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

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