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| SANTOS,QUEILA O.; MORENO,ISLANIA; SANTOS,LEANDRO DOS; SANTOS,ALDENOR G.; SOUZA,VALDINEI S.; BEZERRA,MARCOS A.. |
| A modified simplex algorithm was used to optimize a system of preconcentration for cadmium determination in samples of sediments, cigarettes and food using flame atomic absorption spectrometry. The preconcentration system is based on the sorption of cadmium in a minicolumn packed with Amberlite XAD-2 resin functionalized with 3,4-dihydroxybenzoic acid (DHB). The optimized variables were pH and sampling flow rate and the optimum conditions found for these variables were, respectively 8.7 and 8.8 mL min-1. The developed system showed a preconcentration factor of 15.3, detection limit of 0.49 µg L-1, quantification limit of 1.65 µg L-1 and precision expressed as relative standard deviation (% RSD, n=10) of 5.9. The accuracy of the method was checked by... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Simplex optimization; Preconcentration; Cadmium; Sediments; Cigarettes; Food. |
| Ano: 2016 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652016000300791 |
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| CORREIA,LÍVIA O.; SIQUEIRA JÚNIOR,SÉRGIO; CARNEIRO,PAULO L.S.; BEZERRA,MARCOS A.. |
| This paper presents a study on the viability of the use of tissues of the Leptodactylus ocellatus species (Anura Leptodactylidae) as a bioindicator of metal pollution. The study is based on the determination and correlation of the concentrations of manganese, chromium, zinc, nickel, copper and iron in sediments and tissues (skin, muscles and viscera) of the frog Leptodactylus ocellatus collected in the middle region of the Contas River in Bahia, Brazil. The highest levels of the metals studied were found in the viscera of this animal. In this tissue, a higher correlation of the concentration of these metals with those found in sediments was also observed. The concentrations of elements found in the skin and muscles of these amphibians have revealed no... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Leptodactylus ocellatus; Bioindicators; Sediments; Metals; Contas River. |
| Ano: 2014 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652014000401549 |
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| BARROS,JOÉLIA M.; BEZERRA,MARCOS A.; VALASQUES,GISSELI S.; NASCIMENTO JÚNIOR,BARAQUÍZIO B. DO; SOUZA,ANDERSON S.; ARAGÃO,NÁDIA M. DE. |
| In this work, multivariate optimization techniques were used to develop a method based on the ultrasound-assisted extraction for copper, manganese, nickel and zinc determination from rations for chicken nutrition using flame atomic absorption spectrometry. The proportions of extracting components (2.0 mol.L–1 nitric, hydrochloric and acetic acid solutions) were optimized using centroid-simplex mixture design. The optimum proportions of this mixture taken as percentage of each component were respectively 20%, 37% and 43%. Variables of method (sample mass, sonication time and final acid concentration) were optimized using Doehlert design. The optimum values found for these variables were respectively 0.24 g, 18s and 3.6 mol.L–1. The developed method allows... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Rations to chicken; Ultrasound-assisted extraction; Mixture design; Doehlert design; Metals. |
| Ano: 2013 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652013000300891 |
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