Direct determination of copper in gasoline by flame atomic absorption spectrometry after sorption and preconcentration on Moringa oleifera husks

摘要

In this study a new method for the determination of copper in gasoline using Moringa oleifera husks as a biosorbent in an on-line preconcentration system coupled to flame atomic absorption spectrometry (F AAS) was developed. The flow and chemical variables of the proposed system were optimized through multivariate experimental designs. Initially the influence of sample pH and flow rate, adsorbent mass and eluent concentration were evaluated by a 2~3 factorial design. Adsorbent mass and sample flow rate were evaluated using the Doehlert Matrix. Employing the best conditions, the preconcentration factor was 14.0 and limit of detection for copper was 0.75μgL~(-1) and the precision was below 1.86% (50.0μgL~(-1), n=9). The analytical curve was linear from 0.75 to 500μgL~(-1), with a correlation coefficient of 0.9951. The method developed was successfully applied for direct copper determination in spiked gasoline and the accuracy was assessed through recovery tests, with results ranging from 89.0 to 110%.