121 resultados para Solid phase extraction (SPE)


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This study evaluated the bioaccumulation of tributyltin (TBT) by the blue crab (Callinectes sapidus). Animals were fed with contaminated food containing 30 µg g-1 of TBT expressed as Sn. The analytes were determined in the gills, hepatopancreas and muscle. Acid digestion was used in the total Sn determination, and a solid-phase extraction technique was used for the selective determination of TBT. Limits of detection of 44.6 and 4.46 ng g-1 were found for HG-ICP OES (hydride generation-inductively coupled plasma optical emission spectroscopy) and ICP-MS (ICP-mass spectrometry), respectively. The results for non-contaminated animals were below 50 ng g-1, while the animals subjected to the contaminated food showed higher tissue concentrations of Sn (until 6229 ng g-1) and TBT (until 3357 ng g-1) related to the number of exposure days. According to the results, Sn is bioaccumulated by the blue crab in higher concentrations in the hepatopancreas. For most of these animals, the results suggest that Sn is bioaccumulated as TBT.

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Chemical imprinting technology has been widely used as a valuable tool in selective recognition of a given target analyte (molecule or metal ion), yielding a notable advance in the development of new analytical protocols. Since their discovery, molecularly imprinted polymers (MIPs) have been extensively studied with excellent reviews published. However, studies involving ion imprinted polymers (IIPs), in which metal ions are recognized in the presence of closely related inorganic ions, remain scarce. Thus, this review involved a survey of different synthetic approaches for preparing ion imprinted adsorbents and their application for the development of solid phase extraction methods, metal ion sensors (electrodes and optodes) and selective membranes.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Indiscriminate and inappropriate use of pesticides in agriculture has been pointed out for increasing health problems and environmental damage. Considering that water resources are the principal destiny of those compounds after application, the present study presents optimization and validation of two simple and effi cient analytical methods for pesticides quantifi cation in both surface and groundwater. Were selected the pesticides more commonly used at Dourados (MS - Brazil), region with intense agricultural activity. Pesticides were preconcentrated by solid-phase extraction using C18 (500 mg) cartridges and then divided in two groups for elution and quantifi cation: 2.4-D and 2.4-DCP were eluted with methanol and quantifi ed by high performance liquid chromatography with ultra-violet detector (HPLC-UV) while atrazine, DIA, DEA, trifl uralin and methyl parathion were eluted with ethylacetate (1:1, v/v) and quantifi ed by gas chromatography with thermionic specifi c detector (GC-TSD). The methods showed satisfactory accuracy (76-107%) and precision (<12%) for the substances analyzed at the fortifi ed levels selected for the study, except for DIA (<51%). Study of pesticide stability also presented good results: C18 cartridges could be stored for at least for 21 days at -20ºC with no signs of the compounds degradability. Both methods limits of quantifi cation of the pesticides (0.22 - 0.48 μg L-1) are in accordance to the levels currently established by the Brazilian national legislation for pesticides in water. Although only the pesticide 2.4-D has been detected in two distinct collection points in the study period of time, this work warns for the requirement of systematical analysis of pesticides presence in water destined to human consume, principally in areas of intense agriculture activity. Such monitoring can provide subsidies for public environmental policies.

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

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The antibiotics sulfamethoxazole (SMTX) and ciprofloxacin (CIP) are commonly used in human and veterinary medicine, which explains their occurrence in wastewater. Anaerobic reactors are low-cost, simple and suitable technology to wastewater treatment, but there is a lack of studies related to the removal efficiency of antibiotics. To overcome this knowledge gap, the objective of this study was to evaluate the removal kinetics of SMTX and CIP using a horizontal-flow anaerobic immobilized biomass reactor. Two different concentrations were evaluated, for SMTX 20 and 40 μg L(-1); for CIP 2.0 and 5.0 μg L(-1). The affluent and effluent analysis was carried out in liquid chromatography/tandem mass spectrometry (LC-MS/MS) with the sample preparation procedure using an off-line solid-phase extraction. This method was developed, validated and successfully applied for monitoring the affluent and effluent samples. The removal efficiency found for both antibiotics at the two concentrations studied was 97%. Chemical oxygen demand (COD) exhibited kinetic constants that were different from that observed for the antibiotics, indicating the absence of co-metabolism. Also, though the antibiotic concentration was increased, there was no inhibitory effect in the removal of COD and antibiotics.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Orange juice is a rich source of flavonoids, mainly the flavanones hesperidin and narirutin, associated with health benefits in humans. The objective of this study was to analyze the uptake of flavonoids in humans after the consumption of two types of orange juice, fresh squeezed (fresh juice, FJ) and commercially extracted and pasteurized (processed juice, PJ). Preliminary measurements showed that the main flavanones in PJ were approximately three-fold higher than in FJ. This study involved healthy volunteers including 12 men and 12 women, aged 27 ± 6, with a BMI of 24 ± 3 kg/m2. Volunteers drank 11.5 mL/kg body weight of fresh orange juice, and after an interval of 30 days they drank the same quantity of pasteurized orange juice. Urine was collected from each volunteer during 24 hours following juice consumption. Urine metabolites were recovered by solid phase extraction, and measured by HPLC–ESI–MS. Analyses of the urine samples showed high concentrations of glucuronic acid and sulfate conjugates of hesperetin and naringenin. The data indicate that the concentrations of the flavanone metabolites following consumption of PJ were approximately three times higher than for FJ, thus matching the relative doses of these compounds in the juices provided to the volunteers.

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

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)