Zinc preconcentration by chemofiltration of Eriochrome Black t-metal complex and XRF determination.

MABEL VEGA; MIRIAM AUGUSTO; LILIANA P. FERNÁNDEZ; ADRIANA N. MASI

Cabo Frío, Río de Janeiro, Brasil

Congreso; XI Latin American Seminar of Análisis by X-Ray Techniques; 2008

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The detection of trace metals in diverse materials, the importance of their determination has led to the search of different preconcentration methods for the quantification trough instrumental analysis. In the present work, a preconcentration and separation method for X-ray Spectrometry determination has been developed. The method is based on the formation of a complex using Eriochrome black T, (Ac. 3 hidroxi-4-[(1 hidroxi-2-naftalenil) azo]-7-nitro 1 naftalenosufonic-disodic salt), NET, as a complexing agent which is retained on a polyamide membrane by chemofiltration process. The chemofiltrated materials on the membrane constitute a thin film. Zinc detection is realized directly on the membrane by X-ray Fluorescence Spectrometry As the preconcentration method presented is based on the formation of a complex which will interact with the membrane during the chemofiltration, it was necessary to establish first the optimum conditions for the complex formation of ion-NET and the conditions for thin film obtaining. The pH dependence of chemofiltration of this metal ion on the membrane and other variables, such contact time, enrichment factor, etc., were also determined. The employment of this preconcentration method has the advantage of the formation of a thin film which reduces or removes the matrix effects produced in XRF determinations. Furthermore, it considerably improves the detection limit which is proper for the determination of trace Zinc in environmental samples.