Abstract

Nafion and the ionic liquid 1–ethyl–3–methylimidazolium trifluoromethanesulfonate ([EMIM]F3MSO3) coated on a mercury film electrode (NILHgFE) allow us to determine Pb(II) by adsorptive stripping voltammetry in the presence of Amaranth (Am). The NILHgFE was characterized by square wave voltammetry without and in the presence of different ionic liquids obtaining higher peak current with [EMIM]F3MSO3 (2.5 mol L–1) compared with other ionic liquids with smaller anions. Optimal analytical conditions were found to be: pH = 2.6 (BR buffer); CAm = 0.77 μmol L–1; Eads = –0.30 V and tads = 80 s. The Pb–Am complex is reduced at –0.51 V. Peak current is proportional to Pb concentration over the 0.9–10.0 μg L–1 range, with a 3 detection limit of 0.4 μg L–1. The relative standard deviation for a Pb solution (4.9 μg L−1) was 2.0 % for seven successive assays. The method was validated by determining Pb(II) in certified reference wastewater (SPS–WW1). Finally, the method was applied to the determination of Pb(II) in tap water samples after UV digestion with satisfactory results.