ABSTRACT New analytical procedures and sample mineralization regarding the spectroscopic determination of copper, lead, cadmium, zinc and mercury in matrices involved in food chain as whole-, wheat- and maize-meal are proposed. As regard Cu, Pb, Cd and Zn determinations, concentrated suprapure HCl at 130 ºC for three hours was used for the digestion of each matrix. In the case of Hg a new sample digestion is performed using a concentrated suprapure H2SO4-K2Cr2O7 mixture and the results are compared with those from other conventional methods. Copper, lead, cadmium and zinc were determined by Electrothermal Atomic Absorption Spectroscopy (ET-AAS), while mercury determination is carried out by the cold vapour atomic absorption spectrometry (CS-AAS) with reduction with SnCl2. The analytical procedure has been verified on the standard reference materials Wholemeal BCR-CRM 189, Wheat Flour NIST-SRM 1567a and Rice Flour NIST-SRM 1568a. For all the elements in the certified matrix, the precision as repeatability, expressed as relative standard deviation (sr) was of the order of 3-5 %. The accuracy, expressed as relative error (e) was of the order of 3-7 %, while the detection limits were in the range 0.0015-0.0077 μg/g.
Buy this Article
|