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|Type:||Artigo de periódico|
|Title:||OnLine coupling of a flow injection system to TS-FF-AAS for preconcentration and determination of lead in water and vegetables|
|Abstract:||An online solid phase preconcentration system coupled to thermospray flame furnace atomic absorption spectrometry (TS-FF-AAS) for Pb(II) ions determination is described. In the preconcentration system, Pb( II) ions complexed with ammonium O,O-diethyl-dithiophosphate (DDTP) in an acidic medium are preconcentrated as a neutral complex onto 20 mg of polyurethane foam (PUF) packed into a mini-column. The complex retained in the PUF is then released to TS-FF-AAS by using an 80% (v/v) ethanol solution. Chemical and flow variables associated with the preconcentration, such as the pH dependence of the Pb-DDTP complex, the DDTP concentration, and preconcentration and elution flow rates were optimized by the univariate method. The best sample pH value and DDTP concentration achieved are 2.0 and 0.5% (w/v), respectively, while the best preconcentration and elution flow rates are 2.4 and 1.0 mL min(-1), respectively. Under the optimized conditions, the present method, which is operated in volume mode ( only 2 mL), makes possible the determination of Pb( II) ions within a linear range from 5.2 to 300.0 mu g L-1 with a detection limit of 1.5 mu g L-1 and analytical frequency of 16 h(-1). The precision (n = 10) assessed as relative standard deviation (RSD) is, respectively, 7.3 and 4.8% for 6 and 200 mu g L-1 solutions of Pb(II). The preconcentration system provides an enrichment factor of 6.4 and consumption index of 310 mu L. Hence, the coupling of the preconcentration system to TS-FF-AAS is proven to be an efficient strategy to enhance TS-FF-AAS detectability. The applicability of the method was verified by analyses of spiked water samples as well as with certified and reference vegetable materials.|
|Subject:||flow preconcentration system|
|Editor:||Taylor & Francis Inc|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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