A method for determination of Cr, Cu and Pb in fresh waters, after flotation separation and preconcentration step, by using electrothermal atomic absorption spectrometry (ETAAS) is presented. The possibility of applying iron(III) hepthyldithiocarbamate, Fe(HpDTC)3, as a collector is studied. The experimental parameters affecting the flotation efficiency by a new collector were optimized. It is ascertained that Cr(III), Cr(VI), Cu(II) and Pb(II) can be separated simultaneously from matrix by addition of 20 mg Fe(III) and 6 mL 0.1 mol L-1 HpDTC- to a test sample of 1 L at pH 6.5. The preconcentration factor of the method is 40. The applicability of the new proposed procedure was verified by the method of standard additions and by inductively coupled plasma optical emission spectrometry (ICP OES), as an independent comparative method. The limit of detection for Cu by flotation/ETAAS method is 0.015 µg L-1, for Cr is 0.011 µg L-1, and for Pb 0.025 µg L-1. It was found that for low concentrations (from 0.025-0.2 µg L-1) RSD for Cu is 1.5%, for Cr 4.2% and for Pb is 7.8%, while for the higher concentration level (from 0.2-4.5 µg L-1) RSD for Cu is 1.7%, for Cr 2.8% and for Pb is 3.7%.
water; chromium; copper; lead; flotation; ETAAS
