Flotation separation and electrothermal atomic absorption spectrometric determination of lead in water samples

Abstract

A flotation method based on formation of an ion–associate complex between ferroin and Pb(II)–thiosulfate complex is proposed for the quantitative separation and preconcentration of Pb(II) content in water and some vegetable samples. The flotation process was carried out using a 250-mL aliquot of the aqueous solution at a buffering pH of 8.50. After separating the ion–associate complex, it was dissolved in 5 mL of heated 1 M HNO3, and the Pb(II) content was determined by electrothermal atomic absorption spectrometry. The determination of Pb(II) was carried out in the range of 1.6 × 10−9 to 1.2 × 10−8 M. The limit of detection and relative standard deviation were obtained as 8.5 × 10−10 M and 1.73%, respectively. It was found that a large number of cations and anions, even at high much foreign ion/Pb(II) ratios, were not interfered. The validity of the method was confirmed by determining the Pb(II) contents in two Standard Reference Materials and a synthetic liquid extract of vegetable sample. It was then applied satisfactorily for determination of Pb(II) in several plant foodstuffs, drinking-water, and tap-water samples.