Determination of 2-ethylhexyl nitrate in diesel fuel

The aim of this study was to develop and validate fast and easily applicable GC/MS assay for the quantification of the substance that increases cetane number in diesel fuel (2-ethylhexylnitrate, 2-EHN). These requirements were fulfilled best by a headspace GC-MS assay with negative chemical ionization with methane (HS-GC/MS). Chromatographic separation is achieved using a DB5-MS capillary column after the addition of known amount of internal standard (o-nitrotoluene). The limit of detection was 0.009% v/v for 2-EHN and the limit of quantification was 0.03% v/v. The HS-GC/MS method was applied for the quantification of cetane improver in spiked diesel fuel and real diesel fuel. The method is linear over the studied range (0.03-0.3%, v/v), with satisfactory intra- and inter-assay precision, and the relative standard deviations are lower than 10%. Good accuracy is achieved with bias <10% at all levels tested.