Fast emulsion-based method for simultaneous determination of Co, Cu, Pb and Se in crude oil, gasoline and diesel by graphite furnace atomic absorption spectrometry

Masses around 400 mg of crude oil (A), gasoline (B), diesel (C) and SRM® 1634c of residual oil (D) were weighted in volumetric flask following the sequential addition of 125 µL of hexane and 7.5 mL of Triton X-100® (20% m v−1), 30 min of ultrasonic stirring, and dilution with deionized water to 25 mL for simultaneous determination of Co, Cu, Pb and Se by SIMAAS. The limits of detection were 0.02 μg g−1 (0.32 μg L−1) for Co, 0.03 μg g−1 (0.48 μg L−1) for Cu, 0.04 μg g−1 (0.64 μg L−1) for Pb, and 0.11 μg g−1 (1.76 μg L−1) for Se.