A coprecipitation procedure for the determination of some metals in food and environmental samples by flame atomic absorption spectroscopy

Abstract

A novel, rapid, and simple preconcentration procedure based on the coprecipitation of Cr(III), Cu(II), Fe(III), Pb(II), Pd(II) and Zn(II) ions with Ni(II)–α-benzoin oxime precipitate was developed prior to flame atomic absorption spectrometric determination. The optimum values of the important analytical parameters influencing the quantitative coprecipitation of the analytes were as follows: pH 8.5, amount of α-benzoin oxime: 100 mg, amount of Ni(II) as carrier element: 0.25 mg, time duration: 10 min. The effects of alkali (4000–15 000 mg L⁻¹) and alkaline earth (1000–4000 mg L⁻¹) metals on the recovery were also studied. The alkali metal ions (K⁺ up to 4000 and Na⁺ up to 15 000 mg L⁻¹) and alkaline earth metal ions (Mg²⁺ up to 1000 and Ca²⁺ up to 4000 mg L⁻¹) did not show any interference effect on the recovery of the analytes. Under the optimized conditions, the detection limits (3s, N = 10) for the analytes were in the range of 0.1–5.3 μg L⁻¹. The accuracy of the presented coprecipitation method was checked by the analysis of certified reference materials. The method was applied to the determination of the analytes in real samples such as natural water and food samples, and good results were obtained (relative standard deviation <5%, recovery >95%).