Micelle-mediated methodology for the preconcentration of uranium prior to its determination by flow injection

Laespada, María Esther Fernández; Pavón, José Luis Pérez; Cordero, Bernardo Moreno

doi:10.1039/an9931800209

Cited by 104 publications

(41 citation statements)

References 22 publications

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“…In recent years, on-line combination of CPE with FIA has attracted much attention. For example, Cordero and co-workers [8] were the first to recognize the advantages of combining CPE with FIA, but the cloudpoint methodology was still performed off-line in their experiments. The ability to perform CPE on-line in an FIA system was been reported for the first time by Huie [9].…”

Section: Introductionmentioning

confidence: 99%

Comparison of traditional cloud-point extraction and on-line flow-injection cloud-point extraction with a chemiluminescence method using benzo[a]pyrene as a marker

Song

Hayakawa

et al. 2005

Anal Bioanal Chem

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In this work, using benzo(a)pyrene (BaP) as marker, the analytical merits of on-line flow-injection cloud-point extraction (FI CPE), including preconcentration factor, extraction efficiency, sample throughput, and analysis time were evaluated by use of peroxyoxalate chemiluminescence (CL) detection. Moreover, by detailed discussion of several preconcentration conditions for traditional and on-line FI CPE the advantages of on-line FI CPE became conspicuously apparent. When coupled with separation techniques such as high-performance liquid chromatography (HPLC) or capillary electrophoresis (CE), on-line FI CPE-CL has much potential for analysis of low concentrations of polycyclic aromatic hydrocarbons (PAH) in environmental samples.

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Section: Introductionmentioning

confidence: 99%

Comparison of traditional cloud-point extraction and on-line flow-injection cloud-point extraction with a chemiluminescence method using benzo[a]pyrene as a marker

Song

Hayakawa

et al. 2005

Anal Bioanal Chem

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“…10 U, 11 Er 12 and Gd 13 were determined by spectrophotometry by room temperature phosphorescence; Cu, 14 Cd, 15 Ni and Zn, 16 Ag and Au, 17 by FAAS after CPE using complexing agents. Gold and lead were extracted efficiently without a complexing agent, using a non-ionic surfactant, such as poly oxyethylene nonyl phenyl ether (PONPE 7.5).…”

mentioning

confidence: 99%

Simultaneous Cloud-Point Extraction of Nine Cations from Water Samples and Their Determination by Flame Atomic Absorption Spectrometry

Farajzadeh

Fallahi

2006

ANAL. SCI.

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Several analytical techniques, such as atomic absorption spectrometry (AAS), inductively coupled plasma atomic emission spectrometry (ICP-AES) and inductively coupled plasma mass spectrometry (ICP-MS), are available for the determination of trace metals with sufficient sensitivity for most applications. However, the determination of trace metal ions in natural water samples is difficult due to various factors, particularly their low concentration and matrix effects.Preconcentration and separation can solve these problems and lead to a higher confidence level and an easy determination of trace elements by less sensitive, but more accessible instrumentation, such as flame atomic absorption spectrometry (FAAS) Cloud-point extraction (CPE) is related to the conventional LLE, and is used in micellar liquid chromatography (MLC). 7The first applications of phase separation based on the cloudpoint phenomenon refer to the extraction of metal ions forming complexes that are sparingly soluble in water. The efficiency of the process depends on the hydrophobicity of the ligand and of the complex formed, on the apparent equilibrium constants in the micellar medium, and on the formation kinetics of the complex and on the transference between the phases. This type of extraction by the cloud-point method was initially described by Watanabe and coworkers 8 for the preconcentration of Zn(II) using 1-(2-pyridylazo)naphthol (PAN) as a ligand and PONPE 7.5 as an extractant. Later, this methodology was also applied to the determination of different metal ions in different types of samples. 9 Like for all other established LLE methods, the metal ion is required to be in the uncharged chelated form prior to its extraction to the organic phase.The phase separation phenomenon has also been used for the extraction and preconcentration of metal ions after the formation of sparingly water-soluble complexes. 10 U, 11 Er 12 and Gd 13 were determined by spectrophotometry by room temperature phosphorescence; Cu, 14 Cd, 15 Ni and Zn, 16 Ag and Au, 17 by FAAS after CPE using complexing agents. Gold and lead were extracted efficiently without a complexing agent, using a non-ionic surfactant, such as poly oxyethylene nonyl phenyl ether (PONPE 7.5). Gold 18 in the aqueous phase was determined by ICP-MS and in the surfactant phase by a calculation based on mass balances. Lead 19 in the surfactant-rich phase was determined by FAAS after diluting with ethanol. Recently, the determination of trace elements by X-ray fluorescence spectrometry 20 and ultrasonic nebulization ICP-MS using phase separation with a surfactant have been reported. reviewed the use of surfactant-based assemblies in analytical atomic spectrometry. Also, concentration by CPE has been established for a number of trace organic pollutants from an aqueous phase. 22Based on the present work we report on the results obtained in a study of the simultaneous cloud-point preconcentration of Cu 2+ , Mn 2+ , Ni 2+ , Cd 2+ , Fe 3+ , Co 2+ , Zn 2+ , Cr 3+ and Pb 2+ after the formation of a compl...

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“…Como ocorre a separação de fases no Ponto Nuvem, este pode ser empregado para a extração e pré-concentração de metais, já que duas fases são formadas neste processo: uma delas aquosa e contendo uma pequena quantidade de tensoativo (abaixo da CMC), denominada fase pobre e, a outra, extremamente concentrada em tensoativo e contendo os componentes extraídos da solução (denominada fase rica) 5,16 .…”

Section: O Que é Ponto Nuvem? Como Ocorre a Separação De Fases?unclassified

“…Isso ocorre com o emprego de tensoativos na forma de ambientes micelares, utilizando a extração com separação de fases denominada Ponto Nuvem [3][4][5] (do inglês, "Cloud Point"). Assim, supre-se, de forma segura, os problemas já mencionados quanto ao uso dos solventes orgânicos.…”

Section: Introductionunclassified

Experimentos didáticos em química analítica envolvendo separação de fases e pré-concentração

Nascentes¹,

Arruda²,

Maniasso³

2002

Quím. Nova

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Recebido em 15/1/01; aceito em 5/12/01 DIDACTIC EXPERIMENTS IN ANALYTICAL CHEMISTRY INVOLVING PHASE SEPARATIONS AND PRECONCEN-TRATION. The aim of this work was to propose two different didactic experiments, which can be used in practical classes of analytical chemistry courses. More flexible experiments related to the theme, giving some options to the instructor are proposed. In this way, the Experiment 1 was divided in two parts. In the first one, the visualization of two distinct phases separation is emphasized: the rich and the poor phases in surfactant. In the second part, the metal pre-concentration (Co as example) is emphasized. The Experiment 2 has three different parts. In the first one, the complex formation is pointed out, in the second one, the pH influence is shown and in the last one, the influence of the complexation time is demonstrated.Keywords: separations; preconcentration; cloud point; atomic spectrometry. INTRODUÇÃONos métodos analíticos, as etapas que envolvem separação de fases são empregadas, geralmente, visando a melhora em sensibilidade e/ou em seletividade 1 . Estas etapas envolvem, às vezes, o emprego de solventes orgânicos, sendo que o uso destes pode acarretar certos problemas ambientais, decorrentes da alta toxicidade dos mesmos. Devido a isto, existe a necessidade de desenvolver novas metodologias, as quais visem a substituição destes solventes por compostos biodegradáveis 2 , principalmente quando se considera a condução de uma aula prática.Neste sentido, este trabalho aborda experimentos que permitem visualizar didaticamente o fenômeno da separação de fases em uma solução homogênea. Isso ocorre com o emprego de tensoativos na forma de ambientes micelares, utilizando a extração com separação de fases denominada Ponto Nuvem 3-5 (do inglês, "Cloud Point"). Assim, supre-se, de forma segura, os problemas já mencionados quanto ao uso dos solventes orgânicos.Os tensoativos foram escolhidos por serem biodegradáveis e também pela sua ampla utilização na prospecção de petróleo, como componente de óleos automotivos, em fármacos, em produtos de higiene pessoal como xampus, em cosméticos, e em produtos domésticos como amaciantes, detergentes, entre outros 6,7 .O objetivo deste trabalho foi propor métodos alternativos, envolvendo a extração no Ponto Nuvem de analitos na forma de complexos, para serem aplicados em aulas práticas de química analítica, enfatizando alguns conceitos tais como complexação, pré-concentração, extração e separação de fases.Desta forma, este trabalho é dividido em 2 partes principais, apresentando-se sugestões de aulas práticas, envolvendo os temas descritos acima. A forma de apresentação das práticas possibilita ampla discussão em sala de aula, já que cada experimento pode ser direcionado de acordo com a proposta do professor, com o tema curricular a ser abordado, e com o tempo disponível para sua realização. Assim sendo, o fator chave para o êxito dos experimentos propostos é, sem dúvida, a criatividade do docente, já que a aula prática pode ser moldada de acordo com ...

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Micelle-mediated methodology for the preconcentration of uranium prior to its determination by flow injection

Cited by 104 publications

References 22 publications

Comparison of traditional cloud-point extraction and on-line flow-injection cloud-point extraction with a chemiluminescence method using benzo[a]pyrene as a marker

Comparison of traditional cloud-point extraction and on-line flow-injection cloud-point extraction with a chemiluminescence method using benzo[a]pyrene as a marker

Simultaneous Cloud-Point Extraction of Nine Cations from Water Samples and Their Determination by Flame Atomic Absorption Spectrometry

Experimentos didáticos em química analítica envolvendo separação de fases e pré-concentração

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