Recent advances on sample preparation procedures for elemental determination in biodiesel

Abstract

In recent years, renewable oilseeds have been investigated as viable alternatives sources for enhanced production of biofuels. However, due to the recent investigation for new energy sources, greater attention is being given to ensure quality of the final products, in particular to the elemental content, to increase the diversity of biodiesel. The elemental determination of biodiesel is often performed by spectrometric techniques, and most of them require a sample pretreatment to match the sample characteristics (i.e., high organic matter content, physicochemical properties, and low concentrations of analyte) to the analytical techniques available. Moreover, due to the advances on environment-friendly procedures (based on the principles of green chemistry), alternative sample pretreatments based on nondestructive measurement have been proposed, not only for the determination of metals in biodiesel, but also in the entire biodiesel production chain. By the way, it is important to emphasize that a nondestructive sample preparation procedure does not involve the complete decomposition of the matter by concentrated acid and heating. The use of nondestructive sample preparation in oily matrices for the determination of metals by atomic spectrometry is still a recent practice. Some of these are based on extraction procedures or by the formation of emulsion and microemulsion stable solutions. In many cases, these procedures can be performed using ultrasonic energies, thermostatic bath, centrifuge, vortex stirring, shaker, and other apparatus which improves the efficiency of the sample preparation procedure selected.