DETERMINATION OF TRACE-ELEMENTS IN EDIBLE VEGETABLE-OILS BY ATOMIC-ABSORPTION SPECTROPHOTOMETRY

Methods are described for the direct determination of Al, Cr, Cu, Fe, Ni and Ph by atomic absorption spectrophotometry in sunflower oil and olive oils. Metallic contamination after storage under different controlled conditions and in contact with carbon steel, austenitic steel, ferritic steel and aluminum was examined. Additionally, chemical characteristics related to quality (acid value, peroxide value, K-270 and oxidative stability) and some physical para meters of interest were evaluated after storage. When the samples were atomized directly off the tube wall, matrix interferences were not observed in the determination of Cr, Cu, Ni and Pb, whereas such interferences were noted when Al and Fe were determined. The results indicated that the L'Vov platform for Al and Fe determinations eliminates the matrix effects. Contamination with Fe was only detected in the olive oil that had been in contact with carbon steel, Fe concentration increased from 120 +/- 12 to 3,520 +/- 157 ppb. The physicochemical characteristics were affected only by the storage conditions, regardless of the metal sheets with which they were in contact. Virgin olive oil showed lowered stability after storage in contact with a carbon-steel sheet than when stored in absence of metal.