Determination of fatty acid derivatives in fuel and diesel oil

Abstract

Fuel oil plays one of the most important roles as thermal energy source in domestic application. Due to its common use, a careful monitoring of the grade and the deviation of the quality is required. Recently it has been observed that the presence of polar fatty acid derivatives is leading to problems in the fuel injection systems and consequently can cause a damage of the engine. A fast and reliably working procedure is presented, which allows the group determination of these polar compounds, namely glycerides, soaps and fatty acids. A sample preparation succeeded, which accomplishes the extraction, the clean up and the derivatization in one single reaction vessel. Derivatives were methylated with acetyl chloride and methanol and quantified with gas chromatography mass spectrometry. The complexity of fuel oil requires a careful elaboration of the clean up and the extraction procedure. Owing to the novelty of this procedure an accurate investigation and optimization of influential parameters were performed. Optimum conditions for the solid phase extraction with polar sorbents were provided for all target compounds. Additionally, the necessity of the clean up is shown with the relation between investigated analytes and matrix effects. Finally, method performance was verified with an accurate validation and analyses of spiked samples.