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Search Results: 1 - 10 of 231402 matches for " Queiroz Maria Eliana Lopes Ribeiro de "
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Influência da matéria organica na adsor??o do fungicida triadimenol pelo solo
Lopes, Nilva Pereira;Queiroz, Maria Eliana Lopes Ribeiro de;Neves, Ant?nio Augusto;Zambolim, Laércio;
Química Nova , 2002, DOI: 10.1590/S0100-40422002000400006
Abstract: the adsorption of triadimenol (1-(4-chlorophenoxy)-3,3-dimethyl-1-(1h-1,2,4-triazol-1-yl)butan-2-ol) on soil samples with varying contents of organic matter was studied. the adsorption was described by means of the freundlich's isoterm. an increase in the capacity of adsorption was observed as the content of organic carbon in the matrix increased. that effect was observed when removing the organic matter from the soil, when adding a urban waste compost to the soil sample as well as to the soil sample without organic matter, and also after leaving proportions of urban waste compost incubated in these matrices for a period of 120 days. the results show that the adsorption of the triadimenol in the soil is dependent of its content of organic carbon.
Influência da matéria organica na adsor o do fungicida triadimenol pelo solo
Lopes Nilva Pereira,Queiroz Maria Eliana Lopes Ribeiro de,Neves Ant?nio Augusto,Zambolim Laércio
Química Nova , 2002,
Abstract: The adsorption of triadimenol (1-(4-chlorophenoxy)-3,3-dimethyl-1-(1H-1,2,4-triazol-1-yl)butan-2-ol) on soil samples with varying contents of organic matter was studied. The adsorption was described by means of the Freundlich's isoterm. An increase in the capacity of adsorption was observed as the content of organic carbon in the matrix increased. That effect was observed when removing the organic matter from the soil, when adding a urban waste compost to the soil sample as well as to the soil sample without organic matter, and also after leaving proportions of urban waste compost incubated in these matrices for a period of 120 days. The results show that the adsorption of the triadimenol in the soil is dependent of its content of organic carbon.
Determina o de resíduos de organoclorados em águas fluviais do município de Vi osa - MG
Chagas Cíntia Maria,Queiroz Maria Eliana Lopes Ribeiro de,Neves Ant?nio Augusto,Queiroz José Humberto de
Química Nova , 1999,
Abstract: In this work the contamination, by organochlorinated, of a drinking water source located in the region of Vi osa, MG, was evaluated. The identification and quantification of the analytes was carried out using a gas-chromatograph equipped with an electron capture detector after liquid-liquid extraction and concentration. Four insecticides, Aldrin, Epoxy heptachloride, Endrin and op'- DDT were detected in concentrations that are higher than the safety limits established in the Brazilian legislation.
Otimiza??o e valida??o da técnica de extra??o líquido-líquido com parti??o em baixa temperatura (ELL-PBT) para piretróides em água e análise por CG
Vieira, Heulla Pereira;Neves, Ant?nio Augusto;Queiroz, Maria Eliana Lopes Ribeiro de;
Química Nova , 2007, DOI: 10.1590/S0100-40422007000300006
Abstract: the liquid-liquid extraction with the low temperature partition technique was developed for the analysis of four pyrethroids in water by cg. using a factorial design the extraction technique was optimised evaluating the effect of the variables ionic strength, contact time and proportion between sample and solvent volumes. the validation parameters sensitivity, precision, accuracy and detection and quantification limits were evaluated. the lod and loq of the method varied from 1.1 to 3.2 μg l-1 and 2.7 to 9.5 μg l-1, respectively.
Fast Determination of Benzodiazepines in Human Urine via Liquid-Liquid Extraction with Low Temperature Partitioning and LC-HRMS  [PDF]
Elisangela Jaqueline Magalh?es, Clésia Cristina Nascentes, Rodinei Augusti, Maria Eliana Lopes Ribeiro de Queiroz, Júlio César Cardoso da Silva, Robson José de Cássia Franco Afonso
American Journal of Analytical Chemistry (AJAC) , 2012, DOI: 10.4236/ajac.2012.32017
Abstract: A simple and high-throughput method to simultaneously determine selected benzodiazepines (i.e., diazepam, lorazepam, clonazepam, and bromazepam) in urine was developed and validated. The entire methodology consisted of the application of an innovative extraction/cleanup procedure, namely liquid-liquid extraction with low-temperature partitioning (LLE-LTP), and analysis by liquid chromatography combined with high-resolution mass spectrometry (LC-HRMS). The LLE-LTP procedure was optimized via factorial design and by evaluating crucial variables, specifically the freezing mode (either slow or fast), the urine/acetonitrile volume ratio, and the sample ionic strength. The benzodiazepines were quantified using matrix-matched calibration curves where the following parameters were assessed by validation protocol: in general, linearity range of 17 - 200 μg?L–1 (r > 0.9957); limits of detection lower than 5 μg?L–1; relative standard deviations (RSD) lower than 12.5%; and accuracy ranging from 72.3 to 117%. To test this procedure’s performance, the method was applied to determine the content of diazepam in actual urine samples. The validation results obtained for the method demonstrated that the present methodology could be potentially applied in proficient laboratories as a routine approach for determining benzodiazepines compounds content in urine.
Evaluation of pesticide adsorption in gas chromatographic injector and column
Pinho, Gevany Paulino de;Silvério, Flaviano Oliveira;Neves, Ant?nio Augusto;Queiroz, Maria Eliana Lopes Ribeiro de;
Química Nova , 2012, DOI: 10.1590/S0100-40422012000400016
Abstract: components in complex matrices can cause variations in chromatographic response during analysis of pesticides by gas chromatography. these variations are related to the competition between analytes and matrix components for adsorption sites in the chromatographic system. the capacity of the pesticides chlorpyrifos and deltamethrin to be adsorbed in the injector and chromatographic column was evaluated by constructing three isotherms and changing the column heating rate to 10 and 30 oc min-1. by using ancova to compare the slope of calibration graphs, results showed that the higher the injector temperature (310 oc) the lower the pesticide adsorption. also, deltamethrin influenced the adsorption of chlorpyrifos on the column chromatographic.
Desenvolvimento de metodologia para determina??o de piretroides em manteiga
Marthe, Deyse de Brito;Bittencourt, Leila Moreira;Queiroz, Maria Eliana Lopes Ribeiro de;Neves, Ant?nio Augusto;
Química Nova , 2010, DOI: 10.1590/S0100-40422010000600030
Abstract: the objective of this study was to evaluate the use of the matrix solid-phase dispersion technique associated with purification at low temperature for the determination of pyrethroids in butter. evaluated parameters included: sample/adsorbent ratio, type of adsorbent and extractor solvent. the optimized method was validated based on predetermined requirements. the detection limits of the pyrethroids cypermethrin and deltamethrin were 0.082 and 0.11 μg g-1, and quantification limit were 0.28 and 0.32 μg g-1, respectively, with extraction percentages near 90% and coefficients of variation less than of 10%..
Determina??o de resíduos de organoclorados em águas fluviais do município de Vi?osa - MG
Chagas, Cíntia Maria;Queiroz, Maria Eliana Lopes Ribeiro de;Neves, Ant?nio Augusto;Queiroz, José Humberto de;Oliveira, Tania Toledo de;Nagem, Tanus Jorge;
Química Nova , 1999, DOI: 10.1590/S0100-40421999000400007
Abstract: in this work the contamination, by organochlorinated, of a drinking water source located in the region of vi?osa, mg, was evaluated. the identification and quantification of the analytes was carried out using a gas-chromatograph equipped with an electron capture detector after liquid-liquid extraction and concentration. four insecticides, aldrin, epoxy heptachloride, endrin and op'- ddt were detected in concentrations that are higher than the safety limits established in the brazilian legislation.
Perfil lipídico tecidual de ratos alimentados com diferentes fontes lipídicas
Almeida, Martha Elisa Ferreira de;Queiroz, José Humberto de;Queiroz, Maria Eliana Lopes Ribeiro de;Costa, Neuza Maria Brunoro;Matta, Sérgio Luis Pinto;
Revista de Nutri??o , 2009, DOI: 10.1590/S1415-52732009000100005
Abstract: objective:to determine if lipid sources with different unsaturated to saturated fatty acid ratios, (pufa+mufa)/sfa in the diet alter the lipid profile of tissues, the lipid concentration (mg/g) of the hepatic and mesenteric tissues and the lipid digestibility. methods:gas chromatography was used to determine the profile of fatty acids in the hepatic and adipose tissues of rats fed with different lipid sources. the digestibility coefficient was determined based on the ratio between lipid intake and excreted in the feces. results:different lipid sources (soy oil, butter, margarine and pig and fish fat) did not alter the digestibility coefficient and the hepatic weight, but they altered the lipid deposition in all adipose tissue evaluated. no direct correlation was observed between dietary non-essential fatty acid profile and its deposition in the studied adipose tissues, because of de novo which impedes the identification of the dietary fatty acid. conclusion:a direct relationship was not verified between the dietary fatty acid profile and its deposition in the studied adipose tissues, except for the trans and linoleic (c18:2) fatty acids which are not synthesized in the rat. the tissue concentration of these fatty acids was directly proportional to their dietary sources. the (pufa+mufa)/sfa ratio found in the hepatic tissue of the different groups, was directly proportional to the values presented in the dietary lipid sources. however, this association was not observed in the adipose tissue.
Análise de risco de contamina??o de águas superficiais e subterraneas por pesticidas em municípios do Alto Paranaíba - MG
Andrade, André Santana;Queiroz, Vagner Tebaldi de;Lima, Diego Tolentino de;Drumond, Luis César Dias;Queiroz, Maria Eliana Lopes Ribeiro de;Neves, Ant?nio Augusto;
Química Nova , 2011, DOI: 10.1590/S0100-40422011000700005
Abstract: a preliminary analyses of the possible contamination of surface and groundwater by the active ingredients of the pesticide products used in the areas with intensive agricultural activities of alto paranaíba region, mg, brazil, was carried out. the active ingredients and formulated products most used in the region were identified and their characteristics of environmental importance were presented. the epa screening criteria, the groundwater ubiquity score (gus) and the criteria proposed by goss were used to evaluate which pesticides might contaminate the local waters. among the active ingredients studied, several present risks to the local aquatic environment.
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