Determination of copper, iron and nickel in edible oils using emulsified solutions by ICP-AES

Abstract

The determination of copper, iron and nickel in edible oils was carried out using emulsion sample preparation followed by analysis by ICP-AES. Response surface methodology was applied in order to find the optimum emulsion and surfactant concentrations. The optimum amount of oil in the emulsion was in the range ca. 2-35% in most of the surfactants studied, except for Triton X-100, which showed a maximum response above 35% oil. The surfactant concentration in the emulsion varied between 0.5 and 9%. Good agreement was found between calibration curves for emulsified aqueous standards solutions and oil-in-water emulsions for most elements studied with Tween 80, ethoxynonylphenol and Triton X-100. The best agreement for all elements was shown when Tween 80 was used. Hence emulsified aqueous standard solutions could be used for the determination of these elements in emulsified edible oil samples using ICP-AES. Recoveries ranged from 90 to 110% for most of the elements studied, with relative standard deviations lower than 8%.