Direct determination of P in biodiesel by high-resolution continuum source graphite furnace atomic absorption spectrometry

The direct determination of P in biodiesel by high-resolution continuum source graphite furnace atomic absorption spectrometry has been investigated. A slow drying stage proved to be essential for good repeatability. Optimization was performed by a D optimal planning. The atomization temperature and modifier composition were the most relevant parameters. Thus, using a mixture of Pd (30 mu g) and Mg(NO3)(2) (20 Kg) as the modifier, previously deposited onto the platform of the graphite tube and dried, a five step drying stage, and pyrolysis and atomization temperatures of 1000 and 2700 degrees C, respectively, a limit of detection of 0.5 mu g g(-1) was obtained. The analysis of biodiesel of different origins confirmed that external calibration with organic P standard solutions, diluted in P-free biodiesel, could be used. In this way, excellent agreement between the found and expected results was observed in the analysis of an ANP interlaboratorial exercise sample. (C) 2011 Elsevier B.V. All rights reserved.