Metals Determination in Biodiesel (B100) by ICP-OES with Microwave Assisted Acid Digestion

Elemental composition of biodiesel is required for product quality-control, auto-engine life, emissions control, and researching appropriate additives. The use of microwave assisted acid digestion reaction system to prepare neat biodiesel (B100) samples in an aqueous medium for simultaneous inductively coupled plasma optical emission spectrometer (ICP-OES) analyses is reported. Biodiesel produced by transesterification reaction was subjected to the test method using calibration standards prepared in an aqueous medium. Significant correlation for the spiked B100 samples, instrument detection limits, accuracy, and precision data showed that elemental concentrations can easily be determined within the specified limits. The method avoids switching any of the ICP-OES accessories required for high organic loads. This method is most appropriately devised for biodiesel analysis than petrochemicals analysis. A consistent quality assurance program is necessary to avoid performance issues in vehicle engines and to ensure sustainable growth of biodiesel production. Inorganic constituents in the final product can promote residue build up in the engine, cause corrosion and ultimately affect engine life. Elements introduced during production process (Na, K, Ca, and Mg) are of particular concern, while other elements present in the feedstock (P, S, and Zn), or used as additives (Si, Mn, Cr, Fe, and Ni) require monitoring in order to avoid undesirable combustion products in the engines (6). Since metallic elements in fuel are undesirable even at lower concentrations, their determination in fuel is necessary to evaluate fuel quality, to see their effect on auto engines, and to control environmental pollution.