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

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 degreesC and 2600 degreesC, 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 mug l(-1) was obtained using 20 mul of micro-emulsion, which corresponds to 1.2 mug l(-1) in petroleum condensate. The precision, expressed as relative standard deviation, was 2.0% or 2.8% for copper concentrations of 30 mug l(-1) and 5.0 mug 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.