Rapid digestion procedure for the determination of lead in vegetable tissues by electrothermal atomisation atomic absorption spectrometry

Abstract

A rapid digestion procedure is described for the determination of lead in vegetables. Vegetable tissues were digested to clear solutions using a simple three-step procedure in an open beaker using a mixture of nitric and perchloric acids. All carbonaceous matter and silicates were decomposed. Lead was determined quantitatively by graphite furnace atomic absorption spectrometry using a direct method in the presence of 1%m/V(NH₄)₂HPO₄ as matrix modifier. The application of the method to reference materials (tomato and citrus leaves) gave results in agreement with values given by the National Institute of Standards and Technology: 6.3 ± 0.3 µg g^–1 for Standard Reference Material (SRM) 1573 Tomato Leaves and 13.3 ± 2.4 µg g^–1 for SRM 1572 Citrus Leaves. Recoveries of lead from vegetable samples ranged between 100 and 101%. The relative standard deviation was less than 4%.