Trace element quantification in light fuels by total reflection X-ray fluorescence spectrometry

The presence of elemental impurities in fuels is a key topic with important consequences: they may both adversely affect the performances of engines and contribute to the contamination of the environment, primarily air, but on the long term also waters and soils. Accordingly, the determination of trace elements in fuels is of the utmost importance in several fields, ranging from quality control to regulatory issues (e.g. control of emissions). Traditionally, atomic spectrometric techniques have been employed to this aim: these techniques typically require a pretreatment step involving either sulfate ashing, microwave digestion or dilution in solvents. Here we propose a fast, direct and sensitive method for the quantification of V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As and Pb at trace level in light and middle distillates, namely gasoline, racing and jet fuel, by Total Reflection X-Ray Fluorescence (TXRF). A simple sample treatment procedure, based on on-site enrichment, allowed to achieve limits of detection below 1 ng/g. The quantification method by internal standard was assessed and validated by recovery tests: its optimization and limits will be presented and discussed.