Isolation and Identification of Nitrogen Species in Jet Fuel and Diesel Fuel

Abstract

Many performance characteristics of liquid fuels including lubricity, the ability to swell seal materials, storage stability, and thermal stability are determined, to a large degree, by the trace polar species that the fuel contains. Because the polar fraction comprises such a small portion of the fuel matrix, it is difficult to detect these species without first isolating them from the bulk fuel. This manuscript describes the extension of previous work that established a protocol for the isolation and identification of oxygenates in jet fuels. The current work shows that a liquid−liquid extraction using methanol, followed by an isolation step using high-performance liquid chromatography (HPLC) with a silica column, can successfully separate polar nitrogen-containing species from the fuel, in addition to separating oxygenates. The analytical protocol further isolates the polar target species using a polar capillary gas chromatography (GC) column and a nontraditional oven heating program. The method is amenable to milliliter quantitites of fuel samples and produces a matrix that can be analyzed directly, using typical GC methods. The method was evaluated using spiked surrogate fuels, as well as actual petroleum-derived jet fuel samples. Furthermore, it is shown that the method also can be extended for use on diesel fuels.