Chemical Analysis of Jet Fuel Polar, Heteroatomic Species via High-Performance Liquid Chromatography with Electrospray Ionization-Mass Spectrometric Detection

High-performance liquid chromatography (HPLC) with electrospray ionization–mass spectrometry (ESI–MS) was used to identify several classes of heteroatomic, polar compounds containing oxygen, nitrogen, and sulfur in a variety of jet fuel samples. While nitrogen, oxygen, and sulfur compounds are present only at low concentrations in jet fuel, they contribute significantly to some important fuel properties. These trace, heteroatomic species can provide positive (e.g., improved lubricity) or negative (e.g., reduced thermal stability) impacts. Reversed-phase liquid chromatography with ESI–MS detection allows for the polar components to be selectively ionized and subsequently identified, despite the complex hydrocarbon fuel matrix. Phenols and carbazoles are detected in negative-ion [M – H]− mode, while anilines, pyridines, indoles, and quinolines are observed in positive-ion [M + H]+ mode. Accurate mass measurements allow for the molecular formula of the polar components to be determined, while different structural classes of isomeric compounds could be determined via HPLC separation and the formation of derivatives. Derivatization shifts the retention time, species masses, and potentially, the ion charge formed of specific compound classes, allowing them to be positively identified. The usefulness and limits of HPLC with ESI–MS for quantitation of these fuel polar, heteroatomic species are also explored