition. For this condition, it was observed the kinetic rate of 0.0515 min-1, the quantum yield of 1.22 × 10-5 mol Einstein-1 and a half-life time of 13.46 min. All experimental conditions tested proved to be strongly influenced by pH and temperature. The application of the optimized process in distilled and drinking water spiked with parathion-methyl provided residues of this pesticide at levels below the maximum permitted by Brazilian legislation, which is 9.0 µg L-1.

A new method for the extraction of pesticide residues from soil was developed, optimized, validated and applied to real samples. The technique consisted of combining single-drop microextraction and solid-liquid extraction with low temperature partitioning (SLE/LTP-SDME) followed by analysis using gas chromatography with electron capture detection (GC/ECD). This method was used to determine the presence of alachlor, methyl parathion, trifluralin, endrin, lindane, dieldrin and dichloro-diphenyl-trichloroethane (4,4’-DDT) in soil samples. Recoveries ranging from 67.2 to 122.5% were achieved, coefficients of variation (repeatability) were lower than 22.4% and limits of detection ranged from 0.18 to 0.59 µg kg-1. Recovery from soils fortified with different concentrations of the pesticides ranged from 61.5 to 123.5%. The new method combines the primary advantages of the two techniques: purification of the sample using SLE/LTP and preconcentration using SDME. The new method also enables the determination of low volatility compounds without requiring the sample to be heated.

Due to uncontrolled use of pesticides and disregard for harvest intervals, some pesticide residue is present in various foods. Treatments using ozone as an alternative for food decontamination have been studied in recent years due to ozone’s high oxidation potential even at low concentrations. The present work aimed to evaluate chlorothalonil removal from table grapes by the immersion of fruit in distilled water continuously bubbled with ozone gas. This strategy allowed the removal of 60% of chlorothalonil from table grapes (pulp and skin), regardless of ozone concentration. Ozone treatment of table grapes at a gas concentration of 3 mg L−1 changed most of the quality parameters evaluated. Treatment at 2 mg L−1 maintained the fruit quality for a longer storage period compared to the untreated control table grapes.

O monitoramento de pesticidas em amostras ambientais em baixas concentrações é necessário devido aos riscos que estes compostos representam a saúde humana e ao meio ambiente. Neste trabalho, o método microextração em gota única (SDME) foi otimizado e validado para a determinação das concentrações traço de oito pesticidas em água utilizando cromatografia gasosa com detector por captura de elétrons (GC/ECD). A cinética de transferência de matéria da fase aquosa para a fase orgânica durante o processo de extração também foi avaliada. O método mostrou recuperações entre 89,5 e 122,7%, com coeficientes de variação menores que 22,9%, e os limites de detecção entre 5,9 e 58,9 ng L-1. O método foi aplicado a amostras fortificadas em diferentes níveis de concentração, e recuperações entre 50,5 e 148% foram obtidas. O processo de extração pode ser descrito pelo modelo de difusão de Noyes-Whitney, e a parationa metílica apresentou a maior taxa de transferência entre as duas fases.

The monitoring of pesticides in environmental samples at low concentrations is needed due to the risks that these compounds can pose to human health and the environment. In this work, a single drop microextraction (SDME) method was optimized and validated for the determination of trace concentrations of eight pesticides in water, using gas chromatography with electron capture detector (GC/ECD). The kinetics of the transfer of material from the aqueous phase to the organic phase during the extraction process was also evaluated. The method showed recoveries between 89.5 and 122.7%, with coefficients of variation smaller than 22.9%, and detection limits between 5.9 and 58.9 ng L-1. The method was applied to spiked samples at different concentration levels, and recoveries between 50.5 and 148% were obtained. The extraction process could be described by the Noyes-Whitney diffusion model, and methyl parathion showed the highest rate of transfer between the two phases.

Parâmetros de maturação de frutos de tomate como pH, ºBrix, acidez e teores de licopeno e β-caroteno foram avaliados. Cinco agrotóxicos foram quantificados em extratos orgânicos de tomate em diferentes fases de maturação. A técnica de extração sólido-líquido com partição em baixa temperatura (ESL-PBT) foi utilizada para a obtenção desses extratos orgânicos. O efeito da matriz tomate foi calculado a partir dos resultados da análise por cromatografia gasosa com detector de captura de elétrons (CG-DCE). Correlações entre os parâmetros de maturação e efeito matriz foram estudadas. A correlação entre o teor de carotenoides e o efeito matriz foi elevada para todos os pesticidas estudados. Os resultados indicam que o efeito produzido pela matriz tomate está correlacionada com a presença de licopeno e β-caroteno em extratos orgânicos. A análise de componentes principais (PCA) mostrou que o licopeno, caroteno e a mistura de ambos têm efeitos significativos sobre a resposta cromatográfica de pesticidas.

Some parameters of tomato fruits ripening such as color, pH, ºBrix, acidity and lycopene and β-carotene content were evaluated during the ripening of fruits. Five pesticides were quantified in organic extracts derived from tomatoes at different stages of maturation. The solid-liquid extraction technique with partition at low temperature (SLE-PLT) was used to obtain these organic extracts. The matrix effect of tomato was calculated from the results of analysis by gas chromatography with electron capture detector (GC-ECD). Correlations between maturation parameters and matrix effect were performed. The correlation between the content of carotenoids and matrix effect was high for all pesticides studied. The results indicate that the effect produced by the tomato matrix is correlated with the presence of lycopene and β-carotene in organic extracts. The principal component analysis (PCA) showed that lycopene, carotene and the mixture of both have significant effects on the chromatographic response of pesticides, separating them into distinct groups.

O principal objetivo deste trabalho foi avaliar a presença de resíduos de clorpirifós e tiametoxam em amostras de batata e solo em diferentes circunstâncias, após a otimização e validação da técnica de extração sólido-líquido e partição em baixa temperatura. Porcentagens de recuperação entre 93% e 105% foram obtidas para os pesticidas nas amostras. O método otimizado e validado foi aplicado às amostras de batata obtidas em supermercado e foi obtido resíduo de clorpirifós na concentração de 0,67 mg kg-1. Batatas cultivadas no campo foram tratadas com os pesticidas em diferentes dias e resíduo de clorpirifós foi detectado. As batatas cultivadas em vasos foram tratadas com clorpirifós e tiametoxam somente no plantio. Após 91 dias, foi observada uma concentração de tiametoxam acima do LMR permitido. O método proposto foi eficiente na determinação de clorpirifós e tiametoxam e foi concluído que o monitoramento de agrotóxicos deve ser realizado periodicamente para garantir a qualidade dos produtos e a saúde do consumidor.

The main objective of this work was to evaluate the presence of residues of chlorpyrifos and thiamethoxam in potato and soil samples under different circumstances after optimization and validation of solid-liquid extraction and partitioning at low temperature technique. Recovery percentages between 93% and 105% were obtained for pesticides in the samples. The optimized and validated method was applied to potatoes from supermarkets and it was obtained chlorpyrifos residue at concentrations of 0.67 mg kg-1. Potatoes grown in the field were treated with pesticide on different days and chlorpyrifos was the only residue detected. The potatoes grown in pots were treated with chlorpyrifos and thiamethoxam only at planting. After 91 days, it was observed the concentration of thiamethoxam in the potatoes higher than the tolerable MRL. The proposed method was efficient in the determination of chlorpyrifos and thiamethoxam and it was concluded that the monitoring of pesticides in food must be performed periodically to ensure the product quality and the safety of consumer's health.

Um método para determinação simultânea de 14 agrotóxicos (organoclorados e piretroides) em água foi desenvolvido utilizando microextração em gota única (SDME) e cromatografia gasosa com detector de captura por elétrons. Variáveis experimentais incluindo solvente orgânico, volume da microgota, tempo de extração, volume e velocidade de agitação da amostra e adição de sal foram avaliadas a fim de maximizar o desempenho da técnica SDME. Coeficientes de variação (CV), abaixo de 20% e recuperações relativas entre 71 e 107% indicaram boa precisão e exatidão do método. O protocolo desenvolvido também mostrou seletividade e boa linearidade com coeficientes de correlação (r) superiores a 0,99. Os limites de detecção dos analitos de interesse apresentaram-se entre 0,003 e 0,6 µg L-1, todos abaixo dos respectivos níveis máximos de contaminantes para água potável. Amostras de água potável foram analisadas utilizando o método proposto e nenhum dos pesticidas foi detectado.

A method for simultaneous determination of 14 pesticides (organochlorine and pyrethroid) in water was developed using the single drop microextraction (SDME) and gas chromatography with an electron capture detector. Experimental variables including organic solvent, volume of the microdrop, extraction time, volume and stirring speed of the sample and the addition of salt were evaluated to maximize the performance of the SDME technique. Coefficients of variation (CV) lower than 20% and relative recoveries between 71 and 107% indicated good precision and accuracy of the method. The developed protocol also showed selectivity and good linearity with correlation coefficients (r) greater than 0.99. Limits of detection of the analytes of interest were between 0.003 and 0.6 µg L-1, all below the respective maximum contaminant levels (MCL) for drinking water. Drinking water samples were analyzed using the proposed method and none of the pesticides were detected.

Carbamatos são os pesticidas mais frequentemente encontrados em alimentos e bebidas de coloração escura em casos de intoxicação acidental ou intencional. Neste trabalho, extração líquido-líquido com partição em baixa temperatura (LLE-LTP) foi otimizada e validada para determinação dos carbamatos aldicarb, carbofuran e carbaril em bebidas de sucos de uva e leite achocolatado. Este método envolve a extração com acetonitrila, partição líquido-líquido em baixa temperatura e análise por cromatografia líquida de alta eficiência com detecção ultravioleta (HPLC-UV). O método é rápido, eficiente e de baixo custo, emprega pequenos volumes de solvente por amostra e não necessita de limpeza dos extratos. O método de extração foi seletivo e apresentou porcentagens de extração acima de 90%. As premissas relacionadas com os testes estatísticos de linearidade foram verificadas e confirmadas. O método de extração e análise foi validado com resultados satisfatórios e pode ser aplicado em análises de rotina e forenses.

Carbamates are the pesticides most commonly found in dark colored foods and beverages in cases of accidental or intentional poisoning. In this work, the liquid-liquid extraction with low temperature partitioning (LLE-LTP) was optimized and validated for determination of the carbamates aldicarb, carbofuran and carbaryl in grape juice and chocolate milk beverages. This method involved extraction with acetonitrile, liquid-liquid partition at low temperature and the analysis by high performance liquid chromatography with ultraviolet detection (HPLC-UV). The method is rapid, efficient and of low-cost, employing small volumes of solvent per sample and requiring no cleanup of the extracts. The extraction methodology was selective and presented recovery percentages above 90%. The premises related to the statistical linearity tests were checked and confirmed. The method of extraction and analysis was validated with satisfactory results, and may be applied in forensic and routine analysis.