Determination of copper, iron, lead and nickel in gasoline by electrothermal atomic absorption spectrometry using three-component solutions

An alternative procedure for the determination of copper, iron, lead and nickel in gasoline at μg l−1 levels, by graphite furnace atomic absorption spectrometry is described. The sample is stabilized by the formation of a three-component solution, prepared by mixing appropriate volumes of water, gasoline and n-propanol. This mixture resulted in a one-phase medium, which was indefinitely stable. No changes in the analyte signals were observed over several weeks, proving the ability of long-term stabilization. Appropriate calibration was achieved by using analytical solutions prepared in the same three-component medium or by the analyte addition technique. The palladium and magnesium nitrates modifier in aqueous solution proved to be efficient for iron and lead determination, while no modifier was necessary for copper and nickel. The characteristic masses in the three-component solution medium were 4.6, 18, 5.0 and 26 pg for copper, iron, nickel and lead, respectively. The detection limits (3s) for the whole analytical procedure were 0.4, 3.0, 0.8 and 1.8 μg l−1 for copper, iron, nickel and lead, respectively, in the original sample. Good agreement was observed between the results obtained by the proposed and comparative methods.