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Simultaneous preconcentration ofCu, Fe and Pb as 2,5-dihydroxy-3-undecyl-1,4-benzoquinone complexes on naphthalene adsorbent and FAAS

Ali Moghimi, Mohammad Amiri

A simultaneous preconcentration method was developed for determination of trace amounts of Cu, Fe and Pb by atomic absorption spectrometry. The method is based on the retention of their 2,5-dihydroxy-3-undecyl- 1,4-benzoquinone complexes by naphthalene methyltrioctyl ammonium chloride adsorbent in a column. The adsorbedmetal complexeswere eluted from the column with nitric acid and Cu, Fe and Pb were determined by flame atomic absorption spectrometry. Several parameters such as pH of the sample solution, ligand concentration, volume of the sample and the amount ofmethyltrioctyl ammoniumchloride loaded on naphthalene were evaluated. The effect of diverse ions on the preconcentration was also investigated.Apreconcentration factor of up to 100 or more can easily be achieved depending on the volume of the sample taken. The calibration graphswere obtained in the range of 5-40, 10-100 and 10-200ngml-1 forCu, Fe and Pb in the initial solution, respectively, when using 500 ml of the solution. The detection limit based on three standard deviations of the blank was 0.59, 3.1, and 4.9ng ml-1 for Cu, Fe and Pb, respectively. The relative standard deviations (R.S.D.) of 1.2-2.5%for Cu, 2.1-3.3%for Fe and 1.3-2.1% for Pb were obtained. The method was applied to the determination of Cu, Fe and Pb in river and wastewater samples.