Browsing by Author Lemos, Valfredo Azevedo

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Issue DateTitleAuthor(s)Type
2009A procedure for determination of cobalt in water samples after dispersive liquid–liquid microextractionBaliza, Patrícia Xavier; Teixeira, Leonardo Sena Gomes; Lemos, Valfredo AzevedoArtigo de Periódico
2007On-line system for preconcentration and determination of metals in vegetables by Inductively Coupled Plasma Optical Emission SpectrometryBezerra, Marcos de Almeida; Santos, Walter Nei Lopes dos; Lemos, Valfredo Azevedo; Korn, Maria das Graças Andrade; Ferreira, Sergio Luis CostaArtigo de Periódico
1999Selectivity enhancement in spectrophotometry: on-line interference suppression using polyurethane foam minicolumn for aluminum determination with Methyl Thymol BlueCassella, Ricardo Jorgensen; Santelli, Ricardo Erthal; Branco, Aline Garcia; Lemos, Valfredo Azevedo; Ferreira, Sergio Luis Costa; Carvalho, Marcelo Souza deArtigo de Periódico
2006Mercury determination in petroleum products by electrothermal atomic absorption spectrometry after in situ preconcentration using multiple injectionsDias, Fábio de Souza; Teixeira, Leonardo Sena Gomes; Santos, Walter Nei Lopes dos; Rebouças, Márcio das Virgens; Pereira, Madson de G.; Lemos, Valfredo AzevedoArtigo de Periódico
2011Multi-element determination of Cu, Fe, Ni and Zn content in vegetable oils samples by high-resolution continuum source atomic absorption spectrometry and microemulsion sample preparationFernandes, Andréa Pires; Nunes, Luana Sena; Barbosa, José Tiago Pereira; Lemos, Valfredo Azevedo; Santos, Walter Nei Lopes dos; Korn, Maria das Graças Andrade; Teixeira, Leonardo Sena GomesArtigo de Periódico
2006A pre-concentration procedure using coprecipitation for determination of lead and iron in several samples using flame atomic absorption spectrometryFerreira, Sergio Luis Costa; Saracoglu, S.; Soylak, Mustafa; Peker, D. S. Kacar; Elci, L.; Santos, Walter Nei Lopes dos; Lemos, Valfredo AzevedoArtigo de Periódico
2003Use of factorial design and Doehlert matrix for multivariate optimisation of an on-line preconcentration system for lead determination by flame atomic absorption spectrometryFerreira, Sergio Luis Costa; Santos, Walter Nei Lopes dos; Bezerra, Marcos de Almeida; Lemos, Valfredo Azevedo; Bosque-Sendra, Juan ManuelArtigo de Periódico
1998Spectrophotometric Determination of Aluminium in Iron Ores Using Solid-Phase ExtractionFerreira, Sergio Luis Costa; Lemos, Valfredo Azevedo; Costa, Antonio Celso Spinola; Jesus, Djane Santiago de; Carvalho, Marcelo Souza deArtigo de Periódico
1997Sensitive spectrophotometric determination of ascorbic acid in fruit juices and pharmaceutical formulations using 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (Br-PADAP)Ferreira, Sergio Luis Costa; Bandeira, Marcus Luciano Souza de Ferreira; Lemos, Valfredo Azevedo; Santos, Hilda Costa dos; Costa, Antonio Celso Spinola; Jesus, Djane S. deArtigo de Periódico
2001On-line preconcentration system for nickel determination in food samples by flame atomic absorption spectrometryFerreira, Sergio Luis Costa; Santos, Walter Nei Lopes dos; Lemos, Valfredo AzevedoArtigo de Periódico
2001An automated on-line flow system for the pre-concentration and determination of lead by flame atomic absorption spectrometryFerreira, Sergio Luis Costa; Lemos, Valfredo Azevedo; Santelli, Ricardo Erthal; Ganzarolli, Edgard; Curtius, Adilson JoséArtigo de Periódico
2000Copper determination in natural water samples by using FAAS after preconcentration onto amberlite XAD-2 loaded with calmagiteFerreira, Sergio Luis Costa; Ferreira, Janeide R.; Dantas, Alailson Falcão; Lemos, Valfredo Azevedo; Araújo, Neyla Margarida Lopo de; Costa, Antonio Celso SpinolaArtigo de Periódico
2000An on-line continuous flow system for copper enrichment and determination by flame atomic absorption spectroscopyFerreira, Sergio Luis Costa; Lemos, Valfredo Azevedo; Moreira, Barbara C.; Costa, Antonio Celso Spinola; Santelli, Ricardo ErthalArtigo de Periódico
2007Review of procedures involving separation and preconcentration for the determination of cadmium using spectrometric techniquesKorn, Maria das Graças Andrade; Ferreira, Sergio Luis Costa; Andrade, Jailson Bittencourt de; Lemos, Valfredo Azevedo; Santos, Walter Nei Lopes dos; Souza, Anderson Santos; Ferreira, Hadla Sousa; Rodrigues, Frederico de Medeiros; Pereira, Madson de Godoi; Silva, Erik Galvão Paranhos daArtigo de Periódico
2006Separation and preconcentration procedures for the determination of lead using spectrometric techniques: A reviewKorn, Maria das Graças Andrade; Ferreira, Sergio Luis Costa; Andrade, Jailson Bittencourt de; Jesus, Djane S. de; Lemos, Valfredo Azevedo; Bandeira, Marcus Luciano Souza de Ferreira; Santos, Walter Nei Lopes dos; Bezerra, Marcos de Almeida; Amorim, Fábio Alan Carqueija; Souza, Anderson SantosArtigo de Periódico
2008On-line preconcentration using a resin functionalized with 3,4-dihydroxybenzoic acid for the determination of trace elements in biological samples by thermospray flame furnace atomic absorption spectrometryLemos, Valfredo Azevedo; Bezerra, Marcos de Almeida; Amorim, Fábio Alan CarqueijaArtigo de Periódico
2000Application of polyurethane foam loaded with BTAC in an on-line preconcentration system: cadmium determination by FAASLemos, Valfredo Azevedo; Santelli, Ricardo Erthal; Carvalho, Marcelo Souza de; Ferreira, Sergio Luis CostaArtigo de Periódico
Sep-2000Application of polyurethane foam loaded with BTAC in an on-line preconcentration system: cadmium determination by FAASLemos, Valfredo Azevedo; Santelli, Ricardo Erthal; Carvalho, Marcelo Souza de; Ferreira, Sergio Luis CostaArtigo de Periódico
2008Development of a new sequential injection in-line cloud point extraction system for flame atomic absorption spectrometric determination of manganese in food samplesLemos, Valfredo Azevedo; Baliza, Patrícia Xavier; Carvalho, Anaildes Lago de; Oliveira, Rafael Vasconcelos; Teixeira, Leonardo Sena Gomes; Bezerra, Marcos de AlmeidaArtigo de Periódico
2001On-line preconcentration system for lead determination in seafood samples by flame atomic absorption spectrometry using polyurethane foam loaded with 2-(2-benzothiazolylazo)-2-p-cresolLemos, Valfredo Azevedo; Ferreira, Sergio Luis CostaArtigo de Periódico