CHEMOFILTRATION OF ERIOCHROME BLACK T-ZINC COMPLEX AND DETERMINATION BY X RAY SPECTROMETRY

MABEL VEGA; MIRIAM AUGUSTO; MARÍA C. TALIO; LILIANA P. FERNÁNDEZ

MICROCHEMICAL JOURNAL

ELSEVIER SCIENCE BV

Año: 2011 vol. 99 p. 425 - 428

0026-265X

The detection of trace metals in diverse materials and the importance of their determination have led to the search of different preconcentration methods for their subsequent quantification trough instrumental analysis. In the present work, a new methodology for zinc preconcentration and separation and its determination by x-ray spectrometry is proposed. The methodology is based on the formation of a complex using Eriochrome black T (1-naphtalensulfonic acid, 3-hidroxy-4-((1-hidroxy-2-naphtalenyl)azo)-7-nitro, monosodium salt), EBT, as complexing agent. Next, the complex is retained on a polyamide membrane by a chemofiltration process. The chemofiltrated material on the membrane constitutes a thin film, which minimizes or eliminates the interelemental effects. 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 first to establish the optimal conditions for the complex formation of Zn-EBT and then the conditions for obtaining the thin film. The pH dependence of the metal ion chemofiltration on the membrane and other variables, such as contact time and capacity of retention of the membrane, were also optimized. Chemofiltration step provided an enrichment factor of 30,000, improving considerably the detection limit and allowing the determination of trace zinc in environmental samples.