Application of multivariate technique in method development for the direct determination of copper in petroleum condensate using graphite furnace atomic absorption spectrometry

Abstract

A method has been developed for the direct determination of copper in petroleum condensate using detergentless micro-emulsions (three-component solutions) and graphite furnace atomic absorption spectrometry. The optimization was performed using a three-level full factorial design, resulting in pyrolysis and atomization temperatures of 920 °C and 2600 °C, respectively. Using the secondary copper line at 327.4 nm, which is less affected by the magnetic field of the Zeeman-effect background correction system, a characteristic mass of 39 pg, and detection limit of 0.4 μg l⁻¹ was obtained using 20 μl of micro-emulsion, which corresponds to 1.2 μg l⁻¹ in petroleum condensate. The precision, expressed as relative standard deviation, was 2.0% or 2.8% for copper concentrations of 30 μg l⁻¹ and 5.0 μg l⁻¹, respectively. The spike recovery of 105% for copper added to a petroleum condensate sample proved that this procedure could be applied satisfactorily to a determination in this matrix.