Use of silica gel chemically modified with zirconium phosphate for preconcentration and determination of lead and copper by flame atomic absorption spectrometry

An analytical method using silica gel chemically modified with zirconium (IV) phosphate for preconcentration of lead and copper, in a column system, and their sequential determination by flame atomic absorption spectrometry (FAAS), was developed. Sample solutions are passed through a glass column packed with 100 mg of the sorbent material, at pH 4.5, and lead and copper are eluted with 1.0 mol l−1 HNO3 at a flow rate of 2.0 ml min−1. The extraction of copper is affected by Fe(II), Mn(II), Zn(II), Ni(II) and Co(II) while only Fe(II) interferes in the lead determination. These interferences may be overcome with an appropriate addition of a KI or NaF solution. An enrichment factor of 30 was obtained for both metals. While the limits of detection (3σ) were 6.1 and 1.1 μg l−1, for Pb and Cu, respectively, the limits of determination were 16.7 and 3.3 μg l−1. The precision expressed as relative standard deviation (R.S.D.) obtained for 3.3 μg l−1 of Cu and 16.7 μg l−1 of Pb were 4.3 and 4.7%, respectively, calculated from ten measurements. The proposed method was evaluated with reference material and was applied for the determination of lead and copper in industrial and river waters.