ABSTRACT

The purpose of the study was utilization of emission atomic absorption spectrometry with excitation in induction-coupled plasma, and molecular spectrometry for determination of lead in milk and dairy products after condensation in ammonia atmosphere. Two methods were proposed for lead condensation on lanthanum carrier - in form of hydroxide or sulphide. By coprecipitation of lead on lanthanum in ammonia atmosphere lead was separated and selectively condensed. Other metals (Zn, Cd, Cu) coexistent in food products remained as aminocomplexes in the solution. The sediment remaining after lead condensation was dissolved in 2 mol/dm³ hydrochloric acid solution. The selected conditions of lead separation and condensation make possible determination of the metal in the concentrations from 0.01 mcg/ml to 0.2 mcg/ml by the ICP-ARS and dithisone methods. The method of condensation and determination was used for lead determination of the metal in the concentrations from 0.01 mcg/ml to 0.2 mcg/ml by the ICP-ARS and dithisone methods. The method of condensation and determination was used for lead determination in milk and dairy products in concentations below 1.5 x 10^-5%. The studied food products were mineralized with concentrated HN0₃, H₂S0₄ and perhydrol. This mineralization method makes it possible to determine in one mineralisate directly copper and zinc by ICP-ARS and dithisone methods, and lead after condensation. The obtained results were precise and reproducible.