Immobilized stearic acid as a new sorbent for on-line preconcentration and determination of lead by flow injection flame atomic absorption spectrometry

Abstract

O presente estudo examina a possibilidade de imobilização do ácido esteárico em naftaleno microcristalino para a preparação de microcoluna e avalia seu potencial para adsorção e pré-concentração de quantidades traço de íons metálicos. Esse sorvente apresentou alta afinidade para chumbo. Conseqüentemente, foi elaborada uma rápida estratégia de pré-concentração empregando sistema de injeção em fluxo para determinação de chumbo por Espectrometria de Absorção Atômica com chama. A pré-concentração foi baseada no acúmulo do analito na microcoluna de ácido esteárico imobilizado e subseqüente eluição por injeção de pequeno volume de solução de ácido nítrico 1 mol L -1 (250 μL). Um volume de amostra de 20 mL resultou em um fator de pré-concentração de 84 vezes e o desvio padrão relativo para soluções contendo 40 e 200 μg L -1 foi 5,1 e 1,2%, respectivamente. O procedimento foi aplicado para água de torneira, de rio e de mar, suco de maçã, folha de beterraba, urina e aço inoxidável certificado. A exatidão foi comprovada por experimentos de recuperação, por Espectrometria de Absorção Atômica com Forno de Grafite e análise de um material de referência certificado composto por aço inoxidável.The present study examines the possibility of immobilization of stearic acid on microcrystalline naphthalene for preparation of microcolumn and evaluation of its potential for adsorption and preconcentration of trace amounts of metal ions. It was found that this sorbent has high affinity for lead. Consequently, a rapid on-line preconcentration technique for the determination of lead by Flow Injection Flame Atomic Absorption Spectrometry had been devised. Preconcentration was based on accumulation of analyte on immobilized stearic acid microcolumn and subsequent elution by injection of a small volume of nitric acid (250 μL of 1 mol L -1 ). A sample volume of 20 mL resulted in a preconcentration factor of 84, and relative standard deviations for solutions containing 40 and 200 μg L -1 were 5.1 and 1.2%, respectively. The procedure was applied to tap water, river water, sea water, apple juice, beet leaf, urine, and certified stainless steel. The accuracy was proved by performing recovery experiments, Graphite Furnace Atomic Absorption Spectrometry measurements, and analysis of a stainless steel certified reference material.

Separation, preconcentration and measurement of inorganic iron species by cloud point extraction and flow injection flame atomic absorption spectrometry

“…Expensive analytical methods such as inductively coupled plasma mass spectrometry (ICP-MS) [6], inductively coupled plasma optical emission spectrometry (ICP-OES) [7] and capillary electrophoresis (CE) [8] have been employed for the determination of Fe(II) and Fe(III). Flame atomic absorption spectrometry (FAAS) has been widely used for the determination of metal ions [9][10][11]. Common availability of the instrumentation, simplicity of the procedures and the speed, precision and accuracy of the technique still make flame atomic absorption method an attractive alternate.…”

On-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 spectrometry

“…Solid-phase extraction has been performed by using several solid materials, such as multiwalled carbon nanotubes [11], microcrystalline naphthalene [12], polyurethane foam [13], silica-gel [14], styrene-divinylbenzene [15,16], chitosan [17] and other sorbents [18]. Styrene-divinylbenzene is commercially available as Amberlite XAD resin series.…”

Old and New Flavors of Flame (Furnace) Atomic Absorption Spectrometry

“…As previously stated, FAAS presents, as one of its main limitations, low sensitivity for metals determinations at μg/L levels and may be strongly affected by matrix effects [212]. Among the various approaches to overcome these drawbacks, it has been proposed preconcentration/separation procedures [213].…”