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|Type:||Artigo de periódico|
|Title:||Silica modified with zirconium oxide for on-line determination of inorganic arsenic using a hydride generation-atomic absorption system|
|Abstract:||In the present work, an on-line pre-concentration system, using SiO2/ZrO2 as solid phase adsorbent, for the determination of low concentrations of arsenic was developed. In this procedure, total inorganic arsenic present in the sample is reduced to As (111) with L-Cysteine and the solution is passed into a glass column (phi(i) = 3 mm; h = 35 mm) containing 70 mg of SiO2/ZrO2 (100-230 mesh) to retain the As (III), with the solution flowing at 3.2 mL min(-1). After 2 min, the concentrated species are eluted with 3 mol L-1 HCl (3.2 mL min(-1)) loading a 150 mu L loop while a 1.0% (m/v) sodium borohydride solution loads the other loop of a FI-HG AAS system. The elution step is carried out during 7 s and, at the same time, the SiO2/ZrO2 phase is regenerated for the next concentration cycle. The arsine generated is carried with N-2 (flow rate = 90 mL min(-1)) to a quartz cell where the electrothermal atomization process occurs. Under these conditions, a 20-fold enrichment factor is obtained considering the increase of sensitivity in the analytical curve after the concentration step. The limits of detection and quantification were 0.05 and 0.35 mu g L-1, respectively, with an injection frequency of about 28 h(-1) and relative standard deviation lower than 8%. Four metallurgical reference materials were analyzed with the proposed method after their acid dissolution. The results obtained were in good agreement with certified values. (c) 2006 Elsevier B.V. All rights reserved.|
|Editor:||Elsevier Science Bv|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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