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

摘要

A novel, rapid, and simple preconcentration procedure based on the coprecipitation of Cr(III), Cu(n), Fe(III) Pb(II), Pd(II) and Zn(II) ions with Ni(II)-a-benzoin oxime precipitate was developed prior to flame atomic absorption spectrometric determination. The optimum values of the important analytical parameter: influencing the quantitative coprecipitation of the analytes were as follows: pH 8.5, amount of ex-benzoin oxime: 100 mg, amount of Ni(II) as carrier element: 0.25 mg, time duration: 10 min. The effect: of alkali (4000-15 000 mg L~(-1)) and alkaline earth (1000-4000 mg L~(-1)) metals on the recovery were alsc studied. The alkali metal ions (K~+ up to 4000 and Na~+ up to 15 000 mg L~(-1)) and alkaline earth meta ions (Mg~(2+) up to 1000 and Ca~(2+) up to 4000 mg IT1) 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 ng L~(-1). The accuracy of the presented coprecipitation method wa: checked by the analysis of certified reference materials. The method was applied to the determinatior of the analytes in real samples such as natural water and food samples, and good results were obtainec (relative standard deviation <5%, recovery >95%).